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DEC-11-0IMRA-A-D

December 1975

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Document:	IAS/RSX-11 MACRO-11 Reference Manual
Order Number:	DEC-11-0IMRA-A-D
Revision:	0
Pages:	189
Original Filename:	http://bitsavers.org/pdf/dec/pdp11/rsx11m_s/RSX11M_V2/DEC-11-OIMRA-A-D_MACRO_1975.pdf

OCR Text

IAS/RSX-11
MACR0-11 Reference Manual
Order No. DEC-11-0IMRA-A-D

IAS Version 1
RSX-llM Version 2
RSX-llD Version 6B (Version 6.1}

digital equipment corporation · maynard. massachusetts

First Printing, December 1975
The information in this document is subject to change without notice
and should not be construed as a commitment by Digital Equipment
Corporation. Digital Equipment Corporation assumes no responsibility
for any errors that may appear in this document.
The software described in this document is furnished under a license
and may only be used or copied in accordance to the terms of such
license.
Digital Equipment Corporation assumes no responsibility for the use
or reliability of its software on equipment that is not supplied by
Digital.

(Q)

1975 by Digital Equipment Corporation

The postage prepaid READER'S COMMENTS form on the last page of this
document requests the user's critical evaluation to assist us in
preparing future documentation.
The following are trademarks of Digital Equipment Corporation:

DIGITAL
DEC
PDP
DECUS
UNIBUS
COMPUTER LABS
COMTEX
DDT
DECCOMM

DECsystem-10
DECtape
DIBOL
EDU SYSTEM
FLIP CHIP
FOCAL
INDAC
LAB-8

10/76-:-~

MASS BUS
OMNIBUS
OS/8
PHA
RSTS
RSX
TYPESET-8
TYPESET-11

CONTENTS

PREFACE
0.1
0.2
0.3

ix
ix
x
xi

0.4

MANUAL OBJECTIVES AND READER ASSUMPTIONS
STRUCTURE OF THE DOCUMENT
ASSOCIATED DOCUMENTS
DOCUMENT CONVENTIONS

PART I

INTRODUCTION TO MACR0-11

MACR0-11 FEATURES

1-1

1.1
1.1.1
1.1.2

OVERVIEW OF MACR0-11
Assembly Pass 1
Assembly Pass 2

1-1
1-2

SOURCE PROGRAM FORMAT

2-1

2.1

2-1

2.2.l
2.2.2
2.2.3
2.2.4
2.3

STANDARDS AND CONVENTIONS
STATEMENT FORMAT
Label Field
Operator Field
Operand Field
Comment Field
FORMAT CONTROL

PART II

PROGRAMMING IN MACR0-11 ASSEMBLY LANGUAGE

SYMBOLS AND EXPRESSIONS

3-1

3 .1.1
3 .1. 2
3 .1. 3
3.2
3.2.1
3.2.2
3.3
3.4
3.5
3.6
3.7
3.8
3.9

CHARACTER SET
Separating and Delimiting Characters
Illegal Characters
Unary and Binary Operators
MACR0-11 SYMBOLS
Permanent Symbols
User-Defined and Macro Symbols
DIRECT ASSIGNMENT STATEMENTS
REGISTER SYMBOLS
LOCAL SYMBOLS
CURRENT LOCATION COUNTER
NUMBERS
TERMS
EXPRESSIONS

3-1
3-2
3-3

CHAPTER

RELOCATION AND LINKING

4-1

CHAPTER

ADDRESSING MODES

5-1

5.1
5.2
5.3
5.4
5.5
5.6

REGISTER MODE
REGISTER DEFERRED MODE
AUTOINCREMENT MODE
AUTOINCREMENT DEFERRED MODE
AUTODECREMENT MODE
AUTODECREMENT DEFERRED MODE
INDEX MODE

5-2
5-2
5-2
5-3
5-3
5-4
5-4

CHAPTER

.., ,

..) • J..

5.7

iii

1-1

2-1
2-2
2-4
2-5
2-5
2-6

3-4
3-5
3-5
3-5
3-7
3:....9
3-10
3-11
3-13
3-14
3-15

CONTF.NTS (Cont.)

CHAPTER

5.8
5.9
5.10
5 .11
5.12
5 .13
5.14
5.15

INDEX DEFERRED MODE
IMMEDIATE MODE
ABSOLUTE MODE
RELATIVE MODE
RELATIVE DEFERRED MODE
SUMMARY OF ADDRESSING FORMS
BRANCH INSTRUCTION ADDRESSING
USING TRAP INSTRUCTIONS

PART III

MACR0-11 DIRECTIVES

GENERAL ASSEMBLER DIRECTIVES

6-1

6.1
6.1.1
6.1. 2
6 .1. 3

LISTING CONTROL DIRECTIVES
.LIST and .NLIST Directives
Page Headings
.TITLE Directive
.SBTTL Directive
.IDENT Directive
.PAGE Directive/Page Ejection
FUNCTION DIRECTIVES: .ENABL AND .DSABL
DATA STORAGE DIRECTIVES
.BYTE Directive
.WORD Directive
ASCII Conversion Characters
.ASCII Directive
.ASCIZ Directive
.RAD50 Directive
RADIX AND NUMERIC CONTROL FACILITIES
Radix Control and Unary Control Operators
.RADIX Directive
Temporary Radix Control Operators: AD,
"o, and "B
Numeric Directives and Unary Control
Operators
.FLT2 and .FLT4
Temporary Numeric Control Operators:
"c and "F
LOCATION COUNTER CONTROL DIRECTIVES
.EVEN Directive
.ODD Directive
.BLKB and .BLKW Directives
TERMINATING DIRECTIVES
.END Directive
.EOT Directive
PROGRAM BOUNDARIES DIRECTIVE:
.LIMIT
PROGRAM SECTIONING DIRECTIVES
.PSECT Directive
Creating Program Sections
Code or Data Sharing
Memory Allocation Considerations
.ASECT and .CSECT Directives
SYMBOL CONTROL DIRECTIVE:
.GLOBL
CONDITIONAL ASSEMBLY DIRECTIVES
Conditional Assembly Block Directive: .IF
Subconditional Assembly Block Directives:

6-1
6-1
6-5
6-10
6-11
6-12
6-12
6-13
6-16
6-17
6-18
6-18
6-19
6-21
6-22
6-23
6-23
6-23

6 .1. 4

6 .1. 5
6 .1. 6
6.2
6.3
6.3.1
6.3.2
6.3.3
6.3.4
6.3.5
6.3.6
6.4
6.4.1
6.4.1.1
6.4.1.2
6.4.2
6.4.2.1
6.4.2.2
6.5
6.5.1
6.5.2
6.5.3
6.6
6.6.l
6.6.2
6.7
6.8
6.8.l
6.8.1.1
6.8.1.2
6.8.1.3
6.8.2
6.9
6.10
6.10.l
6.10.2

• IFF,

• IFT,

• IFTF

5-4
5-4
5-5
5-6
5-7
5-7
5-8
5-9

6-24
6-25
6-27
6-27
6-28
6-29
6-29
6-29
6-30
6-30
6-31
6-31
6-31
6-32
6-36
6-38
6-38
6-38
6-39
6-41
6-41

CONTENTS (Cont.)

6.10.3
6.10.4
CHAPTER

Immediate Conditional Assembly Directive:
.IIF
PAL-llR Conditional Assembly Directives

MACRO DIRECTIVES

7-1

7.1
7 .1.1
7 .1. 2
7 .1. 3
7 .1. 4
7.2
7.3

DEFINING MACROS
.MACRO Directive
.ENDM Directive
.MEXIT Directive
MACRO Definition Formatting
CALLING MACROS
ARGUMENTS IN MACRO DEFINITIONS AND MACRO
CALLS
Macro Nesting
Special Characters in Macro Arguments
Passing Numeric Arguments as Symbols
Number of Arguments in Macro Calls
Creating Local Symbols Automatically
Concatenation of Macro Arguments
MACRO ATTRIBUTE DIRECTIVES:
.NARG, .NCHR,
AND .NTYPE
.NARG Directive
.NCHR Directive
.NTYPE Directive
.ERROR AND .PRINT DIRECTIVES
INDEFINITE REPEAT BLOCK DIRECTIVES:
.IRP

7-1
7-1
7-2
7-3
7-3
7-3

7.3.1
7.3.2
7.3.3
7.3.4
7.3.5
7.3.6
7.4
7.4.1
7.4.2
7.4.3
7.5
7.6

Jl..ND • IRPC

CHAPTER

6-46
6-46

7-4
7-5
7-6
7-6
7-7
7-8

7-9
7-10
7-10
7-11
7-12
7-12
7-13
7-14
7-15
7-16

7.6.l
7.6.2
7.7
7.8

.IRP Directive
.IRPC Directive
REPEAT BLOCK DIRECTIVE:
.REPT
MACRO LIBRARY DIRECTIVE:
.MCALL

PART IV

OPERATING PROCEDURES

8-1

8.1
8 .1.1
8.1.1.1
8.1.1.2
8.1.1.3
8.1.1.4

RSX-llD AND RSX-llM OPERATING PROCEDURES
Initiating MACR0-11 Under RSX-llM/RSX-llD
Method 1 - Direct MACR0-11 Call
Method 2 - Using RUN Facility
Method 3 - Single Assembly
Method 4 - Install, Run Immediately, and
Remove on Exit
Method 5 - Using Indirect Filename
Facility
RSX-11 Command String Format
RSX-11 File Specification Switches
IAS MACR0-11 OPERATING PROCEDURES
Initiating MACR0-11 Under IAS
IAS Command String Format
IAS Indirect Command Files
IAS Command String Examples
IAS/RSX-11 FILE SPECIFICATION FORMAT
MACR0-11 ERROR MESSAGES

8-1
8-1
8-1
8-2
8-2

8.1.1.5

8 .1. 2
8 .1. 3
8.2
8.2.1
8.2.2
8.2.3
8.2.4

8.3
8.4

8-2
8-2
8-3
8-5

8-8
8-8

8-8
8-10
8-11
8-11
8-12

CONTENTS (Cont.)

APPENDIX

MACR0-11 CHARACTER SETS

A-1

A. l
A. 2

ASCII CHARACTER SET
RADIX-50 CHARACTER SET

A-1
A-4

MACR0-11 ASSEMBLY LANGUAGE AND ASSEMBLER
DIRECTIVES

B-1

B.l
B.2
B.3

SPECIAL CHARACTERS
SUMMARY OF ADDRESS MODE SYNTAX
ASSEMBLER DIRECTIVES

B-1
B-1
B-3

PERMANENT SYMBOL TABLE (PST)

C-1

C.l

c.2

OP CODES
MACR0-11 DIRECTIVES

C-1
C-4

DIAGNOSTIC ERROR MESSAGE SUMMARY

D-1

D.l

MACR0-11 ERROR CODES

D-1

SAMPLE CODING STANDARD

E-1

E.l
E.2
E.3
E.4
E.4.1
E.4.1.l
E.4.1.2
E.4.1.3
E.4.2
E.4.3
E.4.4
E.4.5
E.4.5.1
E.4.5.2
E.4.5.3
E.4.5.4
E.5
E.5.1
E.5.2
E.5.3
E.5.4
E.5.4.1
E.5.4.2
E.5.4.3
E.5.4.4
E.5.4.5
E.6
E.6.1
E.6.2
E.6.3

INTRODUCTION
LINE FORMAT
COMMENTS
NAMING STANDARDS
Register Standards
General Purpose Registers
Hardware Registers
Device Registers
Processor Priority
Other Symbols
Using the Standard Symbols
Symbols
Global Symbols
Symbol Examples
Program-local Symbols
Macro Names
PROGRAM MODULES
General Comments on Programs
The Module Pref ace
Formatting the Module Pref ace
Modularity
Calling Conventions (Inter-Module)
Exiting
Intra-Module Calling Conventions
Success/Failure Indication
Module Checking Routines
FORMATTING STANDARDS
Program Flow
Common Exits
Code with Interrupts Inhibited
PROGRAM SOURCE FILES
FORBIDDEN INSTRUCTION USAGE
RECOMMENDED CODING PRACTICE
Conditional Branches

E-1
E-1
E-2
E-2
E-2
E-2
E-2
E-2
E-3
E-3
E-3
E-3
E-3
E-4
E-5
E-5
E-5
E-5
E-5
E-6
E-8
E-9
E-9
E-9
E-9
E-9
E-10
E-10
E-11
E-12
E-12
E-12
E-13
E-13

E.7
E.8
E.9
E.9.1

CONTENTS

APPENDIX

(Cont.)

E.10
E.10.l
E.10.2

PDP-11 VERSION NUMBER STANDARD
Displaying the Version Identifier
Use of the Version Number in the Program

E-13
E-14
E-15

CONSERVING DYNAMIC MEMORY

F-1

F.l
F.2
F.3

GENERAL HINTS AND SPACE-SAVING GUIDELINES
MACRO DEFINITIONS AND EXPANSIONS
OPERATIONAL TECHNIQUES

F-1
F-2
F-4

FEATURES/FUNCTIONS NOT SUPPORTED BY THE
RSX-llM 8K ASSEMBLER

G-1

APPENDIX

WRITING POSITION INDEPENDENT CODE

H-1

APPENDIX

SAMPLE ASSEMBLY LISTING

I-1

FIGURES

FIGURE

3-1

6-1
6-2
6-3
6-4
6-5

6-6
7-1

H-1
H-2

Assembly Listing Showing Local Symbol Block
Example of Line Printer Assembly Listing
Example of Terminal Assembly Listing
Listing Produced With Listing Control
Directives
Assembly Listing Table of Contents
Example of .ENABL and .DSABL Directives
Example of .BLKB and .BLKW Directives
Exampler of .IRP and .IRPC Directives
Position-Dependent Code
Position-Independent Code

3-11

6-6
6-7
6-8
6-11
6-16
6-30
7-15
H-3
H-3

TABLES
TABLE

3-1
3-2
3-3
3-4
3-5

6-1
6-2
6-3
6-4
6-5
6-6
8-1
8-2

Special Characters Used in MACR0-11
Legal Separating Characters
Legal Delimiting Characters
Legal Unary Operators
Legal Binary Operators
Symbolic Arguments of Listing Control
Directives
Symbolic Arguments of Function Control
Directives
Symbolic Arguments of .PSECT Directive
Non-IAS/RSX-11 Program Section Default
Values
Legal Condition Tests for Conditional
Assembly Directives
Subconditional Assembly Block Directives
File Specification Default Values
MACR0-11 File Specification Switches for
RSX-11

vii

3-1
3-3
3-3
3-4
3-5
6-3
6-13
6-33
6-39
6-42
6-44
8-5
8-6

PREFACE

0.1

MANUAL OBJECTIVES AND READER ASSUMPTIONS

The intent of this manual is to enable users of RSX-11 and IAS
operating systems to develop programs coded in the MACR0-11 assembly
language. No prior knowledge of the MACR0-11 Relocatable Assembler is
assumed.
Although the description of the assembly
language
is
wholly
self-contained within this manual,
the reader is assumed to be
familiar with the PDP-11 processors and related terminology, as
presented in the PDP-11 Processor Handbooks (11/05/10/35/40 and 11/45
versions). No attempt is made in this document to describe the PDP-11
hardware or the functions of the various PDP-11 instructions.
Since the development of programs necessarily involves the use of the
Task Builder to create an executable task image,
the reader is
encouraged to become familiar with this system program,
as presented
in the applicable Task Builder reference manual (see section 0.3).
In presenting MACR0-11, a tutorial bias has been adopted to enlarge
upon the reference material.
This posture· is reflected in the
examples and the accompanying commentary describing MACR0-11 language
elements in typical applications.

0.2

STRUCTURE OF THE DOCUMENT

This manual is structured into three parts.
Part I, consisting of two
chapters, briefly introduces MACR0-11.
Chapter 1 lists the key
features of MACR0-11, and Chapter 2 identifies advantages which can be
realized through adherence to certain programming standards and
conventions. Also described is the format used in coding MACR0-11
source programs.
Part II, consisting of three chapters, presents general information
essential to programming with the MACR0-11 assembly language.
Chapter
3 describes the symbols, terms, and expressions that form the elements
of MACR0-11 instructions. Also, the character set is listed, and the
various types of programming symbols that may be defined by the user
are discussed.
Chapter 4 describes the output of MACR0-11 and
presents concepts essential to the proper relocation and linking of
object modules by the Task Builder. Chapter 5 briefly describes how
data stored in memory can be accessed and manipulated using the
various addressing modes recognized by the PDP-11 hardware.

Part III, consisting of two chapters, describes
the
MACR0-11
directives that control the processing of source statements during
assembly. Chapter 6 discusses those directives which accomplish
generalized MACR0-11 functions, while Chapter 7 deals with those
directives used in the definition and expansion of macros.
Part IV, consisting
procedures essential
MACR0-11 programs.

only of Chapter 8, presents the operating
to the assembly, linking, and initiating of

Finally, several appendixes are provided,
supplying
information of interest to the MACR0-11 programmer.

additional

Appendix A lists the ASCII and Radix-50 character sets that. may be
used in MACR0-11 programs. Appendix B lists the special characters
recognized by MACR0-11, summarizes the syntax of
the
various
addressing modes used in PDP-11 processors, and briefly describes the
MACR0-11 directives in alphabetical order. The permanent symbols that
have been defined for use with MACR0-11 are listed alphabetically in
Appendix C.
The diagnostic error codes produced by MACR0-11 to identify various
types of errors detected during the assembly process are listed
alphabetically in Appendix D. Appendix E contains a sample coding
standard that is suggested as recommended practice in preparing
MACR0-11 programs. Appendix F discusses several methods of conserving
dynamic memory space for the benefit of those users of small systems
who may experience difficulty in assembling MACR0-11 programs.
Appendix G lists the features and functions that are not supported in
the 8K RSX-llM version of MACR0-11. MACR0-11 is available in two
versions under RSX-llM. One is a 14K version which is functionally
identical to the RSX-llD assembler and which has all the features
described in this manual. The other assembler is an 8K version which,
because of size limitations, supports an extensive subset of MACR0-11
features. Appendix H is a discussion of position independent code
(PIC).

0.3

ASSOCIATED DOCUMENTS

The reader should ref er to the
listed below for descriptions
manual.

applicable documentation
of documents associated

IAS Documentation Directory, Order No.

DEC-11-0IDDA-A-D

RSX-llD Documentation Directory, Order No.
RSX-llM/RSX-llS
Documentation
DEC-11-0MUGA-B-D

directory
with this

DEC-11-0XUGA-C-D

Directory,

Order

No.

0.4

DOCUMENT CONVENTIONS

The symbols defined below are used throughout this manual.
Symbol

Definition

[]

Brackets indicate
optional.

that

the

enclosed

Vertical bars indicate that a single
made from a list of arguments.

argument
choice

must

is
be

Ellipsis indicates optional continuation of an argument
list in the form of the last specified argument.
UPPER CASE

Upper-case characters indicate elements of the language
that must be used exactly as shown.

lower case
characters

Lower-case characters indicate elements of the language
that are supplied by the programmer.

PART I
INTRODUCTION TO MACR0-11

CHAPTER l
MACR0-11 FEATURES

The MACR0-11 Assembler provides the following features:
1.

Program and command string control of assembly functions;

Device and
files;

Error listing on command output device;

Alphabetized, formatted symbol table listing;

Relocatable object modules;

Global symbols for linking independent object modules;

Conditional assembly directives;

Program sectioning directives;

User-defined macros and macro libraries;

10.

Comprehensive system macro library;

11.

Extensive program
functions; and

12.

An indirect command
assembly process.

1.1

filename

and

specifications
,

command
file

for

string

facility

input

control
for

and

output

listing

controlling

the

OVERVIEW OF MACR0-11

MACR0-11 is a two-pass assembler.
The functions and operations
relevant to each assembly pass are described in the following
sections.

1.1.1

Assembly Pass 1

The first stage of assembly pass 1 is the initialization of all impure
data areas that MACR0-11 uses internally for the assembly process.
These areas include all dynamic storage areas and buffer areas used as
file storage regions.

1-1

MACR0-11 FEATURES
After initializing memory areas, MACR0-11 issues a call to a system
subroutine which transfers a command line into memory.
This command
line contains the specifications of the files to be used during
assembly. After scanning the command line for proper syntax, MACR0-11
initializes the specified output files.
These files are opened to
determine if valid output file specifications have been passed in the
command line. They are then closed to minimize requirements for
active file space.
As the assembly process begins, MACR0-11 initiates a routine which
retrieves source lines from the input file.
If no such file is
currently open, as is the case at the beginning of assembly,
MACR0-11
opens the next input file specified in the command line previously
read and begins to assemble the source statements. The main objective
of assembly pass 1 is to locate and read all required macros from
libraries, to build symbol tables and program section tables for
the
program, while at the same time performing a rudimentary assembly of
each source statement.
MACR0-11 determines the length of each
instruction and assembles it accordingly as one word, two words, or
three words.
At the end of assembly pass 1, MACR0-11 reopens the output files
described above and writes out information that is to be used later by
the Task Builder in linking the object modules.
Such information as
the object module name,
the program version number, and the global
symbol directory (GSD) entries for each program section are output to
the object file.
After writing out the GSD entries for a given
program section, MACR0-11 scans through the symbol tables to find all
the global symbols that are bound to that particular program section.
MACR0-11 then writes out GSD records to the object file
for
these
symbols.
This process continues for each program section, bringing to
a close assembly pass 1.

1.1.2

Assembly Pass 2

As an integral part of pass 2, MACR0-11 simultaneously writes the
object records to the output file and generates the assembly listing,
followed finally by the symbol table listing for the program.
Basically, assembly pass 2 consists of the same steps performed in
assembly
pass 1, except that all source statements containing
MACR0-11-detected errors are flagged with an error code as the
assembly listing file is created.
The object file that is created as
the final consequence of pass 2 contains all the object records,
together with relocation records containing information necessary for
subsequent Task Builder linking of the object file.
The information thus passed to the Task Builder enables the global
symbols in the object modules to be associated with absolute or
virtual memory addresses, thereby forming an executable body of code.
While not within the scope of this manual, the user may wish to become
familiar with the macro object file format and description.
This
information is presented in the applicable Task Builder Reference
Manual (see section 0.3 in the Preface).

1-2

CHAPTER 2
SOURCE PROGRAM FORMAT

2.1

STANDARDS AND CONVENTIONS

Assembly level programming deals directly with the host hardware.
Hence, great care must be exercised in establishing programming
standards and conventions to enable code written by one group to be
interchanged easily with another group.
A number of advantages accrue
from strict adherence to a set of standards.
When applied to the
program development process,
the observance of standards makes the
programming effort easier to:
Plan;
Comprehend;
Test;
Modify; and
Convert.
Even though standards must accommodate local requirements, many
aspects
of
the
program
development
process
have universal
applicability.
The standards common to a11 of u1g~tal's PDP-11
software products are presented in Appendix E as a model for users.
Observance of these standards is beneficial to Digital and its users
by,
simplifying both communications and the continuing task of
software maintenance and enhancement.

2.2

STATEMENT FORMAT

A source program is composed of a sequence of source coding lines.
Each line contains a single assembly-language statement consisting of
up to 132(10) characters. Although MACR0-11 will accept a source line
of 132(10)
characters, due to listing format and terminal line size
constraints, 80(10) characters is the recommended length.
A MACR0-11 statement may be composed of as many as four fields.
These
fields are identified by their order of appearance within the
statement and/or by specified separating characters between fields.
The general format of a MACR0-11 statement is:
Label:

Operator Operand

;Comment(s)

The label and comment fields are optional. The operator and operand
fields are interdependent,
i.e., when both fields are present in a
source statement, each field is evaluated by MACR0-11 in the context
of the other.

2-1

SOURCE PROGRAM FORMAT
Although a statement may contain an operator field and no operand
field, the reverse is not true. A statement containing an operand
with no operator does not conform to established MACR0-11 coding
conventions;
such a statement is currently interpreted by MACR0-11
during assembly as an implicit .WORD directive (see section 6.3.2).
MACR0-11 interprets and processes source program statements one by
one, generating one or more binary instructions or data words, or
performing a specified assembly process. Blank lines, although legal,
have no significance in the source program.
An assembly-language statement must be completed on one
no continuation lines are allowed in MACR0-11.

source

line;

The tab character can be used following each field of the source
statement to format the fields into aligned columns in accordance with
DEC's standard source program format, as shown below:
Label - begins in column l;
Operator - begins in column 9;
Operand(s) - begin(s) in column 17;
Comment(s) - begin(s) in column 33.
For example, the following statement should be formatted in the source
program into specific columns, increasing its readability in the
assembly listing:
REGTST:BIT#MASK,VALUE;COMPARES BITS IN OPERANDS.
1

REGTST: BIT

#MASK,VALUE

;COMPARES BITS IN OPERANDS.

Although the above formatting conventions do not have to be observed
in coding MACR0-11 programs (since free-field coding is permissible),
it is recommended nonetheless that source programs be prepared in
accordance
with
these conventions for consistency and clarity
throughout.

2.2.1

Label Field

A label is a user-defined symbol which is assigned the value of the
current location counter and entered into the user-defined symbol
table. The current location counter is the means by which MACR0-11
assigns memory addresses to the source program statements as they are
encountered during the assembly process. The address value of the
label is thus absolute or relocatable, depending on whether the
current program section being assembled is absolute or relocatable.
(The concept of program sections and the attributes that may be
specified for such modules are discussed in detail in section 6.8.)
In the case of an absolute program section, the value of the current
location counter is likewise absolute, i.e., its value references an
absolute virtual memory address (such as location 100).
Similarly,
the value of the current location counter in a relocatable program
section is also relocatable; however, a relocation bias calculated by

2-2

SOURCE PROGRAM FORMAT
the Task Builder will be added to the apparent value of the current
location counter to establish its effective absolute virtual address
at execution time.
A label is thus a means of symbolically referring to a specific
location within a program. If present, a label always appears as the
first field in a source statement and must be terminated by a colon.
For example, if the current location counter value is absolute 100(8),
the statement:
ABCD:

MOV

A,B

assigns the value 100(8) to the label ABCD. Subsequent references to
this label would then yield a value of absolute 100(8). In this
example, if the location counter value were relocatable, the final
value of ABCD would be 100(8)+K, where K represents the relocation
bias of the program section, as calculated by the Task Builder at link
time.
More than one label may appear within a single label field;
each
label so specified, is assigned the same address value. For example,
if the current location counter value is 100(8), the multiple labels
in the following statement:
ABC:

$DD:

A7.7:

MOV

A,B

are each assigned the value 100(8).
Multiple labels may also appear on successive lines.
following statements:
ABC:
$DD:
A7.7:

MOV

For example, the

A,B

likewise cause the same current location counter value to be
to all three labels.

assigned

Of the two methods of assigning labels contrasted above, the latter
method is preferred, since consistency of field positioning within the
source program enhances its readability.
A double colon (::) defines the label as a global symbol.
Such a
label an be referenced by independently-assembled object modules.
References to this label in other modules will be resolved by the Task
Builder when the modules are linked as a composite executable task.
For example, the following statement:
ABCD::

MOV

A,B

establishes the label ABCD as a global symbol.
The distinguishing
attribute of a global symbol is that it can be referenced from within
another object module remote to that in which the symbol is defined
(see section 6.9).
The legal characters for defining labels are:
A through Z
0 through 9
(Period)
$ (Dollar Sign)

2-3

SOURCE PROGRAM FORMAT
NOTE
By convention, the dollar sign ($) and
are reserved for use in defining
software symbols.
It is therefore
that these characters not be used
labels in MACR0-11 source programs.

period
(.)
DEC system
recommended
in defining

A label may be any length; however, only the first six characters are
significant and, therefore, must be unique among all the labels in the
source program. All labels are terminatd by a colon (:) which is not,
however, considered part of the ·label. It is a mandatory delimiter.
An error code (M) is generated in the assembly listing if the first
six characters in two or more labels are the same (see Appendix D).
A symbol used as a label must not be redefined within the source
program.
If the symbol is redefined, a label with a multiple
definition results, causing MACR0-11 to generate an error code (M)
in
the assembly listing (see Appendix D). Furthermore, any statement in
the source program which references such a multi-defined label results
in an additional diagnostic message; in this case, an error code (D)
is generated in the assembly listing (see Appendix D).

2.2.2

Operator Field

The operator field follows the label field in a source statement.
This field may contain an instruction mnemonic (op-code), an assembler
directive, or a macro call. Thus, the operator field is that element
of a MACR0-11 instruction which specifies the action to be performed
by the instruction. Chapters 6 and 7 are devoted to a description of
these three types of operator field entries.
The operator field need not be preceded by a label;
on the other
hand, it may be preceded by one or more labels and followed by one or
more operands and/or a comment.
Furthermore, leading and trailing
spaces or tabs in the operator field have no significance; such
characters serve only to separate the operator field from the
preceding and following fields.
When the operator is an instruction mnemonic, the mnemonic op-code
specifies the machine instruction to be generated. MACR0-11 then
continues with the evaluation of the address(es) of the operand(s)
which follow(s).
When the operator is a directive, the directive
causes MACR0-11 to perform certain control actions or processing
operations during the assembly of the source program. Finally, when
the operator is a macro call, MACR0-11 inserts the appropriate code,
as generated by the macro expansion.
An operator is terminated by a space, tab, or any non-RAD50 character,
as in the following examples:
MOV A,B
MOV
A,B
MOV@A,B

;THE SPACE TERMINATES THE OPERATOR
;MOV.
;THE TAB TERMINATES THE OPERATOR MOV.
;THE @ CHARACTER TERMINATES THE
;OPERATOR MOV.

2-4

SOURCE PROGRAM FORMAT
Although the above statements are all equivalent in
second statement is the recommended form because
MACR0-11 coding conventions.

2.2.3

function, the
it conforms to

Operand Field

When the operator field contains an instruction mnemonic (op-code),
the operand field specifies those program variables that are to be
evaluated/manipulated by the operator. The operand field may also be
used to supply arguments to MACR0-11 directives and macro calls, as
described in Chapters 6 and 7, respectively.
Operands may be expressions or symbolic arguments (within the context
of the specified operation). Multiple expressions used in the operand
field of a MACR0-11 statement must be separated by a comma;
multiple
symbolic arguments similarly used may be delimited by any legal
separator, i.e., a comma, tab, and/or space.
An operand should be
preceded by an operator field; if it is not, the statement is treated
by MACR0-11 as an implicit .WORD directive (see section 6.3.2).
When the operator field contains an op-code, associated operands
always expressions, as shown in the following statement:
MOV

are

RO,A+2(Rl)

On the other hand, when the operator field contains a MACR0-11
directive or a macro call, associated operands are normally symbolic
arguments, as reflected in the following statement:
.MACRO

ALPHA

ARG1,ARG2

Users are advised to refer to the narrative descr101ng each MACR0-11
directive to determine the type and number of operands required in
issuing the directive.
The operand field is terminated by a semicolon when the field
followed by a comment. For example, in the following statement:
LABEL:

MOV

A,B

;COMMENT FIELD

the tab between MOV and A terminates the operator field and defines
the beginning of the operand field; a comma separates the operands A
and B; and a semicolon terminates the operand field and defines the
beginning of the comment field. When no comment field follows, the
operand field is terminated by the end of the source line.

2.2.4

Comment Field

The comment field normally begins in column 33 and extends through the
end of the line.
This field is optional and may contain any ASCII
characters
except
null,
RUBOUT,
carriage-return,
line-feed,
vertical-tab or form-feed.
All other characters appearing in the
comment field, even special characters reserved for use in MACR0-11,
are checked only for ASCII legality and then included in the assembly
listing as they appear in the source text.

2-5

SOURCE PROGRAM FORMAT
All comment fields must begin with the semicolon character(;).
When
lengthy comments extend beyond the end of the source line (column 80),
the comment may be resumed in a following line.
Such a line must
contain a leading semicolon, and it is suggested that the body of the
comment be continued in the same columnar position in which the
comment began.
A comment line can also be included as an entirely
separate line within the code body.
Comments do not affect assembly processing or program execution.
However, comments are useful in source listings for later analysis,
debugging, or documentation purposes.

2.3

FORMAT CONTROL

Horizontal formatting of the source program is controlled by the space
and tab characters. These characters have no affect on the assembly
process unless they are embedded within a symbol, number, or ASCII
text string, or unless they are used as the operator field terminator.
Thus, the space and tab characters can be used to provide an orderly
and readable source program, as reflected by the following statements:
LABEL:MOV(SP)+,TAG;POP VALUE OFF STACK.
LABEL:

MOV

(SP)+,TAG

;POP VALUE OFF STACK.

The latter statement conforms to the standard horizontal formatting
conventions, i.e., the statement elements are separated into four
distinct fields and are therefore easily discernible, while the
preceding statement does not exhibit these desirable characteristics.
Page formatting and assembly listing considerations are discussed in
Chapter 6 in the context of appropriate MACR0-11 directives that may
be specified to accomplish desired formatting operations. Appendix E
describes the coding conventions used in all Digital PDP-11 operating
system software.

2-6

PART II
PROGRAMMING
IN MACR0-11 ASSEMBLY
LANGUAGE

CHAPTER 3
SYMBOLS AND EXPRESSIONS

This chapter
describes
the
various
components
of
MACR0-11
instructions.
The
character set; the conventions observed in
constructing symbols, and the use of numbers, operators, terms and
expressions are discussed as they relate to MACR0-11 programming.

3.1

CHARACTER SET

The following characters are legal in MACR0-11 source programs:
1.

The letters A through z. Both upper and lower case letters
are acceptable, although, upon input, lower case letters are
converted to upper case (see Section 6.2, .ENABL LC).

The digits 0 through 9.

These
The characters
(period) and $ (dollar sign).
characters
are
reserved for use as Digital Equipment
Corporation system program symbols.

The special characters listed in Table 3-1.
Table 3-1
Special Characters

in MACR0-11

Function

Character

Designation

Colon

Label terminator.

Double colon

Label terminator; defines the
label as a global label.

Equal sign

Direct assignment operator.

Double equal
sign

Direct assignment operator;
defines the symbol as a global
symbol.

Percent sign

Tab

Item or field terminator.

Space

Item or field terminator.

3-1

SYMBOLS AND EXPRESSIONS
Table 3-1 (Cont'd)
Special Characters Used in MACR0-11
Function

Character

Designation

Number sign

Immediate expression
indicator.

At sign

Deferred addressing indicator.

(

Left parenthesis

Initial register indicator.

)

Right parenthesis

Terminal register indicator.

Comma

Operand field separator.

Semicolon

Comment field indicator.

Left angle
bracket

Initial argument or expression
indicator.

Right angle
bracket

Terminal argument or expression indicator.

Plus sign

Arithmetic addition operator
or autoincrement indicator.

Minus sign

Arithmetic subtraction operator or autodecrement indicator.

Asterisk

Arithmetic
operator.

Slash

Arithmetic division operator.

Ampersand

Logical AND operator.

Exclamation point

Logical inclusive OR operator.

Double quote

Double ASCII character indicator.

Single quote

Single ASCII character indicator.

Up arrow or
circumflex

Universal unary operator or
argument indicator.

Backslash

Macro call numeric argument
indicator.

3.1.1

multiplication

Separating and Delimiting Characters

Reference is made in the remainder of this manual to legal separating
characters and legal argument delimiters. These terms are defined
below in Tables 3-2 and 3-3.

3-2

SYMBOLS AND EXPRESSIONS
Table 3-2
Legal Separating Characters
Character
Space

Definition

Usage

One or more spaces
and/or tabs

A space is a legal separator
between instruction fields and
symbolic
arguments
between
within the
operand
field.
Spaces within expressions are
ignored (see section 3. 9) .

Comma

A comma is a legal separator
arguments
between
symbolic
within the
operand
field.
M11l+-;nlo
expressions used , ,..,
the operand field must
be
separated by a comma.
1.·.1. \,A. -L

'-...&...I::-' -L '\..,.

... l l

Table 3-3
Legal Delimiting Characters
Character

<••• >

Definition

Usage

Paired angle brackets

Paired angle brackets may be
used anywhere in a program to
enclose an
expression
for
treatment as a single term.
Paired angle brackets are also
used
to
enclose
a macro
argument, particularly
when
that argument contains separating characters (see section
7. 3) .

Up-arrow (unary operator)
construction,
where the up=arrow is
followed
by an argument that is bracketed
by any paired printing
characters (x).

"x ••• x

3.1.2

This construction is equivalent in function to the paired
angle brackets described above
and is generally used only
where the argument itself contains angle brackets.

Illegal Characters

A character is determined to be illegal for either of two reasons:
1.

A character is not an element of the recognized MACR0-11
character set. Such a character causes immediate termination
of the current line and the printing of an error code (I) in
the assembly listing (see Appendix D).

A legal MACR0-11 character is illegal in the context of its
usage within the source statement, i.e., its syntax is
illegal or questionable. Such a character causes an error
code (Q) to be printed in the assembly listing (see Appendix
D) •

3-3

SYMBOLS AND EXPRESSIONS
3.1.3

Unary and Binary Operators

The legal unary operators for use in MACR0-11 source programs are
described in Table 3-4. Unary operators are used in connection with
single terms (arguments or operands) to indicate an action to be
performed on that term during assembly. A term preceded by a unary
operator is considered to contain that operator.
The term so
specified thus becomes a value which can be used alone or as an
element of an expression.
Table 3-4
Legal Unary Operators
Unary
Operator

Explanation

Example

Plus sign

the
Produces
value of A.

Minus sign

-A

the
negative
Produces
(2's complement) value of
A.

Up-arrow, universal unary operator.
(This usage is
described in detail
in sections 6.4.1.2
and 6.4.2.2)

"C24

Produces the l's complement value of 24 ( 8).

"Dl27

Interprets 127 as a
decimal number.

F3.0

3.0
as
a
Interprets
one-word, floating-point
number.

I
~034

"811000111

Effect
positive

Interprets 34 as an octal
number.
Interprets 11000111 as
binary number.

Unary operators can be used adjacent to each other or in constructions
involving multiple terms, as shown below:
-"D50
~C"Ol2

(Equivalent to -<"D50>)
(Equivalent to ~C<~Ol2>)

The legal binary operators for use in MACR0-11 source programs are
described in Table 3-5.
In contrast to unary operators, binary
operators specify actions to be performed on multiple items or terms
within an expression. Thus, binary operators conjoin items or terms
within an expression to invoke a specific relationship between them as
the expression is evaluated during assembly. Table 3-5 shows the
relationships that can be established between expression terms through
the use of binary operators.

3-4

SYMBOLS AND EXPRESSIONS
Table 3-5
Legal Binary Operators
Binary
Operator
+

Explanation

Example

Addition

A+B

Subtraction

A-B

Multiplication

A*B (16-bit product returned)

Division

A/B (16-bit quotient returned)

Logical AND

A&B

T.nn~~~l

A!B

~~~·~~·

inclusive OR

All binary operators have equal priority.
Items or terms can be
grouped for evaluation within an expression by enclosing them within
angle brackets. Terms so enclosed are evaluated first, and remaining
operations are performed from left to right, as shown in the examples
below:
.WORD
.WORD

3.2

1+2*3
1+<2*3>

;EQUALS 11(8).
;EQUALS 7(8).

MACR0-11 SYMBOLS

Three types of symbols may be defined for use within MACR0-11 source
programs: permanent symbols, user-defined symbols, and macro symbols.
Correspondingly, MACR0-11 maintains three types of symbol tables: the
Permanent Symbol Table
(PST) , the User Symbol Table (UST), and the
Macro Symbol Table (MST). The PST contains all the permanent symbols
defined within (and thus automatically recognized by) MACR0-11 and is
part of the MACR0-11 task image. The UST and MST are constructed as
the source program is assembled.

3.2.1

Permanent Symbols

Permanent symbols consist of the instruction mnemonics
(see Appendix
C) and MACR0-11 directives
(see Chapters 6 and 7 and Appendix B).
These symbols are a permanent part of the MACR0-11 task image and need
not be defined before being used in the operator field of a MACR0-11
source statement (see section 2.2.2).

3.2.2

User-Defined and Macro Symbols

In developing programs, user-defined symbols are those symbols treated
by the programmer as labels (see section 2.2.1) or that are equated to
a specific value through a direct assignment statement
(see section
3.3).
These symbols are added to the User Symbol Table as they are
encountered during assembly. Macro symbols are those symbols used as
macro names (see section 7.1). Similarly, these symbols are added to
the Macro Symbol Table as they are encountered during assembly.

3-5

SYMBOLS AND EXPRESSIONS
User-defined and macro symbols can be composed of alphanumeric
any other
characters, dollar signs {$), and periods (.) only;
character is illegal.
NOTE
The dollar sign ($) and period (.) characters are
reserved for use in defining Digital Equipment
Corporation system software symbols. For example,
READ$ is a file-processing system macro. The user
is cautioned not to employ these characters in
constructing user-define symbols or macro symbols
in order to avoid possible conflicts with existing
or future Digital Equipment Corporation system
software symbols.
The following rules govern the
symbols:

creation

user-defined

and

macro

The first character of a symbol must not be a number
in the case of local symbols, see section 3.5).

{except

The first six characters of a symbol must be unique.

A symbol can be written with more than six legal characters,
but the seventh and subsequent characters are checked only
for ASCII legality and are not otherwise evaluated or
recognized by MACR0-11.

Spaces, tabs, and illegal characters must not be embedded
within a symbol. The legal MACR0-11 character set is defined
in section 3.1.

The value of a symbol depends upon its use in the program.
When a
symbol appears in the operator field, it may be any one of the three
symbol types described above i.e., permanent, user-defined, macro. To
determine the value of an operator-field symbol, MACR0-11 searches the
symbol tables in the following order:
1.

Macro Symbol Table

Permanent Symbol Table

User-Defined Symbol Table

This search order allows redefinition of Permanent Symbol Table
entries as macro symbols. But the user must keep in mind the sequence
in which the search for symbols is performed in order to avoid
incorrect interpretation of the symbol's use.
When a symbol appears in the operand field, the User-Defined
Table is searched first, then the PST is searched.

Symbol

Depending on their use in the source program, user-defined symbols
have either a local {internal) attribute or a global {external)
attribute.
Normally, MACR0-11 treats all user-defined symbols as local, that is,
their definition is limited to the module in which they appear.

3-6

SYMBOLS AND EXPRESSIONS
However1 symbols can be explicitly
through any one of three methods:

declared

global

symbols

Use of the .GLOBL directive (see section 6.9).

Use of the double colon (::) in defining a label (see section
2.2.1).

Use of the double equal {==)
statement (see section 3.3).

sign

direct

assignment

All symbols within a module that remain undefined at the end
assembly are treated by MACR0-11 as default global references.

NOTE
Undefined symbols at the end of assembly are
assigned a value of zero and placed into the
user-defined symbol table as undefined default
global references. If the .DSABL GBL directive is
in effect, however,
(see section
6.2),
the
automatic global reference default function of
MACR0-11 is inhibited, causing the
statement
containing the undefined symbol to be flagged with
an error code (U) in the assembly listing
(see
Appendix D).
Global symbols provide linkages between independently-assembled object
modules within the task image. A global symbol which is defined as a
label, for example, may serve as an entry-point address to another
section of code within the task image. Such symbols are referenced
from other source modules in order to transfer control throughout cne
task's execution.
These global symbols are resolved by the Task
Builder at link time, ensuring that the resulting task image is a
logically coherent and complete body of code.

3.3

DIRECT ASSIGNMENT STATEMENTS

A direct assignment statement allows the programmer to equate a symbol
to a specific value. When a direct assignment statement is first used
to define a symbol, that symbol is entered into the User-Defined
Symbol Table.
A symbol defined in this manner may be redefined in a
subsequent direct assignment statement by assigning a new value to the
previously-defined symbol.

The general format for a direct assignment statement is:
symbol=expression
or
symbol==expression
where:

expression

- can have only one level of forward
(see 5. below).

reference

- cannot contain an undefined global reference.

3-7

SYMBOLS AND EXPRESSIONS
A direct assignment statement embodying the double equal (==) sign, as
shown above, defines the symbol as having a global attribute (see
section 6.9).
The following examples illustrate
statements:

the

coding

direct

assignment

A=l

;THE SYMBOL A IS EQUATED TO THE
;VALUE 1.

B=A-l&MASKLOW

;THE SYMBOL B IS EQUATED TO THE
;VALUE OF THE ENTIRE EXPRESSION
;WHICH FOLLOWS.

D=.
#1,ABLE

MOV

;THE SYMBOL DIS EQUATED TO., AND
;THE LABELS C AND E ARE ASSIGNED A
;VALUE THAT IS EQUAL TO THE LOCATION
;OF THE MOV INSTRUCTION.

The last of the three examples above does not necessarily reflect good
programming practice; this example is provided only to illustrate the
performance of MACR0-11 in such situations.
The following conventions apply to the
statements:

coding

direct

assignment

An equal sign (=) or double equal sign (==) must separate the
symbol from the expression defining the symbol's value.
Spaces preceding and/or following the direct assignment
operators, although permissible, have no significance in the
resulting value.

The symbol being assigned in a direct assignment statement is
placed in the label field.

Only one symbol can be defined in a single direct
statement.

assignment

A direct assignment statement
comment field.

only

Only one level of forward referencing is allowed, as shown in
the following example:

may

followed

X=Y
Y=Z

(Illegal forward reference)

Z=l
The above example would result in the generation of an error code (U)
in the assembly listing (see Appendix D) on the line containing the
illegal forward reference.
Although one level of forward referencing is allowed in MACR0-11 for
local symbols, a global symbol defined in a direct assignment
statement must not contain a forward reference, i.e., the global
assignment expression must not itself contain an undefined reference
to another symbol. Such a forward reference is illegal, causing an
error code
(A) to be generated in the assembly listinq (see Appendix
D).

3-8

SYMBOLS AND EXPRESSIONS
3.4

The eight general registers of the PDP-11 processor are numbered O
through 7 and can be expressed in the source program in the following
manner:
%0
%1

%7
where % indicates a reference to a register rather than a location.
The digit specifying the register can be replaced by any legal,
absolute term which can be evaluated during the first pass of
assembly.
It is recommended that the programmer use standard symbolic
names for all register references.
The register definitions listed below are automatically assigned by
MACR0-11, i.e., these definitions are the normal default values and
remain valid for all register references within the source program.
R0=%0
Rl=%1
R2=%2
R3=%3
R4=%4
R5=%5
SP=%6
PC=%7

;REGISTER 0 DEFINITION.
;REGISTER l DEFINITION.
;REGISTER 2 DEFINITION.
;REGISTER 3 DEFINITION.
;REGISTER 4 DEFINITION.
;REGISTER 5 DEFINITION.
;STACK POINTER DEFINITION.
;PROGRAM COUNTER DEFINITION.

Note that registers 6 and 7 are given special names because
unique system functions.

their

A register symbol may be defined in a direct assignment statement
appearing in the program.
The defining expression of a register
symbol must be a legal, absolute value.
Although the user can
reassign the standard register symbols, if desired, through the use of
the .DSABL REG directive (see section 6.2), this practice is not
recommended.
An attempt by the user to redefine a default register
symbol without first specifying the .DSABL REG directive to override
the normal register definitions causes that assignment statement to be
flagged with an error code (R) in the assembly listing
(see Appendix
D).
The symbolic default names assigned to the registers, as listed
above, are the conventional names used in all DEC-supplied PDP-11
system programs. For this reason, the user is well advised to follow
these conventions.
All non-standard register symbols must be defined before they are
referenced in the source program. A register expression less than 0
or greater than 7 is flagged with an error code (R)
in the assembly
listing (see Appendix D).

3-9

SYMBOLS AND EXPRESSIONS
The % character may be used with any legal term
specify a register. For example, the statement:
CLR

expression

%3+1

is equivalent in function to the statement
CLR

and clears the contents of register 4.
In contrast, the following statement:
CLR

clears the contents of virtual memory location 4.

3.5

LOCAL SYMBOLS

Local symbols are specially formatted symbols used as labels within a
given block of coding that has been delimited as a local symbol block.
Local symbols are of the form n$, where n is a decimal integer from l
to 65535, inclusive. Examples of local symbols are:
1$
27$
59$
104$
A local symbol block is delimited in one of three ways:
1.

The range of a local symbol block usually consists of those
statements between two normally-constructed symbolic labels
(see Figure 3-1). Note that a statement of the form:
ALPHA=expression
is a direct assignment statement (see section 3.3), but does
not create a label and thus does not delimit the range of a
local symbol block.

The range of a local symbol block is normally terminated upon
encountering a .PSECT, .CSECT, or .ASECT directive in the
source program (see Figure 3-1).

The range of a local symbol block
MACR0-11 directives, as follows:

delimited

Starting delimiter:

.ENABL LSB

(see section 6.2)

Ending delimiter:
or
Followed by one of:

.DSABL LSB

(see section 6.2)

Symbolic label
.PSECT (see section 6.8.l)
.CSECT (see section 6.8.2)
.ASECT (see section 6.8.2)

3-10

through

SYMBOLS AND EXPRESSIONS
Local symbols provide a convenient means of generating labels for
branch instructions and other such references within a local symbol
block.
Using local symbols reduces the possibility of symbols with
multiole definitions aooearino within a user oroqram.
In addition,
the use of local symbols-differentiates entry-point-labels from local
labels,
since local symbols cannot be referenced from outside their
respective local symbol block.
Thus, local symbols of the same name
can appear in other local symbol blocks without conflict.
The use of local symbols is encouraged, since they require less symbol
table space than other types of symbols. When defining local symbols,
the programmer is advised to use the range from 1$ to 63$ first,
then
the range from 128$ to 65535$.
Local symbols within the range 64$
through 128$, inclusive, can be generated automatically as a feature
of MACR0-11.
Such local symbols are useful in the expansion of macros
during assembly and are described in detail in this context in section
7.3.5.
Care must be exercised in specifying local symbols in order to avoid
multiple definitions within the same local symbol block.
For example
if the local symbol 10$ is defined two or more times within the same
local symbol block, each symbol represents a different address value.
Such a multi-defined symbol causes an error code (P) to be generated
in the assembly listing (see Appendix D).
For examples of local symbols and local symbol blocks as
in a source program, see Figure 3-1.

121
122
123
124

they

appear

PROGRAM INITIALIZATION CODE

125 0ei000

126 01110000
127 "HHHll04
128 000006
129 000012
130

01270ei
005020

01110000 !

0227121~

QH:''0000'

101374

BHI

. 131 000000
~ 1270Q!

132 00~Hl0Vl
133 000004
134 000006

12122700

i35 00l00i2

i~i374

136
13,. 12100000
138 00000~
139 000004
140 000006
141 000012
142

,PSECT
XC:TPRG1 IMOV
151
C:LR
CMP

V'IV'l0000'

005(1!21'1

12112700
005020
1212271210
1'11374

0 0 0 ,;_•l((Hl I

• PSEC!
XCTPAS11MOV
CLR
151
CMP
Bi-il

Ql01211!100 I
0000001

0 PSEc:T
XC:TLIN11MOV
1 SI
C:LR
CMP

BHI

XC:TPRG,GBL.
#!MPURE::,R0
(R0)•

JIMPURE DA T.l INITIALIZATION

#!MPURT,R~

XCTPAS,GBL
#!MPPAS,R0

JPASS INITIALIZATION

(R0)•

#P1PPAT,R0
i $

XC:TL!N,GE:!L
#IMPLIN,R0

J LI"<E INITIALIZATION

(R0)•

#P1PLIT,R0

Figure 3-1
Assembly Listing Showing Local Symbol Block

3.6

CURRENT LOCATION COUNTER

The period (.) is the symbol for the current location counter.
When
used in the operand field of an instruction, it represents the address
of the first word of the instruction, as shown in the first example
below.
When used in the operand field of a MACR0-11 directive, it
represents the address of the current byte or word, as shown in the
second example below.

3-11

SYMBOLS AND EXPRESSIONS
A:

MOV

#.,RO

;THE PERIOD (.) REFERS TO THE ADDRESS
;OF THE MOV INSTRUCTION.

(The function of the #symbol is explained in section 5.9.)
SAL=O
.WORD

177535,.+4,SAL

;THE OPERAND .+4 IN THE .WORD
;DIRECTIVE REPRESENTS A VALUE
;THAT IS STORED AS THE SECOND
;OF THREE WORDS DURING
;ASSEMBLY.

In the above example, assume that the current value of the location
counter is 500.
During assembly, MACR0-11 then reserves storage in
response to the .WORD directive (see section 6.3.2), beginning with
location 500. The operands accompanying the .WORD directive determine
the values so stored. The value 177535 is thus stored in location
500.
The value represented by .+4 is stored in location 502; this
value is derived as the current value of the location counter
(which
is .now 502), plus the absolute value 4, thereby depositing the value
506 in location 502. Finally, the value of SAL, previously equated to
0, is deposited in location 504.
At the beginning of each assembly pass, MACR0-11 resets the location
counter.
Normally, consecutive memory locations are assigned to each
byte of object data generated. However, the value of the location
counter can be changed through a direct assignment statement of the
following form:
.=expression
Similar to other MACR0-11 symbols, the current location counter symbol
(.) has an attribute of relocatability associated with it, i.e., it is
either absolute or relocatable, depending on the specific such
attribute of the current program section.
(A program section and its
attributes are defined through the use of the .PSECT directive
described in section 6.8.1.) The existing attribute (or mode) of the
current location counter cannot be changed by specifying a defining
expression having a different attribute.
Furthermore, such a defining expression must not force the location
counter into another program section (.PSECT area), even though the
program sections so involved may both be absolute or relocatable. The
expression defining the location counter value must not contain a
forward reference, i.e., the expression must not contain a reference
to
a symbol that is not previously defined.
Such violations
constitute a general assembly error, resulting in an error ~ode (A) in
the assembly listing (see Appendix D).
Thus, the attribute (or mode) of the current location counter takes on
the
attribute of the current program section.
Therefore, its
attribute from program section to program section can be changed only
through
the program sectioning directives
(.PSECT,
.ASECT, and
. CSECT) , as described in section 6. 8.

3-12

SYMBOLS AND EXPRESSIONS
The following coding illustrates
counter:

the

use

the

current

location

.ASECT
.=500
FIRST:

MOV

.+10,COUNT

.=520
SECOND: MOV

.,INDEX

;SET LOCATION COUNTER TO
;ABSOLUTE 500{0CTAL).
;THE LABEL "FIRST" HAS THE VALUE
;500{0CTAL).
;.+10 EQUALS 510(0CTAL}. THE
;CONTENTS OF THE LOCATION
;510(0CTAL) WILL BE DEPOSITED
;IN THE LOCATION "COUNT."
;THE ASSEMBLY LOCATION COUNTER
;NOW HAS A VALUE OF
;ABSOLUTE 520(0CTAL).
;THE LABEL SECOND HAS THE
;VALUE 520(0CTAL).
;THE CONTENTS OF LOCATION
;520(0CTAL), THAT IS, THE BINARY
;CODE FOR THE INSTRUCTION
;ITSELF, WILL BE DEPOSITED IN THE
;LOCATION "INDEX."

.PSECT
.=.+20
THIRD:

.WORD

;SET LOCATION COUNTER TO
;RELOCATABLE 20 OF THE
;UNNAMED PROGRAM SECTION.
;THE LABEL THIRD HAS THE
;VALUE OF RELOCATABLE 20.

Storage areas may be reserved in the program by advancing the location
counter.
For example, if the current value of the location counter is
1000, each of the following statements:
.=.+40
or
.BLKB 40
or
.BLKW 20
reserves 40(8) bytes of storage space in the source program.
The
.BLKB and .BLKW directives, however, are recommended as the preferred
ways to reserve storage space (see section 6.5.3).
3.7

NUMBERS

MACR0-11 assumes that all numbers in the source program are to be
interpreted in octal radix, unless otherwise specified. An exception
to this is that operands to PDP-11/45 and PDP-11/70 floating point
instructions are treated as decimal (see section 6.4.2).
This default
radix can be altered with the .RADIX di~ective (see section 6.4.1.1).
Also,
individual numbers can be designated as decimal, binary, or
octal numbers through temporary radix control operators
{see section
6.4.l.2).
For every statement in the source program that contains a digit that
is not in the current radix, an error code (N) is generated in the
assembly listing (see Appendix D).
However, MACR0-11 continues with
the scan of the statement and evaluates each such number encountered
as a decimal value.

3-13

SYMBOLS AND EXPRESSIONS
Negative numbers must be preceded by a minus sign;
MACR0-11
translates such numbers into two's complement form.
Positive numbers
may (but need not) be preceded by a plus sign.
A number containing more than 16 significant bits, i.e., greater than
177777(8), is truncated from the left and flagged with an error code
(T) in the assembly listing (see Appendix D).
Numbers are always considered to be absolute values,
not relocatable.

i.e.,

they

are

Single-word floating-point numbers may be generated with the AF
operator (see section 6.4.2.2) and are stored in the following format:
15

Sign
Bit

8-bit
Exponent

7 6

7-bit
Mantissa

Refer to the appropriate PDP-11 Processor Handbook for details of
floating-point number format.

3.8

the

TERMS

A term is a
following:

component

expression

and

may

A number, as defined in section 3.7, whose
used.

A symbol, as defined in section 3.2.
as follows:

one

16-bit

Symbols

are

the

value

evaluated

A period (.) specified in an expression causes the
of the current location counter to be used.

value

A defined symbol is located in the
Table (UST) and its value is used.

User-Defined

Symbol

A permanent symbol's basic value is
substituted for any arguments.

used,

An undefined symbol is assigned a value of zero and
inserted in the User-Defined Symbol Table as an undefined
default global reference. If the .DSABL GBL directive
(see section 6.2)
is in effect, the automatic global
reference default function of MACR0-11 is inhibited, in
which case, the statement containing the undefined symbol
is flagged with an error code (U) in the assembly listing
(see Appendix D).

but

zero

An ASCII conversion operation using either a single quote
followed by a single ASCII character or a double quote
followed by two ASCII characters. This type of expression
construction is explained in detail in section 6.3.3.

3-14

SYMBOLS AND EXPRESSIONS
4.

3.9

A term may also be an expression enclosed in angle brackets
(<>). Any expression so enclosed is evaluated and reduced to
a single term before the remainder of the expression in which
it appears is evaluated. Angle brackets, for example, may be
used to alter the left-to-right evaluation of expressions (as
in A*B+C versus A*<B+C>), or to apply a unary operator to an
entire expression (as in -<A+B>).

EXPRESSIONS

Expressions are combinations of terms joined together by binary
operators (see Tables 3-4 and 3-5) and which reduce to a 16-bit
expression value.
The evaluation of an expression includes the
determination of its attributes. A resultant expression value may be
any one of four types (as described later in this section): absolute:
relocatable, external, or complex relocatable.
Expressions are evaluated from left to right with no operator
hierarchy rules, except that unary operators take precedence over
binary operators. A term preceded by a unary operator is considered
to contain that operator.
(Terms are evaluated, where necessary,
before their use in expressions.) Multiple unary operators are valid
and are treated as follows:
-+-A
is equivalent to:
-<+<-A>>
A missing term, expression, or external symbol is interpreted as a
zero.
A missing or illegal operator terminates the expression
analysis, causing an error code (A) or (Q), or both, to be generated
in the assembly listing (see Appendix D), depending on the context of
the expression itself. For example, the expression:
TAG ! LA 177777
is evaluated as

TAG ! LA
because the first non-blank character following the symbol LA is not a
legal binary operator, an expression separator (i.e., a comma), or an
operand field terminator (i.e., a semicolon or the end of the source
line). It should be noted that spaces within expressions are ignored.
The value of an external expression, as evaluated by MACR0-11, is
equal to the value of the absolute part of that expression. For
example, the expression EXTERN+A, where "EXTERN" is an external
symbol, has a value at assembly-time that is equal to the value of the
internal symbol A. This expression, however, when evaluated by the
Task Builder a link time then takes on the resolved value of the
symbol EXTERN, plus the value of symbol A.

3-15

SYMBOLS AND EXPRESSIONS
Expressions, when evaluated by MACR0-11, are determined to be one of
four types: absolute, relocatable, external (or global). or complex
relocatable. For the MACR0-11 programmer, the following distinctions
are important:
1.

An expression is absolute if its value is fixed.
An
expression whose terms are numbers and ASCII conversion
characters will reduce to an absolute value.
A relocatable
expression or term minus a relocatable term, where both
elements being evaluated belong to the same program section,
are also absolute, since such an expression is reduced to a
single term by MACR0-11 upon completion of the expression
scan. For example, the expression TAG2-TAG1, where both TAGl
and TAG2 are defined in the same program section, is an
absolute expression.

An expression is relocatable if its value is fixed relative
to the base address of the program section in which it
appears, but it will have an offset value added at task-build
time.
Expressions whose terms contain labels defined in
relocatable program sections will have a relocatable value;
similarly, a period {.) in a relocatable program section,
representing the value of the current location counter, will
also have a relocatable value.

An expression is external {or global) if it contains a single
global reference {plus or minus an absolute expression value)
that is not defined within the current program.
Thus, an
external expression is only partially defined following
assembly and must therefore be resolved by the Task Builder
at link time.

An expression is complex relocatable
following conditions applies:

any

one

the

- It contains a global reference and a relocatable symbol.
- It contains more than one global reference.
- It contains relocatable
program sections.

terms

belonging

different

The value resulting from the expression has more than one
level of relocation.
For example, if the relocatable
symbols TAGl and TAG2 associated with the same program
section are specified in an expression construction in the
form TAGl+TAG2, two levels of
relocation
would
be
introduced, since each symbol is evaluated in terms cf the
relocation bias in effect for the program section.
- An operation other than
undefined global symbol.

addition

specified

- An operation other than addition, subtraction, negation, or
complementation is specified for a relocatable value.
The evaluation of relocatable, external,
expressions is completed at link time.

3-16

and

complex

relocatable

CHAPTER 4
RELOCATION AND LINKING

The output of MACR0-11 is an object module which must be processed by
the Task Builder before it can be loaded and executed. Essentially:
the Task Builder fixes (i.e., makes absolute) the values of external
or relocatable symbols in the object module, thus rendering the object
module, or several such object modules, into an executable task image.
This process is called linking.
To enable the Task Builder to fix the value of an expression, MACR0-11
issues certain directives to the Task Builder, together with other
required parameters. In the case of relocatable expressions in the
object module, the Task Builder adds the base of the associated
relocatable program section to the value of the relocatable expression
provided by MACR0-11. In the case of external expression values, the
Task Builder determines the value of the external term in the
expression (since the external symbol must be defined in one of the
other object modules being linked together) and then adds it to the
absolute portion of the external expression, as provided by MACR0-11.
All instructions that require modification by the Task Buiider are
flagged in the assembly listing, as illustrated in the example below.
The apostrophe (') following the octal expansion of the instruction
indicates that simple relocation is required; the letter G indicates
that the value of an external symbol must be added to the absolute
portion of an expression;
and the letter C indicates that complex
relocation analysis by the Task Builder is required in order to fix
+-h .....
._..1..1.~

n,,.1110
vuiuc

,...-F
v..1...

+-ho
'-'.1."'-

ovnrocciAn
'-rtr..~.1..'-_,_, •
....., .......

EXAMPLE:
OOS06S CLR
OOOOOOG

EXTERN (RS)

;THE VALUE OF THE i'EXTERN" SYMBOL IS
;ASSEMBLED AS ZERO AND IS TO BE
;RESOLVED BY THE TASK BUILDER.

OOS06S CLR
000006G

EXTERN+6 (RS)

;THE VALUE OF THE SYMBOL uEXTERN"
;IS TO BE RESOLVED BY
;THE TASK BUILDER AND ADDED TO
;THE ABSOLUTE PORTION (+6) OF
;THE EXPRESSION.

OOS06S CLR
000040'

RELOC (RS)

;ASSUMING THAT THE VALUE OF THE
;SYMBOL "RELOC" IS RELOCATABLE
;40, THE TASK BUILDER WILL ADD A
;RELOCATION BIAS TO THIS VALUE.

4-1

RELOCATION AND LINKING
005065

ooooooc

CLR

-<EXTERN+RELOC>(R5) ;THIS EXPRESSION IS COMPLEX
;RELOCATABLE BECAUSE IT REQUIRES
;THE NEGATION OF AN EXPRESSION
;THAT CONTAINS A GLOBAL (EXTERN)
;REFERENCE AND A RELOCATABLE TERM.

For a complete description of object records output by MACR0-11, refer
to the applicable Task Builder Reference Manual (see section 0.3 in
the Preface).

4-2

CHAPTER 5
ADDRESSING MODES

The program counter {PC), register 7 of the eight general registers in
the PDP-11 processor, always contains the address of the next word to
be fetched, i.e., the address of the next instruction to be executed,
or the second or third word of the current instruction.
In order to understand how the address modes operate and how they
assemble, the action of the program counter must be understood. The
key rule to remember is:
"whenever the processor implicitly uses the program counter
{PC)
to fetch a word from memory, the program counter is
automatically incremented by two after the fetch operation
is completed."
In the case of 2- or 3-word instructions, the processor uses the PC to
fetch the following words as well.
The following symbols are
throughout this chapter:

used

describing

addressing

modes

E is any expression, as defined in Chapter 3.

Risa register expression 1 i.e., any expression containing a
term preceded by a percent sign (%) or a symbol previously
equated to such a term, as shown in the examples below:
R0=%0
Rl=RO+l
R2=1+%1

;GENERAL REGISTER 0.
;GENERAL REGISTER 1.
;GENERAL REGISTER 2.

The symbol R may also represent any of
register definitions {see section 3.4).

the

normal

default

ER is a register expression or an absolute expression in
range 0 to 7, inclusive.

A is a general addressing specification which produces a
6-bit
mode address field, as described in the PDP-11
Processor Handbooks. The addressing specification, A,
is
described in terms of E, R, and ER, as defined above. Each
addressing specification within this section is illustrated
using either the single operand instruction CLR or the double
operand instruction MOV.

5-1

the

ADDRESSING MODES
5.1

The register itself (R) contains the operand to be manipulated by
instruction.
Format for A:

the

Example:
CLR

5.2

;CLEARS REGISTER 3.

The register (R) contains the address of the operand to be manipulated
by the instruction.
Format for A:

@R or {ER)

Examples:
CLR
CLR
CLR

5.3

@Rl
{Rl)
( 1)

;ALL THESE INSTRUCTIONS CLEAR
;THE WORD AT THE ADDRESS
;CONTAINED IN REGISTER 1.

AUTOINCREMENT MODE

The contents of the register (ER) are incremented immediately
being used as the address of the operand (see Note below).
Format for A:

(ER)+

Examples:
CLR
CLR
CLR

{RO)+
(R4)+
{R2)+

;EACH INSTRUCTION CLEARS
;THE WORD AT THE ADDRESS
;CONTAINED IN THE SPECIFIED
;REGISTER AND INCREMENTS
;THAT REGISTER'S CONTENTS
;BY TWO.
NOTE

Certain
special
instruction/address
mode
combinations, which are rarely or never used, do
not operate exactly the same on all
PDP-11
processors, as described below.
In the autoincrement mode, both the JMP and JSR
instructions autoincrement the register before its
use on the PDP-11/40, but not on the PDP-11/45 or
11/10.
In double
operand
instructions
having
the
addressing form Rn, {Rn)+ or Rn,-{Rn), where the
source and destination registers are the same, the
source operand is evaluated as the autoincremented

5-2

after

ADDRESSING MODES
or autodecremented value, but the destination
register, at the time it is used, still contains
the originally-intended effective address. In the
following example, as executed on the PDP-11/40,
Register 0 originally contains 100(8):
MOV

RO, (RO)+

;THE QUANTITY 102 IS MOVED
;TO LOCATION 100.

MOV

RO,-(RO)

;THE QUANTITY 76 IS MOVED
;TO LOCATION 100.

The use of these forms should be avoided, since
they are not compatible with the entire family of
PDP-11 processors.
An error code
(Z)
is printed in the assembly
listing
(see Appendix D) with each instruction
which is not compatible among all members of the
PDP-11 family.

5.4

AUTOINCREMENT DEFERRED MODE

The register (ER) contains a pointer to the address of the operand.
The contents of the register are incremented after being used as a
pointer.
Format for A:

@(ER)+

Example:
CLR

JoJ

@(R3)+

;THE CONTENTS OF REGISTER 3 POINT
;TO THE ADDRESS OF A WORD TO BE
;CLEARED BEFORE THE CONTENTS OF THE
;REGISTER ARE INCREMENTED BY TWO.

AUTODECREMENT MODE

The contents of the register (ER) are decremented before being used as
the address of the operand (see Note above in section 5.3).
Format for A:

-(ER)

Examples:
CLR

-(RO)

CLR
CLR

-(R3)
- (R2)

;DECREMENT THE CONTENTS OF THE SPECI;FIED REGISTER (0, 3, OR 2) BY TWO
;BEFORE USING ITS CONTENTS
;AS THE ADDRESS OF THE WORD TO BE
;CLEARED.

5-3

ADDRESSING MODES
5.6

AUTODECREMENT DEFERRED MODE

The contents of the register (ER} are decremented before being used as
a pointer to the address of the operand.
Format for A:

@-(ER)

Example:
CLR

5. 7

@-(R2)

;DECREMENT THE CONTENTS OF
;REGISTER 2 BY TWO BEFORE
;USING ITS CONTENTS AS A POINTER
;TO THE ADDRESS OF THE WORD TO BE
;CLEARED.

INDEX MODE

The value of an expression (E} is stored as the second or third word
of
the instruction.
The effective address of the operand is
calculated as the value of E, plus the contents of register ER.
The
value E is the offset of the instruction, and the contents of register
ER form the base.
Format for A:

E(ER)

Examples:

5.8

CLR

X+2(Rl)

MOV

R0,-2(R3)

;THE EFFECTIVE ADDRESS OF THE WORD
;TO BE CLEARED IS X+2, PLUS THE
;CONTENTS OF REGISTER 1.
;THE EFFECTIVE ADDRESS OF THE
;DESTINATION LOCATION IS -2, PLUS
;THE CONTENTS OF REGISTER 3.

INDEX DEFERRED MODE

An expression (E) , plus the contents of a register
(ER), yields a
pointer to the address of the operand. As in index mode above, the
value E is the offset of the instruction, and the contents of register
ER form the base.
Format for A:

@E(ER)

Example:
CLR

5.9

@114 (R4}

;IF REGISTER 4 CONTAINS 100, THIS
;VALUE, PLUS THE OFFSET 114, YIELDS
;THE POINTER 214. IF LOCATION 214
;CONTAINS THE ADDRESS 2000, LOCATION
;2000 WOULD BE CLEARED.

IMMEDIATE MODE

The immediate mode allows the operand itself (E) to be stored as the
second or third word of the instruction. This mode is assembled as an
autoincrement of regisler 7 (the PC).
Format for A:

#E
5-4

ADDRESSING MODES
Examples:
MOV
MOV

#100,RO
#X,RO

;MOVE THE VALUE 100 INTO REGISTER 0.
;MOVE THE VALUE OF SYMBOL X INTO
; REGISTER 0.

The number sign
(#)
in the MACR0-11 character set has special
significance as an addressing mode indicator. When this character
appears in the operand field, as shown above, it specifies the
immediate addressing mode, indicating to MACR0-11 that the operand
itself immediately follows the instruction word.
The operation of this mode can be shown through
MOV #100,RO, which assembles as two words:
Location 20:

0 1 2 7 0 0

Location 22:

0 0 0 1 0 0

Location 24:

Next instruction

the

first

example,

Note that the source operand (the value 100) is assembled immediately
following the instruction word, i.e., as the second word in the
instruction. Upon execution of the instruction, the processor fetches
the first word (MOV) and increments the PC by two so that it points to
location 22 (which contains the source operand).
After the next fetch and increment cycle, the source operand (100)
is
moved into register 0, leaving the PC pointing to location 24 (the
next instruction).

5.10

ABSOLUTE MODE

The absolute mode is the equivalent of the immediate mode deferred.
The address expression @#E specifies an absolute address which is
stored as the second or third word of the instruction.
In other
words, the value immediately following the instruction word is taken
as the absolute address of the operand.
The absolute mode is
assembled as an autoincrement deferred of register 7 (the PC).
Format for A:

@#E

Examples:
MOV

@#100,RO

CLR

@#X

;MOVE THE CONTENTS OF LOCATION 100
;INTO REGISTER RO.
;CLEAR THE CONTENTS OF THE LOCATION
;WHOSE ADDRESS IS SPECIFIED BY
;THE SYMBOL X.

The operation of this mode can be shown through
MOV @#100,RO, which assembles as two words:
Location 20:

0 1 3 7 0 0

Location 22:

0 0 0 1 0 0

Location 24:

Next instruction

5-5

the

first

example,

ADDRESSING MODES
Note that the absolute address 100 is assembled immediately following
the instruction word, i.e., as the second word in the instruction.
Upon execution of the instruction, the processor fetches the first
word
(MOV) and increments the PC by two so that it points to location
22 (which contains the absolute address of the source operand). After
the next fetch and increment cycle, the contents of absolute address
100 (the source operand) are moved into register 0, leaving the PC
pointing to location 24 (the next instruction).

5.11

RELATIVE MODE

It is
The relative mode is the normal mode for memory references.
assembled as index mode, using register 7 (the PC) as the index
register.
Format for A:

Examples:
CLR

100

MOV

RO,Y

;CLEAR LOCATION 100, RELATIVE TO
;THE CONTENTS OF THE PC.
;MOVE THE CONTENTS OF REGISTER 0
;TO LOCATION Y, RELATIVE TO THE
;CONTENTS OF THE PC.

In relative mode, the offset for the address calculation is assembled
as the second or third word of the instruction. This value is added
to the contents of the PC (the base register) to yield the address of
the source operand.
The operation of the relative mode can be
MOV 100,R3, which assembles as two words:
Location 20:

0 1 6 7 0 3

Location 22:

0 0 0 0 5 4

Location 24:

Next instruction

shown

with

the

statement

Note that the constant 54 is assembled immediately following the
instruction word, i.e., as the second word in the instruction. Upon
execution of the instruction, the processor fetches the first word
(MOV) and increments the PC by two so that it points to location 22
{containing the value 54). After the next fetch and increment cycle,
the processor calculates the effective address of the source operand
by taking the contents of location 22 (the offset) and adding it to
the current value of the PC, which now points to location 24 (the next
instruction). Thus, the source operand address is the result of the
calculation
OFFSET+PC = 54+24 = 100(8),
causing the contents of
location 100 to be moved into register 3.
Since MACR0-11 considers the contents of the current location counter
(.) as the address of the first word of the instruction, an equivalent
index mode statement is shown below:
MOV

100-.-4{PC),R3

This instruction has a relative addressing mode because the operand
address is calculated relative to the current value of the location

5-6

ADDRESSING MODES
counter. The offset is the distance (in bytes) between the operand
and the current value of the location counter. If the operator and
its associated operand(s) are moved in memory so that the distance
between the operator and the data remains constant, the instruction
will operate correctly anywhere in memory, i.e., the instruction is
relocatable (position-independent).

5.12 RELATIVE DEFERRED MODE
The relative deferred mode is similar in operation to the relative
mode above, except that the expression E is used as a pointer to the
address of the operand. In other words, the operand following the
instruction word is added to the contents of the PC to yield a pointer
to the address of the operand.
Format for A:

Example:
MOV

5.13

@X,RO

;RELATIVE TO THE CURRENT VALUE OF
;THE PC, MOVE THE CONTENTS OF THE
;LOCATION WHOSE ADDRESS IS POINTED
;TO BY LOCATION X INTO REGISTER 0.

SUMMARY OF ADDRESSING FORMS

Each PDP-11 instruction takes at least one word. Operands of the form
listed below do not increase the length of an instruction.
Form

Meaning

@R or (ER)

(ER)+

Autoincrement mode

@(ER)+

Autoincrement deferred mode

-(ER)

Autodecrement mode

@-(ER)

Autodecrement deferred mode

Operands of the following forms add one word to the instruction length
for each occurrence of an operand of that form:
Form

Meaning

E(ER)

Index mode

@E(ER)

Index deferred mode

Immediate mode

@#E

Absolute mode (see Note below)

Relative mode

Relative deferred mode
5-7

ADDRESSING MODES
The syntax of the addressing modes is
Additional
discussion
of addressing
applicable PDP-11 Processor Handbook.

summarized in Appendix B.
modes is provided in the

NOTE
An alternate form for @R is
(ER).
However, the
form @(ER) is only logically, but not physically
equivalent to
the
expression
@O(ER).
The
addressing form @#E differs from form E in that
the second or third word of the instruction
contains the absolute address of the operand,
rather than the relative distance between the
operand and the PC.
Thus, the instruction CLR
@#100 clears absolute location 100, even if the
instruction is moved from the point at which it
was assembled. See the description of the .ENABL
AMA function in section 6.2, which causes all
relative mode addresses to be
assembled
as
absolute mode addresses.

5.14

BRANCH INSTRUCTION ADDRESSING

The branch instructions are 1-word instructions. The high-order byte
contains the operator, and the low-order byte contains an 8-bit signed
offset (seven bits, plus sign), which specifies the branch address
relative to the current value of the PC. The hardware calculates the
branch address as follows:
1.

Extends the sign of the offset through bits 8-15.

Multiplies the result by 2, creating
than a word offset.

Adds the result to the current value of the PC
effective branch address.

byte

offset
to

rather

form

the

MACR0-11 performs the reverse operation to form the word offset from
the specified address. Remember that when the offset is added to the
current value of the PC, the PC is pointing to the word following the
branch
instruction;
hence,
the
factor -2 in the following
calculation:
Word offset

(E-PC)/2 truncated to eight bits.

Since the value of the PC

.+2, we have:

Word offset = (E-.-2)/2 truncated to eight bits.
In using branch instructions, the programmer
avoid the following error conditions:
1.

must

exercise

Branching from one program section to another;

5-8

care

ADDRESSING MODES
2.

Branching to a location
(global) symbol; or

that

defined

Specifying a branch address that is out of range,
~=c=,
the
branch offset is a value that does not lie within the range
-128 (10) to +127 (10).

The above conditions cause an error code (A) to be generated
assembly listing for the statement in error (see Appendix D).

5.15

external

the

USING TRAP INSTRUCTIONS

THE EMT and TRAP instructions do not use the low-order byte of the
instruction word, allowing information to be transferred to the trap
hana1ers in the low-order byte. ir tne t;J.VIT or T.t<.F...I:' instruction is
followed by an expression, the value of the expression is stored in
the low-order byte of the word. However, if the expression is greater
than 377(8), it is truncated to eight bits and an error code (T) is
generated in the assembly listing (see Appendix D).

5-9

PART III
MACR0-11 DIRECTIVES

Chapters 6 and 7 describe all the directives used with MACR0-11.
Directives are stateroents which cause MACR0-11 to perform certain
operations during assembly. Chapter 6 describes several types of
directives, including those which control sy~bol interpretation,
listing header material, program sections, data storage formats, and
assembly listings.
Chapter 7 describes those directives concerning
macros, macro arguments, and repetitive coding sequences.
MACR0-11 directives can be preceded by a label
(subject to any
restrictions associated with specific directives) and followed by a
comment. A MACR0-11 directive occupies the operator field of a source
statement.

Only

one

directive

can be included in any given source

line. The operand field may be occupied by one or wore operands
left blank; legal operands differ with each directive specified.

CHAPTER 6
GENERAL ASSEMBLER DIRECTIVES

6.1

LISTING CONTROL DIRECTIVES

Several listing control directives are provided in MACR0-11 to control
the
content,
format, and pagination of all line printer and
teleprinter listing output generated during assembly. Facilities also
exist for creating object module names and other identification
information in the listing output.

6.1.1

.LIST and .NLIST Directives

Listing control options can be specified in the text of a MACR0-11
program through the .LIST and .NLIST directives. These directives are
of the form:
.LIST
.LIST
.NLIST
.NLIST
where:

arg

arg
arg
represents one or more of the optional
arguments defined in Table 6-1.

symbolic

As indicated above, the listing control directives may be used without
arguments, in which case, the listing directives alter the listing
level count. The listing level count is initialized to zero (0).
At
each occurrence of a .LIST directive, the listing level count is
incremented; at each occurrence of an .NLIST directive, the listing
level count is decremented. When the listing level count is negative,
the listing is suppressed
(unless the line contains an error).
Conversely, when the listing level count is greater than zero, the
listing is always generated. Finally, when the count is zero (0), the
line is either listed or suppressed, contingent upon the other listing
controls currently in effect for the program.
For example, the
following macro definition employs the .LIST and .NLIST directives to
selectively list portions of the macro body when the macro is
expanded:
.MACRO LT EST
A-THIS LINE SHOULD LIST
.NLIST
B-THIS LINE SHOULD NOT LIST
.NLIST
C-THIS LINE SHOULD NOT LIST
.LIST

;LIST TEST
; LISTING LEVEL COUNT IS 0.
; LISTING LEVEL COUNT IS -1.
;LISTING LEVEL COUNT IS -2.
; LISTING LEVEL COUNT IS -1.

6-1

GENERAL ASSEMBLER DIRECTIVES
D-THIS LINE SHOULD NOT LIST
. LIST
E-THIS LINE SHOULD LIST
.ENDM

;LISTING ~EVEL COUNT IS 0 .
;LISTING LEVEL COUNT IS BACK TO 0.

. LIST
ME
LT EST
A-THIS LINE SHOULD LIST
E-THIS LINE SHOULD LIST

;LIST MACRO EXPANSION .
;CALL THE MACRO
;LISTING LEVEL COUNT IS 0.
;LISTING LEVEL COUNT IS BACK TO 0.

An important purpose of the level count is to allow macro expansions
to be listed selectively and yet exit with the listing level count
restored to the value existing prior to the macro call.
When used with arguments, the listing directives do not alter the
listing level count; however, the .LIST and .NLIST directives can be
used to override current listing control, as shown in the example
below:
.MACRO

.LIST

;LIST NEXT LINE.

.NLIST

;DO NOT LIST REMAINDER OF MACRO
;EXPANSION .

X=.

. ENDM
. NLIST

;DO NOT LIST MACRO EXPANSIONS .

X=.
The allowable symbolic arguments for use with the listing directives
are described in Table 6-1. These arguments can be used singly or in
combination with each other. If multiple arguments are specified in a
listing directive, each argument must be separated by a comma, tab, or
space. For any argument not specifically included in a listing
control statement, the associated default assumption (List or No list)
is applicable throughout the source program. The default assumptions
for the listing control directives also appear in Table 6-1.

6-2

GENERAL ASSEMBLER DIRECTIVES
Table 6-1
Symbolic Arguments of Listing Control Directives
Function

Default

SEQ*

List

Controls the listing of source line
sequence numbers.
If this field is
suppressed
through
an
.NLIST
SEQ
directive, MACR0-11 generates a tab,
effectively allocating space for the
field, but fills the field with blanks.
Thus, the inter-positional relationships
of subsequent fields in the listing
remain undisturbed. During the assembly
process, MACR0-11 examines each source
line for possible error conditions. For
any line in error, an appropriate error
flag is printed preceding the
line
sequence number field (see Appendix D) .

LOC*

List

Controls the listing of the current
location counter field. Normally, this
field is not suppressed. However, if it
is suppressed through the .NLIST LOC
directive, MACR0-11 does not generate a
tab, nor does it allocate space for the
-F;
, ,::i
,,_ .Le..Lu,
as is the case with the source
line
sequence
number
field
(SEQ)
described above. Thus, the suppression
of the current location counter (LOC)
field effectively left-justifies
all
subsequent
fields
(while preserving
inter-positional relationships) to that
position otherwise normally occupied by
this field.

BIN*

List

Controls the listing of generated binary
code.
If this field is suppressed
through
an
.NLIST
BIN
directive,
left-justification of the source code
field occurs
in
the
~ame
manner
described above for the current location
counter (LOC) field.

BEX

List

of
binary
listing
Controls
the
i.e. , the locations and
extensions,
binary contents beyond those that will
fit on the source statement line. This
is a subset of the BIN argument.

SRC*

List

Controls the listing of source lines.

* If the .NLIST arguments SEQ, LOC, BIN, and SRC are in effect at the
same time, i.e., if all four significant fields in the listing are
to be suppressed, the printing of the resulting blank line is
inhibited.

6-3

GENERAL ASSEMBLER DIRECTIVES
Table 6-1 (Cont'd)
Symbolic Arguments of Listing Control Directives
Argument

Default

Function

COM

List

Controls the listing of comments.
This
is a subset of the SRC argument. The
.NLIST COM directive reduces listing
time and space when comments are not
desired.

List

Controls
the
listing
of
macro
definitions and repeat range expansions.

List

Controls the listing of macro calls
repeat range expansions.

No list

Controls
the
expansions.

MEB

No list

Controls the listing of macro expansion
binary code.
A .LIST MEB directive
causes only
those
macro
expansion
statements that generate binary code to
be listed. This is a subset of the ME
argument.

CND

List

Controls the listing of
unsatisfied
conditional coding and associated .IF
and .ENDC directives in the
source
program.
This
argument
permits
conditional assemblies to be
listed
without
including
unsatisfied
conditional coding.

No list

Controls the listing of all listing
directives having no arguments, i.e.,
those listing directives that alter the
listing level count.

TOC

List

Controls the listing of the table of
contents during assembly pass 1 (see
section 6.1.4 describing the
.SBTTL
directive).
This argument does not
affect the printing of the full assembly
listing during assembly pass 2.

SYM

List

Controls the listing of the symbol table
resulting
from the assembly of the
source program.

TTM

List
(Teleprinter
mode)

Controls the listing output format. The
.LIST TTM directive, the default mode,
causes output to be formulated into
teleprinter format
(see Figure 6-2);
the .NLIST TTM directive causes output
to
be formulated into line printer
format (see Figure 6-1).

6-4

listing

and
macro

GENERAL ASSEMBLER DIRECTIVES
Any argument specified in a .LIST/.NLIST directive other than those
listed in Table 6-1 causes the directive to be flagged with an error
code (A) in the assembly listing {see Appendix D).
An example of an assembly listing, as sent to a 132-column line
printer, is shown in Figure 6-1. Note that binary extensions for
statements generating more than one word are formatted horizontally on
the source line.
An example of an assembly listing, as sent to a teleprinter
{in the
same format as for an 80-column line printer), is shown in Figure 6-2.
Notice that binary extensions for statements generating more than one
word are printed on subsequent lines. There is no explicit truncation
of output to 80 characters by the assembler.
The listing control options can also be specified during assembly
through switches included in the command string to MACR0-11 (see
Chapter 8). The use of these switches overrides all corresponding
listing control
(.LIST or .NLIST) directives specified in the source
program.
Figure 6-3 shows a listing, produced in line printer
format,
reflecting the use of the .LIST and .NLIST directives in the source
program and the effects such directives have on the assembly listing
output.

6.1.2

Page Headings

MACR0-11 outputs each assembly page in the format shown in either
Figure 6-1 or Figure 6-2, depending on the listing mode {see TTM,
Table 6-1). On the first line of each page, MACR0-11 prints the
following (from left to right):
1.

Title of the object module, as established through the .TITLE
directive (see next section).

Assembler version identification.

Date.

Time-of-day.

Page number.

The second line of each assembly listing page contains the subtitle
text specified in the last-encountered .SBTTL directive (see section
6.1.4).

6-5

CSITST -- TEST o~ cs11 AND C8I2 MACRO Mli'l107
READ AND PA~SE COMMAND LINES
209
210
211
212
213
214
215
216
211
218
219
220
221
222
223
224
225

°'I
°'

121211230
01211244
01211246
01211254
(:ll;i! 131210
001324
01211326
001332
001336
1211211360
01211404
001412
12101416
01211424
0121145121
2Ui 001474
227
228 001476
229 001502
230 12101504
231 i;hH512
232 01211520
233 001522
234 001!126
235 01211552
236 12101576
237 01211602
238 1210162121
239 1211211622
240 001626
241 001634
242 001636
243 001662
244 001666
245 1211211104
246 00171216
247 01211712
248 01211720
249 001722

09•JUL•74 15147

GETLNI
10312103
1S I

103064
016046
16612116
0661216121
16266121
166060

0121012120
01710004
01210016

00'11021'!

00~002

1211(1001 b

000002

000655
01215760
001652
112767
13276121
01211402
105267

01i'10V'102

251
176432
000001

GC:MLS
BCC
EXITSS
TYPE
CSIS1
BCC
MOV
SUB
TYPE
TYPE
AOD
SUB
SUB
TYPE
TYPEM

•GC:LBLK
1S

TST
BEQ
MOVB

BI TB

176416
OPARSE I

103441
0'110020

0001'101

INCB
TYfo)EM
TVPEM
CALL
CSIS2
BCS
CALL

BITB

BNE
TYPEM
IPARSE1 CALL
C:SIS2
BCS
CALL

10341217
132760
001360
000412

READ ANO PARSE COMMAND LINES

BEQ

105 I

13276121
001360

,SBTTL

000060
12100040

000001

PAGE 5

6ITB

BNE
BR

IGET LINE VIA GCML
JSKIP IF NO ERRO~
IELSt., t.XIT
G,CMLD•2(R0),G,C:M~OCR0),•!0
ISEND OUT THE INPUT LINE
•CSIBLK,GCLBLK+G,CMLD+2,GCLBLK•G,C:ML0
2S
JBRANCH IF NO ERROR DETECTED
C,FILD•2(R0),~CSP)
1PUT STRING ERROR AODR IN STK
C,CMLD•2(w0),(SP)
1CALCULATE LENGTH OF FIRST PART
C,CML0+2CR0), (SP),•IS
JSENO OUT FIRST PART OF STRING
C,FILD+2CR0),C,fILDCR0),•'5
JSENO OUT SECOND PART
C:,FILDCR0) 1 C,FILD•2CR0) JCALC ADDR OF LAST PART OF STRING
(SP)+,C,CML0CR0)
JDEOUCT LENGTH OF FIRST PART
C,FILD(R0),C,CMLDCR0)
JCALC LENGTH OF LAST PA~T
C,FILD•2CR0),C,CML0CR0),•40
JSENO OUT LAST PART
STX,40
JSENO SYNTAX ERROR MESSAGE
GETLN
JTRV FOR MO~E
C,CMLOCR0)
JCHECK LENGTH OF LINE
GETLN
IIF NULL, SKIP BACK FOR NEXT LINE
*'0,EQUBIT
JASSUME EQUAL SIGN NOT FOUND
•CS,EQU,C,STAT(R0)
JCHECK STATUS
105
ISKIP IF EQUAL SIGN NOT SEEN
EQUAIT
IELSE, INDICATE EQUAL SIGN FOUND
EQU,40
JSENO EQUAL SIGN STATUS MESSAGE
OPT,40
ISEND OUTPUT SCAN MESSAGE
INIT2
IINIT LOCNS FOR CSI2 CALL/TEST
,OUTPUT,#SWTBL JPARSt. OUTPUT SPEC
CS2ERR
JSKIP ON ERROR
EVALU8
IEVALUATE RESULTS OF SEMANTIC PARSE
*C:S,MOH,C,STAT(R0)
JADDITIONAL OUTPUT SPECS?
OPARSE
IYES, CONTINUE WITH OUTPUT SCAN
IPT,4~
ISENO INPUT !CAN MESSAGE
INIT2
JINIT LOCNS FOR CSI2 CALL/TEST
,INPUT,•SWTBL
IPA~SE INPUT SPEC
CS2ERR
JSKIP ON ERROR
EVALU8
JEVALUATE RESULTS OF SEMANTIC PARSE
#CS,MOR,C,STAT(R0)
IAODITIONAL INPUT SPECS?
?PARSE
JYES, CONTINUE WITH INPUT SCAN
JMPGET
JGET ANOTHER COMMAND LINE

Figure 6-1
Example of Line Printer Assembly Listing

GENERAL ASSEMBLER DIRECTIVES

CSITST P • TEST OF CSI1 ANO CSI2 MACRO M0707
READ AND PARSE COMMAND LINES
209
211
212
21J
214
215
216
217

12101230
001244
001246
001254
001300
001324
001326

216 001332
219 001336
220 001360
221 001404
222 001412

GE TL NI
103003

103064
016046
000020
166016
000004
066060
00121016
000020
162660

PAGE 5

READ AND PARSE COMMAND LINES

GCM~S
BCC

•GCLBLK
15

DIT!S

15 I

15159

SBTTL

2i0

09~JUL•74

T'(PE
CSIS1
BCC
MOY

JGET LINE VIA GCML
JSKIP IF NO ERROR
JELSE, EXIT
G,CMLD•2(R0),G,CMLDCR0l,•'0
JSEND OUT THE INPUT LIN!
#CSIBLK,GCLBLK•G,CMLD•2,GCLBLK•G,CMLD
2$
JBRANCH IF NO ERROR DETECTED
C,FILD•2CR0),•(SP)
IPUT STRING ERROR AODR IN STK

SUB

ICALCULATE LENGTH OF FIRST PART

TYPE
TYPE
ADD

C,CMLD•2CR0),(SP),#IS
ISENO OUT FIRST PART OF STRING
C,FILD•2CR0),C,FILO(R0),# 1 S
ISEND OUT SECOND PART
C,FILD(R0),C,FILD•2CR0) JCALC ADDR OF LAST PART OF STRII

SUB

CSP)•,C,CMLDCR0)

IDEDUCT LENGTH OF FIRST PART

SUB

C,FILO(R0),C,CMLDCR0)

JCALC LENGTH OF LAST PART

TYPE
TVPEM
BR

C,FILD•2(Re),C,CMLD(R0) 1 #40
JSEND OUT LAST PART
STX,40
JSENO SYNTAX ERROR MESSAGE
GETLN
JTRV FOR MORE

TST

C,CMLDCR0)

JCHECK LENGTH OF LINE

BEQ
MOVB

GE TLN

*'0,EQUBIT

JIF NULL, SKIP BACK FOR NEXT LINE
JASSUME EQUAL SIGN NOT FOUND

BITB

•Cs,Eau,C,STAT(R0)

BEQ
INCB

EQUBIT

JSKIP IF EQUAL SIGN NOT SEEN
JELSE, INDICATE EQUAL SIGN FOUND

TYPEM
TVPEM
CALL
CSIS2
BCS
CALL

EQU,40
OPT,40
lNIT2
,OUTPUT,#SwTBL
CS2ERR
EV ALU8

JSEND EQUAL SIGN STATUS MESSAGE
JSENO OUTPUT SCAN MESSAGE
JINii LOCNS FOR CSI2 CALL!iESi
JPARSE OUTPUT SPEC
JSKIP ON ERROR
JEVALUATE RESULTS OF SEMANTIC PARSE

BITB

#CS,MOR,C,STAT(R0)

BNE
TYPEM
CALL
CSIS2
BCS
CALL
BITB

OPARSE

BNE

I PARSE

000002

223 001416
224 001424
225 0014~0
226 001474
227
228 001476
229 0015'1!2
230 001504
231 001512
232 001520
233 001522
234
235
236
237
238
239

166060
000016
000002
000655
01115760
000002
001fl52
112767
000060
176432
132760
000040
000001
001402
105267
176416

2!1

1051

001526
001552
001576

OPARSE I

0~1602

001620
001622

240 001626

103441
132760

U'l $

JCHECK STATUS

JADDIT!ONAL OUTPUT SPECS?

000020

241
242
243
244
245
246
247

liH1l1634
001636
001662
01211666
0eJ1704
001706
001712

248 01211720

00121001
001360
I PARSE I
10341217
132760
1210121020
00121001
001360

JYES, CONTINUE wITH OUTPUT SCAN
JSEND INPUT SCAN MESSAGE
INIT2
JINIT LOCNS FOR CSI2 CALLIT~Si
,INPUT,•SwTBL
JPARSE INPUT SPEC
CS2ERR
JSKIP ON ERROR
EVALU8
JEVALUATE RESULTS OF SEMANTIC PARSE
#CS,MOR,C,STAT(R0)
JADDITIONAL INPUT SPECS?
IPT,4~

JYES, CONTINUE wITH INPUT SCAN

Figure 6-2
Example of Terminal Assembly Listing

6-7

27
28

29 000062

000062
000070

000001
000004

000002
000005

000003

30
3l
32 000074
00007•

000001

000002

000003

LSTMAC
I NLI s T
, WORD

COM
COM
l.2,3,4,5

,LIST

COM

LSTMi\C
,NLI ST
1 1110RD
IL.. Is T

<COM,BEX>
COM,BEX
l,2,3,4,5
COM,8EX

JCOMMENT LINES TEST

JCOMMENT LINES AND EXTENDED BINARY TEST

G1
t'Ij

zt'Ij

t-1

,MAIN,

MACRO M0707

09 .. JUL .. 74 16129

?AGE l •l

:t>'
(/)
(/)

°'I
CX)

t'Ij

33
34
35
36
37
J8 000106
000106
000110
000112
000 ll 4
000116

...::..
"""'

,LIST

TTM

JNARROW

LISTI~G

MOOE IS IN EFFECT

000001
000002
ia00003
000004
11100005

LSTMAC
, NLI ST
,wORO

SEQ

JSEQUENCE NUMBERS TEST

SEQ
1,2,J,•,5

JTHIS IS A COMMENT

()

1-:3
H

,LIST

SEQ

000001

LSTMAC
,NLIST
,WORD
,LI ST

BEX
BEX
i.2,J,4,5
BEX

00000 l I

,ENO

41 000120

42
43
44

t'Ij

!;U

<:
t'Ij

39
40
000120

to
t-1

JEXTENDED BINARY TEST
JTHJS IS A COMMENT

Figure 6-3
Listing Produced With Listing Control Directives

MAilll,

MACRO M0707

09•JUL•74 16129

PAGE 1
I NLIS1'
,LIST

l
2
J
4

TT"1
ME

J wIDE LISTI NG MOOE IS IN EFFECT
J LIST MACRO EXPANSIONS

L.:CSTING CONlROL TEST MACRCl

5
6

I "'ACRC:I
, NLI ST
1 w0Ro
, LIST
, ElllDM

8
9

11
12
13
14

1..STMAC ARG
ARG
l.2,J,4,5
ARG

JTHIS IS A COMMENT

16
p 000012
I

000001
000004

000002
000005

000003

NL.X ST

,wOFW

l..STMAC L.OC
L.OC:
1, 2. 3, 4, 5
,LI ST

LOC

LST"'AC

BIN

Jl..OCATION COUNTER TEST
I THIS

IS A COMMENT

18
19

°'I
'°

20 000024

,NLIST
,1110RD

000024

BIN
11 2 I J,, 4 I 5

21
22
23 000036
000036

000001

000002

0000021

JGENERATED BINARY TEST

JTHI S IS A COMMENT
BIN
,LIST
1..STMAC
, NL! ST
,WORD
,LIST

BEX

JEXTElllDED BINARY TEST

BEX
11 2 I 3 I 4 I!)
BEX

inns IS A COMMENT

LST"1AC

SRC

JSOURCE LINES TEST

, I.. I ST

SRC

25
26 000050
000050
000056

000001
000004

000002

00000~1

000005

Figure 6-3 (Cont'd)
Listing Produced With Listing Control Directives

GENERAL ASSEMBLER DIRECTIVES
6.1.3

.TITLE Directive

The .TITLE directive is used to assign a name to the object module as
the first entry in the header of each page in the assembly listing.
The name so assigned is the first six non-blank characters following
the .TITLE directive. This name should be six Radix-SO characters or
less in length; any characters beyond the first six are checked for
ASCII legality, but they are not used by MACR0-11 as part of the
object module name. For example, the directive:
.TITLE

PROGRAM TO PERFORM DAILY ACCOUNTING

causes the assembled object module to be named PROGRA.
(It should be
noted that this 6-character name bears no relationship to the file
name of the object module, as specified in the command string to
MACR0-11.) The name of an object module appears in the Task Builder
load map. This is also the module name which the Librarian will
recognize.
If the .TITLE directive is not specified, MACR0-11 assigns the default
name .MAIN. to the object module. If more than one .TITLE directive
is specified in the source program, the last
such
directive
encountered establishes the name for the entire object module.

6-10

GENERAL ASSEMBLER DIRECTIVES
All spaces and/or tabs up to the first non-space/non-tab character
following the .TITLE directive are ignored by MACR0-11 when evaluating
the text string.
If the .TITLE directive is specified without an object module name, or
if the first non-space/non-tab character in the object module name is
not a Radix-50 character, the directive is flagged with an error code
(A) in the assembly listing (see Appendix D).
A table of Radix-50 characters is provided in section A.2 of
A.

6.1.4

Appendix

.SBTTL Directive

The .SBTTL directive is used to provide the elements for a printed
table of contents immediately preceding the assembly listing and to
further identify each page in the listing. In the latter case, the
text following the .SBTTL directive is printed as the second line of
the header of each page in the listing, continuing until altered by
the next occurrence of a .SBTTL directive in the program. For
example, the directive:
.SBTTL

CONDITIONAL ASSEMBLIES

causes the text

CONDITIONAL ASSEMBLIES
to be printed as the
listing.

second

line

the

header

the

assembly

During assembly pass 1, a table of contents is printed for the
assembly listing, containing the line sequence number, the page
number, and the text accompanying each .SBTTL directive. The listing
of the table of contents is suppressed whenever an .NLIST or
.NLIST TOC directive is encountered in the source program
(see Table
6-1).
An example of a table of contents listing is shown in Figure
6-4.

CSITST ~- TEST OF CS!1 ANO CSI2 MACRO
TABLE OF CONTENTS
2• 55
3• 74

4•153
5•209
6•255
7•345

~0707

09•JUL•74 15141

MACRO DEFINITIONS
MESSAGE STRINGS
MISCELLANEOUS DATA
READ AND PARSE COMMAND LINES
EVALUATE THE SEMANTIC ANALYSIS
SUBROUTINES

Figure 6-4
Assembly Listing Table of Contents

6-11

GENERAL ASSEMBLER DIRECTIVES
6.1.5

.IDENT Directive

The .IDENT directive provides an additional means of labeling the
object module produced by MACR0-11.
In addition to the name assigned
to the object module with the .TITLE directive (see section 6.1.3), a
character string up to six Radix-50 characters in length can be
specified between paired printing delimiters to label the object
module with the program version number. This directive takes the
following form:
.IDENT
where:

/string/

string

represents a string of
six
legal
Radix-50
characters or less which establishes the program
version number. This number is included in the
global symbol directory of the object module.

represent delimiting characters. These delimiters
may be any paired printing characters, other than
the equal sign {=), the left angle bracket {<), or
the semicolon
{;), as long as the delimiting
character is not repeated within the text string
itself.
If the delimiting characters do not
match, or if an illegal delimiting character is
used, the
.IDENT directive is flagged with an
error code
(A)
in the assembly listing
{see
Appendix D) .

An example of the .IDENT directive is shown below:
.IDENT

/V05A/

The character string V05A is converted to Radix-50 representation and
included in the global symbol directory of the object module. This
character string also appears in the Task Builder load map and the
Librarian directory listings.
When more than one .IDENT directive is encountered in a given program,
the last such directive encountered establishes the character string
which forms part of the object module identification.

6.1.6

.PAGE Directive/Page Ejection

A page eject operation in a MACR0-11 assembly listing is
in one of four ways:

accomplished

After reaching a count of 58 lines in the listing, MACR0-11
automa~ically
performs a page eject to skip over page
perforations on line printer paper
and
to
formulate
teleprinter output into pages.

In addition, the .PAGE directive is used within the source
program to perform a page eject at desired points in the
listing. The format of this directive is:
.PAGE

6-12

GENERAL ASSEMBLER DIRECTIVES
This directive takes no arguments and causes a skip to the
top of the next page when encountered. It also causes the
page number to be incremented. The .PAGE directive does not
appear in the iisting.
When used within a macro definition, the .PAGE directive is
ignored during the assembly of the macro definition. Rather,
the page eject operation is performed as the macro itself is
expanded. In this case, the page number is also incremented.

6.2

When encountering a form-feed character, a page eject is
performed. If the form-feed character appears within a macro
definition, a page eject occurs during the assembly of the
macro definition, but not during the expansion of the macro
itself. A page eject resulting from the use of the form-feed
character likewise causes the page number to be incremented.

Encountering a new source file causes the page number
incremented and the line sequence count to be reset.

FUNCTION DIRECTIVES:

.ENABL AND .DSABL

Several function control options are provided by MACR0-11 through the
.ENABL and .DSABL directives.
These directives are included in a
source program to invoke or inhibit certain MACR0-11 functions and
operations
incident
to the assembly process itself.
Using a
3-character symbolic argument to designate a desired function,
these
directives take the following form:
.ENABL
.DSABL
where:

arg
arg

arg

represents one or more of the optional
arguments defined in Table 6-2.

symbolic

Table 6-2
of Function Control Directives

Symbolic

Argument

Default

Function

ABS

Disable

Enabling this function produces absolute
binary output.

AMA

Disable

Enabling this
function
causes
all
relative addresses (address mode 67) to
be assembled as
absolute
addresses
(address mode 37).
This function is
useful during the debugging phase of
program development.

CDR

Disable

Enabling this function causes source
columns 73 and greater, i.e., to the end
of the line, to be treated as a comment.
The most common use of this feature is
to permit sequence numbers in
card
columns 73-80.

6-13

GENERAL ASSEMBLER DIRECTIVES
Table 6-2 (Cont'd)
Symbolic Arguments of Function Control Directives
Function

Argument

Default

FPT

Disable

Enabling this function causes floating- I
point
truncation;
disabling
this I
function causes floating-point rounding.

Disable

Enabling this function causes MACR0-11
to accept lower case ASCII input instead
of converting it to upper case. If this
function is not enabled, all text is
converted to upper case.

LSB

Disable

This argument permits the enabling or
disabling
of a local symbol block.
Although a local
symbol
block
is
normally established by encountering a
new symbolic label or a .PSECT directive
in the source program, an .ENABL LSB
directive establishes a new local symbol
block which is not terminated until
another
symbolic
label
or
.PSECT
directive is encountered following a I
paired .DSABL LSB directive.

LSB

Disable

Although the
.ENABL
LSB
directive
permits a local symbol ~lock to cross
.PSECT boundaries, local symbols cannot
be defined in a program section other
than that which was in effect when the
block was entered. The basic function I
of this directive
with
regard
to
.PSECT's is limited to those instances
where it is desirable to leave a program
section temporarily to
store
data,
followed by a return to the original
program section.
Attempts to define
local symbols in an alternate program
section are flagged with an error code
(P)
in
the
assembly listing
(see
Appendix D).
An example of the .ENABL LSB and .DSABL
LSB directives, as typically used in a
source program, is shown in Figure 6-5.

PNC

Enable

Disabling this function inhibits binary
output until an .ENABL PNC statement is
encountered within the same module.

6-14

GENERAL ASSEMBLER DIRECTIVES
Table 6-2 (Cont'd)
Symbolic Arguments of Function Control Directives
Argument

Default

Function

REG

Enable

When specified, the .DSABL REG directive
inhibits the normal MACR0-11 default
register definitions; if not disabled,
the default definitions listed below
remain in effect.

REG

Enable

R0=%0
Rl=%1
R2=%2
R3=%3
R4=%4
R5=%5
SP=%6
PC=%7
The .ENABL REG statement may be used as
the logical complement of the .DSABL REG
directive. The use of these directives,
however,
is
not
recommended.
For
logical consistency,
the
programmer
should use the normal default register
definitions listed above.

I
GBL

Enable

When the .ENABL
GBL
directive
is
specified, MACR0-11 treats all symbol
references that are undefined at the end
of assembly pass 1 as default global
references;
when
the
.DSABL
GBL
directive is specified, MACR0-11 treats
all
such
references
as
undefined
symbols.
In assembly pass 2, if the
.DSABL GBL function is still in effect,
these undefined symbols are flagged with
an error code
(U)
in the
assembly
listina
<see Aooendix D); otherwise,
th~y-~~ntinue to-be regarded by MACR0-11
as global references.

Any argument specified in an .ENABL/.DSABL directive other than those
listed in Table 6-2 causes that directive to be flagged with an error
code (A) in the assembly listing (see Appendix D).

6-15

GENERAL ASSEMBLER DIRECTIVES

SQUEEZE MACRO M0707
272
273
274
275
276
277
2''8 003142
279 01213144
280

0~3146

281
282
283
284
285
286
287

003150
0031!52
003156
003160
0~3162

003164

288 003166

289
290
291
292
293
294
295
296
297
298

003170
003172
003176
003200
003204
003206
003210
003212
003214
0tiJ3216
299 003220
300
J01
302

09•JUL•74 15' 1 J

PAGE

,ENABL
010103
060203
020301
001422
124327
001373
010302
000412
060102
020201
001412
124227
001773
121227
001770
005202
160102
000241
000401
000261

000073

000011
0~0040

LSB

FNDSMI I MOV
ADO
CMP
1S I
BEQ
CMPB
BNE
MQV
BR

Fq ,R3

SKPBLKI ADO
CMP
10Sr
BEQ
CMPB
BEQ
CMPB
BEQ
!NC
2051
SUB
CLC
BR
30S1
SEC
4(c)S I
RE TURI-<
,DSABL

Rt,R2
R2,R1
305
-CR2),#TAB

R2,R3
R3,R1
305
•CRJ),•SEMIC
ts

RJ,R2
205

UlS

(R2) 1 1111BLANK
10$
R2
Rt,R2
405
LSB

JPUT ADDR OF LINE IN R3
JPOINT R3 PAST LAST CMAR IN LI
JOOES RJ POINT TO START OF LIN
JIF SO, LEAVE INDICATING FAILU
JIS TME LAST CHARACTER SEMICO~
JNO, CONTINUE LOOKING
JYES, POINT R2 PAST NEW END•OF
JLEAVE VIA COMMON SUCCESS CODE
JPOINT R2 PAST ENO•OF•LINE
JDOES R2 POINT TO START OF LIN
IIF SO, LEAVE WITH FAILURE
JIS THE LAST CHARACTER A TAB?
JIF SO, IGNORE IT
J IS IT A BLANK?
IIF SO, IGNORE IT
JNON•BLANK CHARACTER••POINT PA
JRE•COMPUTE LINE LENGTH
JINDICATE SUCCESS
JBRANCH TO LEAvt:.
IINDICATE FAILURE

Figure 6-5
Example of .ENABL and .DSABL Directives

6.3

DATA STORAGE DIRECTIVES

A wide range of data and data types can be generated with the
following directives, ASCII conversion characters, and radix-control
operators:
.BYTE
.WORD
.ASCII
.ASCIZ
.FLT2
.FLT4
.RAD50
"B
"D
"p

These MACR0-11 facilities are described in the following sections.

6-16

GENERAL ASSEMBLER DIRECTIVES
6.3.1

.BYTE Directive

The .BYTE directive is used to generate successive bytes
data in the object module.
The directive is of the form:

binary

.BYTE

exp

;WHICH STORES THE BINARY VALUE
;OF THE EXPRESSION "EXP" IN THE NEXT
;BYTE.

.BYTE

expl,exp2,expn

;WHICH STORES THE BINARY VALUES
;OF THE LIST OF EXPRESSIONS IN
;SUCCESSIVE BYTES.

A legal expression must reduce to eight bits of data or less.
The
operands of a .BYTE directive are evaluated as word expressions before
being truncated to the low-order eight bits.
The 16-bit value of the
specified expression must have a high-order byte (which is truncated)
that is either all zeros (0) or all ones (1).
Each expression value
is
stored
in the next byte of the object module.
Multiple
expressions, which must be separated by commas,
are stored in
successive bytes, as illustrated and described below:
SAM=S
.=410
.BYTE

"D48,SAM

;THE VALUE 060 (OCTAL EQUIVALENT OF 48
;DECIMAL) IS STORED IN LOCATION 410.
;THE VALUE 005 IS STORED IN LOCATION
; 411.

If the high-order byte of the expression reduces to a value other than
0 or -1,
the value is truncated to the low-order eight bits and
flagged with an error code (T) in the assembly listing
(see Appendix
D) •

The construction "D in the first operand of the .BYTE directive above
reflects the use of a temporary radix-control operator.
The function
of such special unary operators is described in detail
in section
6.4.1.2.
At link time, it is likely that a relocatable expression will
result
in a value having more than eight bits, in which case, the Task
Builder issues a
truncation diagnostic for
the object module in
question.
For example,
the following statements induce such a
possibility:
.BYTE

;STORES OCTAL 23 IN NEXT BYTE.

.BYTE

;RELOCATABLE VALUE A WILL PROBABLY
;CAUSE TASK BUILDER TRUNCATION
;DIAGNOSTIC.

If an expression following
the
.BYTE directive is null,
interpreted as a zero, as illustrated and described below:

.=420
.BYTE

'''

;ZEROS ARE STORED IN BYTES 420, 421,
;422, AND 423.

Note in the above example, that four bytes of storage result from the
.BYTE directive.
The three commas in the operand field represent an
implicit declaration of four null
values,
each separated from the
other by a comma.
Hence, four bytes, each containing a value of zero
(0), are reserved in the object module.

6-17

GENERAL ASSEMBLER DIRECTIVES
6.3.2

.WORD Directive

The .WORD directive is used to generate successive words
the object module.
The directive is of the form:

data

.WORD

exp

;WHICH STORES THE BINARY EQUIVALENT
;OF THE EXPRESSION EXP IN THE NEXT
;WORD.

.WORD

expl,exp2,expn

;WHICH STORES THE BINARY EQUIVALENTS
;OF THE LIST OF EXPRESSIONS IN
;SUCCESSIVE WORDS.

A legal expression must result in 16 bits of data or less.
Each
expression is stored in the next word of the object program. Multiple
expressions must be separated by commas and stored in successive
words, as shown in the following example:
SAL=O
.=500
.WORD

177535,.+4,SAL

;STORES THE VALUES 177535, 506, AND
;0 IN WORDS 500, 502, AND 504,
;RESPECTIVELY.

If an expression following the .WORD directive contains a null value,
it is interpreted as a zero, as shown in the following example:
.=500
.WORD

, 5,

;STORES THE VALUES 0, 5, AND 0 IN
;LOCATION 500, 502, AND 504,
;RESPECTIVELY.

A statement containing a blank operator field, i.e., a symbol that is
not recognized by MACR0-11 as a macro call, an instruction nmemonic, a
MACR0-11 directive, or a semicolon is currently interpreted during
assembly as an implicit
.WORD directive, as shown in the example
below:
.=440
LABEL:

100,LABEL

;THE VALUE 100 IS STORED IN LOCATION
;440 AND THE VALUE 440 IS STORED IN
;LOCATION 442.

The implicit use of the .WORD directive in this manner is discouraged,
since this convention may not be the default case in future PDP-11
assemblers.

6.3.3

ASCII Conversion Characters

The single quote (') and the double quote
(")
characters are unary
operators that can appear in any MACR0-11 expression. When so used,
these characters cause a 16-bit expression value to be generated.
When the single quote is used, MACR0-11 takes the next character
in
the expression and converts it from its 7-bit ASCII value to a 16-bit
expression value.
The 16-bit value is then used as an absolute term
within the expression.
For example, the statement:
MOV

#'A,RO

6-18

GENERAL ASSEMBLER DIRECTIVES
results in the following 16-bit
register 0:

expression

value

being

moved

into

00000000 01000001
Binary Value of ASCII A

Thus, in the example above, the expression 'A results in a value of
101(8).
It should be noted that the high-order byte is always zero
(0) in the resulting expression value when the single quote unary
operator is used.
The ' character must not be followed by a carriage-return, null,
RUBOUT, line-feed, or form-feed character; if it is, an error code
(A) is generated in the assembly listing (see Appendix D).
When the double quote is used, MACR0-11 takes the next two characters
in the expression and converts them to a 16-bit binary expression
value from their 7-bit ASCII values. This 16-bit value is then used
as
an absolute term within the expression.
For example, the
statement:
MOV

#"AB,RO

results in the following 16-bit
register 0:

expression

value

being

moved

into

Binary Value of ASCII A
'--Binary Value of ASCII B

Thus, in the example above, the expression "AB results in a
041101 (8).

value

The " character also must not be followed by a carriage-return, null,
RUBOUT, line-feed, or form-feed character; if it is, an error code
(A) is likewise generated in the assembly listing (see Appendix D).
The ASCII character set is listed in section A.l, Appendix A.

6.3.4

.ASCII Directive

The .ASCII directive translates character strings into their 7-bit
ASCII equivalents and stores them in the object module. The format of
the .ASCII directive is as follows:
.ASCII
where:

/string l/ .•. /string n/

string

is a string of printable ASCII characters.
are
legal.
printable ASCII characters

6-19

All

The

GENERAL ASSEMBLER DIRECTIVES

vertical-tab, null, line-feed, RUBOUT, and all
other non-printable ASCII
characters,
except
carriage-return
and
form-feeo,
are
illegal
characters.
Such
an
illegal
non-printing
character is flagged with an error code (I) in the
assembly
listing
(see
Appendix
D).
The
carriage-return and form-feed characters terminate
the scan of the source line.
This premature
termination of the .ASCII statement results in the
generation of an error code (A)
in the assembly
listing, because MACR0-11 is unable to complete
the scan of the matching delimiter at the end of
the character string.

represent delimiting characters. These delimiters
may be any paired printing characters, other than
the equal sign (=), the left angle bracket (<), or
the semicolon
(;), as long as the delimitinq
character is not repeated within the text string
itself.
If the delimiting characters do not
match, or if an illegal delimiting character is
used, the .ASCII directive is flagged with an
error code
(A)
in the assembly listing
(see
Appendix D).

A non-printing character can be expressed in an .ASCII statement
by enclosing its equivalent octal value within anqle brackets.
set of angle brackets so used represents a single character.
example, in the following statement:
.ASCII

only
Each
For

<15>/ABC/<A+2>/DEF/<5><4>

the expressions <15>, <A+2>, <5>, and <4> represent the values of
non-printing characters. Furthermore, the expressions must reduce to
eight bits of absolute data or less, subject to the same rules for
generating data as with the .BYTE directive (see section 6.3.1).
Angle brackets can be embedded between delimiting characters in the
character string, but angle brackets so used do not take on their
usual significance as delimiters for non-printing characters.
For
example, the statement:
.ASCII

/ABC<expression>DEF/

contains a single ASCII character string, and performs no evaluation
of the embedded, bracketed expression. This use of the angle brackets
is reflected in the third example of the .ASCII directive illustrated
below:
;STORES THE BINARY REPRESENTATION
;OF THE LETTERS HELLO IN FIVE
;CONSECUTIVE BYTES .

.ASCII

/HELLO/

. ASCII

/ABC/<15><12>/DEF/ ;STORES THE BINARY REPRESENTATION
;OF THE CHARACTERS A,B,C,CARRIAGE
;RETURN,LINE FEED,D,E,F IN EIGHT
;CONSECUTIVE BYTES .

. ASCII

/A<l5>B/

;STORES THE BINARY REPRESENTATION
;OF THE CHARACTERS A, <, 1, 5, >,
;AND B IN SIX CONSECUTIVE BYTES.
6-20

GENERAL ASSEMBLER DIRECTIVES
The semicolon (;) and equal sign
(=) can be used as delimiting
characters in an ASCII string, but care must be exercised in so doing
because of their significance as a comment indicator and assignment
operator, respectively, as illustrated in the examples below:
.ASCII

;ABC;/DEF/

;STORES THE BINARY REPRESENTATION OF
;THE CHARACTERS A, B, C, D, E, AND F
;IN SIX CONSECUTIVE BYTES; NOT
;RECOMMENDED PRACTICE .

. ASCII

/ABC/;DEF;

;STORES THE BINARY REPRESENTATIONS OF
;THE CHARACTERS A, B, AND C IN THREE
;CONSECUTIVE BYTES; THE CHARACTERS D,
;E, F, AND ; ARE TREATED AS A COMMENT •

. ASCII

/ABC/=DEF=

;STORES THE BINARY REPRESENTATION
;OF THE CHARACTERS A, B, C, D, E, AND
;F IN SIX CONSECUTIVE BYTES; NOT
;RECOMMENDED PRACTICE.

An equal sign is treated as an assignment operator when it appears as
the first character in the ASCII string, as illustrated by the
following example:
.ASCII

6.3.5

=DEF=

;THE DIRECT ASSIGNMENT OPERATION
;.ASCII=DEF IS PERFORMED, AND A Q
; (SYNTAX) ERROR IS GENERATED UPON
;ENCOUNTERING THE SECOND = SIGN.

.ASCIZ Directive

The .ASCIZ directive is equivalent to the .ASCII directive described
above, except that a zero byte is automatically inserted as the final
character of the string. Thus, when a list or text string has been
created with an .ASCIZ directive, a search for the null character in
the last byte can effectively determine the end of the string, as
reflected by the coding below:
CR=l5
LF=l2
HELLO:

10$:

.ASCIZ
.EVEN

MOV
MOV
MOVE
BNE

#HELLO,Rl
#LINBUF ,R2
(Rl)+, (R2)+

10$

;INTRODUCTORY MESSAGE

;GET ADDRESS OF MESSAGE.
;GET ADDRESS OF OUTPUT BUFFER.
;MOVE A BYTE TO OUTPUT BUFFER.
;IF NOT NULL, MOVE ANOTHER BYTE.

The .ASCIZ directive is subject to the same checks for character
legality and proper character string construction as described above
for the .ASCII directive.

6-21

GENERAL ASSEMBLER DIRECTIVES
6.3.6

.RADSO Directive

The .RADSO directive allows the user to generate data in Radix-SO
packed format.
Radix-SO form allows three characters to be packed
into sixteen bits (one word); therefore, any 6-character symbol can
be stored in two consecutive words. The form of the directive is:
.RADSO
where:

/string l/ ... /string n/

string

represents a series of characters to be packed
(three characters per word).
The string may
consist of the characters A through Z, 0 through
9, dollar sign($), period(.) and space ( ).
An
illegal printing character causes an error flag
(Q)
to be printed in the assembly listing (see
Appendix D).
If fewer than three characters are to be packed,
the string is packed left-justified within the
word, and trailing spaces are assumed.
As with the .ASCII directive described in section
6.3.4, the presence of the vertical:tab, null,
line-feed, RUBOUT, and all other non-printing
characters, except carriage-return and form-feed,
are illegal characters, resulting in an error code
(I)
in the assembly listing.
Similarly, the
carriage-return and form-feed characters result in
an error code (A) because these characters end the
scan of the line, preventing
MACR0-11
from
detecting the terminating matching delimiter.

represent delimiting characters. These delimiters
may be any paired printing characters, other than
the equal sign (=), the left angle bracket (<), or
the semicolon (;), provided that the delimiting
character is not repeated within the text string
itself.
If the delimiting characters do not
match, or if an illegal delimiting character is
used, the .RADSO directive is flagged with an
error code
(A)
in the assembly listing
(see
Appendix D).

Examples of .RADSO directives are shown below:
.RADSO
. RAD50
. RADSO

/ABC/
/AB/
/ABCD/

;PACKS ABC INTO ONE WORD .
;PACKS AB (SPACE) INTO ONE WORD .
;PACKS ABC INTO FIRST WORD AND
; D (SPACE) (SPACE) INTO SECOND WORD.

Each character is translated into
indicated in the following table:
Character
(space)
A-Z
$

(undefined)
0-9

its

Radix-SO

Raoix-c::io Octal Equivalent

1-32
33
34
3S
36-47

6-22

equivalent,

GENERAL ASSEMBLER DIRECTIVES
The Radix~SO equivalents for characters l
combined as follows:
Radix-50 Value

through

(Cl,C2,C3)

are

((Cl*50)+C2)*50+C3

For example:
Radix-50 Value of ABC= ((1*50)+2)*50+3 = 3223
Refer to section
equivalents.

A.2

Appendix

for

table

Radix-SO

Angle brackets (<>) must be used in the .RADSO directive whenever
special codes are to be inserted in the text string, as shown in the
example below:
.RAD SO

;STORES 3255 IN ONE WORD=

CHRl=l
CHR2=2
CHR3=3

.RADSO

6.4

6.4.l

<CHRl><CHR2><CHR3> ;EQUIVALENT TO .RAD50 /ABC/.

RADIX AND NUMERIC CONTROL FACILITIES

Radix Control and Unary Control Operators

The normal default assumption for numeric values or expression values
appearing in a MACR0-11 source program is octal. However, numerous
instances may occur where an alternate radix is useful for portions of
a program or for variables within a given statement. It may be
useful, for example, to declare a given radix for applicability
throughout a program or to specify a numeric value or expression value
in a manner that causes it to be interpreted as a binary, octal, or
decimal value during assembly.
In other such instances, it may be
useful to complement numeric values or expression values.
These
MACR0-11 facilities are described in the following sections.
NOTE
When two or more unary operators appear together,
modifying
the
same term, the operators are
applied, from right to left, to the term.

6.4.1.l .RADIX Directive - Numbers used in a MACR0-11 source program
are initially considered to be octal values; however, the programmer
has the option to declare any one of the following radices for
applicability
throughout the source program or within specific
portions of the program:
2, 4, 8, 10

6-23

GENERAL ASSEMBLER DIRECTIVES
This is accomplished via a .RADIX directive of the form:
.RADIX
where:

represents one of the four acceptable radices
listed above. If the argument n is not specified,
the octal default radix is assumed.

The argument in the .RADIX directive is always interpreted as a
decimal value.
Any alternate radix declared in the source program
through the .RADIX directive remains in effect until altered by the
occurrence of another such directive, i.e., a given radix declaration
is valid throughout a program until changed.
For example, the
statement:
.RADIX

. RADIX

;BEGINS A SECTION OF CODE HAVING A
;DECIMAL RADIX.

;REVERTS TO OCTAL RADIX .

Any value other than null, 2, 4, 8, or 10 specified as an argument in
the .RADIX directive causes an error code (A) to be generated in the
assembly listing (see Appendix D).
In general, it is recommended that macro definitions not contain or
rely on radix settings established with the .RADIX directive. Rather,
temporary radix control operators should be used within a macro
definition.
Where a possible radix conflict exists within a macro
definition or in possible future uses of that code, it is recommended
that the user specify numeric or expression values using the temporary
radix control operators described below.

6.4.1.2 Temporary Radix Control Operators: AD, AO, and AB - Once the
user has specified a given radix for a section of code or has decided
to use the default octal radix, he may discover a number of cases
where an alternate radix is more convenient or desirable (particularly
within macro definitions). The creation of a mask word, for example,
might best be accomplished through the use of a binary radix.
MACR0-11 has three unary operators which allow the user
an alternate radix, as shown below:
ADx
AOx
ABx

establish

(x is evaluated as a decimal number)
(x is evaluated as an octal number)
(x is evaluated as a binary number)

Thus, an alternate radix can be declared temporarily to meet a
localized requirement in the source program. Such a declaration can
be made at any time, regardless of the existence of the default octal
radix or another specific radix declaration elsewhere in the program.
In other words, the effect of a temporary radix control operator is
limited to the term or expression immediately following the operator.
Any value specified in connection with a temporary radix control
operator is evaluated during assembly as a 16-bit entity. Temporary
radix control declarations can be included in the source program
anywhere a numeric value is legal.

6-24

GENERAL ASSEMBLER DIRECTIVES
The expressions below are representative of the methods of
temporary radix control operators:
AD123
Ao 47
AB 00001101
AO<A+l3>

specifying

Decimal radix
Octal Radix
Binary Radix
Octal Radix

Note that the up-arrow and the radix control operator may not be
separated, while the radix control operator and the following term or
expression can be physically separated by spaces or tabs
for
legibility or formatting purposes. A multi-element term or expression
that is to be interpreted in an alternate radix should be enclosed
within angle brackets, as shown in the last of the four temporary
radix control expressions above.
The following example also reflects the use of angle brackets to
delimit an expression that is to be interpreted in an alternate radix:
.RADIX

.WORD

AO<A+lO>*lO

A=lO
When the temporary radix expression in the .WORD directive above is
evaluated, it effectively yields the following equivalent statement:
.WORD

180.

MACR0-11 also allows a temporary radix change to decimal using another
convention.
This change is accomplished by specifying a number,
immediately followed by a decimal point (.), as shown below:
100.
1376.
128.

Equivalent to 144(8)
Equivalent to 2540(8)
Equivalent to 200(8)

The above expression forms are equivalent in function to those
below:

listed

ADlOO
AD1376
AD128

6.4.2

Numeric Directives and Unary Control Operators

Two storage directives and two numeric control operators are available
to simplify the use of the floating-point hardware on the PDP-11.
These facilities, described in the
following
sections,
allow
floating-point data to be created in the program, and numeric values
to be complemented or treated as floating-point numbers.
A floating-point number is represented by a string of decimal digits.
The string (which can be a single digit in length) may optionally
contain a decimal point, and may be followed by an optional exponent
indicator in the form of the letter E and a signed decimal integer
exponent. The number may not contain embedded blanks, tabs or angle
brackets and may not be an expression. Such a string will result in
one or more errors (A or Q) in the assembly listing (See Appendix D) .

6-25

GENERAL ASSEMBLER DIRECTIVES
The list of numeric representations below contains seven
valid representations of the same floating-point number:

distinct,

3
3.

3.0
3.0EO
3EO
.3El
300E-2
As can be inferred, the list could be extended indefinitely (e.g.,
3000E-3, .03E2, etc.). A leading plus sign is optional (e.g., 3.0 is
considered to be +3.0). A leading minus sign complements the sign
bit. No other operators are allowed (e.g., 3.0+N is illegal).
All floating-point numbers are evaluated as 64 bits in
format:
64

EEEEEEEE

the

following

MMM ..... MMM
Mantissa
Exponent
Sign

(55 bits)
(8 bits)
(1 bit)

MACR0-11 returns a value of the appropriate size and precision via one
of
the floating-point directives.
The values returned may be
truncated or rounded (See Section 6.2).
Floating-point numbers are normally rounded.
That is, when
a
floating-point number exceeds the limits' of the field in which it is
to be stored, the high-order bit of the unretained·word is added to
the low-order bit of the retained word, as shown below. For example,
if the number is to be stored in a 2-word field, but more than 32 bits
are needed to express its exact value, the highest bit (32) of the
unretained field is added to the least significant bit (0) of the
retained field (See illustration below). The .ENABL FPT directive is
used to enable floating-point truncation;
.DSABL FPT is used to
return to floating-point rounding (see Table 6-2).
Bit
32

Bit
0
Retained
field

Bit
32 31

T
I
I

Bit
0

Unretained
field

Note that all numeric
operands
in
PDP-11/45
and
PDP-11/70
floating-point instructions are automatically evaluated as single-word
decimal, floating-point values unless a temporary radix control
operator is specified.
For example, to add (floating) the octal
constant 41040 to the contents of floating accumulator zero, the
following instruction must be used:
ADDF
where:

#~041040,FO

FO is assumed to represent floating accumulator zero.

Floating-point numbers are described
applicable PDP-11 Processor Handbook.
6-26

greater

detail

the

GENERAL ASSEMBLER DIRECTIVES
6.4.2.1 .FLT2
and
.FLT4
Floating-point
Storage
Directives - MACR0-11
supports
two
directives
which
evaluate
successive floating-point numbers and store the results in the object
module.
These directives are similar to the .WORD directive and are
of the form:
. FLT2
. FLT4
where:

argl,arg2, ...
argl,arg2, •..

argl,arg2, ...

represent one or more floating point numbers
as described in Section 6.4.2.
Multiple
arguments must be separated by commas .

. FLT2 causes two words of storage to be generated for each argument,
while .FLT4 generates four words of storage for each argument.

6.4.2.2 Temporary Numeric Control Operators:
AC and AF - A unary
operator for numeric control is available in MACR0-11 which allows the
programmer to specify an argument that is to be complemented as it is
evaluated during assembly.
As with the radix control operators
described above, the numeric control operator
(AC) can be used
anywhere in the source program that an expression value is legal.
Such a construction is evaluated by MACR0-11 as a 16-bit binary value
before being complemented. For example, the following statement:
TAG4:

.WORD

causes the l's complement of the value 151 (octal) to be stored as a
16-bit value in the program. The resulting value expressed in octal
form is 177626(8).
Since the AC construction is a unary operator, the operator and its
argument are regarded as a term. Thus, more than one unary operator
may be applied to a single term.
For example, the following
construction:

causes the decimal value 25 to be complemented during assembly.
The
resulting binary value, when expressed in octal form, reduces to
177746(octal).
The term created through the use of the temporary numeric control
operator thus becomes an entity which can be used alone or in
combination with other expression elements.
example,
the
For
following construction:

is equivalent in function to that shown below:

This expression is evaluated during assembly as the l's complement of
2, plus the absolute value of 6. When these terms are combined, the
resulting expression value generates a carry beyond
the
most
significant bit, leaving 000003(8) as the reduced value.

6-27

GENERAL ASSEMBLER DIRECTIVES
As shown above, when the temporary numeric control operator and its
argument are coded as a term within an expression, the use of angle
brackets as delimiters is recommended to ensure precise evaluation and
readability.
MACR0-11 also supports a unary operator for numeric control which
allows the programmer to specify an argument consisting of a 1-word
floating-point number.
For example, the following statement:
A:

MOV

creates a 1-word floating-point number at location A+2 containing
value 3.7 formatted as shown below.
BIT 15

EEEEEEEE

MMMMMMM

Sign (bit 15)

Exponent (bits 14-7)

Mantissa (bits 6-0)

An example of the importance
operators is shown below.
AFl.O
AF-1.0
-AFl.0
-AF-1.0

ordering

the

with

respect

unary

020400
120400
157400
057400

The value created by the AF unary operator and its argument is then
term which can be used by itself or in an expression. For example:

is equivalent to:

For this reason, the use of angle brackets is advised.
Expressions
used as terms or arguments of a unary operator must be explicitly
grouped.

6.5

LOCATION COUNTER CONTROL DIRECTIVES

The directives used in controlling the value of the current location
counter and in reserving storage space in the object program are
described in the following sections.
In this connection, it should be noted that several
MACR0-11
statements may cause an odd number of bytes to be allocated, as listed
below:
1.

.BYTE directive;

.BLKB directive;

.ASCII or .ASCIZ directive;

6-28

GENERAL ASSEMBLER DIRECTIVES
4.

.ODD directive;

A direct assignment statement of the form .=.+expression,
which results in the assignment of an odd address value.

In those cases above which yield an odd address value, the next
word-boundaried instruction automatically forces the location counter
to an even value, but that instruction is flagged with an error code
(B) in the assembly listing (see Appendix D).

6.5.l

.EVEN Directive

The .EVEN directive ensures that the current location counter contains
an even value by adding one if the current value is odd. If the
current location counter is already even, no action is taken.
Any
operands following an .EVEN directive are flagged with an error code
(Q) in the assembly listing (see Appendix D).
The .EVEN directive is used as follows:

6.5.2

.ASCIZ
.EVEN

/THIS IS A TEST/

. WORD

XYZ

;ENSURES THAT THE NEXT STATEMENT WILL
;BEGIN ON A WORD BOUNDARY .

.ODD Directive

The .ODD directive ensures that the current location counter contains
an odd value by adding one if the current value is even. If the
current location counter is already odd, no action is taken.
Any
operands following an .ODD directive are also flagged with an error
code (Q) in the assembly listing (see Appendix D).

6.5.3

.BLKB and .BLKW Directives

Blocks of storage can be reserved in the object program using the
.BLKB and .BLKW directives. The .BLKB directive is used to reserve
byte blocks; similarly, the .BLKW directive reserves word blocks.
The two directives are of the form:
.BLKB
.BLKW
where:

exp
exp

exp

Figure 6-6 example
directives.

represents the specified number of bytes or words
to be reserved in the object program. If no
argument is present, a default value of 1 is
assumed.
Using
these
directives
without
arguments, however, is not recommended.
Any
expression
which
is
completely
defined at
assembly-time and that reduces to an absolute
value is legal.
If the expression specified in
either of these directives is not an absolute
value, the statment is flagged with an error code
(A) in the assembly listing (see Appendix D).
illustrates

the

6-29

use

the

.BLKB

and

.BLKW

GENERAL ASSEMBLER DIRECTIVES

,PSECT

166 000000

PASS11

161 000000
168
169 000000

SI.IOI

178

,PSECT
SYMBOL I I I BL.IOI
MODE11
FLAGS11 ,BL.KB
SECTOR11,BLl<B
VALUE~I ,BL.KW
RELLVLI 1,BLKW
,REPT
,BLKW
,ENOR

179
180 000020
181 000024
182 000025
183 000026
184 000030
18!5 000032
186 000034
181 01.110036
188 000000

CLCNAM11,BLKW
CLCFGS11 1 BLKB
CLCSEC11,BLKB
CLCLOC11,BLKW
CLCMAX 11, BLl<W
CMRPNT11 1 BLl<W
SY"1BEG 11, BLt<W
ENDFL.Ci11,BLl<1rj
,PSECT

110 000000
171 000004
172 0000U
173 000005
174 000006
175 000010
176

000003

177

IMPU~E,O

lMPPAS,O,GBL

JPASS FLAG
JNEXT GROUP MUST STAY TOGETMER
JSYMBOL ACCUMULATOR
IMODEIFLAGS BYTE

1SYMBOL/EXPRESSION TYPE
IEXPRESSlON VALUE
JRELOCATION LEVEL
MAXXMT•<<,•SYMBOL>/2>
1

JCURRENT LOCATION COUNTER NAME

1
1
1
1

JENO OF GROUPED DATA
JCMARACTER POINTER
JPOINTER TO START OF SYMBOL

1
1

Figure 6-6
Example of .BLKB and .BLKW Directives
The .BLKB directive in a source program has the
following statement:

same

effect

the

.=.+expression
which causes the value of the expression to be added to the current
value of the location counter.
The .BLKB directive, however, is
easier to interpret in the context of the source code in which it
appears and is therefore the recommended method of reserving storage
space.

6.6

TERMINATING DIRECTIVES

6.6.l

.END Directive

The .END directive, indicating the logical end of
takes the following form:
.END
where:

exp

the

source

input,

exp
represents an optional expression value which, if
present, indicates the program-entry point, i.e.,
the transfer address at which program execution is
to begin.

When MACR0-11 encounters a valid occurrence of the .END directive, it
terminates the current assembly pass. Hence, additional text that may
occur beyond this point in the current source file, as well as in
additional source files identified in the command line, will be
ignored.

6-30

GENERAL ASSEMBLER DIRECTIVES
When creating a task image consisting of several object modules, only
a s ngle ob ect module may be terminated with an .END exp statement
spec fying th starting address. All other object modules must be
term nated w th an .END statement without an address argument;
otherwise, the Task Builder will issue a diagnostic message.
If no
starting address is specified in any of the object modules, task
execution will begin at location 1 of the task and immediately fault
because of an odd addressing error.
The .END statement must not be used within a macro expansion or a
conditional assembly block; if it is so used, it is flagged with an
error code (0) in the assembly listing (see Appendix D).
The .END
statement may be used, however, in an immediate conditional statement
(see section 6.10.2).
If the source program input is not terminated with an .END directive,
an error code (E) results in the assembly listing (see Appendix D).

6.6.2

.EOT Directive

Under RSX-11 and IAS operating systems, the MACR0-11 .EOT directive is
ignored and simply treated as a directive without effect, i.e., as a
no-op.

6.7

PROGRAM BOUNDARIES DIRECTIVE:

.LIMIT

It is often desirable to know the upper and lower address boundaries
of the task image.
When the .LIMIT directive is specified in the
source program, MACR0-11
effectively
generates
the
following
instruction:
.BLKW

causing two storage words to be reserved in the object module. Later,
at link time, the address of the bottom of the task's stack is
inserted into the first reserved word, and the address of the first
free word followina the task image is inserted into the second
reserved word.
During linking, the size of the task image is rounded
nearest 2-word boundary.

upward

the

For a discussion of task memory allocation and mapping, refer to the
applicable Task Builder reference manual
(see section 0.3 in the
Preface).

6.8

PROGRAM SECTIONING DIRECTIVES

The MACR0-11 program sectioning directives are used to declare names
for
program sections and to establish certain program section
attributes essential to Task Builder processing.

6-31

GENERAL ASSEMBLER DIRECTIVES
6.8.1

.PSECT Directive

The .PSECT directive allows the user to exercise absolute control over
the memory allocation of a program at link time, since any program
attributes established through this directiv~ are passed to the Task
Builder.
For example, if a programmer is writing programs for a
multi-user environment, a program section containing pure
code
(instructions only) or a program section containing impure code (data
only) may be explicitly declared through the .PSECT directive.
Furthermore, these program sections may be explicitly declared as
read-only code, qualifying them for use as protected, reentrant
programs.
In addition, program sections exhibiting the global (GBL)
attribute can be explicitly allocated in a task's overlay structure by
the user at link time.
The advantages gained through sectioning
programs in this manner therefore relate primarily to control of
memory allocation, program modularity, and more effective partitioning
of memory. Refer to the applicable Task Builder reference manual for
a discussion of memory allocation (see section 0.3 in the Preface).
The .PSECT directive is formatted as follows:
.PSECT
where:

name,argl,arg2, ... argn

name

represents the symbolic name of
section, as described in Table 6-3.

the

represents any legal separator (comma, tab
space).
argl,
arg2, ...
argn

program
and/or

represent one or
more of the legal
symbolic
arguments defined
for
use with
the
.PSECT
directive, as described in Table 6-3.
The slash
separating each pair of symbolic arguments listed
in the table indicates that
these
optional
arguments are mutually exclusive, i.e., one or the
other, but not both, may be specified.
Multiple
arguments must be separated by a legal separating
character. Any symbolic argument specified in the
.PSECT directive other than those listed in Table
6-3 will cause that statement to be flagged with
an error code
(A)
in the assembly listing (see
Appendix D) .

6-32

GENERAL ASSEMBLER DIRECTIVES
Table 6-3
Symbolic Arguments of .PSECT Directive
Meaning

Argument

Default

Name

Blank

Establishes the program section name,
which
is
specified as one to six
Radix-50 characters. If this argument
is omitted, a comma must appear in lieu
of the name parameter.
The Radix-50
character set is listed in section A.2
of Appendix A.

RO/RW

Defines which
type
of
access
permitted to the program section:

RO=Read-Only Access
RW=Read/Write Access
NOTE
IAS and RSX-llD set hardware protection
for RO program sections RSX-llM does not
provide such protection.
I/D

program
section
as
the
Defines
(I) or
containing either instructions
data ( D) . These attributes allow the
Task Builder to differentiate global
symbols that are program entry-point
from those that are
(I)
instructions
data values In\
\..,I•

GBL/LCL

LCL

the
program
of
Defines the scope
section, as subsequently interpreted by
the Task Builder.
In building single-segment programs, the
GBL/LCL
arguments
have
no meaning
whatsoever, because the total memory
allocation for the program will go into
the root segment of the task.
The
GBL/LCL arguments apply only in the case
of overlays.
If an object module contains a local
program
section,
then
the storage
allocation for that module will occur
within the segment in which the module
resides.
Many modules can reference
this
same program section, and the
memory allocation for each module is
either concatenated or overlaid within
the segment, depending on the argument
of the program section (.PSECT) defining

6-33

GENERAL ASSEMBLER DIRECTIVES
Table 6-3 (Cont'd)
Symbolic Arguments of .PSECT Directive
Argument

Default

GBL/LCL
(cont'd)

LCL

its allocation requirements (see CON/OVR
below). If an object module contains a
global
program
section,
the
contributions to this program section
are collected across segment boundaries, I
and the allocation of memory for that
section will go into the segment nearest
the root in which the first contribution
to this program section appeared.
{The
term contribution implies an allocation
of memory to the program section.)

ABS/REL

REL

Defines the relocatability attribute
the program section:

Meaning

ABS=Absolute (non-relocatable).
When
the ABS argument is specified, the
program section is regarded by the
Task Builder as an absolute module,
thus requiring no relocation.
The
program section is assembled and
loaded, starting at absolute virtual
address 0.
The location of data in absolute
program sections must fall within
the virtual memory limits of the
segment
containing
the
program I
section;
otherwise,
an
error
results at link time. For example,
the following code, although valid
at during assembly, may generate a
Task Builder
error
message
if
virtual location 100000 is outside
the segment's virtual address space:
.PSECT
.=.+100000
.WORD

ALPHA,ABS
X

The above coding assembles properly,
but the resulting load address may
be outside the respective segment's
boundaries. In such cases, the Task
Builder recognizes
this
as
an
attempt to load data outside the
task image and responds accordingly
with an appropriate error message.

6-34

GENERAL ASSEMBLER DIRECTIVES

Table 6-3 (Cont'd)
Symbolic Arguments of .PSECT Directive
Argument

Default

ABS/REL
(Cont'd)

REL

CON/OVR

CON

Meaning
REL=Relocatable. When the REL argument is
specified, the Task Builder calculates a
relocation bias and adds it to all
references within the program section,
i.e., all references in the program
section must have a relocation bias
added to them to make them absolute.
Defines the allocation
the program section:

requirements

CON=Concatenated. All program section contributions are to be concatenated with
other references to this same program
section in order to determine the total
memory allocation requirements for this
program section.
OVR=Overlaid. All program section contributions are to be overlaid. Thus, the
total allocation requirement for the
program section is equal to the largest
allocation request made by any individual contribution to this program section.

The only argument in the .PSECT directive that is position-dependent
is NAME.
If it is omitted, a comma must be used in its place. For
example, the directive:
.PSECT

,GBL

shows a .PSECT directive with a blank name argument and the GEL
argument.
Default values
(see Table 6-3) are assumed for all other
unspecified arguments.
Once the attributes of a program section are declared through a .PSECT
directive, MACR0-11 assumes that these attributes remain in effect for
all subsequent .PSECT directives of the same name that are encountered
within the module.
MACR0-11 provides for 256(10) program sections, as listed below:

. ABS.);

One default absolute program section

One default unnamed relocatable program section;

Two-hundred-fifty-four named program sections.

(

and

The .PSECT directive enables the user to:
1.

Create program sections (see section 6.8.1.1);

and,

Share code and

(see

data

among

6.8.1.2).

6-35

program

sections

section

GENERAL ASSEMBLER DIRECTIVES
For each program section specified or implied, MACR0-11 maintains
following information:
1.

Program section name;

Contents of the current location counter;

Maximum location counter value encountered;

Program section attributes,
described in Table 6-3 above.

i.e.,

the

and,
.PSECT

arguments

6.8.1.1 Creating Program Sections - MACR0-11 automatically begins
assembling source statements at relocatable zero (0) of the unnamed
program section, i.e., the first statement of a source program is
always an implied .PSECT directive.
The first occurrence of a .PSECT directive with a given name assumes
that the current location counter is set at relocatable zero. The
scope of this directive then extends until a directive declaring a
different program section is specified.
Further occurrences of a
program section name in subsequent .PSECT statements cause the
resumption of assembly where that section previously ended. For
example:
A:

B:
C:
X:
Y:

.PSECT
.WORD
.WORD
.WORD
.PSECT
.WORD
. WORD
.PSECT
.WORD

0
0

;DECLARES UNNAMED RELOCATABLE PROGRAM
;SECTION ASSEMBLED AT RELOCATABLE
;ADDRESSES 0, 2, AND 4.

ALPHA
0
0
0

;DECLARES RELOCATABLE PROGRAM SECTION
;NAMED ALPHA ASSEMBLED AT RELOCATABLE
;ADDRESSES 0 AND 2 .
;RETURNS TO UNNAMED RELOCATABLE
;PROGRAM SECTION AND CONTINUES ASSEM;BLY AT RELOCATABLE ADDRESS 6.

A given program section may be defined completely upon encountering
its first .PSECT directive. Thereafter, the section can be referenced
by specifying its name only or by completely respecifying its
attributes.
For example, a program section can be declared through
the directive:
.PSECT

ALPHA,ABS,OVR

and later referenced through the equivalent directive:
.PSECT

ALPHA

which requires no arguments.
By maintaining separate location counters for each program section,
MACR0-11 allows the user to write statements which are not physically
contiguous within the program, but which can be loaded contiguously
following assembly, as shown in the following example.

6-36

GENERAL ASSEMBLER DIRECTIVES

A:
B:
C:
ST:

.PSECT
.WORD
.WORD
.WORD
CLR
CLR
CLR
.PSECT

SECl,REL,RO
0
0
0
A
B

c
SECA,ABS

.WORD
.PSECT

. +2,A
SECl

INC

;START A RELOCATABLE PROGRAM SECTION
;NAMED SECl ASSEMBLED AT RELOCATABLE
;ADDRESSES O, 2, AND 4.
;ASSEMBLE CODE AT RELOCATABLE
;ADDRESSES 6 THROUGH 12.
;START AN ABSOLUTE PROGRAM SECTION
;NAMED SECA. ASSEMBLE CODE AT
;ABSOLUTE ADDRESSES 0 AND 2 •
;RESUME RELOCATABLE PROGRAM SECTION
;SECl. ASSEMBLE CODE AT RELOCATABLE
;ADDRESSES 14 AND 16.

All labels in an absolute program section are absolute; likewise, all
labels in a relocatable section are relocatable. The current location
counter symbol (.) is also relocatable or absolute when referenced in
a relocatable or absolute program section, respectively.
Any labels appearing on a line containing a .PSECT (or .ASECT or
.CSECT) directive are assigned the value of the current location
counter before the .PSECT (or other) directive takes effect. Thus, if
the first statement of a program is:
A:

.PSECT

ALT,REL

the label A is assigned to relocatable address zero of the unnamed (or
blank) program section.
Since it is not known during assembly where relocatable program
sections will be loaded, all references between relocatable sections
in a single assembly are translated by MACR0-11 to references relative
to the base of the referenced section. Thus, MACR0-11 provides the
Task Builder with the necessary information to resolve the linkages
between various program sections. Such information is not necessary,
however, when referencing an absolute program section, since all
instructions in an absolute program section are associated with an
absolute virtual address.
In the following example, references to the symbols X and Y are
translated into references relative to the base of the relocatable
program section named SEN .
. PSECT
.=.+1000
A:
CLR

Y:
X:

ENT,ABS

JMP

.PSECT
MOV
JMP
HALT
.WORD

SEN,REL
RO,Rl
A

;ASSEMBLED AS CLR BASE OF
;RELOCATABLE SECTION + 10.
;ASSEMBLED AS JMP BASE OF
;RELOCATABLE SECTION + 6.
;ASSEMBLED AS JMP 1000.

6-37

GENERAL ASSEMBLER DIRECTIVES
NOTE
In the above example, using a
constant
in
conjunction with the current location counter
symbol (.) in the form .=1000 would result in an
error, since constants are always absolute and are
always associated with the
program's
.ASECT
(. ABS.). If the form .=1000 is used, a program
section incompatibility would be detected.
See
section 3.6 for a detailed discussion of the
current location counter.

6.8.1.2 Code or Data Sharing - Named relocatable program sections
with the argument GBL and OVR operate in the same manner as FORTRAN
COMMON, i.e., program sections of the same name with the arguments GBL
and OVR from different assemblies are all loaded at the same location
by the Task Builder. All other program sections, i.e., those with the
argument CON, are concatenated.
Note that no conflict exists between internal symbolic names and
program section names, i.e., it is legal to use the same symbolic name
for both purposes. Considering FORTRAN again, using the same symbolic
name is necessary to accommodate the following statement:
COMMON

/X/ A,B,C,X

where the symbol X represents the base of the program section and also
the fourth element of that section.

6.8.1.3 Memory Allocation Considerations - The assembler does not
generate an error when a module ends at an odd location. This may
occur when a user places odd length data at the end of a module.
However, when several modules contain object code contributions to the
same program section having the concatenate attribute (see Table 6-3),
odd length modules
(except the last) may cause the Task Builder to
link succeeding modules starting at odd locations thereby making the
linked program unexecutable.
To avoid this problem, code and data
should be separated from each other and be placed in separately named
program sections.
This permits the Task Builder to automatically
begin each program section on an even address.
Refer to the
applicable Task Builder reference manual for further information on
memory allocation of tasks (see section 0.3 in the Preface).

6.8.2

.ASECT and .CSECT Directives

IAS and RSX-11 assembly-language programs use the .PSECT and .ASECT
directives exclusively, since the .PSECT directive affords all the
capabilities of the .CSECT directive defined for other
PDP-11
assemblers.
MACR0-11 will accept both .ASECT and .CSECT directives,
but assembles them as if they were .PSECT directives with the default
attributes listed in Table 6-4. Also, compatibility exists between
other MACR0-11 programs and the IAS/RSX-11 Task Builders, since the
respective Task Builders recognize the .ASECT and .CSECT directives
that appear in such programs and likewise assign the default values
listed in Table 6-4.

6-38

GENERAL ASSEMBLER DIRECTIVES
Table 6-4
Non-IAS/RSX-11 Program Section Default Values
l

Default Value
Attribute
.ASECT

.CSECT (unnamed)

.CSECT (named)

Name

. ABS.

name

Blank

Access

Type

Scope

GBL

Relocation

ABS

REL

Allocation

OVR

CON

The allowable syntactical forms of the .ASECT
are:
.ASECT
.CSECT
.CSECT

LCL

and

.CSECT

are

assumed

directives

symbol

Note that the statement:
.CSECT

JIM

is identical to the statement:
.PSECT

JIM,GBL,OVR

because the .CSECT default values GBL and
named program section.

6.9

SYMBOL CONTROL DIRECTIVE:

OVR

for

the

.GLOBL

MACR0-11 produces a relocatable object module and a listing file
containing the assembly listing and symbol table. The Task Builder
joins separately-assembled object modules into a single executable
task image.
During linking, object modules are relocated as a
function of the specified base of the module. The object modules are
then linked via global symbols, such that a global symbol in one
module, defined either by a global assignment operator (==), a global
label operator
(::), or the .GLOBL directive can be referenced from
another module. Thus, all symbols which will be referenced by other
program modules must be singled out as global symbols in the defining
modules.
The .GLOBL directive is provided to define (and thus provide linkage
to) symbols not otherwise defined as global symbols within a module.
For example, if the .DSABL GBL directive is

effect

(see

section

6.2), .GLOBL directives might be included in a source program to
effect linkage to library routines. For a global symbol definition,

6-39

GENERAL ASSEMBLER DIRECTIVES
the directive .GLOBL A,B,C is equivalent to:
A==expression (or A::)
B==expression (or B::)
C==expression (or C::)
Thus, the general form of the .GLOBL directive is:
.GLOBL
where:

syml,sym2, ... symn

syml,
sym2, ...
symn

represent legal symbolic names. When multiple
symbols are specified, they are separated by any
legal separator (comma, space, and/or tab).

A .GLOBL directive may also embody a
field.

label

field

and/or

comment

At the end of assembly pass 1, MACR0-11 determines whether a given
global symbol is defined within the current program section or whether
it is to be treated as an external symbol.
All internal symbols
appearing within a given program must be defined at the end of
assembly pass 1 or they will be assumed to be default global
references.
Refer
to
section
6.2
for
a
description
of
enabling/disabling of global references.
In the example below, A and B are entry-point symbols. The symbol A
has been explicitly defined as a global symbol through the .GLOBL
directive, and the symbol B has been explicitly defined as a global
label through the double colon
(::).
Since the symbol C is not
defined as a label within the current assembly, it is an external
reference.
DEFINE A SUBROUTINE WITH 2 ENTRY POINTS WHICH CALLS AN
EXTERNAL SUBROUTINE

A:
X:
B·.

. PSECT
. GLOBL
MOV
MOV
JSR
RTS
MOV
CLR
BR

@(RS)+,RO
#X,Rl
PC,C
RS
(RS)+,Rl
R2

;DECLARE THE UNNAMED PROGRAM SECTION .
;DEFINE A AS A GLOBAL SYMBOL .
;DEFINE ENTRY POINT A.
;CALL EXTERNAL SUBROUTINE C.
;EXIT.
;DEFINE ENTRY POINT B.

External symbols can appear in the operand field of an instruction or
MACR0-11 directive as a direct reference, as shown in the examples
below:
CLR
.WORD
CLR

EXT
EXT
@EXT

External symbols may also appear as a term within
shown below:
CLR
.WORD
CLR

expression,

EXT+A
EXT-2
@EXT+A(Rl)

It should be noted that an undefined external symbol cannot be used in
the evaluation of a direct assignment statement or as an argument in a
conditional assembly directive (see sections 6.10.1 and 6.10.3).
6-40

GENERAL ASSEMBLER DIRECTIVES
6.10

CONDITIONAL ASSEMBLY DIRECTIVES

Conditional assembly directives enable the programmer to include or
exclude blocks of source code during the assembly process, based on
the evaluation of stated condition tests within the body of the
program. This capability allows several variations of a program to be
generated from the same source code.

6.10.1

Conditional Assembly Block Directive:

.IF

The general form of a conditional assembly block is as follows:
. IF

where:

cond,argument{s) ;START CONDITIONAL ASSEMBLY BLOCK .

range

;RANGE OF CONDITIONAL ASSEMBLY BLOCK.

. ENDC

;END OF CONDITIONAL ASSEMBLY BLOCK .

cond

represents a specified condition which must be met
if the block is to be included in the assembly.
The conditions which may be tested
by
the
conditional assembly directives are defined in
Table 6-5.
represents any
and/or tab).

legal

separator

{comma,

space,

argument{s)

represent{s)
the
symbolic
argument(s)
or
expression(s) of the specified conditional test.
These arguments are thus a function of
the
specified condition to be tested (see Table 6-5).

range

represents the body of code which is either
included in the assembly or excluded, depending
upon whether the specified condition is met.

.ENDC

terminates the conditional assembly block.
This
directive must be present to end the conditional
assembly block.

A condition test other than those listed in Table 6-5, an illegal
argument, or a null argument specified in an .IF directive causes that
line to be flagged with an error code (A) in the assembly listing (see
Appendix D).

6-41

GENERAL ASSEMBLER DIRECTIVES
Table 6-5
Legal Condition Tests for Conditional Assembly Directives
Conditions
Arguments

Assemble Block If:

Expression

Expression is equal to 0
(or not equal to 0) •

Expression

Expression
is
than 0 (or less
equal to 0).

Expression

Expression is less than 0
(or greater than or equal
to 0) •

NDF

Symbolic
argument

Symbol is defined (or not
defined).

Macro-type
argument

Argument is blank (or
non-blank).

IDN

DIF

Two macro-type
arguments

Arguments are identical
(or different).

Expression

Same as EQ/NE.

Expression

Same as GT/LT.

Positive

Complement

greater
than or

NOTE
A macro-type argument (which is a form of symbolic
argument), as shown below, is enclosed within
angle brackets or denoted with
an
up-arrow
construction (as described in section 7.3.1).
<A,B,C>
"/124/
An example of a conditional assembly directive follows:
. IF EQ

ALPHA+l

;ASSEMBLE BLOCK IF ALPHA+l=O .

.ENDC
The two operators & and ! have special meaning within DF and NDF
conditions, in that they are allowed in grouping symbolic arguments.
&

Logical AND operator
Logical inclusive OR operator

6-42

GENERAL ASSEMBLER DIRECTIVES
For example, the conditional assembly statement:
.IF DF

SYMl & SYM2

.ENDC
results in the assembly of the conditional block if the
and SYM2 are both defined.

symbols

SYMl

Nested conditional directives take the form:
Conditional Assembly Directive
Conditional Assembly Directive

.ENDC
.ENDC
For example, the following conditional directives:
.IF DF
.IF DF

SYMl
SYM2

.ENDC
.ENDC
can govern whether assembly is to occur. In the example above, the
outermost condition is unsatisfied, no deeper level of evaluation of
nested conditional statements within the program occurs.
Each conditional assembly block must be terminated with an .ENDC
directive.
An .ENDC directive encountered outside a conditional
assembly block is flagged with an error code
(0)
in the assembly
listing (see Appendix D).
MACR0-11 permits a nesting depth of 16(10) conditional assembly
levels.
Any statement which attempts to exceed this nesting level
depth is flagged with an error code (0) in the assembly listing
(see
Appendix D).

6.10.2

Subconditional Assembly Block Directives:

Subconditional directives may be placed
blocks to indicate:

conditional

assembly

The assembly of an alternate body of code when the
of the block tests false.

condition

The assembly of a non-contiguous body of code within the
conditional assembly block, depending upon the result of the
conditional test in entering the block.

The unconditional assembly
conditional assembly block.

6-43

within

.IFF, .IFT, .IFTF

body

code

within

GENERAL ASSEMBLER DIRECTIVES
The subconditional directives are described in detail in Table 6-6.
If a subconditional directive appears outside a conditional assembly
block, an error code (0) is generated in the assembly listing
(see
Appendix D).
Table 6-6
Subconditional Assembly Block Directives
Subconditional
Directive

Function

.!FF

The code following this directive, and continuing
up to the next occurrence of a subconditional
conditional
directive or to the end of the
assembly block, is to be included in the program,
providing that the condition tested upon entering
the conditional assembly block is false.

.!FT

The code following this directive, and continuing
up to the next occurrence of a subconditional
directive or to the end of the
conditional
assembly block, is to be included in the program,
providing that the condition tested upon entering
the conditional assembly block is true.

.IFTF

The code following this directive, and continuing
up to the next occurrence of a subconditional
directive or to the end of the
conditional
assembly block, is to be included in the program,
regardless of the result of the condition tested
upon entering the conditional assembly block.

The implied argument of a subconditional directive is the condition
test that is specified upon entering the conditional assembly block,
as reflected by the initial directive in the conditional coding
examples below.
Conditional or subconditional directives in nested
conditional assembly blocks are not evaluated if the previous
(or
outer) condition in the block is not satisfied. Examples 3 and 4
below illustrate such nested directives that are not evaluated because
of previous unsatisfied conditional coding.
EXAMPLE 1: Assume that symbol SYM is defined.
.IF DF

SYM

;TESTS TRUE, SYM IS DEFINED. ASSEMBLE
;THE FOLLOWING CODE.

.!FF

;TESTS FALSE. SYM IS DEFINED. DO NOT
;ASSEMBLE THE FOLLOWING CODE.

.IFT

;TESTS TRUE. SYM IS DEFINED. ASSEM;BLE THE FOLLOWING CODE.

.IFTF

;ASSEMBLE FOLLOWING CODE UNCONDITION;ALLY.

.!FT

;TESTS TRUE. SYM IS DEFINED. ASSEM;BLE REMAINDER OF CONDITIONAL ASSEM;BLY BLOCK .

. ENDC
6-44

GENERAL ASSEMBLER DIRECTIVES
EXAMPLE 2:

Assume that symbol X is defined and
defined.

. IF DF
• IF DF
.IFF

X
Y

that symbol Y is not

;TESTS TRUE, SYMBOL X IS DEFINED .
;TESTS FALSE, SYMBOL Y IS NOT DEFINED .
;TESTS TRUE, SYMBOL Y IS NOT DEFINED,
;ASSEMBLE THE FOLLOWING CODE.
;TESTS FALSE, SYMBOL Y IS NOT DEFINED .
;DO NOT ASSEMBLE THE FOLLOWING CODE .

• IFT

. ENDC
.ENDC
EXAMPLE 3:

Assume that symbol A is defined and that symbol B is not
defined.

. IF DF

MOV

A,Rl

.IFF

;TESTS TRUE.
A IS DEFINED .
;ASSEMBLE THE FOLLOWING CODE.

;TESTS FALSE.
A IS DEFINED.
DO NOT
;ASSEMBLE THE FOLLOWING CODE.

MOV

Rl,RO

.IF NDF B

;NESTED CONDITIONAL DIRECTIVE IS NOT
;EVALUATED .

. ENDC
.ENDC

Assume that symbol X ~u not defined and that symbol Y is

EXAMPLE 4:

defined.
. IF DF

.IF DF

;TESTS FALSE. SYMBOL X IS NOT DEFINED .
;DO NOT ASSEMBLE THE FOLLOWING CODE.
;NESTED CONDITIONAL DIRECTIVE IS NOT
;EVALUATED.

.IFF

;NESTED SUBCONDITIONAL DIRECTIVE IS
;NOT EVALUATED.

.IFT

;NESTED SUBCONDITIONAL DIRECTIVE IS
;NOT EVALUATED .

. ENDC
.ENDC

6-45

GENERAL ASSEMBLER DIRECTIVES
6.10.3

Immediate Conditional Assembly Directive: .IIF

An immediate conditional assembly directive provides a means for
writing a 1-line conditional assembly block. In using this directive,
no terminating .ENDC statement is required, and the condition to be
tested
is completely expressed within the line containing the
directive. Immediate conditional assembly directives are of the form:
.IIF
where:

cond,arg,statement

cond

represents one of the legal condition
tests
defined for conditional assembly blocks in Table
6-5.
represents any
and/or tab).

arg

legal

separator

(comma,

represents the argument associated
immediate
conditional
directive,
expression, symbolic argument,
or
argument, as described in Table 6-5.

space,

with
the
i.e.,
an
macro-type

represents the separator between the conditional
argument
and
the
statement field.
If the
preceding argument is an expression, then a comma
must be used; otherwise, a comma, space, and/or
tab may be used.
statement

represents the specified statement to be assembled
if the condition is satisfied.

For example, the immediate conditional statement:
.IIF

DF FOO,BEQ ALPHA

generates the code
BEQ

ALPHA

if the symbol FOO is defined within the source program.
As with the .IF directive, a condition test other than those listed in
Table 6-5, an illegal argument, or a null argument specified in an
.IIF directive results in an error code (A) in the assembly listing
(see Appendix D).

6.10.4

PAL-llR Conditional Assembly Directives

In order to maintain compatibility with programs developed under
PAL-llR, the following conditionals remain permissible under MACR0-11.
It is advisable, however, to develop future programs using the format
for MACR0-11 conditional assembly directives.

6-46

GENERAL ASSEMBLER DIRECTIVES
Directive
.IFZ or
.IFNZ or
.IFL or
.IFG or
.IFLE
.IFDF
.IFNDF

.IFEQ
.IFNE
.IFLT
.IFGT

Arguments

Assemble Block if

expression
expression
expression
expression
expression
symbolic argument
symbolic argument

expression=O
expression not equal 0
expression<O
expression>O
expression is < or =O
symbol is defined
symbol is undefined

The rules governing the usage of these directives are the same as for
the MACR0-11 conditional assembly directives previously described.

6-47

CHAPTER 7
MACRO DIRECTIVES

7.1

DEFINING MACROS

In assembly-language programming, it is often convenient and desirable
to generate a recurring coding sequence by invoking a single statement
within the program. In order to do this, the desired coding sequence
is first established with dummy arguments as a macro definition. Once
a macro has been defined, a single statement calling the macro by name
with a list of real arguments
(replacing the corresponding dummy
arguments in the macro definition) generates the desired coding
sequence. This sequence is called the macro expansion.

7.1.l

.MACRO Directive

The first statement of a macro definition must be a .MACRO
This directive takes the form:
label:
where:

.MACRO

directive.

name; dummy argument list

label

represents an optional statement label.

name

represents the programmer-assigned symbolic name
of the macro. This name may be any legal symbol
and may be used as a label elsewhere in the
program.
represents any
and/or tab).

dummy
argument
list

legal

separator

(comma,

space,

represents a number of legal symbols which may
appear
anywhere in
the body
of the
macro
definition, even as a label. These dummy symbols
can be used elsewhere in the program with no
conflict of definition. Multiple dummy arguments
specified in this directive may be separated by
any legal separator.

A comment may follow the dummy argument list in a .MACRO directive, as
shown below:
. MACRO

ABS

A,B

;DEFINES MACRO ABS WITH TWO ARGUMENTS .

7-1

MACRO DIRECTIVES
NOTE
Although it is legal for a label to appear on a
.MACRO directive, this practice is discouraged,
especially in the case of nested macro definitions
because invalid labels or labels constructed with
the concatenation character will cause the macro
directive to be ignored.
This may result in
improper termination of the macro definition.
This NOTE also applied to .IRP, .IRPC, and .REPT.

7.1.2

.ENDM Directive

The final statement of
directive of the form:
.ENDM
where:

every

definition

must

.F.NDM

name
represents an optional argument specifying the
symbolic name of the macro being terminated by the
directive, as shown in the following example:

name

.ENDM
.ENDM

macro

;TERMINATES THE CURRENT
;MACRO DEFINITION.
ABS

;TERMINATES THE CURRENT
;MACRO DEFINITION NAMED ABS.

If specified, the symbolic name in the .ENDM statement must match the
name specified in the corresponding .MACRO directive. Otherwise, the
statement is flagged with an error code (A) in the assembly listing
(see Appendix D).
In either case, the current macro definition is
terminated. Specifying the macro name in the .ENDM statement thus
permits
MACR0-11
to
detect
missing
.ENDM
statements
or
improperly-nested macro definitions.
The .ENDM directive may be followed by a comment field, but
contain a label, as shown below:
.MACRO
JSR
.WORD
.ENDM

TYPMSG MESSGE
RS,TYPMSG
MESSGE

must

not

;TYPE A MESSAGE.
;END OF TYPMSG MACRO.

An .ENDM statement encountered by MACR0-11 outside a macro definition
is flagged with an error code (0) in the assembly listing (see
Appendix D).
NOTES
1.

Labels on .ENDM directives are ignored.

Illegal labels will cause the
to be bypassed.

7-2

directive

MACRO DIRECTIVES
7.1.3

.MEXIT Directive

The .MEXIT directive may be used to terminate a macro expansion before
the end of the macro is encountered. This directive is also legal
within repeat blocks (see sections 7.6 and 7.7). It is most useful in
the context of nested macros. The .MEXIT directive terminates the
current macro as though an .ENDM directive had been encountered.
Using the .MEXIT directive bypasses the complexities of nested
conditional directives and alternate assembly paths, as shown in the
following example:
.MACRO

ALTR N,A,B

. IF EQ

;START CONDITIONAL ASSEMBLY BLOCK •

• MEXIT
. ENDC

;TERMINATE MACRO EXPANSION .
;END CONDITIONAL ASSEMBLY BLOCK .

• ENDM

;NORMAL END OF MACRO .

Considering the above macro, in an assembly where the real argument
for the dummy symbol N is equal to zero {see Table 6-5), the
conditional block would be assembled, and the macro expansion would be
terminated by the .MEXIT directive. When macros are nested, a .MEXIT
directive causes an exit to the next higher level of macro expansion.
A .MEXIT directive encountered outside a macro definition is flagged
with an error code (0) in the assembly listing (see Appendix D).

7.1.4

MACRO Definition Formatting

A form-feed character used within a macro definition causes a page
eject during the assembly of the macro definition. A page eject,
however, is not performed when the macro is expanded.
Conversely, when the .PAGE directive is specified within a macro
definition, it is ignored during the assembly of the macro definition,
but a page eject is performed when that macro is expanded.

7.2

CALLING MACROS

A macro definition must be established through the .MACRO directive
(see section 7.1.l) before the macro can be expanded within the source
program.
Macro calls, providing the means for invoking
macro
definitions, are of the general form:
label:
where:

name

real arguments

label

represents an optional statement label.

name

represents the name of the macro, as specified
the .MACRO directive {see section 7.1.l).

7-3

MACRO DIREC'rIVES
real
represents those symbolic arguments which replace
arguments the dummy arguments specified in the
.MACRO
directive (see section 7.1.1).
When multiple
arguments are specified, they are separated by any
legal separ~tor. Arguments to the macro call are
treated as character strings whose usage
is
determined by the macro definition.
When a macro name is the same as a user label, the appearance of the
symbol in the operator field designates the symbol as a macro call;
the appearance of the symbol in the operand field designates it as a
label, as shown below:
ABS:

7.3

MOV

(RO) ,Rl

;ABS IS DEFINED AS A LABEL.

ABS

;ABS IS CONSIDERED TO BE A LABEL.

ABS

#4,ENT,LAR

;ABS IS A MACRO CALL.

ARGUMENTS IN MACRO DEFINITIONS AND MACRO CALLS

Arguments within a macro definition or macro call are separated from
other arguments by any of the legal separating characters described in
section 3.1.1.
For example, the following macro definition and its
expansion contain multiple arguments:
.MACRO

REN A,B,C

REN

ALPHA,BETA,<Cl,C2>

associated

macro

Arguments which themselves contain separating characters must be
enclosed in paired angle brackets, as shown above. For example, the
macro call:
REN

<MOV

X,Y>,#44,WEV

causes the entire expression
MOV

X,Y

to replace all occurrences of the symbol A in the macro definition.
Real arguments within a macro call are considered to be character
strings and are treated as a single entity during the macro expansion.
The up-arrow (A) construction is provided to allow angle brackets to
be passed as part of the argument. This construction, for example,
could have been used in the above macro call, as follows:
REN

A/<MOV X,Y>/,#44,WEV

causing the entire character string
argument.

7-4

passed

MACRO DIRECTIVES
The following macro call:
REN

#44,WEVA/MOV X,Y/

however, contains only two arguments (#44 and WEVA/MOV X,Y/), because
the up-arrow is a unary operator (see section 3.1.3) and it is not
preceded by an argument separator.
As evident in the examples above, spaces can be used within bracketed
argument
constructions
to
increase
their legibility of such
expressions.

7.3.1

Macro Nesting

The nesting of macros, where the expansion of one macro includes a
call to another, causes one set of angle brackets in the macro
definition to be removed from an argument with each nested call.
The
depth of nesting allowed is dependent upon the amount of dynamic
memory used by the source program being assembled.
To pass an argument containing legal argument delimiters to nested
macros, the argument in the macro definition should be enclosed within
one set of angle brackets for each level of nesting, as shown in the
coding sequence below.
It should be noted that this extra set of
angle brackets for each level of nesting is required in the macro
definition, not in the macro call.
.MACRO
LEVEL2
LEVEL2
.ENDM

LEVELl DUM1,DUM2
<DUMl>
<DUM2>

.MACRO
DUM3
ADD
MOV
.ENDM

LEVEL2 DUM3
#10 ,RO
RO,(Rl)+

A call to the LEVELl macro, as shown below, for example:
LEVELl

<MOV

X,RO>,<MOV

R2,RO>

causes the following macro expansion to occur:
MOV
ADD
MOV
MOV
ADD
MOV

X,RO
#10, RO
RO, (Rl) +
R2,RO
#10,RO
RO, (Rl)+

When macro definitions are nested, i.e., when a macro definition is
contained entirely within the definition of another macro, the inner
definition is not a callable macro until the outer macro has been
called and expanded.

7-5

MACRO DIRECTIVES
For example, in the following coding:
. MACRO

I..Vl A, B

.MACRO

LV2 C

.ENDM
.ENDM
the LV2 macro cannot be called and expanded until the LVl macro has
been so invoked.
Likewise, any macro defined within the LV2 macro
definition cannot be called and expanded until LV2 has also been
invoked.

7.3.2

Special Characters in Macro Arguments

Arguments may include special characters without enclosing them in a
bracketed construction if that argument does not contain spaces, tabs,
semicolons, or commas. For example, the macro definition:
.MACRO
MOV
.ENDM

PUSH ARG
ARG,-(SP)

PUSH

X+3(%2)

causes the following code to be generated:
MOV

7.3.3

X+3 (%2) ,- (SP)

Passing Numeric Arguments as Symbols

When passing macro arguments, a symbol value can be passed which is
treated by the macro as a numeric string. An argument preceded by the
unary operator backslash (\) is treated as a numeric value in the
current program radix. The ASCII characters representing this value
are inserted in the macro expansion, and their function is defined in
the context of the resulting code, as shown in the following example:
.MACRO
CON

INC A,B
A,\B

B=B+l
A'B:

C=O

. ENDM
.MACRO
. WORD
.ENDM

INC

;B IS TREATED AS A NUMBER IN CURRENT
; PROGRA.M RADIX .

CON A,B
4

;A'B IS DESCRIBED IN SECTION 7.3.6 .

X,C

7-6

MACRO DIRECTIVES
The above macro call (INC) would thus expand to:
XO:

.WORD

Note in this expanded code that the label XO: is the result of the
concatenation of two real arguments. The single quote (') character
in the label A'B:
causes the real arguments X and 0 to be
concatenated as they are passed during the expansion of the macro.
This type of argument construction is described in further detail in
section 7.3.6.
A subsequent call to the same macro would generate the following code:
Xl:

.WORD

and so on, for later calls. The two macro definitions are necessary
because the symbol associated with dummy argument B (i.e., C) cannot
be updated in the CON macro definition, because its numeric value has
already been substituted for its symbolic name, i.e., the character 0
has replaced C in the argument string. In the CON macro definition,
the number passed is treated as a string argument.
(Where the value
of the real argument is 0, only a single 0 character is passed to the
macro expansion.)
Passing numeric values in this manner is useful in identifying source
listings.
For
example,
versions of programs created through
conditional assembles of a single source program can be identified
through such coding as that shown below. Assume, for example, that
the symbol ID in the macro call (IDT) has been equated elsewhere in
the source program to the value 6.
.MACRO
. IDENT
.ENDM

IDT SYM
/VOSA'SYM/

;ASSUME THAT THE SYMBOL ID TAKES
;ON A UNIQUE 2-DIGIT VALUE .
;WHERE VOSA IS THE UPDATE
;VERSION OF THE PROGRAM.

IDT

The above macro call would then expand to:
.IDENT

/V05A6/

where 6 is the numeric value of the symbol ID.

7.3.4

Number of Arguments in Macro Calls

If more arguments appear in the macro call than in the macro
definition, the excess arguments cause an error code
(Q) to be
generated in the assembly listing
(see Appendix D) .
If fewer
arguments appear in the macro call than in the macro definition,
missing arguments are assumed to be null values.
The conditional
directives .IF B and .IF NB (see Table 6-5) can be used within the
macro to detect missing arguments. The number of arguments can also
be specified using the .NARG directive (Section 7.4.1). It should be
noted that a macro can be defined with no arguments.

7-7

MACRO DIRECTIVES
7.3.5

Creating Local Symbols Automatically

A label is often required in an expanded macro. In the conventional
macro facilities thus far described, such a label must be explicitly
specified as an argument with each macro call. Care must be exercised
by the programmer in issuing subsequent calls to the same macro in
order to avoid specifying a duplicate label as a real argument.
This
concern can be eliminated through a feature of MACR0-11 which creates
a unique symbol where a label is required in an expanded macro.
As noted in section 3.5, MACR0-11 can automatically create local
symbols of the form n$, where n is a decimal integer within the range
64 through 128, inclusive. Such local symbols are created by MACR0-11
in numerical order, as shown below:
64$
65$

127$
128$
This automatic facility is invoked on each call of a macro whose
definition contains a dummy argument preceded by the question mark (?)
character, as shown in the macro definition below:
.MACRO

ALPHA, A,?B

TST
BEQ
ADD

A
B
#5 ,A

;CONTAINS DUMMY ARGUMENT B PRECEDED BY
;QUESTION MARK.

B:
.ENDM
A local symbol is generated automatically by MACR0-11 only when a real
argument of the macro call is either null or missing, as shown in
Example 1 below, which reflects the expansion of the ALPHA macro
defined above.
If the real argument is specified in the macro call, however, MACR0-11
inhibits the generation of a local symbol and normal argument
replacement occurs, as shown in Example 2 below.
EXAMPLE 1:

Generate a Local Symbol for the Missing Argument:

ALPHA
TST
BEQ
ADD

Rl
Rl
64$
#5,Rl

;SECOND ARGUMENT IS MISSING.
;LOCAL SYMBOL IS GENERATED.

64$:
EXAMPLE 2:

Do Not Generate a Local Symbol:

ALPHA
TST
BEQ
ADD

R2,XYZ
R2
XYZ
#5,R2

;SECOND ARGUMENT XYZ IS SPECIFIED.
;NORMAL ARGUMENT REPLACEMENT OCCURS.

XYZ:
Automatically-generated local symbols are
16(10) arguments of a macro definition.

7-8

restricted

the

first

MACRO DIRECTIVES
It should be noted that automatically-created local symbols resultino
from the expansion of a macro, as described above, do not in any way
influence local symbol block boundaries.
In other words, such
automatically-created local symbols do not establish a local symbol
block in their own right.
However, given a macro having several arguments earmarked
for
automatic local symbol generation, substituting a specific label for
one such argument introduces a risk that assembly errors will result.
This is due to the fact that MACR0-11 constructs its argument
substitution list at the point of macro invocation.
Therefore, the
appearance of any label, the .ENABL LSB directive, or the .PSECT
directive in the macro expansion will create a new local symbol block.
This could leave local symbol references in tbe previous block and the
symbol definitions in the new one, resulting in error codes in the
assembly listing
(see Appendix D). Furthermore, a subsequent macro
expansion that generates local symbols in the new block may duplicate
one of the symbols in question, resulting in an additional error code
(P) in the assembly listing.

7.3.6

Concatenation of Macro Arguments

The apostrophe or single quote character
(') operates as a legal
delimiting character in macro definitions.
A single quote which
precedes and/or follows a dummy argument in a macro definition is
removed, and the substitution of the real argument occurs at that
point. For example, in the following statements:
A'B:

.MACRO
.ASCIZ
.BYTE
.ENDM

DEF A,B,C
/C/
I I A, I I B

when the macro DEF is called through the statement:
DEF

X,Y,<MACR0-11>

it is expanded, as follows:
XY:

.ASCIZ
.BYTE

/MACR0-11/
'X, 'Y

In expanding the first line, the scan for the first argument
terminates upon finding the first ' character. Since A is a dummy
argument, the ' is removed. The scan then resumes with B; B is also
noted as another dummy argument. The two real arguments X and Y are
then concatenated to form the label XY:. The third dummy argument is
noted in the operand field of the .ASCIZ directive, causing the real
argument MACR0-11 to be substituted in this field.
When evaluating the arguments to the .BYTE directive during expansion
of the second line, the scan begins with the first ' character. Since
it is neither preceded nor followed by a dummy argument, this
character remains in the macro expansion. The scan then encounters
the second ' character, which is followed by a dummy argument and is
therefore discarded.
The scan of argument A is terminated upon
encountering the comma (,). The third 'character is neither preceded
nor followed by a dummy argument and again remains in the macro
expansion. The fourth (and last) ' character is followed by another

7-9

MACRO DIRECTIVES
dummy
argument and is likewise discarded.
(Note that four
characters were necessary in the macro definition to generate two
characters in the macro expansion.)

7.4

MACRO ATTRIBUTE DIRECTIVES:

.NARG, .NCHR, AND .NTYPE

Three directives are available in MACR0-11 which allow the user to
determine certain attributes of macro arguments. The use of these
directives permits selective modifications of a macro expansion,
depending on the nature of the arguments being passed.
These
directives are described separately below.

7.4.1

.NARG Directive

The .NARG directive is used to determine the number of arguments in
the macro call currently being expanded. Hence, the .NARG directive
can appear only within a macro definition; if it does not, an error
code (0) is generated in the assembly listing (see Appendix D). This
directive takes the form:
label:
where:

.NARG

symbol

label

represents an optional statement label.

symbol

represents any legal symbol.
This symbol is
equated to the number of arguments in the macro
call currently being expanded. If a symbol is not
specified, the .NARG directive is flagged with an
error code
(A)
in the assembly listing
(see
Appendix D).

An example of the .NARG directive follows:

ABC:

.NARG

;X IS EQUATED TO THE
;NUMBER OF ARGUMENTS IN THE
;CURRENT MACRO EXPANSION.

7.4.2

.NCHR Directive

The .NCHR directive, which can appear anywhere in a MACR0-11 program,
is used to determine the number of characters in a specified character
string. This directive, which is useful in calculating the length of
macro arguments, takes the following form:
label:
where:

.NCHR

symbol,<string>

label

represents an optional statement label.

symbol

represents any legal symbol.
This symbol is
equated
to the number of characters in the
specified character string. If a symbol is not
specified, the .NCHR directive is flagged with an
error code
(A)
in the assembly listing
(see
Appendix D).
represents any
and/or tab).

7-10

legal

separator

(comma,

space,

MACRO DIRECTIVES
<string>

represents a string of printable characters.
The
character string need be enclosed within angle
brackets
(<>) or up-arrows
(A)
only if
the
specified
character
string contains a legal
separator (comma, space, and/or tab).
If the
delimiting characters do not match or if the
ending delimiter cannot be detected because of a
syntactical error in the character string (thus
prematurely terminating its evaluation), the .NCHR
directive is flagged with an error code (A) in the
assembly listing (see Appendix D).

An example of the .NCHR directive follows:
XYZ:

.NCHR

X,<AB,CD>

7.4.3

.NTYPE Directive

;X IS EQUATED TO 5 (THE
;NUMBER OF CHARACTERS BETWEEN THE
;BRACKETS).

The .NTYPE directive is used to determine the addressing mode of a
specified macro argument. Hence, the .NTYPE directive can appear only
within a macro definition; if it appears elsewhere, it is flagged
with an error code (0) in the assembly listing (see Appendix D). This
directive takes the form:
label:

.NTYPE

symbol,aexp

where:

label

represents an optional statement label.

symbol

represents any legal symbol.
This symbol is
equated to the 6-bit addressing mode of the
following argument. If a symbol is not specified,
the .NTYPE directive is flaooed with an error code
(A) in the assembly listing~(see Appendix D).
represents any
and/or tab).

a exp

legal

separator

(comma,

space,

represents any legal address expression, as used
with an opcode. If no argument is specified, the
result will be zero (0).

An example of the use of an .NTYPE directive in a macro definition
shown below:
.MACRO
.NTYPE
.IF
MOV
.IFF
MOV
.ENDC
.ENDM

SAVE ARG
SYM,ARG
EQ,SYM&7
ARG,TEMP

;RELATIVE ADDRESSING MODE.

#ARG,TEMP

;IMMEDIATE ADDRESSING MODE.

For additional information
Chapter 5 and Appendix B.2.

concerning

7-11

addressing

modes,

refer

MACRO DIRECTIVES
7.5

.ERROR AND .PRINT DIRECTIVES

The .ERROR directive is used to output messages to the listing file
during assembly pass 2. A common use of this directive is to provide
a diagnostic announcement of a rejected or erroneous macro call or to
alert the user to the existence of an illegal set of conditions
specified in a conditional assembly.
If the listing file is not
specified, the .ERROR messages are output to the command output
device. The .ERROR directive takes the form:
label:

.ERROR

expr

where:

label

represents an optional statement label.

ex pr

represents an optional expression whose value is
output when the
ERROR directive is encountered
during assembly.

;text

denotes the beginning of the text string.
text

represents the specified message
the .ERROR directive.

Upon encountering an .ERROR directive anywhere in
MACR0-11 outputs a single line containing:

associated
source

with

program,

An error code (P);

The sequence number of the .ERROR directive statement;

The value of the current location counter;

The value of the expression, if one is specified;

The source line containing the .ERROR directive.

For example, the following directive:
.ERROR

;INVALID MACRO ARGUMENT

causes a line in the following form to be output to the listing file:

Seq. Loe.
No. No.

Exp.
Value

512 005642

000076

Text
ERROR

;INVALID MACRO ARGUMENT

The .PRINT directive is identical in function to the .ERROR directive,
except that it is not flagged with the P error code.

7.6

INDEFINITE REPEAT BLOCK DIRECTIVES:

.IRP AND .IRPC

An indefinite repeat block is a structure that is very similar to a
macro definition. Such a structure is essentially a macro definition
that has only one dummy argument. At each expansion of the indefinite
repeat range, this dummy argument is replaced with successive elements
of a specified real argument list.
An indefinite repeat block
directive and its associated repeat range are coded in-line within the
source program. This type of macro definition and expansion does not

7-12

MACRO DIRECTIVES
require calling the macro by name, as required in the expansion of
conventional macros previously described in this ser,tion.
An indefinite repeat block can appear either within or outside another
macro definition, indefinite repeat block, or repeat block (see
section 7.7).
The rules for specifying indefinite repeat block
arguments are the same as for specifying macro arguments (see section
7. 3) .

7.6.1

.IRP Directive

The .IRP directive is used to replace a dummy argument with successive
real arguments specified in an argument string. This replacement
process occurs during the expansion of an indefinite repeat block
range. This directive takes the following form:
label:

. IRP

sym,<argument list>

(range of indefinite repeat block)

.ENDM

where:

label

represents an optional statement label.

sym

represents a dummy argument which is successively
replaced
with
the
specified real arguments
enclosed within the angle brackets. If no dummy
argument is specified, the .IRP directive is
flagged with an error code
(A)
in the assembly
listing (see Appendix D).
represents any
and/or tab) .

legal

separator

(comma,

space,

represents a list of real arguments enclosed
within angle brackets that is to be used in the
expansion of the indefinite repeat range. A real
argument may consist of one or more characters;
multiple arguments must be separated by any legal
separator
(comma, space, and/or tab). If no real
arguments are specified, no action is taken.

range

represents the block of code to be repeated once
for each occurrence of a real argument in the
other
macro
list.
The range
may
contain
The .MEXIT
definitions
and
repeat
ranges.
directive (see section 7.1.3) is legal within the
range of an indefinite repeat block.

.ENDM

indicates the end of the indefinite
range.

repeat

block

An example of the use of the .IRP directive is shown in Figure 7-1.

7-13

MACRO DIRECTIVES
7.6.2

.IRPC Directive

A second type of indefinite repeat block directive is available in
MACR0-11 which handles single character substitution, rather than
argument substitution. On each iteration of the indefinite repeat
range, the dummy argument is replaced with each successive character
in the specified string. The .IRPC directive is specified as follows:
label:

.IRPC

sym,<string>

(range of indefinite repeat block)

.ENDM
where:

label

represents an optional statement label.

sym

represents a dummy argument which is successively
replaced
with
the
specified real arguments
enclosed within the angle brackets. If no dummy
argument is specified, the
IRPC directive is
flagged with an error code
(A)
in the assembly
listing (see Appendix D).
represents any
and/or tab).

legal

separator

(comma,

space,

represents a list of characters enclosed within
angle brackets that is to be used in the expansion
of the indefinite repeat range.
Although the
angle brackets are required only when the string
contains separating characters, their use
is
recommended for legibility.

range

represents the block of code to be repeated once
for each occurrence of a character in the list.
The range may contain macro definitions and repeat
ranges.
The .MEXIT directive (see section 7.1.3)
is legal within the range of an indefinite repeat
block.

.ENDM

indicates the
range.

end of the indefinite repeat

block

An example of the use of the .IRPC directive is shown in Figure 7-1.

7-14

MACRO DIRECTIVES

,TITLE

,L!ST

IRPTST
ME

J
4

!5
6
7
8

liH'J0000
0(ilJ0004
P!;IJ0~ 10
000014
011!0020
000024

000000G
00CH'100G
000000G
000000G
0001210l0G
000000G

016720
016720
016720
016720
016720
016720

X,<AA,BB,CC,DD,EE,FF>
X, ( R0) •

,IRP
MOV
,ENDM
MOV
MOV
MO\/
MOV
MOV
MOV

AA,CR0H
BA,CR0)+
CC: 1 (R0) +
DD,(R0)•
EE,CR0)•
FF,(R0)+

, I RPC:
MOVB

X,<ABCDEF>
#IX 1 •(R1)

10
11
12
1J

.~NDM

0t'10'1l30
0~0034

000040
000044
000050
000054
14
15
16

MOVB
MOVB
MO\IB
MQ\18
MOVB
MOVB

000000G
000000G
000000G
000000G
000000G
000000G

112741
112741
112741
112741
112741
112741

u, .. (R1)
#B, .. ( R1)
#C,,. CR 1)
#D 1 •(R1)
#E,,. CR 1)
#F',•O'l)

,END

000001 1

Figure 7-1
Example of .IRP and . IRPC Directives

7.7

REPEAT BLOCK DIRECTIVE:

.REPT

Occasionally, it is useful to duplicate a block of code a number of
times in-line with other source code. This duplication of code is
accomplished by creating a repeat block using a directive in the form:

label:

.REPT

exp

(range of repeat block)

.ENDM
where:

label

represents an optional statement label.

exp

represents any legal expression
whose
value
controls the number of times the block of code is
to be assembled within the program.
When the
expression value is less than or egual to zero
(0), the repeat block is not assembled.
If this
expression is not an absolute value, the .REPT
statement is flagged with an error code (A) in the
assembly listing (see Appendix D).

range

represents the block of code to be repeated the
number
of times determined by the specified
expression value. The repeat block may contain
macro definitions, indefinite repeat blocks, or
other repeat blocks.
The .MEXIT directive is
legal within the range of a repeat block.
7-15

MACRO DIRECTIVES
.ENDM
or
. ENDR

7.8

indicates the end of the repeat block range. The
terminating statement
in a repeat block can be
either an .ENDM directive or an .ENDR directive .

MACRO LIBRARY DIRECTIVE:

.MCALL

MACR0-11 provides a selection mechanism for the programmer to indicate
in advance those system and/or user-defined macro definitions that are
required in the assembly of the source program. The .MCALL directive,
providing this selection mechanism, allows the programmer to specify
the names of all system or user macro definitions not defined within
the source program but which are required to assemble the program.
The .MCALL directive must appear before the first occurrence of a call
to any externally-defined macro. The .MCALL directive is of the form:
.MCALL
where:

argl,arg2, ... argn

argl,
arg2, ...
argn

represent
the symbolic
names of
the macro
definitions required in the assembly of the source
program.
The symbolic macro
names
may
be
separated by any legal separator (comma, space,
and/or tab).

The .MCALL directive thus provides the means to
access
user-defined and system macro libraries during assembly.

both

The /ML switch under RSX-11 and the /LIBRARY qualifier under IAS
specified in connection with an input file specification indicates to
MACR0-11 that the file is a macro library.
When a macro call is
encountered in the source program, MACR0-11 first searches the user
macro library for the named macro definitions, and, if necessary,
continues the search with the system macro library.
Any number of such user-supplied macro files may be designated.
In
cases of multiple library files, the search for the named macros
begins with the last such file specified.
The search continues in
reverse
order until the required macro definitions are found,
terminating again, if necessary, with a search of the system macro
library.
If any named macro is not found upon completion of the search, i.e.,
if the macro is not defined, the .MCALL statement is flagged with an
error code (U) in the assembly listing (see Appendix D). Furthermore,
a statement elsewhere in the source program which attempts to expand
such an undefined macro is flagged with an error code (0) in the
assembly listing.
The RSX-11 and IAS command strings to MACR0-11, through which a file
specification is supplied, are described in detail in sections 8.1.2
and 8.2.2, respectively.

7-16

PAR'I' IV
OPERATING PROCEDURES

CHAPTER 8
OPERATING PROCEDURES

MACR0-11 assembles one or more ASCII source files containing MACR0-11
statements into a single relocatable binary object file.
The output
of MACR0-11 consists of a binary object file and a file containing the
table of contents listing, the assembly listing, and the symbol table
listing. A sample assembly listing is provided in Appendix I.

8.1

RSX-llD AND RSX-llM OPERATING PROCEDURES

The following sections describe those MACR0-11 operating procedures
that apply exclusively to the RSX-llD and RSX-llM system environments.

8.1.1

Initiating MACR0-11 Under RSX-llM/RSX-llD

Following the entry of CTRL/C (AC) from an operator's console,
the
Monitor Console Routine
(MCR)
indicates its readiness to accept a
command by prompting with the following sequence:
MCR>
MCR then waits for input.
One of five methods can be employed to initiate MACR0-11, as described
below.

8.1.1.1 Method 1 - Direct MACR0-11 Call - The terminal
method 1 is:

sequence

for

MCR>MAC
MAC>macll-cmd-string
The monitor console routine
(MCR)
accepts MAC as input,
causing
MACR0-11 to be activated.
Since an assembly command string is not
present with the MCR line, MACR0-11 then solicits input with the
prompting sequence MAC> and waits for
command string input (see
section 8.1.2 below).
After the assembly of the indicated files has
been completed, MACR0-11 again solicits command string input with the
MAC> prompting sequence.
This process will be repeated until a CTRL/Z
(AZ) is entered.

8-1

OPERATING PROCEDURES
8.1.1.2 Method 2 - Using RUN
method 2 is:

Facility - The

terminal

sequence

for

MCR>RUN ... MAC/UIC=[g,m]
MAC>macll-cmd-string
Method 2 is identical to method 1, except that the MCR RUN command is
used, which requires the entire task name, including the 3-dot prefix.
In addition, the default UIC is changed for one execution.
As in
method 1 above, MACR0-11 again solicits command string input (see
section 8.1.2) after the assembly of the indicated files is completed.
The /UIC is optional.

8.1.1.3
3 is:

Method 3 - Single Assembly - The terminal sequence for method
MCR>MAC macll-cmd-string

In method 3, no prompting from MACR0-11 occurs, since the command
string input is included in the MCR command line. As in methods 1 and
2, the expression macll-cmd-strng is any legal, syntactically correct
MACR0-11 command string of the form described in section 8.1.2.
MACR0-11 then assembles source files under control of the command
string and, when finished, exits.

8.1.1.4 Method 4 - Install, Run Immediately, and Remove On Exit - The
terminal sequence for method 5 is:
MCR>RUN $MAC/UIC=[g,m]
MAC>macll-cmd-string
This method is used when the MACR0-11 assembler is not permanently
installed in the respective system. MCR installs MAC from the system
program directory and requests it under the specified UIC.
As in
method 1, MACR0-11 solicits command string input (see section 8.1.2).
When MACR0-11 exits, it is automatically removed from the system.
NOTE
MACR0-11 can be terminated by entering a
CTRL/Z
(AZ) at any time a request for
command string input is present.

8.1.1.5 Method 5 - Using Indirect Filename Facility - Any one of the
following sequences may be used in initiating RSX-ll's indirect file
facility for command string input:

MCR>MAC
MAC>@f ilespec
or
MCR>RUN ... MAC/UIC=[g,m]
MAC>@f ilespec
or
MCR>MAC @f ilespec
or
MAC>RUN $MAC/DIC=[g,m]
MAC>@filespec
8-2

OPERATING PROCEDURES
These forms use the indirect file facility of
RSX-11,
which
effectively accomplishes the substitution of
@filespec
for the
"macll-cmd-string" input employed in methods l through 4.
The file
specified as
@filespec
contains MACR0-11 command strings. After
this file is opened, command lines are then read from the file until
the end-of-file is detected.
Only three nested levels of indirect
files are permitted in MACR0-11.
11

8.1.2

RSX-11 Command String Format

In response to the MAC> prompting sequence printed by MACR0-11.
the
user types the output and input file specifications in the general
form shown below:
MAC>object,listing=srcl,src2, ... ,srcn
where:

object

represents the binary object (output) file.

listing

represents the assembly listing (output) file
containing the table of contents, the assembly
listing, and the symbol table.
separates output file
file specifications.

srcl,
src 2, ...
srcn

specifications

from

input

represent
the ASCII
source
(input)
files
containing the MACR0-11 source program or
the
user-supplied macro library files to be assembled.

Only two output file specifications in the command string will be
recognized by MACR0-11; any more than two such files will be ignored.
No limit is set on the number of source input files;
however; the
entire command string must fit on an 80-byte command line.
A null specification in either of the output file specification fields
signifies that the associated output file is not desired. A null
specification in the input file field, however, is an error condition,
resulting 1n the error message "MAC -- ILLEGAL FILENAME" on the
command output device (see section 8.4). Note that the absence of
both the device name (dev:) and the name of the file (filename.type)
from a file specification is the equivalent of a null specification.
NOTE
When no listing file is specified, any errors
encountered in the source program are printed on
the terminal from which MACR0-11 was initiated.
When the /NL switch is used in the listing file
specification without an argument, the errors and
symbol table are output to the file specified.

8-3

OPERATING PROCEDURES
Each file specification contains
accordance
with
the
standard
specifications):

the following information
RSX-11
conventions
for

(in
file

filespec /switch:value ...
where:

filespec

is the standard RSX-11 file
described in section 8.3 below.

/switch

represents an ASCII name identifying a switch
option.
This switch option may be specified in
three forms, as shown below, depending on the
function desired:
/SW
/NOSW
/-SW

specification

Invokes the specified switch action.
Negates the specified switch action.
Negates the specified switch action.

In addition, the switch
identifier
may
be
accompanied by any number of the following values:
ASCII character strings, octal numbers, or decimal
numbers.
The default assumption for a numeric
value is octal. Decimal values must be followed
by a decimal point (.).
Any numeric value preceded by a pound sign (#)
is
regarded as an explicit octal declaration; this
option is provided for documentation purposes and
ready identification of octal values.
Also, any numeric value can be preceded by a plus
sign (+) or a minus
(-) sign.
The positive
specification is the default assumption.
If an
explicit octal declaration is specified (#), the
sign indicator, if included, must precede the
pound sign.
/switch
(Cont'd)

All switch values must always
colon (:) .

preceded

The number of permissible switch specifications,
accompanying switch values, and interpretations
thereof are program-dependent, i.e., the switch
specifications are interpreted in the context of
the program to which they apply.
The switch
options applicable to MACR0-11 are described in
Table 8-2 below.
A syntactical error detected in the command string causes MACR0-11 to
output the following error message to the command output device (see
section 8.4):
MAC -- COMMAND SYNTAX ERROR
followed by a copy of the entire command string.
Table 8-1 lists the default values for each file specification.

8-4

OPERATING PROCEDURES
Table 8-1
File Specification Default Values
Default Value
File

Device

Object
File

System
device.

I Device used
for object
I file.

Listing
File
Source
File

System
11 device.

Source 2
to
Source n
File

L'LdCL U

Library

8.1.3

I
device,
I System
.c ------

Filename

Type

Current.

None

.OBJ

Directory
used in
Object file.

None

.LST

Current.

None

I MAC

Directory
used for
source 1 or
last source
file specified.

None

.MAC

I
II None

.MLB

User
1.11'- -

Device used
for source 1 or
last source file
specified.

Directory

.l.l

llldCLU

.c .! ,

.l.ll.e

Current, i f
-- - -- mac
L u
,,...._

r: .!.

L i. l. e

is specified
first; if not,
device used
by last source
file is used.

is specified 'j
first; if not,
directory of I
last source
I
file is used.

System
Macro
Library

System
device.

[ l ' l]

RSXMAC

.SML

Indirect
Command
File

System
Device.

Current

None

.CMD

I
I

RSX-11 File Specification Switches

At assembly time, the programmer may wish to overr1ae certain MACR0-11
directives appearing in the source program or to provide MACR0-11 with
information establishing how certain files are to be handled during
assembly.
This capability is provided through one or more switches
which may be selectively invoked as additional parameters in each file
specification (see Section 8.1.2). The switches available for use in
MACR0-11 file specifications under RSX-11 are listed in Table 8-2.

8-5

OPERATING PROCEDURES
Table 8-2
MACR0-11 File Specification Switches for RSX-11
Switch Option

Function

/LI:arg
/NL:arg

Listing control switches; these options
accept ASCII switch values (arg} which
are equivalent in function and name to
the arguments of the .LIST and .NLIST
directives
specified
in the source
program (see section 6.1.1).

/EN:arg
/DS:arg

Function control switches; these options
accept ASCII switch values (arg) which
are equivalent in function and name to
the arguments of the .ENABL and .DSABL
directives specified
in
the
source
program (see section 6.2).

/ML

The
/ML
switch,
which
takes
no
accompanying switch values, indicates to
MACR0-11 that an input file is a macro
library file. As noted in section 7.8,
any macro that is defined externally
must
be
identified
in the .MCALL
directive before it can be retrieved
from a macro library file and assembled
with the user program.
In locating
macro definitions, MACR0-11 initiates a
fixed search algorithm, beginning with
the last user macro file specified,
continuing in reverse order with each
such file specified, and terminating, if
necessary, with a search of the system
macro library file. If a required macro
definition is not found upon completion
of the search, an error code (U) results
in the assembly listing (see Appendix
D).
This means that a user macro
library file must be specified in the
command line prior to the source file(s)
that use macros defined in the library
file.

8-6

OPERATING PROCEDURES
Table 8-2 (Cont'd)
MACR0-11 File Specification Switches For RSX-11
Switch Option

Function

/ML
(Cont'd)

MACR0-11 does not pre-scan the command
line for marco libraries;
when a new
source file is needed, it parses the
next input file specification. If that
file
specification contains the /ML
switch, it is appended to the front of
the library file list. As a result, a
user macro
library
file
must
be
specified in the command line prior to
the source files which require it in
order to resolve macro definitions.

/PA:l
/PA:2

Assemble the associated
assembly pass 1 only.
Assemble the associated
assembly pass 2 only.

/SP

Spool listing output (default value).

/NOSP

Do not spool output.

/-SP

Do not spool output.

file

during

file

during

NOTE
The /ML, /PA and /SP switches do not interact with
or override MACR0-11 directives.
Rather, they
have meaning only in the command line itself.
Switches for the object file are limited to /EN and /DS;
when
specified, they apply throughout the entire command string. Switch
options for the listing file are limited to /LI, /NL, /SP, and /NOSP.
Switches for input files are limited to /ML, /PA, /EN, and /DS; the
options /ML and /PA apply only to the file immediately preceding the
option so specified, whereas the /EN and /DS options, as noted above,
are also applicable to subsequent files in the command string.
Multiple occurrences of the same switch following a file specification
must be avoided, because the accompanying values of a subsequent like
switch specification override any previously-specified values.
For
example, in the following command string element:
/LI:SRC/LI:MEB
the switch specification /LI:MEB will override
that
specified
previously as /LI:SRC. If both switch values are desired, they can be
specified in the syntactically correct form shown below:
/LI:SRC:MEB

8-7

OPERATING PROCEDURES
Examples:
1.

MAC>OBJFIL,LSTFIL/NL:BEX:COM/LI:ME=SRCFIL
This command string suppresses the listing
of
binary
extensions and the source comments, and lists the macro
expansions. Furthermore, it causes all listing directives in
the source program having the arguments BEX, COM, and ME to
be overridden. In this example, the object output is sent to
the file named OBJFIL.OBJ, and the listing and symbol table
output is sent to the file named LSTFIL.LST.

MAC>OBJFIL,LISTM/NL:TOC=SRCFIL
This command string causes the assembly listing's table of
contents to be suppressed along with all other listing output
(except the symbol table), when the general no-list mode
prevails for listing files, e.g., when the /NL switch is
present in the file specification without an argument.

8.2

IAS MACR0-11 OPERATING PROCEDURES

The following sections describe those MACR0-11 operating
that apply exclusively to the IAS system environment.

8.2.l

procedures

Initiating MACR0-11 Under IAS

The MACRO command is used under IAS to begin MACR0-11 assembler
operations. The command causes MACR0-11 to assemble one or more ASCII
source files containing MACR0-11 statements into a relocatable binary
object file.
The assembler will also produce an assembly listing,
followed by a symbol listing and a cross reference listing.
The command can be issued whenever the IAS Program Development System
(PDS) is at command level in interactive mode. This condition is
signified by the appearance of the prompting sequence:
PDS>
at the user's terminal. The command can be input either directly from
the terminal {interactive mode) or from a batch file (batch mode).
When the specified assembly has completed, MACR0-11
terminates
operations and returns control to PDS.
{Refer to the IAS User's Guide
for further information about interactive and batch mode operations).

8.2.2

IAS Command String Format

A MACR0-11 command string can be specified using any one of the three
formats shown below. The first two formats apply to interactive mode
operation, while the last format applies to batch mode operation.
Notice that, in interactive mode, if the input file specification
(filespec) does not begin on the same line as the MACRO command and
its qualifiers, PDS prints following the prompting message:
FILES?
then waits for the user to specify the input file(s).

8-8

OPERATING PROCEDURES
In batch mode, the command and its arguments must appear on
line unless the PDS line continuation symbol (-) is used.

the

same

The command formats for each operating mode are as follows:
Interactive Mode
input
[
]
filespec /LIBRARY+ ...

PDS> MACRO[qualifiers]

or
PDS> MACRO[qualifiers]
FILES?

Batch Mode

~~i~!pec r/LIBRARYl + ••.
L

$MACRO [qualifiers]

...J

input
[
]
filespec /LIBRARY+ ...

where:
input
f ilespec

is the specification of an input file
(see section 8.3) that contains MACR0-11
source program code. When the program
consists of multiple files, a plus sign
(+) must be used to separate each file
specification from the next. The "wild
card" form of a file specification is
not allowed.

/LIBRARY

specifies that an input file is a macro
library file. As noted in section 7.8,
any macro that is defined externally
must
be
identified
in the .MCALL
directive before it can be retrieved
from a macro library file and assembled
with the user program.
In locating
macro definitions; MACR0-11 initiates a
fixed search algorithm, beginning with
the last user macro file specified,
continuing in reverse order with each
such file specified, and terminating, if
necessary, with a search of the system
macro library file.
If a reguired macro
definition is not found upon completion
of the search, an error code (U) results
in the assembly listing
(see Appendix
D).
This means that a user macro
library file must be specified in the
command line prior to the source file(s)
that uses any macros defined in the
library file. If more than one library
file is specified, the libraries will be
searched in right-to-left order.

8-9

OPERATING PROCEDURES
gualif iers

specifies one or more of the following:

output
/OBJECT :filespec

Produce an object file as specified by
filespec (see section 8.3). The default
is the last named source file having a
.OBJ extension.

/NOOBJECT

Do not produce an object file.

output
/LIST :filespec

Produce a listing file according to
filespec (see section 8.3). If filespec
is not specified, the listing is printed
on the line printer.
The default is
/NOLIST.

/NOLI ST

Do not produce a listing file.
The
default in interactive mode is /NOLIST
and in batch mode is /LIST.
NOTE
When
no
listing
file
is
specified,
any
errors
in
the
source
encountered
program are displayed at the
terminal from which MACR0-11 was
initiated.

PDS accepts the MACRO or $MACRO command as input and initializes the
MACR0-11 assembler, which in turn processes the specified files
according to the options indicated in the command string.
When the
operation is complete, MACR0-11 returns control to PDS to obtain the
next command line either from the terminal or from the batch stream.

8.2.3

IAS Indirect Command Files

The indirect command file facility of PDS can be used with MACR0-11
command strings. This is accomplished by creating an ASCII file that
contains the desired command strings {or portions thereof) in the
forms shown above in section 8.2.2. When an indirect command file
reference is used in a MACR0-11 command string, the contents of the
specified file are taken as all or part of the command string. An
indirect command file reference is specified in the form:
@filespec
where:
@

specifies that the name that
file.

follows

indirect

filespec

is the file specification of a file {see section 8.3)
that contains a command string. The default extension
for the file name is .CMD.

An indirect command file reference must always be the rightmost
in the command {see section 8.2.4 below for examples).

8-10

entry

OPERATING PROCEDURES
8.2.4

IAS Command String Examples

The following examples show typical PDS MACR0-11 command strings.
1.

PDS> MACRO /NOLIST
FILES? A+BOOT;3
In this example, the source files A.MAC and BOOT.MAC;3 will
be assembled to produce an object file called BOOT.OBJ.
No
listing will be produced.

Where the indirect command file TEST.CMD contains the command
string:
MACRO/OBJECT:MYFILE

A+B

The command;
PDS>@TEST
causes MACR0-11 to assemble the two files
into an object file called MYFILE.OBJ.
3.

Where the indirect command
command string segment:

file

A.MAC

IND02.CMD

and

B.MAC

contains

the

ATEST/LIBRARY+BTEST+SRTl.021
The command:
PDS>MACRO/LIST:DKl:FOO

@IND02

causes MACR0-11 to assemble the files BTEST.MAC and SRTl,.021
using the macro library file ATEST.MAC to produce an object
file named SRTl.OBJ.
A listing file names FOO.LST is placed
on disk unit 1.

$MACRO/LIST:DKO:MICR/NOOBJECT
LIB1/LIBRARY+MICR.MAC;002
In this example, the library
MICR.MAC;002.
The program
placed on disk unit 0.

8.3

.c~,_

L.l.le

.:_ assembled with the

.!..::>

listing

file named MICR.LST is

IAS/RSX-11 FILE SPECIFICATION FORMAT

The general form for a file specification in IAS/RSX-11 systems is
shown below.
Detailed information is provided in the applicable
system user's guide or operating procedures manual (see section 0.3 in
the Preface) .
dev: [g,m]name.ext;ver
where:
dev:

is the name of the physical device where the desired
file resides.
A device name consists of two characters
followed by a one or
two digit device unit number
(octal)
and a colon
(e.g.,
DPl:, DKO:, DT3:).
The

8-11

OPERATING PROCEDURES
default device under RSX-llD and RSX-llM
is
as
specified in Table 8-1. The default device under IAS
is established initially by the system manager for each
user and can be changed through the SET command.
[g ,m]

is the User File Directory (UFD) code.
This code
consists of a group number (octal), a comma (,),and an
owner (user) number (octal) all enclosed in brackets
([]). For example:
[200,30].
The
default
Identification
IAS, this can
command.

UFD
is
equivalent
to
the
User
Code (UIC) given at log-in time. Under
be changed through the SET DEFAULT

name

through
9
is the file name and consists of 1
There is no default for a
alphanumeric characters.
filename .

. ext

is a 1- to 3-alphanumeric character filename extension
or type that is preceded by a period (.). An extension
is normally used to identify the nature of the file.
Default values depend on the context of the file
specification and are as follows:
.CMD
.LST
.MAC
.OBJ

;ver

Indirect command (input) file
A listing (print format) file
MACR0-11 source module (input file)
MACR0-11 object module (output file)

is an octal number between 1 and 77777 that is used to
differentiate between versions of the same file. This
number must be prefixed by a semicolon (;).
For input files, the default value is
version number of the file that exists.

the

highest

For output files, the default value is the highest
version number of the file that exists increased by 1.
If no version number exists, 1 is used.

8.4

MACR0-11 ERROR MESSAGES

MACR0-11 outputs an appropriate error message to the command output
device when one of the error conditions described below is detected.
These error messages reflect operational problems and should not be
confused with the diagnostic error messages (see Appendix D) produced
by MACR0-11 during assembly.
All the error messages listed below, with the exception of the "MAC -COMMAND I/O ERROR" message, result in the termination of the current
assembly; MACR0-11 then attempts to restart by reading another
command line.
In the case of a command I/O error, however, MACR0-11
exits, since it is unable to obtain additional command line input.

8-12

OPERATING PROCEDURES
Error Message

Meaning

MAC -- COMMAND I/O ERROR

An error has been returned by
the
file
system
during
MACRO-ll's attempt to read a
command line.
This is an
unconditionally fatal error,
causing MACR0-11 to exit. No
MACR0-11 restart is attempted
when this message appears.

MAC -- COMMAND SYNTAX ERROR

An error has been detected in
the syntax of the MACR0-11
command line.

MAC -- ILLEGAL FILENAME

Neither the device name nor
the filename is present in
the input file specification
(i.e.,
the
input
file
specification is null), or a
"wild
card"
convention
(asterisk) is employed in an
input
or
output
file
specification.
"Wild cardi'
options (*) are not permitted
in
MACR0-11
file
specifications.

MAC -- ILLEGAL SWITCH

An
illegal
switch
is
specified
for a file, an
illegal value is specified
with a switch, or an invalid
use of a switch has been
detected by MACR0-11.

MAC -- INDIRECT COMMAND SYNTAX ERROR

The name of the
indirect
command
file
(@filename)
specified in the
MACR0-11
command line is syntactically
incorrect.
An attempt to exceed
the
maximum allowable number of
nested indirect command files
has occurred.
(Only three
levels of indirect command
files
are
permitted
in
MACR0-11.)

MAC -- INDIRECT FILE DEPTH EXCEEDED

MAC -- INDIRECT FILE OPEN FAILURE

The indirect command
file
specified as "@filename'' in
the MACR0-11 command
line
could not be opened.
See
OPEN FAILURE ON INPUT FILE
for meaning.
11

MAC -- INVALID FORMAT IN MACRO LIBRARY

8-13

The library file has been
corrupted
or
it was not
produced by the
Librarian
Utility Program (LBR).

OPERATING PROCEDURES
Error Message

Meaning

MAC -- I/O ERROR ON INPUT FILE

In reading a record from a
source input file or macro
library file, an error was
detected by the file system,
e.g., a line containing more
than 132(10) characters is
encountered.
This
message
may
also indicate that a
device problem exists or that
either a source file or a
macro library file has been
corrupted
with
incorrect
data.

MAC -- I/O ERROR ON MACRO LIBRARY FILE

Same meaning as I/O ERROR ON
INPUT FILE, except that the
file is a macro library file
and not a source input file.

MAC -- I/0 ERROR ON OUTPUT FILE

In writing a record to the
object output file or the
listing output file, an error
was
detected by the file
system.
This message
may
also indicate that a device
problem exists or that the
storage space on a device has
been exhausted
(i.e.,
the
device is full).

MAC -- OPEN FAILURE ON INPUT FILE

2.
3.
4.
5.

MAC -- OPEN FAILURE ON OUTPUT FILE

2.
3.
4.
5.
6.

MAC -- SYMBOL TABLE OVERFLOW

Specified device does not
exist.
The volume is not
mounted.
A problem exists with the
device.
Specified directory file
does not exist.
Specified file does not
exist.
User does not have access
to the file directory or
the file itself.
Specified device does not
exist.
The volume is not
mounted.
A problem exists with the
device.
Specified directory file
does not exist.
User does not have access
to the file directory.
The volume is full or the
device is write
protected.

Available symbol table space
in dynamic memory has been
exceeded.

8-14

.~PPENDIX

MACR0-11 CHARACTER SETS

A.l

ASCII CHARACTER SET
EVEN
PARITY
BIT

7-BIT
OCTAL
CODE

CHARACTER

0
1

000
001

NUL
SOH

002

STX

003

ETX

004

EOT

005

ENQ

0
1
1

006
007
010

ACK
BEL
BS

011
012

1
0

013

014

VT
FF

015

016

017

1
0

020
021

DLE
DCl

022

DC2

023

DC3

REMARKS
Null, tape feed, CONTROL/SHIFT/P.
Start of heading; also SOM,
start
of message, CONTROL/A.
Start of text; also EOA, end of
address, CONTROL/B.
End of text;
also EOM,
end of
message; CONTROL/C.
End of transmission
(END);
shuts
off TWX machines, CONTROL/D.
Enquiry
(ENQRY);
also
WRU,
CONTROL/E.
Acknowledge; also RU, CONTROL/F.
Rings the bell. CONTROL/G.
Backspace;
also
FEO,
format
effector.
backspaces
some
machines, CONTROL/H.
Horizontal tab.
CONTROL/I.
Line feed or Line space (new line);
advances
paper
to
next line,
duplicated by CONTROL/J.
Vertical tab (VTAB).
CONTROL/K.
Form Feed to top of next page
(PAGE). CONTROL/L.
Carriage return to beginning of
line; duplicated by CONTROL/M.
Shift out; changes ribbon color to
red.
CONTROL/N.
Shift in; changes ribbon color to
black.
CONTROL/O.
Data link escape.
CONTROL/P (DCO).
Device
control
l;
turns
transmitter
(READER) on, CONTROL/Q
(X ON).
Device control 2;
turns punch or
auxiliary on. CONTROL/R (TAPE, AUX
ON).
Device
control
3;
turns
transmitter {READER) off, CONTROL/S
(X OFF).

A-1

MACR0-11 CHARACTER SETS
EVEN
PARITY
BIT

7-BIT
OC'I'AL
CODE

CHARACTER

024

DC4

025

NAK

026

SYN

Synchronous
CONTROL/V.

027

ETB

030
031
032
033
034
035
036
037
040
041
042
043
044
045
046
047
050
051
052
053
054
055
056
057
060
061
062
063
064
065
066
067
070
071
072
073
074
075
076
077
100
101
102
103

CAN
EM
SUB
ESC
FS
GS
RS

End of transmission block;
also
LEM,
logical
end
of
medium.
CONTHOL/W.
Cancel (CANCL).
CONTROL/X.
End of medium.
CONTROL/Y.
Substitute.
CONTROL/Z.
Escape.
CONTROL/SHIFT/K.
File separator.
CONTROL/SHIFT/L.
Group separator.
CONTROL/SHIFT/M.
Record separator.
CONTROL/SHIFT/N.
Unit separator.
CONTROL/SHIFT/O.
Space.

1
1
0
1
0
0

1
1
0
0

1
0
1
1
0
0

1
1
0

1
0
0
1
0
1
1
0
1
0
0

1
1
0

0
1
0

1
l

0
1
0

0
1

us
SP

REMARKS
Device control 4;
turns punch or
auxiliary
off.
CONTROL/T
(AUX
OFF).
Negative acknowledge;
also ERR,
ERROR.
CONTROL/U.
file

#
$
%
&

Accent acute or apostrophe.
(
)

0
1
2
3
4
5
6
7
8
9

>
?
@

A
B

A-2

(SYNC).

MACR0-11 CHARACTER SETS

EVEN
PARITY
BIT

7-BIT
OCTAL
CODE

0
0
1
0
1
1
0
1
0
0
1
1
0
0
1
0
1
1
0
0

104
105
106
107
llO
lll
ll2
ll3
ll4
115
ll6
ll 7
120
121
122
123
124
125
126
127
130
131
132
133
134
135
136
137
140

1
1
0
1
0
0
1
1
0
0
1
0
1
1

141
142
143
144
145
146
147
150
151
152
153
154
155
156

0
l
l

0
0
1
l

0
l

CHARACTER

REMARKS

D
e
f

g
h
i
j
k
1
m
n
0

p
q
r
s
t
u
v

w
x
y
z
]

shift/k.
shift/I.
shif t/m.

-...

*
**

[

Accent grave .

a
b

c
d
e
f

g
h
i
j
k
1
m
n

* ~

Appears as # or

Appears as underscore on some machines.

on some machines.

A-3

MACR0-11 CHARACTER SETS

A.2

EVEN
PARITY
BIT

7-BIT
OCTAL
CODE

0
1
0
0
1
0
1
1
0
0
1
1
0
1
0
0

1S7
160
161
162
163
164
16S
166
167
170
171
172
173
174
17S
176

177

REMARKS

CHARACTER
--0

p
q
r

s
t
u
v
w
x
y

z
This code generated by ALTMODE.
This code generated by pref ix key
(if present).
Delete, Rubout.

RADIX-SO CHARACTER SET
Character

ASCII Octal Equivalent

Radix-SO Equivalent

space

A-Z

101-132

1-32

unused
0-9

3S
60-71

The maximum Radix-SO value is,

36-47

thus~

47*S0**2+47*S0+47=174777
The following table provides a convenient means of translating between
the ASCII character set and its Radix~SO equivalents.
For example,
given the ASCII string X2B, the Radix-SO equivalent is (arithmetic is
performed in octal):
X=ll3000
2=002400
B=000002
X2B=l1S402

A-4

MACR0-11 CHARACTER SETS
Single Char.
or
First Char.

Second
Character

Third
Character

Space
A

000000
003100
B
006200
c
011300
D
014400
E
017500
F
022600
G
025700
H
031000
I
034100
J
037200
K
042300
L
045400
M
050500
N
053600
0
056700
p
062000
065100
Q
R
070200 .
s
073300
T
076400
u
101500
v
104600
w
107700
x
113000
y
116100
z
121200
124300
$
127400
Unused 132500
0
135600
1
140700
2
144000
3
147100
4
152200
5
155300
6
160400
7
163500
8
166600
9
1 71700

c
D

E
F
G
H
I

J
K
L
M
N

0
p

Q
R

u
v

w
x
y

z
$

Unused
0
1
2
3
4
5
6
7
8
9

000000
000050
000120
000170
000240
000310
000360
000430
000500
000550
000620
000670
000740
001010
001060
001130
001200
001250
001320
001370
001440
001510
001560
001630
001700
001750
002020
002070
002140
002210
002260
002330
002400
002450
002520
002570
002640
002710
002760
003030

A-5

c
D

E
F
G

H
I

J
K
L
M
N

0
p

Q
R

u
v

w
x
y

z
$

Unused
0
1
2
3
4
5
6
7
8
9

000000
000001
000002
000003
000004
000005
000006
000007
000010
000011
000012
000013
000014
000015
000016
000017
000020
000021
000022
000023
000024
000025
000026
000027
000030
000031
000032
000033
000034
000035
000036
000037
000040
000041
000042
000043
000044
000045
000046
000047

APPENDIX B
MACR0-11 ASSEMBLY LANGUAGE AND ASSEMBLER DIRECTIVES

B.l

SPECIAL CHARACTERS
Character

tab
space
#
@
(
)

(comma)
+

&
' (apostrophe)

<
>
\

vertical tab

B.2

Function
Label terminator
Direct assignment operator
Register term indicator
Item terminator or field terminator
Item terminator or field terminator
Immediate expression indicator
Deferred addressing indicator
Initial register indicator
Terminal register indicator
Operand field separator
Comment field indicator
Arithmetic addition operator or auto
increment indicator
Arithmetic subtraction operator or auto
decrement indicator
Arithmetic multiplication operator
Arithmetic division operator
Logical AND operator
Logical OR operator
Double ASCII character indicator
Single ASCII character indicator or
concatenation indicator
Assembly location counter
Initial argument indicator
Terminal argument indicator
Universal unary operator or argument
indicator
Macro call numeric argument indicator
Source line terminator

SUMMARY OF ADDRESS MODE SYNTAX

Address mode syntax is expressed in the summary below using the
following symbols:
n is an integer between 0 and 7 representing a
register number; R is a register expression;
E is an expression;
and ER is either a register expression or an expression in the range 0
to 7.

B-1

MACR0-11 ASSEMBLY LANGUAGE AND ASSEMBLER DIRECTIVES

Format

Address
Mode
Name

Address
Mode
Number

@R or
(ER)

(ER)+

Autoincrement

The contents of the register
specified
as
(ER)
are
incremented after being used
as the address of the operand.

@(ER)+

Autoincrement
Deferred

The register specified as (ER)
contains the pointer to the
address of the operand; the
register (ER)
is incremented
after use.

-(ER)

Autodecrement

The contents of the register
specified
as
(ER)
are
decremented before being used
as the address of the operand.

@-(ER)

Autodecrement
Deferred

The contents of the register
specified
as
(ER)
are
decremented before being used
as the pointer to the address
of the operand.

E(ER)

Index

The expression E, plus the
contents
of
the
register
specified as
(ER), form the
address of the operand.

@E(ER)

Index Deferred

The expression E, plus the
contents
of
the
register
specified as
(ER) , yield a
pointer to the address of the
operand.

Immediate

The expression
operand itself.

the

@#E

Absolute

The expression
E
is
address of the operand.

the

Relative

The expression E, plus the
contents of the PC, yield the
effective
address
of
the
operand.

Relative
Deffered

The expression E, plus the
contents of the PC, yield a
pointer
to
the
effective
address of the operand.

B-2

Meaning
R

contains

the

MACR0-11 ASSEMBLY LANGUAGE AND ASSEMBLER DIRECTIVES
B.3

ASSEMBLER DIRECTIVES

The MACR0-11 Assembler directives are summarized in the following
table.
For a detailed description of each directive, the table
contains references to the appropriate sections in the body of the
manual.
Form

Section
Reference
6.3.3
7.3.6

Operation
A
single
quote
(apostrophe}
followed by one ASCII character
generates a word which contains the
7-bit ASCII representation of the
character in the low-order byte and
zero in the high-order byte.
This

character

also

used

concatenation indicator
in
expansion of macro arguments
section 7.3.6).

the
(see

6.3.3

A double quote followed by two
ASCII characters generates a word
which contains the 7-bit
ASCII
representation
of
the
two
characters. The first character is
stored in the low-order byte;
the
second character is stored in the
high-order byte.

"Bn

6.4.1.2

Temporary radix control;
causes
the value n to be treated as a
binary number.

"Cexpr

6.4.2.2

Temporary numeric control;
the
expression's
value
complemented.

"Dn

6.4.1.2

Temporary radix control;
causes
the value n to be treated as a

causes
to be

decimal number.
"Fn

6.4.2.2

Temporary numeric control;
causes
the value n to be treated as a
sixteen-bit floating-point number.

"On

6.4.1.2

causes
Temporary radix control;
the value n to be treated as an
octal number .

. ASCII /string/

6.3.4

Generates
a
block
of
data
containing the ASCII equivalent of
the character string
(enclosed in
delimiting
characters),
one
character per byte .

. ASCIZ /string/

6. 3. 5

Generates
a
block
of
data
containing the ASCII equivalent of
the character string
(enclosed in
delimiting
characters),
one
character per byte, with a
zero
byte
terminating
the specified
string.

B-3

MACR0-11 ASSEMBLY LANGUAGE AND ASSEMBLER DIRECTIVES

Form

Section
Reference

.ASECT

6.8.2

Begin or
resume
program section.

.BLKB exp

6.5.3

Reserves a block of storage space
whose length in bytes is determined
by the specified expression.

.BLKW exp

6.5.3

Reserves a block of storage space
whose length in words is determined
by the specified expression.

.BYTE expl,exp2, •.

6.3.1

Generates successive bytes of data;
each byte contains the value of the
corresponding specified expression .

. CSECT name

6.8.2

Begin or resume named or unnamed
relocatable program section. This
directive
is
provided
for
compatibility
with other PDP-11
assemblers.

.DSABL arg

6.2

Disables the function specified
the argument.

.ENABL arg

6.2

Enables (invokes)
the
function
specified by the argument.

.END exp

6.6

Indicates the logical end of the
source
program.
The
optional
argument specifies the
transfer
address where program execution is
to begin.

.ENDC

6.10.l

Indicates the end of a
assembly block.

.ENDM name

7 .1. 2

Indicates the end of the current
repeat
block, indefinite repeat
block, or macro definition.
The
optional name, if used, must be
identical to the name specified in
the macro definition.

.ENDR

7.7

Indicates the end of the current
repeat block.
This directive is
provided for compatibility
with
other PDP-11 assemblers.

.EOT

6.6.2

Ignored;
indicates
end-of-tape
(which is detected automatically by
the hardware). It is included for
compatability
with
earlier
assemblers .

. ERROR exp;text

7.5

User
invoked
error
directive;
causes output to the listing file
or the
command
output
device
containing the optional expression
and the statement containing the
directive.

Operation

B-4

the

absolute

conditional

MACR0-11 ASSEMBLY LANGUAGE AND ASSEMBLER DIRECTIVES

Form

Section
Reference

.EVEN

6.5.l

Ensures that the current location
counter contains an even address by
adding 1 if it is odd.

.FLT2 argl,arg2, ...

6.4.2.1

Generates
successive
two-word
floating-point equivalents for the
floating-point numbers specified as
arguments.

.FLT4 argl,arg2, ...

6.4.2.1

Generates
successive
four-word
floating-point equivalents for the
floating-point numbers specified as
arguments.

.GLOBL syml,sym2, ...

6.9

Defines the symbol(s) specified
global symbol(s) .

. IDENT /string/

6 .1. 5

Provides a means of labeling the
object
module with the program
version number. The version number
is the Radix-50 string appearing
between
the
paired
delimiting
characters.

.IF cond,argl

6.10.2

Begins a conditional assembly block
of source code which is included in
the assembly only if the stated
condition is met with respect to
the argument(s) specified.

.IFF

6.10.2

Appears only within a conditional
assembly
block,
indicating the
beginning of a section of code to
be assembled if the condition upon
entering the block tests false.

.IFT

6.10.2

Appears only within

Operation

a conditional
indicating the
beginning of a section of code to
be assembled if the condition upon
entering the block tests true.
assemo~y

o~ocK,

.IFTF

6.10.2

Appears only within a conditional
assembly
block,
indicating the
beginning of a section of code to
be assembled unconditionally.

.IIF cond,arg,
statement

6.10.3

Acts as a one-line
conditional
assembly block where the condition
is
tested
for
the
argument
specified.
The
statement
is
assembled only if the condition
tests true.

.IRP sym,
<argl,arg2, ••. >

7.6.1

Indicates
the
beginning of an
indefinite repeat block in which
the symbol specified is replaced
with successive elements of the
real argument list enclosed within
angle brackets.

B-5

MACR0-11 ASSEMBLY LANGUAGE AND ASSEMBLER DIRECTIVES

Form

Section
Reference

Operation

.IRPC sym,<string>

7.6.2

Indicates the beginning
of
an
indefinite repeat block in which
the specified symbol takes on the
value
of successive characters,
optionally enclosed within angle
brackets.

.LIMIT

6.7

Reserves two words into which the
Task Builder inserts the low and
high addresses of the task image.

• LIST arg

6 .1.1

Without an argument, the
.LIST
directive increments the listing
level count
by
1.
With
an
argument, this directive does not
alter the listing level count, but
formats
the
assembly
listing
according
to
the
argument
specified.

.MACRO name,argl,
arg2, ...

7 .1.1

Indicates
definition
name
and
arguments .

. MCALL argl,arg2, ...

7.8

Specifies the symbolic names of the
user or system macro definitions
required in the assembly of' the
current user program, but which are
not defined within the program.

.MEXIT

7 .1. 3

Causes an exit from the current
macro
expansion
or
indefinite
repeat block.

.NARG symbol

7.4.1

Can appear only within a macro
definition;
equates the specified
symbol to the number of arguments
in the macro call currently being
expanded.

.NCHR symbol,<string>

7.4.2

Can appear anywhere in a source
program;
equates
the
symbol
specified
to
the
number
of
characters in the specified string.

• NLIST arg

6 .1.1

Without an argument, the .NLIST
directive decrements the listing
level count
by
1.
With
an
argument, this directive suppresses
that
portion
of
the
listing
specified by the argument.

.NTYPE symbol,aexp

7. 4. 3

Can appear only within a macro
definition;
equates the symbol to
the 6-bit addressinq mode of the
specified address expression.

B-6

the start of a macro
having the
specified
the
following dummy

MACR0-11 ASSEMBLY LANGUAGE AND ASSEMBLER DIRECTIVES

Form

Section
Reference

Operation

6.5.2

Ensures that the current location
counter contains an odd address by
adding 1 if it is even.

.PAGE

6.1.6

Causes the assembly listing to skip
to the top of the next page.

.PRINT exp;text

7.S

User invoked message
directive;
causes output to the listing file
or the
command
output
device
containing the optional expression
and the statement containing the
directive.

.PSECT name,attl, •..
attn .

6.8.1

Begin or resume a named or unnamed
program
section
having
the
specified attributes.

.RADIX n

6.4.1.1

Alters the current program radix to
n, where n is 2, 4, 8, or 10 .

. RADSO /string/

6.3.6

Generates
a
block
of
data
containing the Radix-SO equivalent
of the character string enclosed
within delimiting characters.

.REPT exp

7.7

Begins a repeat block; causes the
section of code up to the next
.ENDM or .ENDR directive to be
repeated
the
number
of times
specified as exp .

. SBTTL string

6.1.4

Causes the specified string to be
printed as part of the assembly
listing page header.
The string
component of each .SBTTL directive
is collected into a
table
of
contents at the beginning of the
assembly listing .

. TITLE string

6.1.3

Assigns the first six
Radix-SO
characters in the string as an
object module name and causes the
string to appear on each page of
the assembly listing .

. WORD expl,exp2, ..

6.3.2

Generates successive words of data;
each word contains the value of the
corresponding specified expression.

B-7

APPENDIX C
PERMANENT SYMBOL TABLE (PST)

The permanent symbol table (PST) contains those symbols which are
automatically recognized by MACR0-11.
The symbols so recognized
consist of both op codes and assembler directives.
The op codes
(i.e., the instruction set) are listed first, followed by the
directives which cause specific actions during assembly.
For those desiring a detailed description of the instruction set,
appropriate PDP-11 Processor Handbook may be consulted.

C.l

OP CODES
MNEMONIC

OCTAL
VALUE

ADC
BITB
BLE
BLO
BLOS
BLT
BMI
BNE
BPL
BPT
ADCB
ADD
ASH
ASHC
ASL
ASLB
ASR
ASRB
BCC
BCS
BEQ
BGE
BGT
BHI
BHIS
BIC
BICB
BIS
BISB
BIT

005500
130000
003400
103400
101400
002400
100400
001000
100000
000003
105500
060000
072000
073000
006300
106300
006200
106200
103000
103400
001400
002000
003000
101000
103000
040000
140000
050000
150000
030000

FUNCTIONAL NAME
Add Carry
Bit Test (Byte)
Branch If Less Than Or Equal
Branch I f Lower
Branch I f Lower Or Same
Branch I f Less Than
Branch I f Minus
Branch I f Not Equal
Branch I f Plus
Breakpoint Trap
Add Carry \D.Y '--~ J
Add Source To Destination
Shift Arithmetically
Arithmetic Shift Combined
Arithmetic Shift Left
Arithmetic Shift Left (Byte)
Arithmetic Shift Right
Arithmetic Shift Right (Byte)
Branch If Carry Is Clear
Branch If Carry Is Set
Branch I f Equal
Branch If Greater Than Or Equal
Branch I f Greater Than
Branch I f Higher
Branch I f Higher Or Same
Bit Clear
Bit Clear (Byte)
Bit Set
Bit Set (Byte)
Bit Test
1n .... :__ \

C-1

the

PERMANENT SYMBOL TABLE (PST)

MNEMONIC

OCTAL
VALUE

BR
BVC
BVS
CALL
CCC
CLC
CLN
CLR
CLRB
CLV
CLZ
CMP

000400
102000
102400
004700
000257
000241
000250
005000
105000
000242
000244
020000

CMPB

120000

COM
COMB

005100
105100

DEC
DECB

005300
105300

DIV
EMT
FADD
FDIV
FMUL
FSUB
HALT
INC
INCB

071000
104000
075000
075030
075020
075010
000000
005200
105200

IOT
JMP
JSR
MARK
MFPI

000004
000100
004000
006400
006500

MOV
MOVB

010000
110000

MTPI

006600

MOL
NEG
NEGB
NOP
RESET
RETURN
ROL
ROLB
ROR
RORB
RTI

070000
005400
105400
000240
000005
000207
006100
106100
006000
106000
000002

RTS
RTT

000200
000006

FUNCTIONAL NAME
Branch Unconditional
Branch If Overflow Is Clear
Branch If Overflow Is Set
Jump To Subroutine (JSR PC,xxx)
Clear All Condition Codes
Clear C Condition Code Bit
Clear N Condition Code Bit
Clear Destination
Clear Destination (Byte)
Clear V Condition Code Bit
Clear Z Condition Code Bit
Compare Source To
Destination
Compare Source To
Destination (Byte)
Complement Destination
Complement Destination
(Byte)
Decrement Destination
Decrement Destination
(Byte)
Divide
Emulator Trap
Floating Add
Floating Divide
Floating Multiply
Floating Subtract
Halt
Increment Destination
Increment Destination
(Byte)
Input/Output Trap
Jump
Jump To Subroutine
Mark
Move From Previous
Instruction Space
Move Source To Destination
Move Source To Destination
(Byte)
Move To Previous
Instruction Space
Multiply
Negate Destination
Negate Destination (Byte)·
No Operation
Reset External Bus
Return From Subroutine (RTS PC)
Rotate Left
Rotate Left (Byte)
Rotate Right
Rotate Right (Byte)
Return From Interrupt
(Permits a trace
trap)
Return From Subroutine
Return From Interrupt
(inhibits trace trap)

C-2

PERMANENT SYMBOL TABLE (PST)

MNEMONIC
SBC
SBCB

OCTAL
VALUE

SEC
SEN
SEV
SEZ
SOB
SUB

005600
105600
000277
000261
000270
000262
000264
077000
160000

SWAB
SXT
TRAP
TST
TSTB
WAIT
XOR

000300
006700
104400
005700
105700
000001
074000

sec

FUNCTIONAL NAME
Subtract Carry
5 ..UIJl...L
i...-1--~~.iCarry (Qu+-o'
QI.,,'\ ..._, .1 ' - ' - I
Set All Condition Code Bits
Set C Condition Code Bit
Set N Condition Code Bit
Set V Condition Code Bit
Set z Condition Code Bit
Subtract One And Branch
Subtract Source From
Destination
Swap Bytes
Sign Extend
Trap
Test Destination
Test Destination (Byte)
Wait For Interrupt
Exclusive OR

OP CODES (PDPll/45/70 ONLY)
MNEMONIC

OCTAL
VALUE

ABSD
ABSF
ADDD
ADDF
CFCC

170600
170600
1 72000
172000
170000

CLRD
CLRF
CMPD
CMPF
DIVD

170400
170400
173400
173400
174400

MNEMONIC

OCTAL
VALUE

DIVF
LDCDF

174400
177400

LDC FD

177400

LDC ID

177000

LDC IF

177000

LDCLD

177000

LDCLF

177000

LDD
LDEXP
LDF
LDFPS

17L400
176400
172400
170100

FUNCTIONAL NAME
Make Absolute Double
Make Absolute Floating
Add Double
Add Floating
Copy Floating Condition
Codes
Clear Double
Clear Floating
Compare Double
Compare Floating
Divide Double
T l"'\l\11\ T
r U!'H.... J. .L
V1'1fi.U
riT"l"r.."Tnm

l\l 7\ UD

ncu•1J..J

Divide Floating
Load And Convert From
Double To Floating
Load And Convert From
Floating To Double
Load And Convert Integer To
Double
Load And Convert Integer To
Floating
Load And Convert Long
integer To Double
Load And Convert Long
Integer To Floating
Load Double
Load Exponent
Load Floating
Load FPPs Program Status

C-3

C.2

PERMANENT SYMBOL TABLE

(PST)

MNEMONIC

OCTAL
VALUE

FUNCTIONAL NAME

MFPD

106500

MODD

171400

MODF

171400

MTPD
MULD
MULF
NEGD
NEGF
SETD
SETF
SETI
SETL
SPL
STCDF

106600
171000
171000
170700
170700
1 70011
170001
170002
170012
000230
176000

STCDI

175400

STCDL

175400

STCFD

176000

STCFI

175400

STCFL

175400

STD
STEXP
STF
ST FPS
STST
SUBD
SUBF
TSTD
TSTF

1 74000
175000
1 74000
170200
170300
173000
1 73000
170500
170500

Move From Previous Data
Space
Multiply And Integerize
Double
Multiply And Integerize
Floating
Move To Previous Data Space
Multiply Double
Multiply Floating
Negate Double
Negate Floating
Set Double Mode
Set Floating Mode
Set Integer Mode
Set Long Integer Mode
Set Priority Level
Store And Convert From
Double To Floating
Store And Convert From
Double To Integer
Store And Convert From
Double To Long Integer
Store And Convert From
Floating To Double
Store And Convert From
Floating To Integer
Store And Convert From
Floating To Long Integer
Store Double
Store Exponent
Store Floating
Store FPPs Program Status
Store FPPs Status
Subtract Double
Subtract Floating
Test Double
Test Floating

MACR0-11 DIRECTIVES
DIRECTIVE
. ASCII
.ASCIZ
.ASECT
.BLKB
.BLKW
.BYTE
.CSECT

FUNCTIONAL SIGNIFICANCE
Translates character string to ASCII equivalents .
Translates character string to ASCII equivalents;
inserts zero byte as last character.
Begins absolute program section
(provided for
compatibility with other PDP-11 assembliers).
Reserves byte block in accordance with value of
specified argument.

Reserves word block in accordance

with

value

specified argument.
Generates successive byte data in accordance with
specified arguments.
Begins relocatable program section
(provided
for
compatibility with other PDP-11 assemblers).

C-4

PERMANENT SYMBOL TABLE (PST)
DIRECTIVE
. DSABL
. ENABL
. END
. ENDC
.ENDM
.ENDR
. EOT
.ERROR
. EVEN
.FLT2
.FLT4
. GLOBL
.IDENT
. IF
.IFF
.IFT
.IFTF
.IIF
.IRP
.IRPC

.LIMIT
.LIST
.MCALL
.MEXIT
.NARG
.NCHR
.NLIST
.NTYPE
. ODD
. PAGE
. PRINT
.PSECT
. RADIX
.RAD50

FUNCTIONAL SIGNIFICANCE
Disables specified function .
Enables specified function .
Defines logical end of source program .
Defines end of conditional assembly block .
Defines end of macro definition, repeat block, or
indefinite repeat block.
Defines end of current repeat block (provided for
compatibility with other PDP-11 assemblers).
Define End of Tape condition (ignored) .
Outputs diagnostic message to listing file or
command output device.
Word-aligns the current location counter .
Causes two words of storage to be generated for
each floating-point argument.
Causes four words of storage to be generated for
each floating-point argument.
Declares global attribute for specified symbol(s) .
Labels object module with
specified
program
version number.
Begins conditional assembly block .
Begins
subconditional
assembly
block
(if
conditional assembly block test is false).
Begins
subconditional
assembly
block
(if
conditional assembly block test is true).
Begins subconditional assembly block
(whether
conditional assembly block test is true or false).
Assembles immediate conditional assembly statement
(if specified condition is satisfied).
Begins
indefinite
repeat
block;
replaces
specified symbol with specified successive real
arguments.
Begins
indefinite
repeat
block;
replaces
specified
symbol
with
value
of successive
characters in specified string.
Reserves two words of storage for high and low
addresses of task image.
Controls listing level count and
format
of
assembly listing.
.MACRO Denotes start of macro
definition.
Identifies required
macro
definition(s)
for
assembly.
Exit from current macro definition or indefinite
repeat block.
Equates specified symbol to
the
number
of
arguments in the macro expansion.
Equates specified symbol to
the
number
of
characters in the specified character string.
Controls listing level count
and
suppresses
specified portions of the assembly listing.
Equates specified symbols to the addressing mode
of the specified argument.
Byte-aligns the current location counter .
Advances form to top of next page .
Prints specified message on command output device .
Begins specified program section having specified
attributes.
Changes current program radix to specified radix .
Generates data block having Radix-50 equivalents
of specified character string.

C-5

PERMANENT SYMBOL TABLE (PST)
DIRECTIVE
.REPT
.SBTTL
.TITLE
.WORD

FUNCTIONAL SIGNIFICANCE
Begins repeat block and replicates it according to
the value of the specified expression.
Prints specified subtitle text as the second line
of the assembly listing page header.
Prints specified title text as object module name
in the first line of the assembly listing page
header.
Generates successive word data in accordance with
specified arguments.

The MACR0-11 directives listed above are summarized in greater
in Appendix B.

C-6

detail

APPENDIX D
DIAGNOSTIC ERROR MESSAGE SUMMARY

D.l

MACR0-11 ERROR CODES

A diagnostic error code is printed as the first character in the
source line which contains an error detected by MACR0-11. This error
code identifies a syntactical problem or some other type of error
condition detected during the processing of a source line. An example
of such a source line is shown below:
Q

26 000236

010102

MOV Rl,R2,A

The extraneous argument A in the MOV instruction above causes the line
to be flagged with a Q (syntax) error.
Error Code

Meaning
Assembly error. Because many different types of
error conditions produce this diagnostic message,
all the possible directives which may yield a
general assembly error have been categorized below
to reflect specific classes of error conditions:
CATEGORY 1:

ILLEGAL ARGUMENT SPECIFIED .

. RADIX -- A value other than 2, 4, 8, or 10
specified as a new radix .

. LIST/.NLIST -- Other than a legally defined
argument
(see Table 6-1) is specified with the
directive .
. ENABL/.DSABL -- Other than a legally defined
argument (see Table 6-2) is specified with the
directive .
. PSECT -- Other than a legally-defined argument
(see
Table
6-3)
is
specified with the
directive.

D-1

GIAGNOSTIC ERROR MESSAGE SUMMARY
Error Code
A

(Cont'd)

Meaning
.IF/.IIF -- Other than a legally defined
conditional test (see Table 6-5) or an illegal
argument expression value is specified with the
directive.
CATEGORY 2:

NULL ARGUMENT OR SYMBOL SPECIFIED .

. TITLE -- Program name is not specified in the
directive,
or
first
non-blank
character
following the directive is a
non-Radix-SO
character .
. IRP/.IRPC -- No dummy argument is specified in
the directive .
. NARG/.NCHAR/.NTYPE -- No symbol
in the directive •

. IF/.IIF -- No
conditional
specified in the directive.

argument

CATEGORY 3: UNMATCHED DELIMITER/ILLEGAL
CONSTRUCTION .

specified
is

ARGUMENT

. ASCII/.ASCIZ/.RADSO/.IDENT -- Character string
or argument string delimiters do not match, or
an illegal character is used as a delimiter, or
an illegal argument construction is used in the
directive •
. NCHAR -- Character string delimiters do not
match, or an illegal character is used as a
delimiter in the directive.
CATEGORY 4:

GENERAL ADDRESSING ERRORS.

This type of error results from one of
possible conditions:

several

Permissible range of a branch instruction,
i.e., from -128(10) to +127(10) words, has
been exceeded.

A statement makes invalid
use of
the
current
location
counter,
e.g.,
a
1
11
• • =expression
statement attempts to force
the
current location counter to cross
program section (.PSECT) boundaries.

A statement contains an invalid address
expression.
In cases where an absolute
address expression is required, specifying
a global symbol, a relocatable value, or a
complex relocatable value (see section 3.9)

D-2

DIAGNOSTIC ERROR MESSAGE SUMMARY
Error Code

Meaning
results in an invalid address expression.
Similarly, in cases where a relocatable
address expression is required, either a
relocatable
or
absolute
value
is
permissible, but a global symbol or a
complex relocatable value in the statement
likewise results in an invalid address
expression. Specific cases of this type of
error are those which follow:

(Cont'd)

.BLKB/.BLKW/.REPT -- Other than an absolute
value or an expression which reduces to an
absolute value has been specified with the
directive.
4.

Multiple expressions are not separated by a
comma.
This condition causes the next
symbol to be evaluated as part of the
current expression.

CATEGORY 5:

ILLEGAL FORWARD REFERENCE.

This type of error results from either
possible conditions:
1.

A
global
assignment
(symbol==expression)
contains
reference to another symbol.

two

statement
forward

An expression defining the value of the
current location counter contains a forward
reference.

Bounding error. Instructions or word data are
being assembled at an odd address. The location
counter is incremented by 1.

Doubly-defined symbol referenced.
Reference was
made to a symbol which is defined more than once.

End directive not found. When the end-of-file is
reached during source input and the .END directive
has not yet been encountered, MACR0-11 generates
this
error code, ends assembly pass 1, and
proceeds with assembly pass 2.

Illegal character detected.
Illegal characters
which are also non-printable are replaced by a
question mark (?) on the listing.
The character
is then ignored.

Input line is greater than 132(10) characters in
length. Currently, this error condition is caused
only through excessive substitution
of
real
arguments for dummy arguments during the expansion
of a macro.

D-3

DIAGNOSTIC ERROR MESSAGE SUMMARY
Error Code

Meaning

Multiple definition of a label was encountered
which was equivalent (in the first six characters)
to a label previously encountered.

A number contains a digit that is not in the
current program radix. The number is evaluated as
a decimal value.

Opcode
error.
Directive
out
of
context.
Permissible nesting level depth for conditional
assemblies has been exceeded. Attempt to expand a
macro which was unidentified after .MCALL search.

Phase error. A label's definition of value varies
from one assembly pass to another or a multiple
definition of a local symbol has occurred within a
local symbol block. Also, when in a local symbol
block defined by the .ENABL LSB directive, an
attempt has occurred to define a local symbol in a
program section other than that which was in
effect when the block was entered. A P error code
also appears if an .ERROR directive is assembled.

Questionable syntax. Arguments are missing, too
many arguments are specified, or the instruction
scan was not completed.

Register-type error.
An invalid use
of
or
reference to a register has been made, or an
attempt has been made to redefine a standard
register symbol without first issuing the .DSABL
REG directive.

Truncation error. A number generated more than 16
bits in a word, or an expression generated more
than 8 significant bits during the use of the
.BYTE directive or trap (EMT or TRAP) instruction.

Undefined symbol.
An
undefined
symbol
was
encountered
during
the
evaluation
of
an
expression; such an undefined symbol is assigned
a value of zero. Other possible conditions which
result in this error code include unsatisfied
macro names in the list of .MCALL arguments and a
direct assigment
(symbol=expression)
statement
which contains a forward reference to a symbol
whose
definition
also
contains
a
forward
reference;
also, a local symbol may have been
referenced that does not exist in the current
local symbol block.

Instruction error. The instruction so flagged is
not compatible among all members of the PDP-11
family.

D-4

APPENDIX E
SAMPLE CODING STANDARD

E.l

INTRODUCTION

Standards eliminate variability and the requirement to make
a
decision. Much of the difficulty in establishing standards stems from
the notion that they should be optimal. However, to be successfully
applied, standards must represent an agreement on certain aspects of
the programming process.
This Appendix contains Digital's PDP-11 Program Coding Standard.
It
is suggested that this be used as a model to assist users in preparing
standards for their own installations.

E.2

LINE FORMAT

All source lines shall consist of from one to a maximum of eighty
characters (not including ;**DDDD**, or ;**NEW** added by the SLIPR
(SLP in RSX-llM) editor. This program is described in the applicable
RSX-llM or RSX-llD utilities manual or in the IAS Editing Utilities
Reference Manual (see section 0.3 in the Preface).
Assembly language code lines shall have the following format:
1.

Label Field - if present; the label shall start at tab stop 0
(column 1).

Operation field - the operation field shall start at tab stop
1 (column 9).

Operand field - the operand field shall start at tab
(column 17).

Comments field - the comments field shall start at tab stop 4
(column 33) and may continue to column 80.

stop

Comment lines that are included in tbe code body shall be delimited by
a line containing only a leading semicolon.
The comment itself
contains a leading semicolon and starts in column 3. Indents shall be
1 tab.
If the operand field extends beyond tab stop 4 (column 33) simply
leave a space and start the comment. Comments which apply to an
instruction but require continuation should always line up with the
character position which started the comment.

E-1

SAMPLE CODING STANDARD
E.3

COMMENTS

Comment all coding to convey the global role of an instruction, rather
than simply a literal translation of the instruction into English. In
general this will consist of a comment per line of code.
If a
particularly difficult, obscure, or elegant instruction sequence is
used, a paragraph of comments must immediately precede that section of
code.
Preface text, which describes formats, algorithms, program-local
variables, etc., will be delimited by the character sequence·;+ at the
start of the text and ;- at the end;
these delimiters facilitate
automated extraction of narrative commentary. The comment itself will
start in column 3.
For example:
;+

THE INVERT ROUTINE ACCEPTS
A LIST OF RANDOM NUMBERS AND
APPLIES THE KOLMOGOROV ALGORITHM
TO ALPHABETIZE THEM.
;-

E.4

E.4.1

NAMING STANDARDS

E.4.1.1 General Purpose Registers - Only
permitted as register names;
and may
purpose:
R0=%0
Rl=%1
R2=%2
R3=%3
R4=%4
R5=%5
SP=%6
PC=%7

the
not

following names are
be used for any other

;REG 0
;REG 1
;REG 2
;REG 3
;REG 4
;REG 5
;STACK POINTER (REG 6)
;PROGRAM COUNTER (REG 7)

E.4.1.2 Hardware Registers These
identically to the hardware definition.

registers
must
be
named
For example, PS and SWR.

E.4.1.3 Device Registers - These are symbolically named identically
to the hardware notation. For example, the control status register
for the RK disk is RKCS. Only this symbolic name may be used to refer
to this register.

E-2

SAMPLE CODING STANDARD
E.4.2

Processor Priority

Testing or altering the processor priority is done using the symbols
PRO, PRl, PR2, ...... PR7
which are equated to their corresponding priority bit pattern.

E.4.3

Other Symbols

Frequently-used bit patterns such as CR and
conventional symbolics on an as-needed basis.

E.4.4

will

made

Using the Standard Symbolics

The register standards will be defined within the assembler.
All
other standard symbols will appear in a file and will be linked prior
to program execution.

E.4.5

Symbols*

E.4.5.1 Global Symbols - Global symbols should be easily recognized
by their format. The following standards apply and completely define
symbol standards for PDP-11 Medium/Large software products.

symbol

pos-1

pos-2

pos-3

pos-4

pos-5

pos-6

length

non-glbl-sym

letter

a-nuM/
null

a-nurn/
null

a-num/
null

>=l

':;j..L..L>..L.-<=>:t><•

,...., \...,

~I
"r' / •

a-num/
null

a-nu.11\/
null

a-num/
null

a-nu..rn/
null

>=l

glbl-off set

letter

$/.

a-num

a-nurn/
null

>=3

glbl-bit-ptrn

letter

a-nurn

$/.

a-num/

a-nurn/
null

>=4

local-sym

number

-""~""'

>=2

E-3

SAMPLE CODING STANDARD
where:
a-num
non-glbl-sym
local-sym

is an alphanumeric character.
are non-global symbols.
local symbols, as defined by
MACR0-11.
are global symbols (addresses).
are global offsets (absolute
quantities).
are global bit patterns.

glbl-sym
glbl-offset
glbl-bit-ptrn

A program never contains a .GLOBL statement without showing cause.

E.4.5.2

Symbol Examples

Non-Global Symbols
AlB
ZXCJl
INS RT

Global Address Symbols
$JIM
.VECTR
$SEC
Global Absolute Offset Symbols
A$JIM
A$XT
A.ENT
Global Bit Pattern Symbols
Al$20
B3.6
JI.M
Local Symbols
37$
271$
6$

* Symbols that are branch targets are also called labels, but we
al ways use the term "symbol

1
1 •

** Number is in the range O<number<65535.
E-4

will

SAMPLE CODING STANDARD
E.4.5.3 Program-local Symbols Self-relative address arithmetic
(.+n) is absolutely forbidden in branch instructions; their use in
other contexts must be avoided if at all possible and practical.
Target symbols for branches that exist solely for positional reference
will use local symbols of the form
<num>$:
Use of non-local symbols is restricted, within reason, to those cases
where
reference
to
the
code
occurs external to the code.
Local-symbols are formatted such that the numbers proceed sequentially
down the page and from page to page.

E.4.5.4 Macro Names The last two characters (with the last
character possibly being null) have special significance. The next to
last character is a $, the last, a character specifying the mode of
the macro.
For example, in the three macro forms in-line, stack, and p-section,
the in-line form has no suffix, the stack has an <S>, and the
p-section a <C>. Thus the Queue I/O Macro can be written as any of
QIO$
QI0$S
QI0$C
depending on the form required. These are not reserved letters.
the form of the name is standard.

E.5

E.5.1

Only

PROGRAM MODULES

General Comments on Programs

In our software, a program provides a single distinct function.
No
limits exist on size, but the single function limitation should make
modules larger than lK a rarity. Since any software may eventually
exploit the virtual memory capacity of the 11/40 and 11/45, programs
should make every attempt to maintain a dense reference locus
(don't
promiscuously branch over page boundaries or over a large absolute
address distance).
All code is read-only. Code and data areas are distinct and each
contains explanatory text. Read-only data should be segregated from
read-write data.

E.5.2

The Module Preface

Each program module in the system shall exist as a separate file. The
file name will reflect the name of the module and the file extension
shall be of the form 'NNN'. The 'NNN' signifies the edit number or

E-5

SAMPLE CODING STANDARD
the version number. The version number shall be changed only when a
new base level is created. Furthermore, if no corrections are made to
a file from one base level to the next, the version number will not be
changed. The availability of File Control Services and File Control
Primitives will greatly simplify version number maintenance. Program
modules adhere to a strict format.
This format adds to
the
readability and understandability of the module.
The following
sections are included in each module:
For the Code Section:
1.

A .TITLE statement that specifies the name of the module.
If
a module contains more than one routine, subtitles may be
used.

An .!DENT statement specifying the version number.
PDP-11 version number standard appears in section E.10.

The

A .PSECT statement that defines the program section in
the module resides.

which

A copyright statement, and the disclaimer.
Copyright 1975,
Mass.

Digital

Equipment

Corp.,

Maynard,

This software is furnished to purchaser under a
license for use on a single computer system and can
be copied (with inclusion of DEC's copyright notice)
only for use in such system, except as may otherwise
be provided in writing by DEC.
The information in this document is subject to change
without notice and should not be construed as a
commitment by Digital Equipment Corporation.
DEC assumes no responsibility for the
use
or
reliability of its software on equipment which is not
supplied by DEC.
5.

The version number of the file.
The PDP-11 version number standard is
E.10.

described
on

section

The name of the principal author and the date
module was first created.

which

the

The name of each modifying author and
the
date
of
modification.
Names and modification dates appear one per
line and in chronological order.

A brief statement of the function of the module.

Note: Items 1-8 should appear on the same page.
A list of the definitions of all equated local symbols used
in the module. These definitions appear one per line and in
alphabetical order.

10. All local macro definitions, preferably in alphabetical order
by name.

E-6

SAMPLE CODING STANDARD
11.

All local data.
a.
b.
c.

The data should indicate

Description of each element (type, size, etc.)
Organization (functional, alpha, adjacent, etc.)
Adjacency requirements

12.

A more detailed definition of the function of the module.

13.

A list of the inputs expected by the module.
the
calling
sequence
if non-standard,
settings, and global data settings.

14.

A list of the outputs produced as a result of entering this
module.
These include delivered results, condition code
settings, but not side effects.
(All these outputs are
visible to the caller.)

15.

A list of all effects (including side effects) produced as a
result of entering this module. Effects include alterations
in the state of the system not explicitly expected in the
calling sequence, or those not visible to the caller.

16.

The module code.

E.5.3

This includes
condition code

Formatting the Module Preface

Rules:
1.

The first eight items appear on the same page and will not
have explicit headings.
Item 3 may be omitted if the blank
p-section is being used.

Headings start at the left
indented 1 tab position.

Items 7-14 will have headings which start at the left margin,
preceded and followed by lines containing only a leading <;>.
Items which do not apply may be omitted.

margin*;

descriptive

text

A template for the module preface follows.
FILE-EXAMPL.SOl
.TITLE
.IDENT
.PSECT
COPYRIGHT

EXAMPLE
/01/
KERNEL
1975,

DIGITAL

EQUIPMENT

CORP.,

MAYNARD,

MASS.

THIS SOFTWARE IS FURNISHED TO PURCHASER UNDER A LICENSE FOR USE
ON A SINGLE COMPUTER SYSTEM AND CAN BE COPIED (WITH INCLUSION
OF DEC'S COPYRIGHT NOTICE) ONLY FOR USE IN SUCH SYSTEM, EXCEPT

*The left margin consists of a <;> a <space> then the heading, so
text of the heading begins in column 3.

E-7

the

SAMPLE CODING STANDARD
AS MAY OTHERWISE BE PROVIDED IN WRITING BY DEC.
THE INFORMATION IN THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT
NOTICE AND SHOULD NOT BE CONSTRUED AS A COMMITMENT BY DIGITAL
EQUIPMENT CORPORATION.
DEC ASSUMES NO RESPONSIBILITY FOR
OF ITS SOFTWARE ON EQUIPMENT WHICH

THE USE OR RELIABILITY
IS NOT SUPPLIED BY DEC.

VERSION 01
JOE PASCUSNIK l-JAN-72
MODIFIED BY:
RICHARD DOE

2l~JAN-73

SPENCER THOMAS 12-JUN-73

Brief statement of the module's function
EQUATED SYMBOLS

List equated symbols
LOCAL MACROS

Local Macros
LOCAL DATA

Local data
;+
Module function-details
INPUTS:

Description of inputs
OUTPUTS:

Description of outputs
EFFECTS:

Description of effects
;-

Begin Module Code

E.5.4

Modularity

No other characteristic has more impact on

E-8

the

ultimate

engineering

SAMPLE CODING STANDARD
success of a system than does modularity. Modularity for PDP-11
Medium/Large Software· Engineering's
products
consists
of
the
application of the single-function philosophy described in section
E.5.1, and adherence to a set of calling and return conventions.

E.5.4.1 Calling Conventions
conventions must be observed.

(Inter-Module) - The

following

calling

Transfer of Control
Macros will exist for call and return. The actual transfer will
be via a JSR PC instruction.
For register save routines, a
JSR Rn,SAVE will be permitted.
The CALL macro is:
CALL

subr-name

The RETURN macro is:
RETURN
Register Conventions
On entry, a subroutine minimally saves all registers it intends
~o
alter except result registers.
On exit it restores these
registers.
(State preservation is assumed across calls.)
Argument Passing
Any registers may be used, but their use should follow a coherent
pattern.
For example; if passing three arguments, pass them in
RO, Rl and R2 rather than RO, R2, RS.
Saving and restorinq
occurs in one place.

E.5.4.2
macro.

Exiting -

All subroutine exits occur through a single RETURN

E.5.4.3 Intra-Module Calling Conventions Designer optional, but
consistency favors a calling sequence identical to that of the
inter-module sequence.

E.5.4.4 Success/Failure Indication - The C bit will be used to
return the success/failure indicator, where success equals 0, and
failure equals 1. The argument registers can be used to return values
or additional success/failure data.

E.5.4.5 Module Checking Routines Modules are responsible for
verifying the validity of arguments passed to them. The design of a
module's calling sequence should aim at minimizing the validity checks
by minimizing invalid combinations. Programmers may add test code to
perform additional checks durinq checkout. All code should aim at
discovering an error as close (in terms of instruction executions) to
its occurrence as possible.
E-9

SAMPLE CODING STANDARD
E.6

E.6.1

FORMATTING STANDARDS

Program Flow

Programs will be organized on the listing such that they flow down the
page, even at the cost of an extra branch or jump.
For example:

PROCESS

BBB

AAA

COMMON

shall appear on the listing as:
TST
BNE

BBB

CMN

AAA:

BBB:
CMN:

Rather than:
TST
BNE

BBB

CMN

AAA:

CMN:

BBB:

E-10

SAMPLE CODING STANDARD
E.6.2

Common Exits

A common exit appears as the last code sequence on the listing.
the flow chart:

EXIT

will appear on the listing as:
PRl:
BR

EXIT

PR2:

PR3:

PR4:

EXIT:
And not as:
PRl:

EXIT:

PR2:
BR

EXIT

PR3:

PR4:

E-11

Thus

SAMPLE CODING STANDARD
E.6.3

Code with Interrupts Inhibited

Code that is executed with interrupts inhibited, shall be flagged by a
three semi~colon (;;;) comment delimiter. For example:
.. ERTZ:

;ENABLE BY RETURNING
;BY SYSTEM SUBROUTINES,
#PR7,PS
#PR7,+2(SP)

; ; ;

BI'I'

BEQ

10$

; ; ;
; ; ;

BIS

RTT

10$:

INHIBIT INTERRUPTS

; ; ;
,

; ; ;
; ; ;

E.7

M
M
E
N

'I'

PROGRAM SOURCE FILES

Source creation and maintenance shall be done in base levels. A base
level is defined as a point at which the program source files have
been frozen.
From the freeze point to the next base
level,
corrections will not be made directly to the base level itself.
Rather a file of corrections shall be accumulated for each file in the
base
level.
Whenever an updated source file is desired, the
correction file will be applied to the base file.
The accumulation of corrections shall proceed until a logical breaking
point has occurred
(i.e. a milestone or significant implementation
point has been reached). At this time all accumulated corrections
shall be applied to the previous base level to create a new base
level. Correction files will then be started for the new base level.

E.8

FORBIDDEN INSTRUCTION USAGE
1.

The use of instructions or index words
previous instruction. For example:
MOV

@PC,Register

BIC

Src,Dst

literals

the

uses the bit clear instruction as a literal. This may seem
to be a very "neat" way to save a word but what about
maintaining a program using this trick?
To compound the
problem, it will not execute properly if I/D space is enabled
on the 11/45. In this case @PC is a D bank reference.
2.

The use of the MOV instruction instead of a JMP instruction
For
to
transfer program control to another location.
example:
MOV

#ALPHA,PC

E-12

SAMPLE CODING STANDARD
transfers control to location ALPHA. Besides taking longer
to execute
(2.3 microseconds for MOV vs. 1.2 for JMP) the
use of MOV instead of JMP makes it nearly impossible to pick
up someone else's program and tell where transfers of control
take place. What if one would like to get a jump trace of
the execution of a program (a move trace is unheard of)? As
a more general issue, perhaps even other operations such as
ADD and SUB from PC should be discouraged. Possibly one or
two words can be saved by using these operations but how many
such occurrences are there?
3.

The seemingly neat" use of all single word instructions
where one double-word instruction could be used and would
execute faster and would not consume additional memory.
Consider the following instruction sequence:
11

CMP

-(Rl),(-Rl)

CMP

-(Rl) ,-(Rl)

The intent of this instruction sequence is to subtract 8 from
register Rl (not to set condition codes).
This can be
accomplished in approximately 1/3 the time via a
SUB
instruction (9.4 vs. 3.8 microseconds) at no additional cost
in memory space. Another question here is also, what if Rl
is odd?
SUB always wins since it will always execute
properly and is always faster!

E.9

E.9.1

RECOMMENDED CODING PRACTICE

Conditional Branches

When using the PDP-11 conditional branch instructions,
it
is
imperative that the correct choice be made between the signed and the
unsigned branches.
SIGNED

UNSIGNED

BGE
BLT
BGT
BLE

BHIS
BLO
BHI
BLOS

(BCC)
(BCS)

A common pitfall is to use a signed branch (e.g. BGT) when comparing
two memory addresses.
All goes well until the two addresses have
opposite signs; that is, one of them goes across the 16K (100000(8))
bound.
This type of coding error usually shows itself as a result of
re-linking at different addresses and/or a change in size of the
program.

E.10

PDP-11 VERSION NUMBER STANDARD

The PDP-11 Version Number Standard applies to all modules, parameter
files, complete programs, and libraries which are written or caused to

E-13

SAMPLE CODING STANDARD
be written, as part of the PDP-11 Software Development effort. It is
used to provide unique identification of all released, pre-released,
and in-house software.
It is limited in that, as currently specified, only six characters of
identification
are
used.
Future implementations of the Macro
Assembler, Task Builder, and Librarian should provide for at least
nine characters, and possibly twelve.
It is expected that this
standard will be enhanced as the need arises.
Version Identifier

= <form> <version> <edit> <patch>

<form>

Used to identify a particular form of a module or
program, where applicable, as in the case of
LINK-11. One alphabetic character, if used, and
null (i.e., a binary 0) i f not used.

Used to identify the release, or generation, of a
program.
Two decimal digits, starting at 00, and
incremented at the discretion of the project in
order to reflect what, in their opinion, is a
major change.

<edit>

Used to identify the level to which a particular
release, or generation, of a program or module has
been edited.
An edit is defined to be
an
alteration
to the source form.
Two decimal
digits, beginning at 01, and incremented with each
edit; null if no edits.

<patch>

Used to identify the level to which a particular
release, or generation, of a program or module has
been patched. A patch is defined as an alteration
to a binary form.
One ·alphabetic character,
starting at B, and running sequentially toward Z,
each time a set of patches is released; null if
no patches.

These fields are inter-related.
When <version> is changed, then
<patch> and <edit> must be reset to nulls. It is intended that when
<edit> is incremented, then <patch> will be re-set to null, because
the various bugs have been fixed.

E.10.1

Displaying the Version Identifier

The visible output of the version identifier should appear as:
Key <letter> <form> <version> - <edit> <patch>,
where the following Key Letters have been identified:
V
X
Y

released or frozen version
in-house experimental version
'field test, pre-release, or in-house release version

Note that 'X' corresponds roughly to individual support,
support, and 'V' to company support.

'Y' to

group

The dash which separates <version> from <edit> is used only if

<edit>

E-14

SAMPLE CODING STANDARD
and/or <patch> is not null. When a version identifier is displayed as
part of program identification, then the format is:
<space><key-letter><form><version>-<edit><patch>
Name
Examples:
PIP X03
LINK VB04-C
MACRO YOS-01

E.10.2

Use of the Version Number in the Program

All sources must contain the version number in an .IDENT directive.
For programs (or libraries) which consist of more than one module,
each individual module will follow this version number standard.
The
version number of the program or library is not necessarily related to
the version numbers of the constituent modules;
it is perfectly
reasonable, for example, that the first version of a new FORTRAN
library, VOO, contain an existing SIN routine, say VOS-01.
Parameter files are also required to contain the version number in an
.IDENT directive. Because the assembler records the last .IDENT seen,
parameter files must precede the program.
Entities which consist of a collection of modules or programs, e.g.,
the FORTRAN Library, will have an identification module in the first
position.
An identification module exists
solely
to
provide
identification, and normally consists of something like:
;OTS IDENTIFICATION
.TITLE FTNLIB
.IDENT /003010/
.END

E-15

APPENDIX F
CONSERVING DYNAMIC MEMORY

This appendix is intended for the MACR0-11 user who experiences the
difficulty of not having sufficient dynamic memory available to
complete the desired assemblies.
Users
of
smaller
systems,
particularly those with the SK subset version of MACR0-11, should
become thoroughly familiar with the conventions discussed herein.
In
this regard, Appendix F addresses the following topics:
1.

General hints and space-saving guidelines;

Macro definitions and expansions;

Operational techniques.

and

The user is assumed to have pursued a policy of modular programming,
as advised in Appendix E.
In addition to the obvious advantages
accruing from small, distinct, highly-functional bodies of code, one
can usually avoid the problem of insufficient dynamic memory during
assembly by practicing such a policy. Other suggestions as to how
available memory can be best utilized are discussed in the following
sections.

F.l

GENERAL HINTS AND SPACE-SAVING GUIDELINES

Dynamic memory is shared by MACRO-ll's internal stack and a number of
tables, each of which is allocated space on demand. The tables and
their corresponding entry sizes are, as follows:
1.

User-defined symbols - four words.

Local symbols - three words.

Program sections - five words.

Macro names - three words.

Macro text - eight words.

Source files - five words.

In addition, several scratch pad tables are used during
process, as follows:
1.

Expression analysis - four words.

F-1

the

assembly

CONSERVING DYNAMIC MEMORY
2.

Object code generation - four words.

Macro argument processing - two words.

.MCALL argument processing - four words.

The above information can serve as a guide for estimating dynamic
storage
requirements
and for determining ways to reduce such
requirements.
For example, the use of local symbols whenever possible is highly
encouraged, since their internal representation requires 25% less
dynamic storage than that required for regular user-defined symbols.
The usage of local symbols can often be maximized by extending the
scope of local symbol blocks through the .ENABL LSB/.DSABL LSB
MACR0-11 directives (see sections 3.5 and 6.2).
Since MACR0-11 does not support a purge function, once a symbol is
defined, it permanently occupies its dynamic memory allocation.
Numerous instances occur during conditional assemblies and repeat
loops when a temporarily assigned symbol is used as a count or offset
indicator. If possible, the symbols so used should be re-used.
In keeping with the same principle, special treatment should be given
to the definition of commonly-used symbols.
In lieu of simply
appending a pref ix file which defines all possibly-used symbols for
each assembly, users are encouraged to group symbols into logical
classes. Each class so grouped can then become a shortened prefix
file or a macro in a library (see section F.2 below). In either case,
selective definition of symbolic assignments is achieved, resulting in
fewer defined (but unreferenced) symbols.
An appropriate example of this idea is seen in the definition of
standard symbols.
The system macro library, for example, supplies
several macros used to define distinct classes of symbols.
These
groupings and associated macro names are, as follows:
DRERR$ - Directive return status codes
IOERR$ - I/O return status codes
FILIO$ - File-related I/O function codes
SPCI0$ - Special I/O function codes

F.2

MACRO DEFINITIONS AND EXPANSIONS

By far, dynamic storage is used most heavily for the storage of macro
text.
Upon macro definition or the issuance of an .MCALL directive,
the entire macro body is stored, including all comments appearing in
the macro definition.
For this reason, comments should not be
included as part of the macro text. An RSX-11 utility prooram (called
SQZ for RSX-IlD only) and a Librarian function switch- (fSZ-for RSX-llM
only) are available to compress macro source text by removing all
trailing blanks and tabs, blank lines, and comments. The system macro
library (RSXMAC.SML) has already been compressed. It is recommended
that user-supplied macro libraries (.MLB) and macro definition prefix
files also be compressed. For additional information regarding these
two utility tasks, consult the applicable RSX-llM or RSX-llD utilities
manual (see section 0.3 in the Preface).

F-2

CONSERVING DYNAMIC MEMORY
It often seems expedient to append a macro definition prefix file to
each
assembly to provide commonly-used macros.
This practice,
however, may produce the undesirable allocation of valuable dynamic
storage for unnecessary macros. This side effect can be avoided by
specifying that the pref ix file containing the
macros
is
a
user-supplied macro library file (see Table 8-1). This action imposes
the stipulation that the names of all desired macros must be listed as
arguments in the .MCALL directive (see section 7.8).
Storage for macro text can be re-used effectively by redefining
certain types of macros to null after they have been invoked. This
practice releases their dynamic memory for the storage of later macro
text and also eliminates the overhead and the need for dynamic memory
which would otherwise be required during the subsequent invocation and
expansion of such non-redefined macros. The practice of redefining
macros to null applies mainly to those that only define symbolic
assignments, as shown in the example below. The redefinition process
may be accomplished as follows:
SY Ml
SYM2

.MACRO
VALl
VAL2

OF Fl
OFF2
OFF3

SYMBOL
OFFl+SIZl
OFF2+SIZ2

OFFN

OFFM+SIZM

DEFIN
;DEFINE SYMBOLIC ASSIGNMENTS.

;DEFINE SYMBOLIC OFFSETS.

. MACRO
.ENDM

DEFIN

.ENDM

DEFIN

;MACRO NULL REDEFINITION .

Macros exhibiting this redefinition property should be defined
(or
read via the .MCALL directive) and invoked before all other macro
definition and/or .MCALL processing. So doing ensures more efficient
use of dynamic memory.
The following system macros have
property after once being invoked:

the

automatic

null

DRERR$ - Directive return status codes
IOERR$ - I/O return status codes
FILIO$ - File-related I/O function codes
SPCIO$ - Special I/O function codes
CSI$

- Command String Interpreter codes and offsets

GCMLD$ - Get Command Line codes and offsets
BDOFF$ - FCS buffer descriptor offsets

F-3

redefinition

CONSERVING DYNAMIC MEMORY
FCSBT$ - FCS bit value codes
FDOFF$ - FCS file descriptor block offsets
FSROF$ - FCS file storage region (FSR) offsets
NBOFF$ - FCS filename block offsets
MACR0-11 has a limited ability to recover from the condition of
insufficient dynamic memory.
When this condition occurs, MACR0-11
attempts to re-use dynamic memory by purging all macro definitions not
currently being expanded.
(This applies only to macros defined via
the .MCALL directive or to macros defined at source level from a file
on a non-sequential, directory device. Macros defined inside other
macros are excluded.) Once purged, a macro definition will be
retrieved from its source on demand. Furthermore, it will remain in
memory until the dynamic memory reclamation process
is
again
initiated.
Keeping this in mind, users are advised to relax the absolute macro
storage requirments by limiting the number and size of nested macro
calls. Furthermore, since many of the system-supplied File Control
Services
(FCS) macros contain a number of deeply-nested calls, it is
strongly suggested that they be invoked only at the source level.

F.3

OPERATIONAL TECHNIQUES

When, despite adhering to the guidelines discussed above, there is
still insufficient dynamic memory to continue, several additional
measures may be taken to complete the assembly process, as described
below.
The first measure involves shifting the burden of symbol definition
from MACR0-11 to the Task Builder. In most cases, the definition of
system I/O and FCS symbols (and user-defined symbols of the same
nature) is not necessary during the assembly process, since such
symbols are defaulted to global references (see section 3.9 and
section D.l, category 4 of error code A). The Task Builder attempts
to resolve all global references from the system object library
(SYSLIB.OLB).
Furthermore, by applying the selective search option
for object modules consisting only of global symbol definitions, the
actual additional burden to the Task Builder is minimal.
A second way of making more dynamic memory available is to produce
only one output file (either object or listing), as opposed to two.
The additional file descriptor block (FDB) and file storage region
(FSR) required to support the second output file is allocated from
available dynamic memory at the start of each assembly.
Furthermore,
the size of the file storage region allocated is the minimum required
for the second (listing) output file. For disk files, this would be
264(10) words, and for direct line printer output, it would be 74(10)
words.
The final way of increasing available dynamic memory is related only
to the operating environment. Under RSX-llM, MACR0-11 allocates all
storage between its highest address and the end of its partition as
dynamic memory.
Consequently, the amount of working storage can be
increased by installing and running MACR0-11 in a larger partition.
An alternate method of accomplishing this in RSX-llM only, is to issue

F-4

CONSERVING DYNAMIC MEMORY
the MCR Set command, which alters the size of a system's partition
(see the RSX-llM Operator's Procedures Manual).
In IAS and RSX-llD,
the assembler's dynamic memory is fixed at link time.
If a larger
assembler is not available; you may build one by increasing the size
of the task's stack.
This is accomplished by altering the STACK=
option in the command file to build MACR0-11.

F-5

APPENDIX G
FEATURES/FUNCTIONS NOT SUPPORTED BY THE RSX-llM 8K ASSEMBLER

ITEM

REFERENCE

Search of PST in operand expressions

3.2.2

AF unary operator

3.7 and
6.4.2.2

Z error code

5.3

.ENABL, .DSABL Symbolic Arguments:
ABS
CDR
FPT
LC
PNC

6.2
6.2
6.2
6.2
6.2

Floating-point Storage Directives:
.FLT2
.FLT4

6.4.2.l

PAL-llR Conditional Assembly Directives

6 .11. 3

.EOT directive

6.6.2

More than one level of indirect command files

8.1.1.5

No PDP-11/45/70-0nly Opcodes

C.l

G-1

6.4.2.1

APPENDIX H
WRITING POSITION INDEPENDENT CODE

The output of a MACR0-11 assembly is a relocatable object module. The
Task Builder binds one or more modules together to create an
executable task image. Once built, a task can generally be loaded and
executed only at the virtual address specified by the Task Builder at
link time. This is because the Task Builder has had to modify some
instructions to reflect the memory locations in which the program is
to run. Such a body of code is considered position-dependent (i.e.,
dependent on the virtual addresses to which it was bound).
All PDP-11 processors offer addressing modes that make it possible to
write instructions that are not dependent on the virtual addresses to
which they are
bound.
A
body
of
such
code
is
termed
position-independent and can be loaded and executed at any virtual
address.
In multiprogramming systems like IAS, RSX-llD and RSX-llM, it is
important that many tasks be able to share a single physical copy of
common code; for example a library routine. To make the optimum use
of
a
task's
virtual
address
space, shared code should be
position-independent. Code that is not position-independent can also
be shared, but it must appear in the same virtual locations in every
task using it. This restricts the placement of such code by the Task
Builder and can result in the loss of virtual addressing space.
Position-independent code can improve system efficiency, both in
of virtual address space and in conservation of physical memory.

use

The construction of position-independent code is closely linked to the
proper usage of PDP-11 addressing modes.
The remainder of this
Appendix assumes reader familiarity with the
addressing
modes
described in Chapter 5.
All addressing modes involving
only
register
position-independent. These modes are as follows:
R
(R)

(R)+
@(R)+
-(R)
@-(R)

references

are

register mode
deferred register mode
autoincrement mode
deferred autoincrernent mode
autodecrement mode
deferred autodecrement mode

When using these addressing modes, position-independence is guaranteed
providing the contents of the registers have been supplied such that
they are not dependent upon a particular virtual memory location.

H-1

WRITING POSITION INDEPENDENT CODE
when
a
The relative addressing modes are position-independent
relocatable address is referenced from a relocatable instruction.
These modes are as follows:
A

relative mode
relative deferred mode

Relative modes are not position-independent when an absolute address
(that is a non-relocatable address) is referenced from a relocatable
instruction. In this case, absolute addressing
(i.e., @#A) may be
employed to make the reference position-independent.
Index modes can be either position-independent or position-dependent,
according to their use in the program. These modes are as follows:
X(R)
@X(R)

index mode
index deferred mode

If the base, X, is an absolute value (e.g., a control
the reference is position-independent. For example:
MOV

2(SP),RO

;POSITION-INDEPENDENT

MOV

N(SP) ,RO

;POSITION-INDEPENDENT

block

offset),

N=4
If, however, X is a relocatable
position-dependent. For example:
CLR

ADDR(Rl)

address,

the

reference

;POSITION-DEPENDENT

Immediate mode can be either position-independent or not, according to
its usage.
Immediate mode references are formatted as follows:
#N

immediate mode

When an absolute expression defines the value of N, the code is
position-independent.
When a relocatable expression·defines N, the
code is position-dependent. That is, immediate mode references are
position-independent only when N is an absolute value.
Absolute mode addressing is position-independent only in those cases
where an absolute virtual location is being referenced. Absolute mode
addressing references are formatted as followed:
@#A

absolute mode

An example of a position-independent absolute reference is a reference
to the directive status word ($DSW) from a relocatable instruction.
For example:
MOV

@#$DSW,RO

;RETRIEVE DIRECTIVE STATUS

The RSX-11 library routine, PWRUP, is a FORTRAN callable subroutine to
establish or remove a user power failure AST entry point address.
Imbedded within the routine is the actual AST entry point which saves
all registers, effects a call to the user-specified entry point,
restores all registers on return, and executes an AST exit directive.
The following examples are excerpts from this routine. The first
example has been modified to illustrate position-dependent references,
(see
Figure
H-1).
The
second example, Figure H-2, is the
position-independent version.

H-2

WRITING POSITION INDEPENDENT CODE
PWRUP::
CLR
CALL

-(SP)
.X.PAA

.WORD
MOV
MOV
BNE
CLR
BR

1., $DSW
$0TSV,R4
(SP) +,R2
10$
-(SP)
20$

MOV
MOV

R2,F.PF(R4)
#BA,-(SP)

;SET AST ENTRY POINT
;PUSH AST SERVICE ADDRESS

CALL
. BYTE

. X.EXT
109.,2 .

;ISSUE DIRECTIVE, EXIT .

MOV
MOV
MOV

RO,-(SP)
Rl,-(SP)
R2,-(SP)

;PUSH (SAVE) RO
;PUSH (SAVE) Rl
;PUSH (SAVE) R2

10$:

;

20$:

BA:

;ASSUME SUCCESS
;PUSH (SAVE) ARGUMENT ADDRESSES ONTO
;STACK
;CLEAR DSW, AND SET Rl=R2=SP
;GET OTS IMPURE AREA POINTER
;GET AST ENTRY POINT ADDRESS
;IF NONE SPECIFIED, SPECIFY NO POWER
;RECOVERY AST SERVICE

;

Figure H-1
Position-Dependent Code
PWRUP::
CLR
CALL
. WORD
MOV
MOV
BNE
CLR
BR

-(SP)
.X.PAA
1., $DSW
@#$0TSV,R4
(SP)+,R2

MOV
MOV
ADD

R2,F.PF(R4)
PC,-(SP)
#BA-.,(SP)

;SET AST ENTRY POINT
;PUSH CURRENT LOCATION
;COMPUTE ACTUAL LOCATION OF AST

CALL
. BYTE

.X.EXT
109. ,2 .

;ISSUE DIRECTIVE, EXIT.

, I"\,...

.l u .:;>

;ASSUME SUCCESS
;PUSH ARGUMENT ADDRESSES ONTO STACK
;CLEAR DSW, AND SET Rl=R2=SP .
;GET OTS IMPURE AREA POINTER
;GET AST ENTRY POINT ADDRESS
;IF NONE SPECIFIED, SPECIFY l\lf'I POWER
;RECOVERY AST SERVICE
J.~V

-(SP)
20$

10$:

20$:

ACTUAL AST SERVICE ROUTINE:
1)
2)
3)
4)

SAVE REGISTERS
EFFECT A CALL TO SPECIFIED SUBROUTINE
RESTORE REGISTERS
ISSUE AST EXIT DIRECTIVE

;

BA:

MOV
MOV
MOV

RO,-(SP)
Rl,-(SP)
R2,-{SP)

;PUSH (SAVE) RO
;PUSH (SAVE) Rl
;PUSH (SAVE) R2

Figure H-2
Position-Independent Code
The position-dependent version of the subroutine contains a relative
reference to an absolute symbol ($0TSV) and a literal reference to a
relocatable symbol (BA).
Both references are bound by the Task

H-3

WRITING POSITION INDEPENDENT CODE
Builder to fixed memory locations. Therefore, the routine will not
execute properly as part of a resident library if its location in
virtual memory is not the same as the location specified at link time.
In the position-independent version, the reference to $0TSV has been
changed to an absolute reference. In addition, the necessary code has
been added to compute the virtual location of BA based upon the value
of the program counter. In this case, the value is obtained by adding
the value of the program counter to the fixed displacement between the
current location and the specified symbol. Thus, execution of the
modified routine is not affected by its location in the task's virtual
address space.
The MACR0-11 Assembler provides the user with a way of checking the
position-independence of code.
In an assembly listing, MACR0-11
inserts a ' character following the contents of any word which
requires the Task Builder to perform a relocation operation. In some
cases this character indicates a position-dependent instruction;
in
other cases, It merely draws the user's attention to the use of a
symbol which may or may not be position-independent. The cases which
cause a
character to be inserted in the assembly listing are as
follows:
1.

Absolute mode references are flagged with an ' character when
the reference is relocatable, References are not flagged when
they are position-independent (i.e., absolute). For example:
MOV

ADDR(Rl) ,RS
@ADDR(Rl) ,RS

;NON-PIC IF ADDR IS RELOCATABLE.
;NON-PIC IF ADDR IS RELOCATABLE.

Relative and relative deferred mode references are flagged
with an ' character when the address specified is relocatable
with respect to another program section. For example:
MOV
MOV

;PIC ONLY IF ADDR IS ABSOLUTE.

Index and index deferred mode references are flagged with
' character when the offset is relocatable. For example:
MOV
MOV

@#ADDR,Rl

ADDRl,Rl
@ADDRl,Rl

;NON-PIC WHEN ADDRl IS BOUND
;TO ANOTHER PROGRAM SECTION

Immediate mode references to relocatable addresses are always
flagged with an ' character.
MOV
MOV

#3,RO
#ADDR,Rl

;ALWAYS POSITION-INDEPENDENT.
;NON-PIC WHEN ADDR IS RELOCATABLE.

There is one case in which the MACR0-11 assembler does not flag a
potential position-dependent reference. This occurs where a relative
reference is made to an absolute virtual location from a relocatable
instruction (i.e., MOV $0TSV,R4 in Figure H-1).

Those references requiring more than simple ict~K Builder relocation
are also indicated in the assembly listing. Simple global references
are flagged with the letter G. Those which contain multiple global
references, or complex relocation are flagged with the letter C (see
sections 3.9 and 4.0). In such cases, it is difficult to positively
state which are or are not position-independent. However, in general,
it is safe to· apply the guidelines discussed earlier in this Appendix
to the resulting address value produced by the Task Builder.

H-4

APPENDIX I
SAMPLE ASSEMBLY LISTING

TABLE OF CONTENTS
2- 55
J• 74
4•153
5•211l9

6·255
7•345

MACRO DEFINITIONS
MESSAGE STRINGS
MlSCELLANious DATA
READ AND PARSE COMMAND LINES
EVALUATE THE SEMANTIC ANALYSIS
SUBROUTINES

I-1

CSITST -- TEST OF csr1 AND CSI2 MACRO

M~707

09•JUL•74 15147
,TITLE
I DENT

1
2

J
4
5

/02/

THIS SOFTwARE IS FURNISHED TO PURCHASER
ON A SINGLE COMPUTER SYSTEM, AND CAN BE
OF DEC 1 S COPYRIGHT NOTICE) ONLY FOR USE
AS MAY OTHERWISE BE PROVIDED IN WRITING

1
8
9

10
11

CSITST •• TESY OF CSI1 AND C5I2

H
I

PAGE 1

01754

UNDER A LICENSE FOR USE
COPIED (wlTH INCLUSION
IN SUCH SYSTEM, tXC~PT
BY DEC,

THE INFORMATION IN THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT
NOTICE AND SHOULD NOT BE CONSTRUED AS A COMMITMENi BY DIGITAL
EQUIPMENT CORPORATION,

12
1J
14
t5
16
17
18
19
20
21
22
2J
24
25
26
21

VERSION 02
WRITTEN BYI
JOHN DOE
MODIFIED BY1
JO!oiN DOE

THIS PROGRAM WAS wRtTTEN TO PERFORM A COMPREHENSIVE TEST OF THE
COMMAND STRING INTERPRETER SUBROUTINES CCStl AND CSI2),

28
29

:rn
31

LOCAL ASSIGNMENTS

J2
JJ
J4

35
36
31

00011l15
000012

CR1: 15
LF•12

J8
J9

000001
000002
00111004

ASMSK•t
NUMSK•2
S111MSK • 4

40
41
42
43
44
45
46
41 000000
48 000000
•9 0000111'1!
50 000000
51
!52
!5J

1/AS SWITCH MASK
1/NU SWITCH MASK
1 /Sw SWITCH MASK

,MCALL

CSIS,FDOFFS,GCMLOS,FILIOS

CSU

FOOFFS
GCMLDS
FILIOS

DEFSL

,MCALL
,MCALL

CSIS1,CSIS2,CSISSw,CSI!SV,CSISNO,FSRSZS,GCML$,GCMLBS
CALL,RETURN,EXITSS,QIOS,WTSESS,DIRS

CSITST •• TEST OF CSI1 AND CS12 MACRO
MACRO DEFINITIONS
55

M~707

09•JUL•74 15147
,SBTTL

PAGt 2

MACRO DEFINITIONS

57
58
59

LOCAL MACRO DEFINITIONS

62
63
64
65

66
67
68

M~1CRO

MOV
MOV
MOV
MQV
CALL
,E~DM

TYPE
ADR,LEN,CCTL
#QIODPB+Q,JOPL,R5
A.DR 1 (i::15)+
L.EN, CR5)+
CCTL, CR5)
)(QI 0
TVPE

69
70
71
72

MA.CRO

TY~'E
1

E ~IDM

TVPEM
NAM,CTL
#NAMIMSG,#NAM'LEN,#CTL
TVPEM

CSITST •• TEST OF cs11 ANO CSI2 MACRO M111101
MESSAGE STRINGS
74
75
76

,SBTTL.

PAGE 3

MESSAGE STRINGS

LOC.L. OAU

78
79
80
81
82
83
84
85

09•JUL.,.74 1!5147

,NL.IST

BEX

11111100111~

01 '5
00003:2

077

11177

STX MSG I ,ASCII <CR>/??? SYNTAX ERROR (CSil)/<L.F><LF>
STXL.EN•,•STXMSG

87 000032

07:7
00003 :l

077

SWRMSG1 ,ASCII /??? SWITCH ERROR CCSI2)/<L.F><L.F>
SlllRLEN•,•SlliRMSG

01 :2

055

053

OPTMSG1 ,ASCII <L.F>/••• OUTPUT PARSE
OPTL.U.i. ,•OPTMSG

055

053

IPTMSG1 , ASCII <LF>/•+• INPUT PARSE •+•/
lPTL.EN•, .. IPTMSG

89
90
91 00111063
92
93
94
95 11100110
96

00002~5

01:2

011111102·4

C/l

•+~I

!i:"C
ti
ti:!

~
C/l
C/l

97
H
I

.s::..

98
99 000134
100 000144
101

102
103
104 000146
105 000156
106

01 :2
06,~

103
012

123

00001:2
01

:~
06,~

11113
040

123
040

0000 t:5

ti:!

EQUMSG1 , ASCII <LF>/CS,EQU•/
EQUBIT1 ,ASCII /0/<L.F>
EQULEN•,•EQUMSG

IJj

ti
~

DVFMSGI ,ASCII <LF>/CS,0\IF•/
D\IFBIT1 , ASCII /0 I
D\IFL.EN•,•D\IP:MSG

H
C/l

1-3

107

(j)

108

109 00111161
110 000111
11 l

112
113
114 000174
115 000204
116
117
118
119 000207
120 000217
121
122
123
124
12!5 000221
126 000226
127

01 !5
061~

103
040

DIFMSG1 ,ASCII <CR>/CS,DIF•/
DIF8IT1 ,ASCII /0 I
DIFL.EN•, .. OIFMSG

103
040

123
040

NMFMSGI ,ASCII <CR>/CS,NMf•/
NMFBITI ,ASCII /0 I
NMFL.EN•,•NMFMSG

103

123

WLOMSG1 ,ASCII <CR>/CS,wLD•/
WLDB IT I ,ASCII /0/
1111.0L.EN•,•WLOMSG

040
127

040
047

I ODD BOUNDARY MUST BE
,ODD
I/\
FNOMSG1 I ASCII \
\SWI
SwITCH FOUND\
FNOSWT I ,ASCII
FNOLEN• 1 ooFNOMSG

040

1114li'I

\/AL.MSG I ,ASCII

123

0001111:!
0H1
061~

00001 :3
01 !5
061~

0011101 :l

04,~

12:!
11111101112!5

128

129
130 000246

04"

~ITM

FOLL.OWING \IAL.UESI/

PRESE~\ltO

CSITST •• TEST OF CSI1 AND CSI2 MACRO M0707
SUBROUTINES

09•JUL•74 15147

345
346

I
U1

348 002722
J49 002724
350 002726
351 002734
352 002746
J5J
354
355 002750
356 002754
357 002760
358 002764
J59 002770
360 002774
361 003000
362 003004
363
J64
J65 003006
J66 003012
367 003016
368 003022
J69 003026
370 003030
371 003034
372 003036
HJ 003042
J74 003066
375
376
377 003070
J78 003072
379 003074
380 003076
381 003102
382 003104
383 003110
384 003112
385 003116
386 003120
387 003122
388 003124
389 003126
390 003130
391 003132
392 003134
39J
394
395 003t36
396 0~3142
397 003164
398
399
400
401

SBTTL

SUBROUTINES

TST

• (R5)

347

XQ I 0 I

005745
003410

1S I

au:

#QIODPB
#1

CLR
CLR
CLR
C:LR
CLR
CLR
C:LR
RETURN

ASVAL
ASVAL+4
NUVAL
NUVAL•2
MYMSK2
MASK)(
MASKZ

175624
175624
175624
175622
175620
175620
175612

INIT21

012167
051167
052167
062701
011ll1l1
062701
01t101
012702

175214
175576
175574
000002

SWTFND1 MOV
BIS
BIS
ADD
MOV
ADD
MOV
MOV
SNOFNDI TYPEM
RETURN

01110 t
100003
00541211
112722
005046
012746
010 t 03
042703
050316
00620t
006201
00620t
001366
112622
001376

162702

0012301

000277 I

000055
000060
177770

CVTNUMI MOV
BPL
NEG
MOVB
CLR
6151
62Sr
MOV
MOV
BIC
BIS

6JS1

011102461

DtRS
wTSESS
RETURN

005067
005067
005067
005067
005067
005061
005067

0Pl0002

PAGE 7

ASR
ASR
ASR
BNE
MOVB
BNE
RETURN

TYPVALI SUB
HPE
RETURN

,END

CR1)•,FNDSl~T

(R1),MYMSK2
(R1)+,MASK2
#2,R1
CR 1), R1
#2,R1
(Rt), R1
lfllVAUWF,R2
FND,40

( R1), R1
61S
R1
# 1 • 1 CR2)•
.. CSP)

#10,•(SP)
R1,R3
#177770,R3
RJ,CSP)
R1
Rt
Rt
62S
CS?)+, CR2)·~
6JS

lllVALMSG,R2
#VALMSG, R2 ,1 #40

GETLN

JCHECK LENGTH OF OUTPUT REQUEST
JSKIP TO LEAVE. IF NOT GREATER THAN
JSEND OUT THE LINe
JwAIT FOR I/O DONE

ZE~O

...

JCLEAR LOCATIONS NECESSARY •••
J 100 TO PROPERLY TEST THE
1 11 ,RESULTS OF CSI2

...

~
t"(j

JSET SWITCH IN FOUND MESSAGE
JSET MASK IN BOTH OF THE
LOCAL TALLY wORDS
JBUMP R1 TO PNT TO AODR OF VALUE TABLE
JPUT ADDR OF VALUE TABLE IN Rl
JBUM? Rt TO PNT TO ADDR Of VALUE BUH ER
JPUT AODR Of VALUE BUFFfR IN Rl
JPNT R2 TO VALUE BUFFER IN MSG
JSEND SWITCH FOUND MESSAGE

1:-1

,...

l:rj

en
en

l:rj

:s:
td

1:-1

r-<:

JPUT VALUE IN R1
JSKIP IF NON•NEGATIVE VALUE
I CONVERT IT TO F'OSITIVE
IINSERT MINUS SIGN
ISET TERMINATION CHAR IN STACK
JBASE IS ASCII ZERO
1eOPY REMAINING VALUE INTO R3
JSAVE LEAST SIGNIFICANT DIGIT
JMASK IT INTO BASE
I SHIFT
•••• OUT
1,,, LOWEST DIGIT
JCONTINUE UNTIL ZERO IS LEFT
JPOP RESULTS OFF THE STACK
JUNTIL NULL IS REACHED
JTHEN RETURN

......

JCALC LENGTH OF MESSAGE

,JSEND VALUE -MESSAGE

t-3

zG'1

INDEX
Absolute mode, 5-5
Addressing, branch instruction,
5-8
Addressing forms, 5-7
Addressing modes, 5-1
Address mode syntax, summary of,
B-1
Arguments in macro definitions
and macro calls, 7-4
ASCII character set, A-1
ASCII conversion characters,
6-18
.ASCII directive, 6-19
.ASCIZ directive, 6-21
.ASECT and .CSECT directive,
6-38
Assembler directives, B-3
Assembler limitation for BK
RSX-llM assembler, G-1
Assembly directives, conditional,
6-41, 6-46
Assembly Pass 1, 1-1
Assembly Pass 2, 1-2
Assembly, single, 8-2
Assignment statements, direct,
3-7
Autodecrement deferred mode, 5-4
Autodecrement mode, 5-3
Autoincrement deferred mode, 5-3
Autoincrement mode, 5-2

Binary operators, unary and, 3-4
.BLKB directives, 6-29
.BLKW directives, 6-29
Branches, conditional, E-13
Branch instruction addressing,
5-8
tB, temporary radix control operator, 6-24
.BYTE directive, 6-17

Call, direct MACR0-11 under
RSX-11, 8-1
Calling conventions, E-9
Calling conventions, intramodule, E-9
Calling macros, 7-3
Characters, ASCII conversion,
6-18
Characters, illegal, 3-3
Characters, separating and delimiting, 3-2
Character set, 3-1

Character set, ASCII, A-1
Character set, RADIX-SO, A-4
Character sets, MACR0-11, A-1
Characters, special, B-1
Code or data sharing, 6-38
Code with interrupts inhibited,
E-12
Coding standard, sample, E-1
Codes, MACR0-11, error, D-1
Codes, op, C-1
Coding practice, recommended,
E-13
Command string format,
RSX-11, 8-3
IAS, 8-8
Command string examples,
RSX-11, 8-1
IAS I 8-11
Comment field, 2-5
Comments, E-2
Common exits, E-11
Concatenation of macro arguments, 7-9
Conditional assembly block
directive,.IF, 6-41
Conditional assembly directives,
6-41, 6-46
Conditional branches, E-13
Conserving dynamic memory, F-1
Control, format, 2-6
Control operators, radix, 6-23
Control operators, radix and
unary, 6-23
Control operators, temporary
numeric, 6-27
Control operators, unary, 6-25
Conventions and standards, 2-1
Conventions, calling, E-9
Conventions, intra-module,
calling, E-9
Counter, current location, 3-11
Creating local symbols automatically, 7-8
Creating program sections, 6-36
.CSECT and .ASECT directives,
6-38
tc, temporary numeric control
operator, 6-27
Current location counter, 2-2,
3-11
Data sharing, code or, 6-38
Data storage directives, 6-16
Defining macros, 7-1
Definitions and expansions,
macro, F-3

INDEX-1

INDEX (Cont.)
Delimiting characters, separating
and, 3-2
Device registers, E-2
Diagnostic error message summary,
D-1
Direct assignment statements, 3-7
Directive, .ASCII, 6-19
Directive, .ASCIZ, 6-21
Directive, .BYTE, 6-17
Directive, .ENDM, 7-2
Directive, .EOT, 6-31
Directive, .EVEN, 6-29
Directive, .FLT2, 6-27
Directive, .FLT4, 6-27
Directive, .GLOBL, symbol control,
6-39
Directive, .IDENT, 6-12
Directive, .IF, conditional
assembly block, 6-41
Directive, .IIF, immediate conditional assembly, 6-46
Directive, .IRP, 7-13
Directive, .IRPC, 7-14
Directive, .LIMIT program boundaries, 6-31
Directive, .MACRO, 7-1
Directive, .MCALL, macro library,
7-16
Directive, .MEXIT, 7-3
Directive, .NARG, 7-10
Directive, .NCHR, 7-10
Directive, .NTYPE, 7-11
Directive, .ODD, 6-29
Directive, .PAGE, 6-12
Directive, .PSECT. 6-32
Directive, .RAD50, 6-22
Directive, .RADIX, 6-23
Directive, .REPT, repeat block,
7-15
Directive, .SBTTL, 6-11
Directive, terminating, .END,
6-28
Directive, .TITLE, 6-10
Directive, .WORD, 6-18
Directives, B-1
Directives, .ASECT and .CSECT,
6-38
Directives, Assembler, B-3, C-3
Directives, .BLKB, 6-29
Directives, .BLKW, 6-29
Directives, conditional assembly,
6-41
Directives, data storage, 6-16
Directives, .ENABL, .DSABL,
function, 6-13
Directives, .ERROR, 7-12
Directives, .ERROR and .PRIN~,
7-12
INDEX-2

Directives, Floating-point
storage, 6-27
Directives, general assembler,
6-1
Directives, .IFF, .IFT, .IFTF,
subconditional assembly
6-43
Directives, .LIST, 6-1
Directives, .LIST and .NLIST,
6-·l
Directives, Listing control,
6-1
Directives, location counter
control, 6-28
Directives, macro, 7-1
Directives, macro attribute,
.NARG, .NCHR, .NTYPE, 7-10
Directives, MACR0-11, B-3, C-3
Directives, .NLIST, 6-1
Directives, numeric, 6-25
Directives, .PRINT, 7-12
Directives, program boundaries
and sectioning, 6-31
Displaying the version identifier, E-14
.DSABL function directives,
6-13
tD, temporary radix control
operator, 6-24
Dynamic memory, conserving,F-1

Ejection, page, 6-12
.ENABL function directives,
6-13
.END terminating directive,
6-30
.ENDM directive, 7-2
.EOT directive, 6-31
.ERROR and .PRINT directives,
7-12
Error codes, MACR0-11, D-1
.ERROR directives, 7-12
Error messages, 8-12
Error message summary,
diagnostic, D-1
.EVEN directive, 6-29
Exiting, E-9
Exits, common, E-11
Expansions, Macro, definition
and, F-3
Expression, 3-15
Expressions, symbols and, 3-1

INDEX (Cont.)
Failure indication, E-9
Features/functions not supported
by RSX-llM 8K assembler, G-1
Features, MACR0-11, 1-1
Field, comment, 2-5
Field, label, 2-2
Field, operand, 2-5
Field, operator, 2-4
File specification
Switches, RSX-11, 8-5
Format, RSX-11/IAS, 8-11
Floating-point storage directives,
6-27
.FLT2 directive, 6-27
.FLT4 directive, 6-27
Forbidden instruction usage, E-12
Format, command string,
RSX-11, 8-3
IAS, 8-8
Format control, 2-6
Format, File specification, 8-11
Format, line, E-1
Format, source program, 2-1
Format, statement, 2-1
Formatting, MACRO definition, 7-3
Formatting standards, E-10
Formatting the module preface, E-7
Forms, addressing, 5-7
tF, temporary numeric control
operator, 6-27
Function directives:, .ENABL,
. DSABL, 6-13

General assembler directives, 6-1
General hints, F-1
General purpose registers, E-2
Global symbols, E-3
.GLOBL symbol control directive,
6-39
Guidelines, space-saving, F-1

.IF, conditional assembly
block directive, 6-41
.IFF, subconditional assembly
block directives, 6-43
.IFT, subconditional assembly
block directives, 6-43
.IFTF, subconditional assembly
block directives, 6-43
.IIF, immediate conditional
assembly directive, 6-46
Illegal characters, 3-3
Immediate conditional assembly
directive, .IIF, 6-46
Immediate mode, 5-5
Indefinite repeat block
directives, .IRP and .IRPC,
7-12
Index deferred mode, 5-4
Index mode, 5-4
Indirect command files,
RSX-11, 8-2
'T'7\,...

.L.H..:::> '

11'\

0 - .L v

Initiating MACR0-11 under IAS,
8-8
Initiating MACR0-11 under RSXllD/RSX-llM, 8-1
Direct MACRO call, 8-1
EUN facility: 8-2
Single assembly, 8-2
Install, run and remove-on-exit,
8-2
Indirect filename facility,
8-2
Instruction usage, forbidden,
E-12
Interrupts inhibited, code
with, E-12
Intra-module calling conventions, E-9
.IRP directive, 7-13
.IRP and .IRPC directives,
indefinite repeat block,
7-12
IRPC directive, 7-14

Hardware registers, E-2
Headings, page, 6-5
Hints, general, F-1
IAS
Command string format, 8-8
File specification format, 8-11
Indirect command file, 8-10
MACR0-11 operating procesures,
8-8
.IDENT directive, 6-12

INDEX-3

Label field, 2-2
.LIMIT, program boundaries
directive, 6-31
Line format, E-1
Linking, relocation and, 4-1
.LIST and .NLIST directives,
6-1
Listing control directives, 6-1

INDEX (cont.)
Local symbols, 3-10, 7-8
Location counter, 3-11
Control directives, 6-28

Macro arguments, concatenation of,
7-9
Macro arguments, special characters in, 7-6
Macro attribute directives,
.NARG, .NCHR, .NTYPE, 7-10
Macro calls, arguments in, macro
definitions and, 7-4
Macro calls, number of arguments
in, 7-7
Macros, defining, 7-1
MACRO definition formatting, 7-3
Macro definitions and expansions,
F-3
Macro definitions and macro calls,
arguments in, 7-4
.MACRO directive, 7-1
Macro directives, 7-1
MACR0-11 character sets, A-1
MACR0-11 directives, B-3
MACR0-11 error codes, D-1
messages, 8-12
MACR0-11 features, 1-1
MACR0-11 operating procedures,
RSX-11, 8-1
IAS, 8-8
MACR0-11 symbols, 3-5
Macro library directive, .MCALL,
7-17
Macro names, E-5
Macro nesting, 7-5
Macro symbols, user-defined and,
3-5
Macros, calling, 7-3
.MCALL, macro library directive,
7-16
Memory allocation considerations,
6-38
Memory conserving dynamic, F-1
.MEXIT directive, 7-3
Mode, absolute, 5-5
Mode, autodecrement, 5-4
Mode, autodecrement def er:.:ed, 5-4
Mode, autoincrement, 5-2
Mode, autoincrement defer-·ed, 5-3
Mode, immediate, 5-5
Mode, index, 5-4
Mode, index deferred, 5-4
Mode, register, 5-2
Mode, register deferred, 5~2
Mode, relative, 5-6

INDEX-4

Mode, relative deferred, 5-7
Modes, addressing, 5-1
Modularity, E-8
Module checking routines, E-9
Module preface, E-5
Module preface, formatting the,
E-7
Modules, program, E-5

Names, Macro, E-5
Naming standards, E-2
.NARG directive, 7-10
.NCHR directive, 7-10
Nesting, macro, 7-5
.NLIST directives, 6-1
.NTYPE directive, 7-11
Number of arguments in macro
calls, 7-7
Numbers, 3-13
Numeric arguments as symbols,
7-6
Numeric control operator,
temporary, tC, 6-27
Numeric control operator,
temporary, tF, 6-27
Numeric directives, 6-25

.ODD directive, 6-29
Op codes, C-1
Operand field, 2-5
Operating procedures, MACR0-11,
RSX-11, 8-1
IAS, 8-8
Operational techniques, F-4
Operator field, 2-4
Operator, temporary, numeric
control, tC, 6-27
Operator, temporary, numeric
control, tF, 6-27
Operators, control, 6-23
Operators, numeric control,
6-23
Operators, radix control, 6-23
Operators, temporary radix,
control, tD, to, tB, 6-24
Operators,
unary and binary, 3-4
unary control 6-25
to, temporary radix control
operator, 6-24
Other symbols, E-3

INDEX (Cont.)
.PAGE directive/page ejection,
6-12
PAL-llR conditional assew~ly
directives, 6-45
Page ejection, .PAGE directive/,
6-12
Page headings, 6-5
Passing numeric arguments as
symbols, 7-6
PDP-11 version number standard,
E-13
Permanent symbols, 3-5
Permanent symbol table (PST) ,C-1
PIC, H-1
Pastian-independent code, H-1
Preface, module, E-5
.PRINT directives, 7-12
Priority, processor, E-3
Procedures, operating, 8-1
RSX-11, 8-1
IAS, 8-~
Processor priority, E=3
Program boundaries directive,
.LIMIT, 6-31
Program Format, source, 2-1
Program flow, E-10
Program-local symbols, E-5
Program modules, E-5
Program sectioning directives,
6-31
Program sections, creating, 6-36
Program source files, E-12
.PSECT directive, 6-32
PST, permanent symbol table, C-1

.RAD50 directive, 6-22
Radix and numeric control operators, 6-23
Radix control operators, 6-23
radix control operators, temporary,
tD, tO, tB, 6-24
RADIX-50 character set, A-4
.RADIX directive, 6-23
Recommended coding practive, E-13
Register deferred mode, 5-2
Register mode, 5-2
Registers, device, E-2
Registers, general purpose, E-2
Registers, hardware, E-2
Register standards, E-2
Register symbols, 3-9
Relative deferred mode, 5-7
Relative mode, 5-6
Relocation and linking, 4-1
Repeat block directive, .REPT,
7-15
INDEX-5

Repeat block directives, .IRP,
.IRPC, indefinite, 7-12
.REPT, repeat block directive,
7-15
Routines, module checking, E-9
RSX-11 command string format,
8-3
File specification format,
8-11
File specification switches,
8-5
Indirect corrunand files, 8=2
RSX-llM BK Assembler Limitations, G-1
RUN facility, using, 8-2

.SBTTL directive, 6-11
Separating and delimiting
characters, 3-2
Single assembly, 8-2
Source files, program, E-12
Source program format, 2-1
Space saving guidelines, F-1
Special characters, B-1
Special characters in macro
arguments, 7-6
Standard PDP-11 version number,
E-14
Standards, coding, E-1
Standards and conventions, 2-1
Standards, formatting, E-10
Standards, naming, E-2
Standards, register, E-2
Standard syrriliolics, using the,
E-3
Statement format, 2-1
Statements, direct assignment,
3-7
Subconditional assembly block
directives, .IFF, .IFT,
.IFTF, 6-43
Success/failure indication,
E-9
Summary of address mode syntax,
B-2
Switch options,RSX-11 file specifications, 8-5
Symbol control directive,
.GLOBL, 6-39
Symbol examples, E-4
Symbolics, using the standard,
E-3
Symbols, E-3
Symbols and expressions, 3-1
Symbols automatically, creating
local, 7-8

INDEX (Cont.)
Symbols, global, E-3
Symbols, local, 3-10
Symbols, MACR0-11, 3-5
Symbols, other, E-3
Symbols, passing numeric argument as, 7-6
Symbols, permanent, 3-5
Symbols, program-local, E-5
Symbols, register, 3-9
Symbol table, PST, permanent,
C-1
Symbols, user-defined and macro,
3-5

Table, PST, permanent,symbol,
C-1
Techniques, operational, F-4
Temporary numeric control
operator, tC, 6-27
Temporary numeric control operator,
tF, 6-27
Temporary radix control operators,
tD, tO, tB, 6-24
Terminating directives, .END,.EOT
6-28
Terms, 3-14
.TITLE directive, 6-10
Trap instructions, using, 5-9

INDEX-6

Unary and binary operators,
3-4
Unary control operators, 6-21,
6-29
Use of the version number in
the program, E-15
User-defined and macro symbols,
3-5
Using indirect filename
facility,
RSX-11, 8-2
IAS, 8-10
Using RUN facility, 8-2
Using the standard symbolics,
E-3
Using trap instructions, 5-9

Version identifier, displaying
the, E-14
Version number in the program,
use of the, E-15
Version number standard,
PDP-11, E-13

.WORD directive, 6-18

IAS/RSX-11
MACR0-11
Reference Manual
DEC-11-0IMRA-A-D

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