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Document:	MACRO XVM Assembler Language Manual
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· MACRO XVM ASSEMBLER
LANGUAGE MANUAL
DEC-XV-LMALA-A-D

MACRO XVM ASSEMBLER
LANGUAGE MANUAL
DEC-XV-LMALA-A-D

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 be used or copied only in accordance with 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.

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
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UNIBUS
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MASSBUS
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TYPESET-II

1/76-15

CONTENTS
Page
PREFACE
CHAPTER

CHAPTER

ix
1

INTRODUCTION

1.1
1.2
1.3

MACRO XVM LANGUAGE
HARDWARE REQUIREMENTS
ASSEMBLER PROCESSING

ASSEMBLY LANGUAGE ELEMENTS

2.1
2.1.1
2.1. 2
2.2
2.2.1
2.2.1.1
2.2.1.2
2.2.2
2.2.3
2.2.4
2.2.5
2.2.6
2.3
2.3.1
2.3.2
2.4
2.4.1
2.4.2
2.4.3
2.4.4
2.5
2.5.1
2.5.2
2.5.3
2.5.4
2.6
2.6.1
2.6.2
2.6.3
2.6.4

PROGRAM STATEMENTS
Basic Statement Format
Direct Assignment Statement
SYMBOLS
Evaluation of Symbols and Globals
Special Symbols
Memory Referencing Instruction Format
Variables
Setting Storage Locations to Zero
Redefining the Value of a Symbol
Forward Reference
Undefined Symbols
NUMBERS
Integer Values
Expressions
ADDRESS ASSIGNMENTS
Referencing the Location Counter
Indirect Addressing
Indexed Addressing
Literals
STATEMENT FIELDS
Label Field
Operation Field
Address Field
Comments Field
STATEMENT EVALUATION
Numbers
Word Evaluation
Word Evaluation of the Special Cases
Assembler Priority List

PSEUDO OPERATIONS

3.1
3.1.1
3.1. 2
3.1. 3
3.2
3.2.1

LISTING CONTROL PSEUDO-OPERATIONS
Program Segment Identification (.TITLE)
Listing Control (.EJECT)
Listing Output Control (.NOLST and .LST)
OBJECT PROGRAM OUTPUT PSEUDO-OPERATIONS
Absolute Format (.ABSP and .ABS) (Not
available on XVM/RSX)
Full Binary Format (.FULL and .FULIP) (Not
available in XVM/ RSX)

3.2.2

iii

1-1
1-2
1-2

2-1
2-1
2-3
2-3
2-4
2-6
2-6
2-7
2-7
2-8
2-9
2-10
2-10
2-11
2-12
2-13
2-14
2-14
2-15
2-16
2-17
2-17
2-20
2-21
2-23
2-24
2-24
2-25
2-28
2-29

3-3
3-3
3-3
3-4
3-4
3-4
3-6

Contents (Cant)

Page
3.2.3
3.3
3.3.1
3.3.2
3.3.3
3.3.4
3.3.5
3.4

3.16
3.17
3.18

Relocation Mode (.EBREL and .DBREL)
TEXT HANDLING PSEUDO OPERATIONS
lOPS ASCII Packed Format ( . ASCII)
Trimmed Six-Bit Format (.SIXBT)
.ASCII and .SIXBT Statement Syntax
Text Delimiter
Non-Printing Characters
MACRO DEFINITION PSEUDO-OPERATIONS (.DEFIN,
.ETC, and .ENDM)
COMMON BLOCK PSEUDO-OPERATIONS
Common Block Definition (.CBD)
Common Block Definition--Relative (.CBDR)
Common Block Initialization Start (.CBS)
Common Block Initialization Constant (.CBC)
Common Block Initialization End (.CBE)
CONDITIONAL ASSEMBLY (.IFxxx and .ENDC)
LOCAL SYMBOLS (.LOCAL AND .NDLOC)
LITERAL ORIGIN (.LTORG)
SETTING THE LOCATION COUNTER (.LOC)
RADIX CONTROL (.OCT and .DEC)
RESERVING BLOCKS OF STORAGE (.BLOCK)
END OF PROGRAM (.END)
END OF PROGRAM SEGMENT (.EOT)
GLOBAL SYMBOL DECLARATION (.GLOBL)
REQUESTING AN I/O DEVICE HANDLER .IODEV
(Not supported in XVM/RSX)
DESIGNATING A SYMBOLIC ADDRESS (.DSA)
REPEAT OBJECT CODE (.REPT)
REQUEST PROGRAM SIZE (.SIZE)

MACROS

4.1
4.2
4.3
4.3.1
4.3.2
4.3.3
4.4
4.5
4.6
4.7

DEFINING A MACRO
MACRO BODY
MACRO CALLS
Argument Delimiters
Created Symbols
Concatenation
NESTING OF MACROS
REDEFINITION OF MACROS
MACRO CALLS WITHIN MACRO DEFINITIONS
RECURSIVE CALLS

OPERATING PROCEDURES

5.1
5.2
5.2.1
5.2.2
5.3
5.4
5.4.1
5.4.2
5.4.3
5.4.4
5.5
5.6

INTRODUCTION
CALLING PROCEDURE
XVM/DOS
RSX/XVM
GENERAL COMMAND CHARACTERS
COMMAND STRING
Program File Name
Options
Multiple Filename Commands
Examples of Commands for Segmented Programs
ASSEMBLY LISTINGS
SYMBOL TABLE OUTPUT

3.5
3.5.1
3.5.2
3.5.3
3.5.4
3.5.5
3.6
3.7
3.8
3.9
3.10
3.11
3.12
3.13
3.14
3.15

CHAPTER

3-7
3-8
3-9
3-9
3-9
3-9
3-10
3-11
3-11
3-11
3-12
3-13
3-14
3-14
3-15
3-17
3-20
3-21
3-21
3-22
3-23
3-24
3-24
3-26
3-26
3-26
3-28

4-2
4-3
4-4
4-6
4-7
4-8
4-17
4-18
4-19
4-20

5-1
5-1
5-1
5-1
5-2
5-3
5-3
5-4
5-7
5-10
5-13
5-14

Contents (Cont)

Page
5.7
5.7.1
5.7.2
5.8
5.9

RUNNING INSTRUCTIONS
Paper Tape Input Only
Cross-Reference Output
PROGRAM RELOCATION
SYSTEM ERROR CONDITIONS AND RECOVERY
PROCEDURES
XVM!OOS and BOSS XVM
XVM/RSX
Restart Control Entries (DOS only)
ERROR DETECTION BY THE ASSEMBLER

5-17
5-17
5-18
5-19
5-20

APPENDIX A

CHARACTER SET

A-1

APPENDIX B

PERMANENT SYMBOL TABLE

B-1

APPENDIX C

MACRO CHARACTER INTERPRETATION

C-1

APPENDIX D

SUMMARY OF MACRO XVM PSEUOO-OPS

D-1

APPENDIX E

SOURCE LISTING OF THE ABSOLUTE BINARY LOADER

E-1

5.9.1
5.9.2
5.9.3
5.10

INDEX

5-20
5-21
5-21
5-21

Index-l

LIST OF ALL XVM MANUALS

The following is a list of all XVM manuals and their DEC numbers, including the latest version available.

Within this manual, other XVM

manuals are referenced by title only.

Refer to this list for the

DEC numbers of these referenced manuals.
BOSS XVM USER'S MANUAL

DEC-XV-OBUAA-A-D

CHAIN XVM/EXECUTE XVM UTILITY MANUAL

DEC-XV-UCHNA-A-D

DDT XVM UTILITY MANUAL

DEC-XV-UDDTA-A-D

EDIT/EDITVP/EDITVT XVM UTILITY MANUAL

DEC-XV-UETUA-A-D

8TRAN XVM UTILITY MANUAL

DEC-XV-UTRNA-A-D

FOCAL XVM LANGUAGE MANUAL

DEC-XV-LFLGA-A-D

FORTRAN IV XVM LANGUAGE MANUAL

DEC-XV-LF4MA-A-D

FORTRAN IV XVM OPERATING ENVIRONMENT MANUAL

DEC-XV-LF4EA-A-D

LINKING LOADER XVM UTILITY MANUAL

DEC-XV-ULLUA-A-D

MACII XVM ASSEMBLER LANGUAGE MANUAL

DEC-XV-LMLAA-A-D

MACRO XVM ASSEMBLER LANGUAGE MANUAL

DEC-XV-LMALA-A-D

MTDUMP XVM UTILITY MANUAL

DEC-XV-UMTUA-A-D

PATCH XVM UTILITY MANUAL

DEC-XV-UPUMA-A-D

PIP XVM UTILITY MANUAL

DEC-XV-UPPUA-A-D

SGEN XVM UTILITY MANUAL

DEC-XV-USUTA-A-D

SRCCOM XVM UTILITY MANUAL
UPDATE XVM UTILITY MANUAL
VPl5A XVM GRAPHICS SOFTWARE MANUAL

DEC-XV-USRCA-A-D
DEC-XV-UUPDA-A-D
DEC-XV-GVPAA-A-D

VTl5 XVM GRAPHICS SOFTWARE MANUAL

DEC-XV-GVTAA-A-D

XVM/DOS KEYBOARD COMMAND GUIDE

DEC-XV-ODKBA-A-D

XVM/DOS READER'S GUIDE AND
MASTER INDEX

DEC-XV-ODGIA-A-D

XVM/DOS SYSTEM MANUAL

DEC-XV-ODSAA-A-D

XVM/DOS USERS MANUAL

DEC-XV-ODMAA-A-D

XVM/DOS VIA SYSTEM INSTALLATION GUIDE

DEC-XV-ODSIA-A-D

XVM/RSX SYSTEM MANUAL

DEC-XV-IRSMA-A-D

XVM UNICHANNEL SOFTWARE MANUAL

DEC-XV-XUSMA-A-D

vii

PREFACE
The DIGITAL XVM (XVM) MACRO Assembler program, MACRO XVM, provides the
user with the symbolic programming capabilities of an assembler plus
the added compiler capabilities of a many-for-one macro instruction
generator.

This manual describes the syntax, application and operations

performed by the MACRO X"VrJ! assembler.
In the preparation of this manual it was assumed that the reader was
familiar with the basic XVM symbolic instruction set.
The MACRO XVM program may be operated in:
a.

Disk Operating System (XVM/DOS)

Batch Operating Software System, BOSS, a component of XVM/DOS

XVM/RSX Software System

It is assumed in this manual that the reader is familiar with the manual
describing the software system under which MACRO is to be used.
The manuals involved are:
a.

XVM/DOS Users Manual

BOSS XVM Users Manual

XVM/RSX System Manual

Differences in the use of MACRO in the available monitor systems are
described, where applicable, in this manual.

CHAPTER 1
INTRODUCTION
1.1

MACRO XVM LANGUAGE

MACRO is a basic XVM symbolic assembler language which makes machine
language programming on the XVM easier, faster and more efficient.

permits the programmer to use mnemonic symbols to represent instruction
operation codes, locations, and numeric quantities.

By using symbols

to identify instructions and data in his program, the programmer can
easily refer to any point in his program, without knowing actual machine
locations.
~he

standard output of the Assembler is a relocatable binary object

program that can be loaded for debugging or execution by the Linking
Loader.

MACRO prepares the object program for relocation, and the

Linking Loader, CHAIN or Task Builder, CHAIN (nos), or Task Builder
(RSX) provides relocation and sets up linkages to external subroutines.
Optionally, the binary program may be output either with absolute
addresses (non-relocatable) or in the full binary mode (see Chapter 3
for a description of the binary output modes) .
The programmer directs the Assembler processing by using a powerful set
of pseudo-operation (pseudo-op)

instructions.

These pseudo-ops are

used to set the radix for numerical interpretation by the Assembler,
to reserve blocks of storage locations, to repeat object code, to
handle strings of text characters in 7-bit ASCII code or a special
6-bit code, to assemble certain coding elements if specific

con~itions

are met, and to perform other functions which are explained in detail
in Chapter 3.
The most advanced feature of the Assembler is its powerful macro instruction generator.

This facility permits easy handling of recurring in-

struction sequences, changing only the arguments.

Programmers can use

macro instructions to create new language elements, adapting the Assembler to their specific programming applications.

Macro instructions

may be recursively called up to three levels, nested to any level,
limited only by available memory, and redefined within the program.
The technique of defining and calling macro instructions is discussed
in Chapter 4.
1-1

Introduction

An output listing, showing both the programmer's source code and the
object pro g ram produced by the Assembler, is printed if desired.

This

listing may include all the symbols used by the programmer with their
assigned values.

If assembly errors are detected, erroneous lines are

marked with specific alphabetic error codes, which may be interpreted
by referring to the error list in Chapter 5 of this manual.
Operating procedures for the MACRO XVM assembler are described in
detail in Chapter 5. *
1.2

HARDWARE REQUIREMENTS

The MACRO XVM assembler program may be run in any configuration which
meets the minimum hardware requirements for the following XVM software
systems:

1.3

Disk Operating System (XVtJl/DOS)

Batch Operating Software System (BOSS XVM)

Resource Sharing Executive (XVM/RSX)

ASSEMBLER PROCESSING

The Assembler processes source programs in either a two-pass or threepass operation.

In the two-pass assembly operation the source program

is read twice, with the object program and printed listed (both optional) being produced during the second pass.

During PASS I, the

locations to be assigned the program symbols are resolved and a
symbol table is constructed by the Assembler.

PASS 2 uses the infor-

mation computed during PASS 1 to produce the final object program.
In an optional three-pass assembly operation, PASS 2 calls in PASS 3,
which performs a cross referencing operation during which a listing
is produced that contains:

(a) all user symbols,

(b) where each

symbol is d efined, and (c) the number of each program line in which
a symbol is referenced.

On completion of its operation, PASS 3 calls

the PASS 1 and PASS 2 portions of the assembler program back into
core for further assembly operations.

* These procedures are also described in the XVM/DOS Keyboard Command
Guide and in the On-Line Task Development section of the XVM/RSX
SySt'em Manual.

1-2

Introduction

The standard object code produced by the Assembler is in a relocatable
format which is acceptable to the Linking Loader,
TKB Utility programs.

CPAI~,

PATCH and

Relocatable programs that are assembled sepa-

rately and use global symbols* where applicable, can be combined by
the Linking Loader, CPAIN, and TKB into an executable object program.
MACRO XVM reserves one additional word in a program for every external
symbol**.

This additional word is used as a pointer (called a transfer

vector) to the actual data word in another program.

The Linking Loader

CHAIN or task builder sets up these transfer vectors when the programs
are loaded with the actual address of the global symbol.
Some of the advantages of having programs in relocatable format are as
follows:
a.

Reassembly of one program, which at object time was linked with
other programs, does not necessitate a reassembly of the entire system.

Library routines (in relocatable object code) can be requested
from the system device or user library device.

Only global symbol definitions must be unique in a group of
programs that operate together.

* Symbols which are referenced in one program and defined in another.
**

Symbols which are referenced in the program currently being assembled
but which are defined in another program.

1-3

CHAPTER 2
ASSEMBLY LANGUAGE ELEMENTS
2.1

PROGRAM STATEMENTS

One or more statements may be written on a line of up to 75 characters
where the last character is a carriage-return.

Since the carriage

return is a non-printing character, it is graphically represented as./
in this manual, e.g.,
STATEMENT ..J
Several statements may be written on a single line, separated by semicolons
STATEMENT; STATEMENT; STATEMENT./
Only the last statement may have a comments field, since semicolons
are allowed in and do not delimit comments.

Also, macro calls (a type

of statement described in a later chapter) should not appear in a multistatement line since they cause subsequent statements to be ignored.
Normally, a single statement must fit on one line.

The exception to

this rule is a macro call whose arguments may be continued on a subsequent line.
2.1.1

This is described in the chapter on macros.

Basic Statement Format

A basic statement may contain up to four fields that are separated by
a space, spaces, or a tab character.

These four fields are the label

(or tag) field, the operation field, the address field, and the comments field.

Because the space and tab characters are not printed, the

space is represented by~, and the tab by ~ in this manual.

Tabs are

set 8 spaces apart on DEC-supplied teleprinter machines, and are used
to line up the fields in columns in the source program listing.
This is the basic statement format:
LABEL ~ OPERATION

--I ADDRESS ~ /COMMENTS ..J
2-1

Assembly Language Elements

where each field is delimited by a tab or space, and each statement is
terminated by a semicolon or carriage-return.

The comments field is

preceded by a tab (or space) and a slash (/).
Note that a combination of a space and a tab will be interpreted by the
Assembler as two field delimiters.
Example:

-I OP ~ -I ADR -./}both are
TAG ~ -I OP
-I ADR..-/ incorrect

TAG

These errors will be flagged by the assembler, but will not show on
the listing because the space is hidden by the tab.
A MACRO statement may have an entry in each of the four fields, or
three, or two, or only one field.
(where the character(s)

The following forms are acceptable

indicates one or more of the preceding char-

acter) :
TAG . J

TAG

-l OP~
-l OP -I ADDR~
-l OP -l ADDR~ (s) / comments.~
-l OP ~ (s) / comments ~

TAG
TAG
TAG
TAG

-I

-I ADDR ~

TAG

-l

-l ADDR ~ (s) /comments . J

TAG

-I (s) /comments ~
-I OP~
-l OP
-l OP

-I OP
-I
-I

-l ADDR~
-l ADDR -I (s) /comments ~
-l (s) / comments ~

-I ADDR .-/
-l ADDR -I (s) /comments ~

/comments ~

-I (s) /comments ~
A label (or tag)

is a symbolic address created by the programmer to

identify the statement.
it is said to be defined.

When a label is processed by the Assembler,
A label can be defined only once.

The oper-

ation code field may contain a machine mnemonic instruction code, a
pseudo-op code, a macro name, a number, or a symbol.

2-2

The address field

Assembly Language Elements

may contain a symbol, number, or expression which is evaluated by the
assembler to form the address portion of a machine instruction. In
some pseudo-operations, and in macro instructions, this field is used
for other purposes, as will be explained in this manual.

Comments are

usually short explanatory notes which the programmer adds to a statement as an aid in analysis and debugging.
object program or assembly processing.
program listing.

Comments do not affect the

They are merely printed in the

Comments must be preceded by a slash (/).

The slash

(/) may be the first character in a line or may be preceded by:

2.1.2

Space

Tab

Semicolon (;)

(L...I).

(-l )

Direct Assignment Statement

The Direct Assignment Statement causes no object code to be generated
by the assembler, but rather equates a value to a symbol at assembly
time.

The format of this statement is:
symbol=expression / comments

The symbol is the symbolic name specified to receive the value of the
expression.

The expression is any legal combination of symbols and/or

constants connected by operators as described in Section 2.3.2.

ments are optional, as described in Section 2.1.1 • .
The direct assignment statement is useful for assigning a symbolic
name to a constant and controlling conditional assembly.
are explained in detail later on.

These features

Unlike labels defined in basic state-

ments, which must be defined only once, the symhol defined in a direct
assignment may be redefined at will.
2.2

SYMBOLS

The programmer creates symbols for use in statements to represent
addresses, operation codes and numeric values. A symbol contains one
to six characters from the following set:
The letters A through Z
The digits 0 through 9
Two special characters, period (.) and the percent sign (%).
2-3

Assembly Language Elements

The fir s t character of a symbol must be a letter, a period, or percent
sign.

A period may not be used alone as a symbol.

may not be a symbol.

('X'

The letter 'X' alone

and period alone have a special meaning to

the Assembler, as explained later.)
The following symbols are legal:
.. 1234

%50.99

•%

P9.3

I NP UT

MARKI

The following symbols are illegal:
TAG: 1

is not a legal symbol character.

5ABe

First character may not be a digit.

Letter 'X' alone is illegal.
, alone is illegal as a symbol.

Only the first six characters of a symbol are meaningful to the Assembler, but the programmer may use more for his own information.

If he

writes,
SYMBOL 1
SYMBOL2
SYMBOL3
as the symbolic labels on three different statements in his program,
the Assembler will recognize only SYMBOL and will print "M" error flags
on the lines containing SYMBOL 1 , SYMBOL2 and SYMB OL 3 .
they are duplicates of SYMBOL.

the Assembler

Note that " M" errors are not p roduced

if the duplicate symb ols appear in direct assignment statements.
2.2.1

Evaluation of Symbols and Globals

When the Assembler encounters a symbol during processing of a source
language statement,

it evaluates the symbol by referring to two tables:

the user's symbol table and the permanent symbol table.

The user's

symbol table contains all symb ols defined by the user.

'T'he user defines

symbols by using them as la b els, as variables, as macro names and
global s , and by direct assignment statements.
first used , and canno t
user,

be redefined.

A label is defined when

(When a la b el is defined by the

it is given the current value of the location counter, as will

be explained later in this chapter.)

2-4

Assembly Language Elements

All permanently defined system symbols (excluding the index register
symbol, X), including system macros (except for XVM/RSX) and all Assembler pseudo-instructions use a period (.) as their first character.
The Assembler also has, in its permanent symbol table, definitions of
the symbols for all of the XVM memory reference instructions, operate
instructions, the basic EAE instructions, and some input/output transfer instructions.

(See Appendix B for a complete list of these instruc-

tions. )
XVM instruction mnemonic symbols may be used in the operation field of
a statement without prior definition by the user.
Example:
LAC is a symbol whose appearance in the
operation field of a statement causes the
Assembler to treat it as an op-code rather
than a symbolic aCl.dress.
of 200000

It has a value

which is taken from the opera-

8
tion code definition in the permanent
symbol table.

The user can use instruction mnemonics or the pseudo-instruction mnemonics code as symbol labels.
DZM

For example,

-l DZML...IY"/

where the label DZM is entered in the symbol table and is given the
current value of the location counter, and the op-code DZM is given the
value 140000 from the permanent symbol table.
however,

The user must be careful,

in using these dual purpose (field dependent)

symbols.

Sym-

bols in the operation field are interpreted as either instruction codes
or pseudo-ops, not as symbolic labels, if they are in the permanent
symbol table.

Macro names cannot also be defined as labels or symbols

by the user.

In the following example, several symbols with values

have been entered in the user's symbol table and the permanent symbol
table.

The sample coding shows how the Assembler uses these tables to

form object program storage wor0s.

2-5

Assembly Language Elements

User Symbol Table

Permanent Symbol Table

Symbol

Value

Symbol

Value

TAGl

100

LAC

200000

TAG 2

200

DAC

040000

DAC

300

JMP

600000

010000

The following statements generate the following code:
Statement

Code

-1 DAC

-1 TAG2

040200

TAG 2 -I LAC

-l DAC

200300

TAG1

DAC

-l JMP -l TAG1
-l DAC -I TAG 1, X
-l TAG1

600100
050100
000100

2.2.1.1

Special Symbols - The symbol X is used to denote index register

usage.

It is defined in the permanent symbol table as having the value

of 10000.

The symbol X cannot be redefined and can only be used in the

address field.
2.2.1.2

Memory Referencing Instruction Format - When operating in page

mode the XVM uses 12 bits for addressing, 1 bit to indicate index register usage, 1 bit to indicate indirect addressing, and 4 bits for the
op-code.

I I

10 11 2 31 4
~
Op Code

I5 6

t [dex

9 110 111 112 1 13

I 14

1171
.J

Address
Register Bit

Indirect Addressing

PAGE MODE MEMORY REFERENCE INSTRUCTIOr-,l
When operating in bank mode on the XVM, 13 bits are used for addressing, there is no index register bit, 1 bit is for indirect addressing,
and 4 bits are for the op-code.

2-6

Assembly Language Elements

______________

I 0 11 I 2 I 3 I 4 5 6 7 8 9 10 11 1121 13 14 15 16 17
~

Op Code

Address
Indirect Addressing
BANK MODE MEMORY REFERENCE INSTRUCTION

2.2.2

Variables

A variable is a symbol that is defined in the user's symbol table by
using it in an address field or operation field with the number sign
(#).

Symbols with the # may appear more than once in a program (see

items 1, 3, 4, and 5 of example given below).

A variable reserves a

single storage word which may be referenced by using the symbol at
other points in the program with or without the #.

If the variable

duplicates a user-defined label, it is multiply defined and is flagged
as an error during assembly.
Variables are assigned memory locations at the end of the program.
The initial contents of variable locations are unspecified.

The # can

appear any place within the symbol character string as in the example.
Example:

.i. ......

.1. ,/1:::

2.2.3

Ii:)

Setting Storage Locations to Zero

Storage words can be set to zero as follows:
A

-I .O~ -I O~ -I

In this way, three words are set to zero starting at A.

2-7

Assembly Language Elements

2.2.4

Redefining the Value of

The programmer may

a Symbol

define a symbol directly in the user's symbol table

by means of a direct assignment statement written in the form:
SYMBOL=n -..J
or
SYM1=SYM2 -~
Where n is any number or expression.

There should be no spaces between

the symbol and the equal sign, or between the equal sign and the
assigned value, or symhol.

The Assembler enters the symbol in the

symbol table, along with the assigned value.
way may be redefined.

Symbols entered in this way

These are legal direct assignment statements:

XX=28;A=1;B=2 ~
A symbol can also be assigned a symbolic value; e.g., A=4, B=A, or
SET=IS ZL...ISWITCH :../
In the previous example, the symbol B is given the value 4, and when
the symbol SET is detected during assembly the object code for the
instruction ISZL...ISWITCH will be generated.

This type of direct assign-

ment cannot be used in a relocatable program.

Direct assignment state-

ments do not generate storage words in the object program.
In general, it is good programming practice to define symbols before
using them in statements that geLerate storage words.
will interpret the following sequence correctly.

>",

J;.'

::.1
.... . ,.:

2-8

~he

assembler

Assembly Language Elements

2.2.5

Forward Reference

A symbol may be defined after use.

For example,

This is called a forward reference, and is resolved properly in PASS 2.
When first encountered in PASS 1, the LAC Y statement is incomplete
because Y is not yet defined.

Later in PASS 1, Y is given the value 1.

In PASS 2, the Assembler finds that Y=l in the symbol table, and forms
the complete storage word.
Since basic assembly operations are performed in two passes, only onestep forward references are allowed.

The following example is illegal

because the symbol Y is not defined during PASS 2.

,"-

....

'.) t.) ;,) l)....

r':

.. '. j I,) I•...' I.,,; '.)

(.:;

,"
c. ". ,",:. ,',
'..I!.) .)i.,iI, !i... '

Forward references to internal .GLOBL symbols (see Paragraph 3.9) are
illegal because the internal globals are output at the beginning of
PASS 2 for library searching.

Globals must be defined during PASS 1,

otherwise they will be flagged.

The following example is illegal:

2-9

Assembly Language Elements

2.2.6

Undefined Symbols

If any symbols, except global symbols, remain undefined at the end of
PASS 1 of assembly, they are automatically defined as the addresses of
successive registers following the block reserved for variables at the
end of the program.

All statements that referenced the undefined symbol

are flagged as undefined.

One memory location is reserved for each un-

defined symbol with the initial contents of the reserved location being
unspecified.

, ,·'< t: j
O()() ./,

2.3

,_.

.. . <><:: _
..' (1 .:!

NUMBERS

The initial radix (base) used in all number interpretation by the
Assembler is octal (base 8).

To allow the user to express decimal

values and then restore to octal values, two radix-setting pseudo-ops
(.OCT and .DEC) are provided.

These pseudo-ops, described in Chapter

3, must be coded in the operation field of a statement.

If any other

information is written in the same statement, the Assembler treats the
other information as a comment and flags it as a questionable line.
All numbers are decoded in the current radix until a new radix control
pseudo-op is encountered.

The programmer may change the radix at any

point in the program.
Examples:

:::;

:i. (>
.:.1

....- --::.

00006 R 000 033 A
; :1 II ! '

l!!

;,",

2-10

Assembly Language Elements

2.3.1

Integer Values

An integer is a string of digits, with or without a leading sign.
Negative numbers are represented in two's complement form.

The range

of integers is as follows:
Unsigned
Signed

o -+ 262143 10

o -+ 131071 10

o -+ -131072 10

(777777 ) or
8
(377777 ) or
8
(400000 ) or
8

An octal integer* is a string of digits (0-7), signed or unsigned.

a non-octal digit (8 or 9) is encountered the string of digits will be
assembled as if the decimal radix were in effect and it will be flagged
as a possible error.
Example:

00000 R 00/ 3 03 A

, ucr
...

....1

)'
~3

I :? C :::: () () () () ./}

A decimal integer** is a string of digits (0-9), signed or unsigned.

Examples:
:. L·;::: t::.

. ::~
;'., j

*Preceded at some point by an .OCT pseudo-op and is also the initial
assumption if no radix control pseudo-op is encountered.
**

Preceded at some point by a .DEC pseudo-op.
2-11

Assembly Language Elements

2.3.2

Expressions

Expressions are strings of symbols and numbers separated by arithmetic
or Boolean operators. Expressions represent unsigned numeric values
18
ranging from a to 2 -1. All arithmetic is performed in unsigned integer arithmetic (two's complement), modulo 218.

Division by zero is

regarded as division by one and results in the original d i v idend.
Fractional remainders are ignored; this condition is not regarded as
an error.

The value of an expression is calculated by substituting

the numeric values for each symbol of the expression and performing
the specified operations.
The following are the allowable operators to be used with expressions:
Character
Symbol

Name

Function

Plus
Minus

+
-

Addition (two's complement)
Subtraction (convert to two's
complement and add)

Asterisk

Multiplication (unsigned)

Slash

Division (unsigned)

Ampersand

Logical AND

Exclamation
point
Back slash

Inclusive OR

Exclusive OR

Comma

Exclusive OR

Boolean

Operations are performed from left to right (i.e., in the order in which
they are encountered).

For example, the assembly language statement

A+B*C+D/E-F*G is equivalent to the following algebraic expression
(((((A+B)*C)+D)/E)-F)*G.
Examples:
Assume the following symbol values:
Symbol

Value (Octal)

000002

000010

000003

000005

010000

Comments

Index Register Value

2-12

Assembly Language Elements

The following expressions to be evaluated:
Evaluation (Octal)

Comments

A+B-C,X

010007

Index Register Usage

A/B+A*C

000006

(The remainder of A/B
is lost)

B/A-2*A-1+X

010003

Index Register Usage

A & B

000000

C+A&D

000005

B*D/A

000024

B*C/A*D

000074

A,X+D,X

010007

Expression

Index Register Usage
Error

In the last example the expression is evaluated as follows:
Sequence of arithmetic
a.
b.
c.

= 000002 XORed with 010000 = 010002
A, X+D
010002 + 000005 = 010007
000007
A,X+D,X = 010007 XORed with 010000

A,X

Note that arithmetic produces 000007 yet the value given in the example
is 010007.

Regardless of how the index register is used in the address

field, the index register bit will always be turned on by the Assembler.
In the sequence of address arithmetic above, the line would be flagged
with an X because of the illegal use of the index register symbol (x).
Using the symbol X to denote index register usage causes the following
restrictions:

2.4

X cannot appear in the TAG field

X cannot be used in a .DSA statement

X can be used only once in an expression (see 2.4.3)

-I A
-I .DSA -I A,X
-I LAC -I A,X+D,X

X -I LAC

ADDRESS ASSIGNMENTS

As source program statements are processed, the Assembler assigns consecutive memory locations to the storage words of the object program.
This is done by reference to the location counter, which is initially
set to zero and is incremented by one each time a storage word is formed

2-13

Assembly Language Elements

in the object program.

Some statements, such as machine instructions,

cause only one storage word to be generated, incrementing the location
counter by one.

Other statements, such as those used to enter data or

text, or to reserve blocks of storage words, cause the location counter
to be incremented by the number of storage words generated.
2.4.1

Referencing the Location Counter

The programmer may directly reference the location counter by using the
symbol period (.)

in the address field.

He can write,

-l JMP ......... -1
which will cause the program to jump to the storage word whose address
was previously assigned by the location counter.

The location counter

may be set to another value by using the .LOC pseudo-op, described in
Chapter 3.
2.4.2

Indirect Addressing

To specify an indirect address, which may be used in memory reference
instructions, the programmer writes an asterisk immediately following
the operation field symbol.

This sets the defer bit (bit 4) of the

storage word.
If an asterisk suffixes either a non-memory reference instruction, or
appears with a symbol in the address field, an error will result.
Two examples of legal indirect addressing follow.

-l TAD* -l A
-1 LAC* ..j B
The following examples are illegal.

-l CLA*
-l LAW* ........ 17777

Indirect addressing may not be specified
in non-memory reference instructions.

2-14

Assembly Language Elements

2.4.3

Indexed Addressing

To specify indexed addressing an X is used with an operator directly
after the address.

No spaces or tabs may appear before the operator.

The Assembler will perform whatever operation is specified with the
index register symbol, and then continue to evaluate the expression.
At completion of the expression evaluation, if the index bit (bit 5)
is not on and the location counter is pointing to page

a of any bank,

the line is flagged with a B for bank error because the address (aside
from indexing modifications) must have been greater than 77778 (i.e.,
it pointed to another page) .

The standard code used to indicate index-

ing is:

-I LAC -I A, X
The indexed addressing operation is illustrated in the following
example.

o( )() ()()

,.::.

F:~

::'-! ·...i l.) ;,) I,..'

/.~

~:.:.;

: .~

o() () () J F: () :.:.:j 0 0 (.

ISA ME

;
/ \.
, •.. , "11 . ,"

" .~

'LAC

,.\;" "

.' L. '. .i ~.;

:!. () 0 () :I. i':: ::::::f. () 0 () ()
:L 00 () ,:.:.: (": :? J () 0 0 0

-. '\ ... \

:."

.....',",.'

t.(::.~
('i

:, .. 1-:

"', T ', I" ::: .!.f)()() 3

Expression evaluation where A

000000, B

000001, C

010000,

D = 010001, X = 010000
NOTE:
Location

= exclusive OR
Discussion

Address Field
X

The value of X is added to O.
Absence of an operator always
implies addition.

A,X+1,7-1

000000 @ 010000
010000 B 000001
010001 (9 000007
010006 - 000001

010000
010001
010006
010005

B+X

000001 @ 010000

010001

2-15

0,1

Assembly Language Elements

Location

Address Field

10000

X,D

Discussion
010000

e 010001 = 000001

The index bit has been
turned off during expression evaluation.
Because
the location counter (10000)
is pointing to Page 1, this
line is not flagged, and the
index register bit is turned
on.
10001

C,X

010000

e 010000 =

(JOOOOO

Same as example at Location
10000.
2.4.4

Literals

Symbolic data references in the operation and address fields may be
replaced with direct representation of the data enclosed in parentheses.
This inserted data is called a literal.
address link,

The Assembler sets up the

so one less statement is needed in the source program.

The following examples show how literals may be used, and their equivalent statements.

The information contained within the parentheses,

whether a number,

symbol, expression, or machine instruction,

assembled and assigned consecutive memory locations after the locations
used by the program, unless a
program.

(See section 3.2.5.)

.LTORG pseudo-instruction appears in the
The address of the generated word will

appear in the statement that referenced the literal.
Duplicate literals, completely defined when scanned in the source program during PASS 1, are stored only once so that many uses of the same
literal in a given program result in the allocation of only one memory location for that literal.

Nested literals, that is, literals

within literals, are illegal and will be flagged as a literal (L) error.
The following is an example of a nested literal.

Usage of Literal

Equivalent Statements
One

-lADD~ONE

..,1

-l LAC ~(TAG)
-l LAC ~(DAC

-f TAG)

.., LAC ~(JMP

-4 . +2)

LAC~TAGAD

TAGAD-l

TAG

-l
INST -l
HERE -4
INST -l

LAC
DAC

2-16

INST
TAG
-l
LAC ~ INST
JMP ~ HERE+2
~

Assembly Language Elements

The following sample program illustrates how the Assemb ler handles
literals.

00000
0 0 001
00 002
00003
00004
00 005

(:)

..;

R 200 0 10
R 040100
R 2 0001 J
R 200012
R 200013
R 200013

R
A
R
R

R
R

() ()()O() ()

,",

T()C:!.

L. (:-1 C

(.1.00)

I!...i

Dr,., c·

'! 00

Li':>IC
I... ,-",C
l. .. tlC

': ...ii'li'"

"i.')[;1:-

,..ii'iF

Tr,u:. .')

00006 R 200014 R
00007 R 2 0 0 01 5 R
10

()()()O(>o

L.t·le
!... (:)C

0::

,; ...ii,·j?

0::-

.: o ;~~',c

D:':') C )

,[ND

('I

000 10 R 00 010 0 A t L
000 1 1 R 60 0 007 R *L
00012 R 0 00000 R ~L

51ZE=00017

2.5

000 14 R 6 0 00 0 0 A *1...
00015 R 04 000 7 R *l.
NO ERROR LINES

STATEMENT FIELDS

The following paragraphs provide a detailed explanation of statement
fields,

including how symbols and numbers may be used in each field.

2.5.1

Label Field

If the user wishes to assign a symbolic label to a statement in order
to facilitate references to the storage word generated by the Assembler,
he may do so by beginning the source statement with any desired symbol.
The symbol must not duplicate a system or user defined macro symbol and
must be terminated by a space or tab, or a statement terminating semicolon or carriage-return.
Examples :
TAG-/ fl; TAG2 -/ fl ; TAG3 -/ fl; TAG4-/ fl
A new logical line starts after each semicolon.
to
TAG1 -I

0-./

TAG2 -/

0..J
O..J
0..J

TAG3

-I

TAG4 -/

2-17

This line is equivalent

Assembly Language Elements

If there were a tab or a space after the semicolon the symbol would be
evaluated as an operation instead of a label.
TAG 1-1 0;

-I

TAG2;TAG3

-I

The sequence:

-I TAG4

is evaluated as follows:
TAGl -I 0-/

-I TAG2 -/
TAG 3 -I 0 . )
-I TAG4../
When writing numbers separated by semicolons, the first number must be
preceded by a tab

(-I ) or a space (1-1).

The sequence

TABLEI-Il;2;3;4;5
produces symbol (S) errors because the first symbol of a tag cannot be
numeric.

The correct way to write the table sequence is as follows:

Symbols used as labels are defined in the symbol table with a numerical
value equal to the present value of the location counter.
defined only once.

A label is

If it was previously defined by the user, the cur-

rent definition of the symbol will be flagged in error as a multiple
definition.

All references to a multiply defined symbol will be con-

verted to the first value encountered by the Assembler.

i...' i ~:.:

"L
",

;',.-;

OOOC

R )00( 04 R

_r:,
!....

:,"5

/!.

";' \ .-

>,.-

c:":')

Anything more than a single symbol to the left of the label-field
delimiter is an error; it will be flagged and ignored.
statements are illegal.
2-18

The following

Assembly Language Elements

-I

LAS ..J

LOC*2 -I

RAR~

TAG+1

The line will be flagged with an S for symbol error.

The label will

be ignored but the rest of the line will continue to be processed.
The only time that an error tag is not ignored is when the error occ u rs
after the sixth character.
The statement:
TAGERROR*h....INOP
will be assembled as:
TAG ERR

-I NOP

and the line will be printed and flagged with an S .
Redefinition of certain symbols can be accomplished by using direct
assignments; that is, the value of a symbol can be modified.

If an

Assembler permanent symbol or user symbol (which was defined by a direct
assignment)

is redefined, the value of the symbol can be changed with-

out causing an error me s sage.

If a user symbol, which was first de-

fined as a label, is redefined by either a direct assignment or by
using it again in the label field,

it will cause an error.

Variables

also cannot be redefined by a direct assignment.
Examples :

/i
"','

L(:!C
D(:,C

000 00 R 200003 A
00 GO R 04 0 0 03 A
~'

l~ ')

. . ...',

I""

... ~

' •• 1

OOJ U~ R 20000 4 A
00 00 3 R 0 40 00 ~ A

y ",

.... {"

).. 1 1'; ,.

IER ROR. A LABEL tAN
.,/ i\~ DT ;: -; E ::;~ E: DE:: ~:: I (,! 1. D
./:H U T
(:'1 " i::: (.~ ;" .! r:; :::: ('.: F ..

J ()
l. :I.

I DEFIN ED TO TAE VA LUE 'B'
,."" ':::. ('j (.~ 1: :::: :U ;:: r: :~: j-) ;:::
;::. E:: :: :~ ('j ('; .
000 04 R 0 40 003 R

\.I ,":\L:
F:' ~:::F

,[;j:;
b I :~':':E: :OO(J()(,

2-19

Assembly Language Elements

2.5.2

Operation Field

Whether or not a symbol label is associated with the statement, the
operation field must be delimite0 on its left by a space(s) or tab.
If it is not delimited on its left, it will be interpreted as the label
field.
~Thich

The operation field may contain any symbol, number, or expression
will be evaluated as an 18-bit quantity using unsigned arithmetic

modulo 218.

In the operation field, machine instruction op codes and

pseudo-op mnemonic symbols take precedence over identically named user
defined symbols.

The operation field must be terminated by one of the

following characters:

-I

(field delimiters)

or L.-I( s)

(statement delimiters)

..) or ;
Examples:

. '~

. ;.;.

.::.' .; . .. .. :::(, ::) (:

The asterisk (*) character appended to a memory reference instruction
symbol, in the operation field, causes the defer bit (bit 4) of the
instruction word to be set; that is, the reference will be an indirect
reference.

If the asterisk (*) is appended on either a non-memory

reference instruction or any symbol in the ao.dress field,

it will cause

an error condition which will be flagged as a symbol error (5-flag).
The asterisk will be ignored and the assemb ly process will continue.
Examples:

,',

,',
( )

... i . l !.. ··
I

;! 1

.... .

.. 1\

where A = 1 and B

However, the asterisk (*) may be used anywhere as a multiplication
operator.
2-20

Assembly Language Elements

Examples:
.1.

o() <) c (.1 h:

':. ' t) <) 0 0 <)

00 0 01

000 0 00 R

. / I L t ..J:: :t::. __
QRU vvuu~ n 200005 R
OU 00003 R 000004 R

j:.!,.;<

2.5.3

. i' t, ,~ ,

Address Field

The address field,

if used in a

~tatement,

operation field by a tab, or space(s).

must be separated from the

The address field may contain

any symbol, number, or expression which will be evaluated as an 18-bit
18
quantity using unsigned arithmetis, modulo 2
If op code or pseudo-op
code symbols are used in the address field,

they must be user defined,

otherwise they will be undefined by the Assembler and will cause an
error message.

The address field must be terminated by one of the

following characters:
-I

or ...... (s)

(field delimiters)

...J

or ;

(statement delimiters)

Examples:
LA\,] -1

ICorrectly assembled as 777777

LAW-1

INO separation from the operation field; assembled
as 757777 since -1 is treated as part of the operation field.

TAG2

-I DAC -I. +3
-I
-I TAG2 /5+3 ...... (s)

The address field may also be terminated by a semicolon or a carriag e return.
Examples:
-I JMP

-I BEGIN - )

-I TAD -I A; -I DAC

-IE

-I LAC

In the last example, a tab or space(s)

is required after the semicolon

in order to have the Assembler interpret DAC as being the operation
field rather than the label field.
2-21

Assembly Language Elements

In the second line of the preceding example, the address field B is
delimited by a tab.

The LAC after the B ~

is ignored and is treated

as a comment; but the line is flagged as questionable because only a
comment field may occur on a line after the address field.
had been preceded by a slash (I),

If the LAC

the line would have been correct.

When the address field is a relocatable expression, an error condition
may occur.

If the program is being assembled to run in page mode,

could not execute properly if its size exceeded 4K (4096) words because
it would have to load access a memory page or bank boundary.

In prac-

tice, the binary loaders restrict the size to 4K-16 (4080) to avoid
loading a program into the first 16 locations in a memory page or bank.
This avoids a possible ambiguity where indirect memory references would
be mistaken for autoincrement register references.

Consequently, any

relocatable address field whose value exceeds 4095 (7777 ) is meaningless
8
in page mode and will be flagged by the Assembler as an error.
There is a similar size restriction for programs being assembled to
operate in bank mode.

The Assembler flags in error any relocatable

address field whose value exceeds 8191

(17777 ). The binary loaders
8
restrict the size of bank mode program to 8K-16 (8176) words.

When the address field is an absolute expression, an error condition
will exist if the extended memory and page address bits (3, 4, and 5)
do not match the corresponding bits of the address of the page currently
being assembled into.
NOTE
In absolute mode, the page bits do not have to
be equal if the .ABS or .FULL pseudo-ops are used
instead of the .ABSP or .FULLP pseudo-ops.

2-22

Assembly Language Elements

The Linking Loader will not relocate any absolute addresses; thus,
absolute addresses within a relocatable program are relative to that
page in memory in which the program is loaded.
Example:
Assume that the following source line is part of a relocatable program
that was loaded into bank 1 (2000°
Source Statement

-+ 37777

Effective Address

-I LAC ...... 300

2 0300

An exception to the above rule is the auto-index registers, which occupy
locations 108 - 178 in page

° of memory bank O. The hardware will

always ensure that indirect references to 108 - 178 in any page or bank
will access 108 - 178 of bank 0.
2.5.4

Co~ments

Field

may appear anywhere in a statement.

Co~ments

They must begin with a

slash (/ ) that is immediately preceded by one of the following:
a.

...... (s)

space(s)

-I

tab

c. ~

carriage return/line feed

semicolon

(end of previous line)

Comments are terminated only by a carriage-return or when 74

char-

acters have been encountered in a line.
Examples:
...... (s)/THIS IS A COMMENT (rest of line is blank)
TAG 1

-I LAC ......

/THIS IS A COMMENT

-I RTR ...... /COMMENT ~
-I RTR; -I RTR; /THIS IS A COMMENT
Observe that;

-I A/COMMENT ~ is not a comment, but rather an operation

field expression.

A line that is completely blank (containing 0 to 75

blanks/spaces) is treated as a comment by the Assembler.

2-23

Assembly Language Elements

A statement is terminated as follows:

.J or; or rest of line is completely blank.
Examples:

-I LAC~
-I DAC (the rest of the line is blank)
-I TAG+3
-I RTR; -I RTR; -I RTR ~
In the last example, the statement-terminating character, which is a
semicolon (;) enables one source line to represent more than one word
of object code.

A tab or space is required after the semicolon in order

to have the second and third RTRs interpreted as being in the operation
field and not in the label field.
2.6

STATEMENT EVALUATION

When the Assembler evaluates a statement, it checks for symhols or
numbers in each of the three evaluated fields:
address.
2.6.1

label, operation, and

(Comment fields are not evaluated.)

Numbers

Numbers are not field dependent.

When the Assembler encounters a num-

ber (or expression) in the operation or address fields
illegal in the label field),
word.

(numhers are

it uses those values to form the storage

The following statements are equivalent:

All three statements cause the Assembler to generate a storage word
containing 200010.

A statement may consist of a number or expression

which generates a single 18-bit storage word; for example:

-I 23;1-145;1-1357;1-162

2-24

Assembly Language Elements

This group of four statements generates four words interpreted under
the current radix.

2.6.2

Word Evaluation

When the Assembler encounters a symbol in a statement field,

it deter-

mines the value of the symbol by reference to the user's symbol table
and the permanent symbol table, according to the priority list shown in
paragraph 2.6.4.
The operation field is scanned for the following special cases:
Mnemonic

Operation Field Value

LAW

760000

AAe

7230 0 0

AXR

73700 0

AXS

7250 0 0

EAE instructions

6 4xxx x

If the operation field is not one of the s pecial ca s es, th e object word
value is computed as follows:
If assembling for page mode:
(Operation Field +(Address Field & 7777))=Word Value
If assembling for bank mode:
(Operation Field +(Address Field & 17777))=Word Value
If the index register is used anywhere in the address field,
register bit is set to one in the wore value.

the ind e x

If it is not used, and

you are assembling for page mode then the index register bit is set to
zero in the word value regardless of the address field value.
a.

If index register usage is specified, the result of XORing
bit 5 of the location counter and bit 5 of the adcre s s field
value must be non-zero.

(Otherwise the address without index

modification was in a different page than the locatio n counte r,
and the line is flagged with a B for bank error) .

2-25

Assembly Language Elernents

Example:

:I.
()

() O()

: ? :i. () ( ~~ () :I.

1... tl C
i·i '.:1 F"
, I... ue

...'1../.1.

1 O() O

.:.::~ :i. () () 0 :1.

00:1.

'.1::,
," ,

L.(:·!C:
.;.[i'··lD

~:::;:1 ~.?

[: : ; :J. <) () () .

The result of statement evaluation has produced the following results:
A,X

10001

00001

B,X

00001

10001

Note that when index register usage is specified, the index register
bit mayor may not be on.

For B,X above, the index register bit was

turned off during statement evaluation.

The Assembler turns this bit

on after the word is evaluated, not at statement evaluation time.
At location 10001, the result of XORing bit 5 of A,X and bit 5 of the
location counter is O.

This signals the Assembler that the address

reference (A) is in a different page.
b.

If index register usage is not specified and the program is
not assembled for bank mode*, the result of XORing bit 5 of
the location counter and the address field value must be 0,
otherwise the line is flagged with a B for bank error.

* See pseudo-ops .ABS, .ABSP, .FULL, .FULLP, .EBREL, .DBREL.
2-26

Assembly Language Elements

Example:

, () E':~:; F'

:I.

''')

.~'

L ()C

O OO()()

,LDC

:-5
',/ . :':~. () 0 0 ()

.1\
I::'

0 00 000

S1 Z E " :I. O:."iO!'

:I.

EHF::G::~:

i... I ;,.iE:'

The bank bits (3,4) of the address field value in a relocatable
program must never be on.

The bank bits are always lost when

the address field value and the operation are combined to form
the object word value.
Example:

,.,:I.

j
,':.

,,',.

0 () 0 ()() p
:l. )' ,- ')' ...- F;:
J ) ' ')' .... .. F;:
F:.:
:::.:: () () 0 "
~'

;';
:::: I lE '" ;:'; 000:1.

,00 () 0

/' i} () <) 0 ;.)

!,:'~!

/ ·4 0 G ~) 0
O()OOO()

(',

~.:.:: '

\",

c+!. ././';:'

' ''}

,!:':i< ,..I

(':1

LF:F::fJF< !... I NE::;

The bank bits of an absolute program must equal the bank b its
of the location counter.

If not, the B flag alerts t he pro-

graromer that he is referenc i ng another bank.
Example:
~. (! f~~; F:

.,',.

::? I:) O()O

;,:?,OO O()
200() J.

:I.

..•

'.J
~::) I Z

()O ()()O()

I:::::: :::.~ 0 0 () 3

2 - 27

I.J,e:

L ( ,C;

!... ;-:':iC

;) ' .',)()J

i.. (o)e
, iii \)

·(~nO()

Assembly Language Elements

The bank bits of lines 3 and 5 do not match those of the location counter, therefore, the lines are flagged.

2.6.3

Word Evaluation of the Special Cases
a.

LAW - The operation field value and the address field value
are combined as follows:
Operation Value + (Address Field Value & 17777)

Word Value

A validity check is then performed on the address field value
as follows:
Address Field Value & 760000

Validity Bits

If the validity bits are not equal to 760000 or 0, the line
is flagged with an E to signal erroneous results.
b.

AAC, AXR, AXS - The operation field value and the address
field value are combined as follows:
Operation Value + (Address Field Value & 000777)

Word

Value
The validity check:
Address Field Value & 777000

Validity Bits

If the validity bits are not equal to 777000 or 0, the line
is flagged with an E to signal erroneous results.

The address

field value for this type of instruction cannot be relocated.
The line is flagged with an R if the address field value is
relocatable.
c.

EAE class instructions - The operation field value and the
address field value are combined as follows:
Operation Value + Address Field Value
The validity check:
word value and 640000

Validity Bits

2-28

Word Value

Assembly Language Elements

A validity check is then performeo. on the word value.

If the

validity bits differ from 640000, the line is flagged with an
E error to signal erroneous results.

I
i::.

00000 ~ 77/ 777
0 00 01 R 77 7777
00002 R 777 /77
00003 R 760 000

A
A
A
A

.1.

/ ./..'

I.. (·,ki
L.. t!t,j

T ... .
1::.

() () 0 0 ')' F;.:

"? :=,:.; () (I

0 ()

f:1

00010 K 153 323 A
00011 R 000023 A
11

If numbers are found in the operation and address fields, they are
combined in the same manner as defined symbols.

For example,

-I 2 -Is -I /GENERATES 000007
The value of a symbol depends on whether it is in the label field, the
operation field, or the address field.

The Assembler attempts to

evaluate each symbol by running down a priority list, depending on the
field, as shown below.
2.6.4

Assembler Priority List
Operation Field

Address Field

Pseudo-op

The indexing symbol, X

User or System macro
in macro table

User symbol table (including direct assignments)

Direct assignment in
user symbol table

Undefined

Permanent symbol
table

User symbol table

Undefined

2-29

Assembly Language Elements

This means that if a symbol is used in the address field.

it must be

defined in the user's symbol table before the word is formed during
PASS 2; otherwise. it is undefined.

(See section 2.2.4)

In the operation field. pseudo-ops names take precedence.

Direct

assignments allow the user to redefine machine op codes. as shown in
the example below.
Example:
DPOSIT

DAC

System macros may be redefined by user macros. but may not be redefined
as user symbols by direct assignment or by use as statement labels.
The user may use machine instruction codes and pseudo-op codes in the
label field and refer to them later in the address field.

2-30

Cf-1APTER 3
PSEUDO OPERATIONS
The Assembler has definitions in its permanent symbol table of the
symbols for all the XVM memory reference instructions, operate instructions, the basic EAE instructions, and many commonly used lOT instructions which may be used in the operation field without prior definition by the user.

Also contained in the permanent symbol table are a

class of symbols called pseudo-operations (pseudo-ops) which, instead
of generating instructions, generate data or airect the Assembler on
how to proceed with the assembly.
By convention, the first character of every pseudo-op symbol is a
period (.).

This convention is used in an attempt to prevent the

programmer from inadvertently using,

in the operation field, a pseudo-

instruction symbol as one of his own.
The following is a summary of MACRO XVM Pseudo-ops.
Pseudo-op

Section

Function

.ABS
.ABSP

3.2.1}
3.2.1

Object program is output in absolute, blocked,
checksummed format for loading by the Absolute
P inary Loader.
(Neither is supported with
XVM/RSX. )

.ASCII

3.8.1

Input text strings in 7-bit ASC II code, with
the first character serving as delimiter. Octal
codes for non-printing control characters are
enclosed in angle brackets.

.BLOCK

3.5

Reserves a block of storage words equal to the
expression.
If a label is used, it references
the first word in the block.

.CBC

3.5.4

Initializes a word of a common block to a constant.

.CBD

3.18

Common Block Definition.

.CBDR

3.19

Common Block Definition Relative.

.CBE

3.5.5

End common block initialization section.

.CBS

3.5.3

Start common block initialization section.

.DBREL

3.2.3

Disable bank mode reloation.

3-1

Pseudo Operations

Pseudo-op

Section

.DEC

3.4

Set prevailing radix to decimal.

.DEFIN

3.16

Macro definition.

.DSA

3.11

Generates a transfer vector for the specified
symbol.

. EBREL

3.2.3

Enable bank mode reloration .

.EJECT

3.14

Skip to head of form on listing device.

.END

3.6

Must terminate every source program. The
address field contains the address of the first
instruction to be executed.

. Ef'JDC

3.13

Terminates conditional cooing resulting from
.IF statements.

. EI'''DM

3.16

Terminates the body of a macro definition.

.EOT

3.7

Must terminate physical program segments, except the last, which is terminaten by .FND.

.ETC

3.16

Used in macro definitions to continue the list
of dummy arguments on succeeding lines.

3.2.2

Produces absolute, unblocked, unchecksummed
binary object programs. Used only for paper
tape output.
(Neither supported with YVM/RSX.)

.GLOBL

3.9

Used to declare all internal and external
symbols which reference other programs.

.IFxxx

3.13

If a condition is satisfied, the source coding
following the .IF statement and terminating with
an .ENDC statement is assembled.

. IODEV

3.10

Specifies .DAT slots and associated I/O handlers
required by this program.
(Not supported with
XVM/RSX. )

.LOC

3.3

Sets the location counter to the value of the
expression.

. LOCAL

3.2.4

Allows deletion of certain symbols from the user
symbol table.

.LST

3.17

Continues requested assembly listing output of
source lines. Lines between .NOLST an0 .LST
are not listed.

.LTORG

3.2.5

Allows the user to specifically state where
literals are to be stored.

.NDLOC

3.2.4

Terminates deletion of certain symbols from the
user symbol table containen between .LOCAL and
.NDLOC.

.FULL
.FULLP

)

Function

3-2

,,-

Pseudo-op

Section

.NOLST

3.17

Terminates requested assembly listing output of
source lines of code contained between .NOLST
and .LST.

.OCT

3.4

Sets the prevailing radix to octal.
start of every program.

.REPT

3.12

Repeats the object code of the next object code
generating instruction.

.SIXBT

3.8.2

Input text strings in 6-bit trimmed ASCII with
first character as delimiter.

.SIZE

3.15

Outputs the address of last location plus the one
occupied by the object program.

.TITLF.

3.1

Causes the assembler to accept characters to be
printed at the top of each page of assembly
listing and in the Table of Contents.

3.1

Function

Assumed at

LISTING CONTROL PSEUDO-OPERATIONS

3.1.1

Program Segment Identification (.TITLE)

The program name (or any text) may be written in a .TITLF. statement
as shown in the following examples.

The Assembler will accept up to

5010 characters typed until a carriage return.

A form feed is output

to the listing when .TITLE is encountered in the source program.

The

text will appear at the top of each form (page) until the next .TITLE
pseudo-op.

The .TITLE pseudo-op has no effect on the listing file

name.

-l . TITLE....,NAME OF PROGRAM
-l . TITLE....,NAME OF SUBSECTION IN PROGRAM
If subsections in a program are headed by .TITLE statements, these
can be used to produce a table of contents at the head of the assembly
listing by use of the T option.
3.].2

Listing Control (.EJECT)
Label Field

Operation Field

Address Field

Not used

. EJECT

!,-Tot used

When .EJECT is encountered anywhere in the source program, it causes
the listing device that is being used to skip to top-of-form.

3-3

Pseudo Operations

3.1.3

Listing Output Control (.NOLST and .LST)
Label Field

Operation Field

Address Field

Not used

( . NOLST)
.LST

Not used

If, while performing an assembly listing operation (L, or N assembly
parameters), the Assembler encounters a .NOLST, the listing operation
will be terminated until a .LST is found.

These pseudo-ops are useful

when the user wishes to assemble all of a program, but only needs a
listing of certain modules of the program (e.g., those which may not
yet work properly).

All symbols occurring between . t-TOLST and . LST

will appear in the cross reference and symbol table listings when requested (A, V, X, or S assembly parameters) .
3.2

OBJECT PROGRAM OUTPUT PSEUDO-OPERATIONS

The normal object code produced by the Assembler is relocatable binary
which is loaded at run time by the Linking Loader or loaded to build an
executable task by CHAIN or TKB.

In addition to relocatable output, the

user may specify other types of output code to be generated by the
Assembler.
3.2.1

Absolute Format (.ABSP and .ABS)

(Not available on XVM/RSX)

.ABSP and .ABS, although accepted by the Assembler, will not work
properly in XVM/RSX systems because none of the I/O handlers accept
dump mode data.
Label Field

Operation Field

Address Field

Not used

.ABSP

NLD orL....lor not specified

Not used

.ARS

NLD orL....lor not specified

Both pseudo-ops cause absolute, checksummed binary code to be output
(no values are relocatable).

If no value is specified in the address

field and if the output device is the paper tape punch, the Assembler
will precede the output with the Absolute Binary Loader (ABL) , which
will load the punched output at object time.
hardware readin,

The ABL is loaded, via

into location 17720 of any memory bank.

loads only the paper tape which follows it.)

(The ABL

If the address field of

the pseudo-op contains NLD, indicating "no loader", or if the binary
output device is not the paper tape punch, the ABL will not precede
the output.
3-4

Pseudo Operations

17720
.ABS
LOADFR
USER PROGRAM
. Ej\1D

PAPFR TAPE

START

NOTE
.APS(P) output can be written on directoried
devices. The Assembler assumes .ABS(P) NLD for
all .ABS(P) output to file-oriented devices and
appends an extension of ABS to the filename.
This file can be punched with PIP, using Dump
Mode.
(There will be no absolute loa~er at the
beginning of the tape.)
a.

The .ABS,

.ABSP,

.FULL, and .FULLP pseudo-ops, specifying the

type of output, must appear before any statements generating
object code, otherwise the line will be flagged and ignored.
Once one of these four pseudo-ops is specified, the user is not
allowed to change output modes.
b.

The NLD option provided in the address field of .ABS and .ABSP
is meaningful only if the output device is paper tape.

A description of the absolute output format follows.
Binary Data Block (variable length, up to 348 words)
WORD 1

starting address to load the bloc}: body which follows.

"YORD 2

Number of words in the block body (two's complement) .

WORD 3

Checksum of block body (two's complement of words
1 and 2, 4 through n) •

"lORD 4

Binary data to 10ac1.

WORD 3+n

Binary data to load.

Starting Block -

(two binary words)

WORD 1

Location to start execution of program.
It is distinguished from the binary data block by having bit 0 set
to 1 (negative).

WORD 2

Dummy word.

If the user requests the absolute loader and the value of the expression of the .END statement is equal to 0, the ABL halts after it has
loaded in the object program.

To start the program the user must set

3-5

Pseudo Operations

the starting address in the console address switches and press

STAR~.

mhis allows manual intervention by the user, typically to ready I/O
devices prior to starting his program.
sion is non-zero,

If the value of the .END expres-

it is treated as the program start address to which

the ABL will automatically transfer control after loading the object
program.
The .ABSP pseudo-op causes all memory referencing instructions whose
addresses are in a different page to be flagged as bank errors.

A DBA

instruct jon is executed by the absolute loader before control is given
to the user program.

Word values which have bit 5 on will signal the

processor to use the index register to compute effective addresses.
The .AP.S pseudo-op does not flag memory referencing instructions whose
addresses are in a different page.

An EEA instruction is executed,

and control is given to the user in hank addressing mode.
bank addressing of 8K is allowed.

Complete

The processor will interpret bit 5

of all memory referencing instructions as the high order address bit.
A listing of the Absolute Binary Loader is given in Appendix F.
3.2.2

Full Binary Format (.FULL and .FULLP)

(Not available in XVM/RSX)

.FULL and .FCLLP, although accepted by the Assembler, will not work
properly in XVrJ:/RSX systems becau.se nope of the I/O handlers accept
dump mode data.
Label Field

Operation Field

Ao.oress Field

(Only useful
i f output is

Not used

. FULL

Not used

.FULLP

Fot used

paper tape)

'T'he . FULL and . FlJLLP pseuc'1o-ops cause full binary mode output to be
produced.

""he program is assembled as uncrecksummed absolute coee and

each physical record of output contains nothing other than I8-bit
binary storage words generated by the Assembler.

This mode is used to

produce paper tapes which can be loaded via hardware readin mode.
If no address is specified in the .END statement or if the aedress
value is zero, at the end of tape the Assemhler will punch a BLT instruction with channel 7 punched in the third frame.

If the . F1\1D

address value is non-zero, the Assembler will punch a JMP to that aodress, also with channel 7 of the third frame puncred.

3-6

Pseudo Operations

In addition, with .FULLP assembly direct memory refer ences in page 1
to addresses in page 1 will have bit 5 set to 0 unless indexing is
specified.
The only difference between the .FULL and .FULLP pseudo-ops is that
memory references across page boundaries are flagged in .FULLP mode;
in .FULL mode they are not.
The following specific restrictions apply to programs assembled in
.FULL or .FULLP mod e output.
/'

.LOC

Should be used only at the beginning of the program

.BLOCK

May be used once and only if no literals, variables or
undefined symbols appear in the program, and must imne diately precede .END.

Variables and undefined symbols may be used if no literal s or
.BLOCKS appear in the program.
Literals may be used only if the program has no variables,
.BLOCKs, or undefined symbols.
The reason for these restrictions, not alleviated by the use of .LTORG,
is the fact that .FULL(P) mode output contains no addressing information for storing binary words other than in sequence.

The .LOC and

.BLOCK pseudo-ops do not generate binary output, hence there is no way
to indicate skipped locations in the output.

This is also true of

variables and undefined symbols.
3.2.3

Relocation Mode (.EBREL and .DRREL)
Label Field

Operation Field

Adc1.ress Field

Not used

.EBREL

No t used

Not used

.DBREL

l\ot used

The following two pseudo-ops (.ERREL and
mode switching.
gra~mer

.DBR~L)

enable rel o cation

They car- be used anywhere and as often a s tl-·e pro-

wishes in a relocatable program.

In the absence of one of

these mode declaration pseudo-ops, the page mode assembler assumes it
is assembling 12-bit (page mode) relocatable addresses for memory
reference instructions and the bank mode Assembler assumes 13-bit
addresses (bank mode) .

3-7

Pseudo Operations

A typical user program may omit the use of these pseudo-ops and simply
prepare his object code by using the desired (bank or page mode) version of the Assembler.
For XVM page mode programs which contain display code to be interpreted
by the VT15 graphics processor, it is necessary to
code with .EBREL,

.DBREL.

brac~et

the display

Unlike the Central Processor, the VT15

processor runs only in bank mode; hence its instruction addresses must
be relocated as 13-bit values.
Mnemonic

Description

.EBREL

Enable Bank mode RELocation

.DBREL

Regardless of the type of Assembler being used (bank or
page mode version), .ERREL causes all subsequent memory
reference instruction addresses to be treated as 13-bit
values, i.e., bank mode. Although in this mode, the
page mode assembler will still output the "PROG>4K"
warning message if the program size exceeds 4096. The
12- or 13-bit relocation is performed by the loaders .
. EBREL signals the loaders to switch to 13-bit relocation by causing a dummy data word (v,hich is not loaded)
to be inserted in the binary output and having a loader
code of 31 ,
8
Disable Bank mode RELocation
.DBREL is the counterpart to .EBREL.
It signals the
loaders, with a dUIT'J11Y data word (which is not loaded)
and loader code of 328 to switch to 12-bit (page mode)
relocation.
NOTE
The previous mode is not saved when an .EBREL or
.DBREL is encountered; for this reason, a .DBREL
pseudo-op goes directly to page mode relocation
rather than entering the previous mode.

3.3

TEXT HANDLING PSEUDO OPERATIONS

The two text handling pseudo-ops enable the user to represent the
7-bit ASCII or 6-bit trimmed ASCII character sets.

~he

Assembler

converts the desired character set to its appropriate numerical equivalent (see Appendix A) .
Label Field

Operation Field

Address Field

SYHBOL

(ASCII)
. SIXBT

Delimiter - character
string - delimiter <expression> .....

3-8

Pseudo Operations

Only the 64 printing characters (including space) may be used in the
text pseudo-instructions.

See nonprinting characters, Section 3.8.5.

The numerical values generated by the text pseudo-ops are left-justified
in the storage word(s) they occupy with the unused portion (bits) of a
word filled with zeros.
3.3.1

lOPS ASCII Packed Format (.ASCII)

.ASCII denotes 7-bit ASCII characters.

(It is the character s et used

by the operating system monitor or executive.)

The characters are

packed five per two words of memory with the rightmost bit of every
second word set to zero.

An even number of words will always be out-

put:
First Word
0

Second Word

6 7
1st Char.

3.3.2

13 14

2 3

17 0

9 10

16 17

I 2nd Char. I 3rd Char. 14th Char. I 5th Char. I 0

Trimmed Six-Bit Format (.SIXBT)

.SIXBT denotes 6-bit trimmed ASCII characters, which are formed by
truncating the leftmost bit of the corresponding 7-bit character.
Characters are packed three per storage word.

1st Char.
3.3.3

11 12

5 6

2nd Char.

17
3rd Char.

.ASCII and .SIXBT statement Syntax

The statement format is the same for both of the text pseudo-ops.
The format is as follows.

<expression> .....

3.3.4

Text Delimiter

Spaces or tabs prior to the first text delimiter or angle bracket «)
will be ignored; afterwards, if they are not enclosed by delimiters
or angle brackets, they will terminate the pseudo-instruction.

3-9

Pseudo Operations

Any printing character may be used as the text delimiter, except those
listed below.

< as it is used to indicate the start of an expression.

)

as it terminates the pseudo-instruction.

(The apostrophe (')

is the recommended text delimiting character.)

The text delimiter must be present on both the left-hand and the righthand sides of the text string: otherwise, the user may get more characters than desired.
3.3.5

Non-Printing Characters

The octal codes for non-printing characters may be entered in .ASCII
statements by enclosing them in angle bracket delimiters.
following s tatement,

In the

five characters are stored in t".TO storage words.

-\.ASCIIL....I'AB' <01.5> 'CD.)
Octal numbers enclosed in angle brackets will be truncated to 7 bits
(.ASCII)

or 6 bits

(.SIXET).

Example:
Source Line
Tl\G -\.ASCIIL....I' ABC'
-\. SIXBTL....I' ABC'
-\. SIXBTL....I' ABC' It' lit

Recognized ",ext
ABC
ABC
ABC'I

-\.ASCIIL....I'ABCD'EFGE
-\. ASCI I L....I' ~. B ' < 11>
-\. ASCIIL....I'AB<ll>,

Al3CDFG
AF -\
AB<ll>

-\.ASCIIL....I<15 x O12>'ABC'
-\. ASCII L....I <1 5 x l2>ABC L....I( s) A

AABC
)+RCL....I(S)

COJTlJ11.ents

The # is usen as a
oelimiter in order
that ( ') may be
interpreted as
t e xt.
<11> used to repreThere is
sent tab.
no delimiter after
B, therefore,
« 11»
is treated
as text.

A is interpreted as
the text delimiter.

The following example shows the binary word format wh.ich the Assembler
generates for a given line of text.

3-10

Pseudo Operations

Example:
-.j.Ascrr-.j'ABC'<015 x 12>'DEF'
Generated Coding

3.4

\'Jord Number

Octal

Binary

Word 1

406050

1000001 11000010 11000

Nord 2

306424

011 1 0001101 10001010 1 0

Word 3

422130

1000100

Word 4

600 000

110 1 0000000 100000°1 (1

I 1000101 1 1000

r-1ACRO DEFINITI ON PSEUDO-OPERATIONS (. DEFII\',

. F'T'C, and . Ermr-!)

The .DFFIN pseudo-op is used to define macros (described in Chapter 4).
The address field in the .DEFIN statement contains the macro name,
followed by a list of dummy arguments.

If t.he list of dummy arguments

will not fit on the same line as the .DFFIP pseudo-op,

it may be con-

tinued by means of the .E'T'C pseudo-op in the operation field and additional arguments in the address field of the next line.

'T'he coding

that is to constitute the body of the macro follows the .DEFIN statement.

The body of the macro definition is terminated by an

pseudo-op in the operation field.

.FND~

(See Chapter 4 for more details on

the use of macros.)
3.5

COHf'JION BLOCK PSEUDO- OPERATIONS

This class of pseudo-operations allows the programmer to define,
reference anG initialize FORTRAN-style COMMON blocks.

Spec i o.l Loae'er

Codes are placed in the object output o f the Assemb ler to allow the
Linking Loader, CHAIN, or TKB to allocate memo ry for the specif ied
COMMON blocks and link their addresses to transfer vectors in all programs which reference them.

Additionally, the programmer may speci fy

the initial contents of the COMMON blocks (a facility similar to the
FORTRAN BLOCK DATA function) .
3.5.1

Common Block Definition (.CRD)

Th.e pseudo-op . CBD enables the programmer to declare a COMMOl" area of
an indicated name and size and to specify the word to be set to its
base address.

The general format of this pseudo-op is:

3-11

Pseudo Operations

Label Field

Operation Field

Address Fielc1

User Symbol

.CRD

Name, Size

The .CRD pseudo-op takes a COMMON name and size as arguments, reserves
one word of core for the base address, and outputs loader codes and
parameters to direct the Linking Loader, CRAIN or TKB programs to set
a transfer vector to the base address (first element) of the named
COMMON array.

For example, the statement:

BASE..,. CB~BCD, 6
provides location RASE with the address of the first word of the
COMMON area named ABCD whose size is 6.

FORTRAN blank

given a special name by the system software,
COMMON in a .CRD s tatement,
3.5.2

.XX.

COM~10N

To reference blank

.XX should be given as the COMMON name.

Common Rlock Definition -- Relative (.CBDR)

The pseudo-operation .CBDR (common block definition relative) takes
an offset as its only argument.

The general format of this pseudo-op

is:
Label Field

Operation Field

Address Field

User Symbol

.CRDP.

Displacement

This pseudo-op directs the Linking Loader, CHAIN or TKB to enter the
starting address of the last COMMON block specified in a .CRD plus
the offset given in the .CBDR into the word corresponding to the location of the .CBDR.
For example, the statements
RASE ..., .CBD...,

ABCD,5

BASE3 -/ . CBDR-/

will cause the task builder to enter the starting address of the
COM~ON

block ABCD into the location corresponding to the tag BASE;

in addition, the location corresponding to BASE3 will contain the
starting address of ARCD plus 3.

3-12

Pseudo Operations

Note that .CBDR is relative to the last COMMON definition only.

Any

other assembler instructions or pseudo-operations may intervene
between the .CBD and .CBDR.
3.5.3

Common Block Initialization Start (.CBS)

The pseudo-operation .CBS is used to prepare the Assembler to accept
COMMON block initialization statements.

The general format of this

pseudo-op is:
Label Field

Operation Field

Address Field

Not used

.CBS

name [, size]

The ~ parameter specifies the name of the COMMON block which is to
be initialized, see description in .CBD (Section 3.5.1) for details
regarding blank CO~~ON.

The size parameter is optional, and if speci-

fied represents the minimum size of the COMMON block.
This pseudo-op, unlike .CBD or .CBDR does not generate a transfer
vector, hence, a label on this operation is meaningless.

After a .CBS

instruction and up to the next .CBE instruction (i.e., between .CPS
and .CBE operations), the following rules apply to the type of statements which may be specified.
1.

.CBC statements are allowed.

.DEC, .EJECT, .IFxxx, .ENDC, .LST, .~OLST,
.TITLE, .DEFIN, .ENDM, .ETC are allowed.

Macro instructions which generate only statements belonging
to 1. or 2. above are allowed.

Direct assignment statements are allowed.

Machine instructions and transfer vectors are not allowed.

Pseudo-operations other than those listed in 1 and 2 above
are not allowed.

Macro instructions which generate statements belonging to
5 or 6 above are not allowed.

Example:

-I. CBS -I ABCD, 6

3-13

.OCT,

.REPT,

Pseudo Operations

indicates that a

COMMO~

block named ABCD with a min imum length of

6 words is to be initialized by statements which follow.
3.5.4

Common Block Initialization Constant (.CRC)

The . CBC statement is used to initialize a single word of the CQr.11'10N
block declared in the preceding .CBS statement.

The for mat of the

.CBC statement is:
Label Field

Operation Field

Address Field

j\'ot used

.CRC

Displacement, Constant

The displacement parameter specifies the offset from the start of the
COMMON block of the word to be initialized.

The constant parameter

is an absolute expression, the value of which will be used as the initial contents of the specified wo rd in the
statement is used outside the .CBS and ignored by the Assembler.

CO~~ON

block.

If the .CRC

.CRF instructions, it is flagged

If a .CSC statement is preceded by a

.REPT statement which has a non-zero increment, the data will be incremented, and the displacement will be incremented by one.

Therefore,

the data generated will be placed in succeeding locations in common.
Example:
.CRC

2,4

will set the third word (base add r ess +2) of t.he COM,NON block specified
by the preceding .CBS to the initial value of 4.
3.5.5

Common Block Initialization End (.CRE)

The .CRE pseudo-op is used to terminate the COMMON block init.ialization
section initiated by the .CBS operation.

The general format is:

Label Field

Operation Field

Address Field

Not used

.CBE

Not used

A COt-'lMON block initialization section (consisting of one . CPS followed
by one or more .CBC's followed by a .CBE ) may appear anywhere in a
program wi thout affecting the flow of the object program.

Also , the

same COMMON block may be initiali zed any number of ti mes by any number
of programs.

3-14

Pseudo Operations

3.6

CONDITIONAL ASSEMBLY (.IFxxx and .ENDC)

It is often useful to assemble some parts of the source program on an
optional basis.

This is done in t1ACRO by means of conditional assem-

bly statements, of the form:

....j. I Fxxx....j expression
The pseudo-op may be any of the eight conditional pseudo-ops shown
below, and the address field may contain any number, symbol, or expression.

If there is a symbol, or an expression containing symbolic ele-

ments,

such a symbol must have been previously defined in the source

program or the parameter file

(except for .IFDEF and .IFUND).

If not,

the value of the symbol or expression is assumed to be 0, thereby
satisfying three of the numeric conditionals.
If the condition is satisfied, that part of the source program starting
with the statement immediately following the conditional statement and
up to but not including an .ENDC (end conditional) pseudo-op is assembled.

If the condition is not satisfied, this coding is not assembled.

The eight conditional pseudo-ops (sometimes called IF statements) and
their meanings are shown below.
Pseudo-op

Assemble IF x is:

....j. IFPNZL-Ix

Positive and non-zero

....j. IFNFGL-Ix

Pegative

....j. IFZERL-Ix

Zero

....j.IFPOZL-Ix

Positive or zero

-I. IFNOZL-Ix
-I. IFNZRL-IX

Negative or zero

....j.IFDEFL-IX

A defined symbol

-I. IFUNDL-Ix

An undefined symbol

Not zero

In the following sequence, the pseudo-op .IFZER is satisfied, and the
source program coding between .IFZFR and .ENDC is assembleo.

3-15

Pseudo Operations

:I.

,.DEC

~:~ l.J :t·:~ 'I'"U T :::: 4

0000(:',0

{~I

TO T t,i... I... , ' ilL:

O()OO O F: ::.:.:~OOOO2
GOOO :I F: 04000:.:)

r',

"F~

'.?

00002 F, 00 0 000
000 ():.':) F~ 000000

D
?
10

000060

()OOOO O

~) J i.E:::: OO()04

F i:~ F:U F<

,IFZER

SUB T01-TO TALL

I...(')C
:U,"lC
,. [(lDe

o
o

)'"

()
(~

L. I (lE~3

Conditional statements may be nested.

For each IF statement there

must be a terminating .ENDC statement.

I f the outermost IF statement

is not satisfied, the entire group is not assembled.
is satisfied, the following coding is assembled.

If the first IF

If another IF is

encountered, however, its condition is tested, and the following coding
is assembled only if the second IF statement is satisfied.

Logically,

nested IF stateme nt s are like AND circuits.

s econd, and

If the first,

third conditions are satisfied, then the coding that follows the third
nested IF s tatement

is assembled.

Example:

ICOND • • INIllnTOR
00000 R 200002 R
.IFN:?!'::

D f ' \ C r illJ :!.
,.[i·,WC
'''1

00001

R 1 00002 R

, IF))[F"

D (') C

'r f:':') Ci:?

,[NDC

,ENOC

fCOND. 3 !0ITIATOR

fCOND. 31ER MINAT OR
ICOND. 1 TERMINATOR

Y::::(j

0 0002 R 740000 ~
00003 R 7400 40 A

r I: (,.)
T (:'!:»:I.

Hi... T

Conditional s tateme nts can be for a variety of purpos e s.

On e of the

most useful i s in terminating recursiv e MACRO calls (described in
Chapter 4).

In general, a counter is changed each time through the

loop, or recursive call, until the condition is not satisfied.
process concludes assembly of the loop or recursive call.

3-1 6

This

Pseudo Operations

3.7

LOCAL SYMBOLS (.LOCAL AND .NDLOC)
Label Field

Operation Field

Address Field!

Not used

. LOCAL

Not used

.NDLOC

Not used

The size of a program that can be assembled with the Assembler is
determined by the number of user symbols in that program and therefore
by the amount of core available at assembly time in which to store
those symbols.

Each user symbol requires three words of core in the

assembler's symbol table.

This ad.ditional core is not required at

run-time (unless using a debugging program like DDT) because user
symbols are not loaded into core along with the object code.
The .LOCAL and .NDLOC pseudo-ops enable deletion of certain symbols
from the user symbol table.

In so doing, larger programs can be assem-

bled without increasing core size.

The area between these t\-TO pseudo-

ops is defined as having a number of symbols, most of which are used
only in this area and which can be deleted, once this area has been
passed by the Assembler.
The Assembler creates a separate symbol table (local users symbol
table) when the .LOCAL pseudo-op is encountered.

Only labels and

direct assignments may be stored in this table.

Labels which have

the # sign as part of the symbol are stored in the resio.ent users
symbol table (RUST).

This feature is useful where a subroutine name

is part of a local area but must go into the RUST because of subroutine
calls from without the local area (see Section D of the following
example).

Symbols which are forward references (used before defined)

are stored as part of the resident users symbol table.

When the

.NDLOC pseudo-op is encountered the local table disappears and the
resident UST is left unchanged.
An example of a program which uses the .LOCAL and .NDLOC pseudo-ops
follows.

The symbols that are stored in the tables are represented

in the comment field in the order that they are stored during PASS 1.

3-17

:I.

,. (1D~::;

O()lOO
OOJOO

001.01.

00103
001 ()4

00:1.0 )'

( l. .l:)C
Ctli'"

L ') O:l:l. J
600 .1. 3/

,J",!'"

L. t·~·ll..j

····:i.O

040:L·40

60():1, ::.? ')'
....... ..................... ........ ........

,) () I. !. i.

:I.:'.'.;
.L.:":.
:I. '.?

001 :1 :.':\
C'O .I.:l.4
o (:, J J ~.~'.;
()O :!. J ,S

:I.'';

20
2 :~

"'...'

()OJ 1 ) :

1...1

001 2(>
OO:L ;,:,:::!.
() 0 'I. : . .~ : :.:

" )"')

()OOOO()

><><x

/ (~! r:.: 1::: i"~'l L~ '{ ~:::. 'r u r;.: i::: n J i '.:
. / F:.: ~,J ~'::; ' r !::- F~ !.:J j' -"i t. I (-i ~ /~ (.

ITEMP. STO RAGE OF

./ ::::, U.t.:{ F~ ,.

r r--r" I r. .!

()ooc'()O

000000

(:iO ():i. .1./
('OOL"!:I.

I<h:r:

.Ji"-i j'"

DP,:::;
() ·4 01:l. . :".}

.......

:< .!.

',..I

6::.' 0.i.:I :!.

TT'-(I(·~

, i\IO i.. UC

Lt,C

\ :1.

/ ~JRWAR D

Rl~ERFNCE

j-.:.: !.:.

3' i
::~; ',7

OO()() O()

~::; '( i··ll.

O()OOO ()

~:::: \" 1··..1::.:.:

ITEMP. STORAG E OF

()():I. :.':~;3

() () :!. :'.~ .(~.

':,:,: 00:1.:.:::::1

1... ::\(:"

~::; \' r"i :L

O()J ,':5

i.) ·4 () J 3 ~.:.::

:( 1(: ("..

:::; \ j"'i:}

1
,:,:,;

..Jh:::·";-·4 :l.
O<)()O

:l.

C
D

( E'·'.'\'

3-18

Pseudo Operations

For purposes of illustration, lines 1-11, 12-26, 27-29, and 30-36 are
broken into sections A, B, C, and D respectively.

The following

tables show the resident and local users symbol tables (UST) at the
end of each section (PASS 1 only).
LOCAL UST

RESIDENT UST
SECTION A

(NO SYMBOLS)

A
AA

C
D
KK
TTYIN
SECTION B
A
A.A
C
D
KK
TTYIN

Xl
Y
Z

SECTION C
A

(NO

SYMBOLS)

C
D
KK
TTYIN
Xl
SECTION D
SYM1
SYM2

A
AA

C
D
KK
TTYIN
Xl
TSUBR
In Section A,the symbol TTYIN is usen.

TTYIN is in a local area yet

it is put into the resident user symbol table because it is a forward
reference.

The same is true of symbol Xl from Section C.

Once the

.NDLOC pseudo-op is encountered, the local UST no longer exists.

For

that reason, the Xl reference from line 28 is a forward reference.
At the end of PASS 1, Xl would be represented as an unrlefined symbol.
"Then Section B is processed during PASS 2, the symbol Xl would not be
stored in the local UST because it already
resident table.

3-19

has been put into the

Pseudo Operations

LIMITATIONS
The .LOCAL pseudo-op causes the local UST to be built just above the
macro definitions.

Consequently, the .DEFIN pseudo-op is illegal in

a local area.
3.8

LITERAL ORIGIN (.LTORG)
Label Field

Operation Field

A_ddress Field

Not used

.LTORG

Not used

As previously stated, a literal is an item of data with its value as
stated or listed.

The pseudo-op .LTORG allows the user to specifically

state where he wants his literal table(s) to be stored; thus enabling
the user to store literal tables in different pages or banks.
many as eight literal tables are allowed.

Notice in the following

example that literals are not saved from one .LTORG to the next .

1 ,.

.to

1... '

.:'/!.:.: :-;. :

', -'C"· .

, .

I ',,'

.;~.

;.:,
I,.... .. ;

";" ,. ,1

The literals 1 and 2 are stored twice even though they appear in the
s ame bank.
If more than eight .LTORG statements appear in a program, the excess
ones will be ignored and flagged with an 1 error.

Subsequent literals

will be assigned core locations following the end of the program in
the normal manner.

3-20

Pseudo Operations

3.9

SETTING THE LOCATION COUNTER (.LOC)
Label Field

Operation Field

Address Field

Not used

.LOC

defined expression

The .LOC pseudo-op sets or resets the location counter to the value of
the expression contained in the address field.

The symbolic elements

of the expression must have been defined previously; otherwise, phase
errors will occur in PASS 2.

The .LOC pseudo-op may be used anywhere

and as many times as required.
Examples:

:i.
·;· (.)(lJ

1nU.:·.:
.,. i.. UC
L..(:"!C
Df::IL
')'
....... '"..... . .. '
"

',) ••)

'.) I•••.' 1•.••1

.!.

, Lll::

... .

~" .:

00007 R 200001 R
10
.:' :1.

('),') ,'"'; .: t" \

i:;.:

'.~) " '~.

C' <> J :;.

!..!

12
13
:1.4
.I. :'5

I... ()C
U(,C

i";.:

,, "

.\ \,:\( ..:
VVU L /

R 740 000 A
I::. r·-' .:. ~

A program headed by an absolute statement , e.g.,

.LOC 100 is an ab-

solute binary program and the binary is output in link-loacable format.
3.10

RADIX CONTROL (.OCT and .DEC)

The initial radix (base) used in all number interpretation by the
Assembler is octal (base 8).

In order to allow the user to express

decimal values, and then restore to octal values, two radix setting
pseudo-ops are provided.

3-21

Pseudo Operations

Meaning

Pseudo-op Code
.OCT

Interpret all succeeding numerical values in
base 8 (octal)

.DEC

Interpret all succeeding r..umerical values in
base 10 (decimal)

These pseudo-instructions must be coded in the operation field of a
statement.

All numbers are decoded in the current radix until a new

radix control pseudo-instruction is encountered unless the pseudo-op
occurs within a macro expansion (see Section 4.2).

The programmer

--.

may change the radix at any point in a program.
...

;--. ~' '; :

: .O i:::\:
oo oo ~

20014 4

VUU L~

00003 i A

i... :") I,,,

::: :.. ';
:J~ .. :

')
.!.()

,Oi

:s ,',:)

0000 6 R 0 0003 3 A

f!L e::: (: ,,'

.;. Ci\.!D

;: :ZL ::: l...; I,} ', } 1.) ./

t
"' j

3
4

()( )()(,I J

j:~

... / / '?'?",::.

I':~:

I::"

0<> (.' () :.

h: G() :".,) ~'::) ·4 ',>"

( :!

,..I

I,:'"

(,!

000(J R 007 303 0

')'
~:) J

:Z:E ::: OO() O..:':~

:J.

.. r.: i)1::

OOOCJOO (I
L. I i'lE~:;

EI'~: i:;:DF<

If a number is encountered which contains a decimal digit while in
octal mode. the number is evaluated as if the Assembler were in decimal
mode. and the line is flagged with an N.
3.11

RESERVING BLOCKS OF STORAGE (.BLOCK)

.BLOCK reserves a block of memory equal to the value of the expression
contained in the address field.

If the address field contains a

numerical value. it will be evaluated according to the radix in effect.
The symbolic elements of the expression must have been defined previously. i.e .. no forward referencing is allowed; otherwise. phase

3-22

Pseudo Operations

errors might occur in PASS 2. The expression is evaluated modulo
15
2 (77777 ), The user may reference the first location in the block
8
of reserved memory by defining a symbol in the lahel field.
The
initial contents of the reserved locations are unspecifi ed .
Label Field

Operation Field

Address Field

User Symbol

. BLOCK

defined expression

Examples:
BUFF -I . BLOCK~I:J

-I . BLOCK~A+B+61J
3.12

END OF PROGRAM (.END)

One pseudo-op must be included in every source program.

This is the

.END statement, which must be the last statement in the main program.
This statement marks the physical end of the source program, and also
may contain the location of the first instruction in the object program to be executed at run-time.
The .END statement is written in the general form

START may be a symbol, number, or expression whose value is the address
of the first program instruction to be executed.

In relocatable pro-

grams to be loaded by the Linking Loader, CRl>.IN or TKB, only the main
program requires a starting address; all other subprogram starting
addresses,

if specified, will be ignored.

A starting address may appear in absolute or self-loading programs;
if not, the program will halt after being loaded and the user must
manually start his program.
These are legal .END statements

-I. END~REGIN+..v
-I. El'm~20SJ
If no .END statement is included, the Assembler will treat it as if
a .EOT was included.
3-23

Pseuoo Operations

3.13

END OF PROGRAM SEGMENT (.EOT)

If a program is physically segmented (on paper tape, disk, DEC tape or
magtape), each segment except the last may terminate with an .EOT (endof-tape) statement or with nothing at all (neither .FOT nor .FPD).
Termination with nothing is equivalent to termination with .EOT.
last segment must terminate with an .END statement.

The

The .EOT state-

ment is written without label and address fields, as follows,

-l.EO~
The following are typical reasons for segmenting programs:
1.

A source program is prepared on three different paper tapes
because one tape alone would be too large to fit in the
reader.

A source program is split in two and stored on two DECtapes
because it is larger than the capacity of a single tape.

To simplify program preparation, a disk file containing
commonly used macro definitions is kept physically separate
from user main programs.

Thus, one does not have to include

the macro definitions in each main program.
4.

Programs can be conditionally assembled for different machine
configurations or different software options.

This is done by

defining conditional assembly parameters at assembly time.
The process can be simplified if one prepares paper tapes or
mass storage files defining all parameters for a given set of
options.

The main program and parameter file are physically

segmented one from the other but can be assembled together.
3.14

GLOBAL SYMBOL DECLARATION (.GLOBL)
Label Field

Operation Field

Address Field

Not used

.GLOBL

symbolLsymbol .. J

The standard output of the Asssmbler is a relocatable object program.
The Linking Loader, CHAIN or TKB joins relocatable programs by supplying definitions for global symbols which are referenced in one program
and defined in another.

The pseudo-op .GLOBL, followed by a list of

symbols, is used to define to the Assembler those global symbols which
are either
3-24

Pseudo Operations

internal globals - defined in the current program and referenced by other programs

external symbols - referenced in the current program and defined in another program

The loader

(Linking Loader, CHAI N or TKB) uses this information to

include in the load and then link the relocatable programs to each
other.
All references to external symbols must be indirect references s ince
XVM software systems use transfer vectors for referencing external
symbols.

Each external symbol causes an additional word

vector word) t .O be reserved in the user program.

(the transfer

The loading pro-

gram will store the actual address of the external symbol in the transfer vector word.

Thus, an indirect reference (through the transfer

vector) will cause the external symbol location to be addressed.
Example:
-I.GLOBL -I A,B,C
A-ILAC
-I JMS*

-I D
-I B
-I C

.END

-I D

D-IJMS*

/ A is an internal global
/These two instructions reference
/External symhol s indirectly

The .GLOBL statement may appear anywhere within t h e program.
The example above is assembled as follows:

., '

00 000
0 0001
00002
000 03
00004

' ")

,'.

R 7 400 ~O A
R 2 000 04 R
R 120005 ~
R 1 20006 E
R 740000 H

",t',.- \ ..'

. <',:
J., ;'::jC

.\ ,:

....• ...,; . {:

:1-.: ('

. . ,:!: z. : :. ;: () 0 0 0 '.?

00 005 R 00 00 05 E *E
000 06 R 0000 06 c iF

The real values for locations 3 and 4 will be supplied by the loading
program:

these two words will contain the addresses in memory of

e x ternal symbols Band C.
3-25

Pseudo Operations

3.15

REQUESTING AN I/O DEVICE HANDLER .IODEV (Not supported in XVM/
RSX)

The .IODEV pseudo-op appears anywhere in the program and is used to
cause the Assembler to output code for the Linking Loader or CHAIN
which specifies the slots in the Monitor's device assignment tahle
(DAT) whose associated device handlers are required by the program.
This is used in XVM/DOS where device handlers are brought into core
at the time a program is loaded to run.
Label Field

Operation Field

Address Field

Not used

. IODEV

cats lot [, datslot .. .]

The arguments may be numeric or symbolic.

If the argument is symbolic,

the symbol must be defined by a direct assignment statement.
3.16

DESIGNATING A SYMBOLIC ADDRESS (.DSA)

.DSA (designate symbol address)

is used in the operation field when

it. is desired to create a word composed of just. a transfer vector
(17-bit address).

It is useful when a user tag symbol is also a

permanent instruction or pseudo-op symbol.
Label Field

Operation Fielo

Address Field

User Symbol

.DSA

expression

Examples:
,TMP -I LAC -I TAG
-I . DAS -I Jr1P)
-I
-IJ1'1P

3.17

Equivalent methods of designating the user
symbol JMP (rather than the instruction JMP)
to be in the address field.

REPEAT OBJECT CODE (.REPT)
Label Field

Operation Field

Not used

.RFPT

Address Field
count [, increment]

The .REPT pseudo-op causes the object code of the next sequential
object code generating instruction to be repeated "count" times.
Optionally, the object code may be incremented for each time it is
repeated by specifying an increment.
3-26

The count and increment may be

Pseudo Operations

represented by a numeric or symbolic value.

If a symbol is used,

must be defined by an absolute direct assignment statement which must
occur before the symbol is used.

The repeated instruction may contain

a label, which will be associated with the first statement generated.
Note that arithmetic expressions in the increment field are illegal.
Examples:

00001 R 000000

00 ::,: (.;:::.: (\'

(:'.<

O<>, )()O()

*0
>;<r;.

00 00 3
0000 0 0 A ~R.
0 00 04 R 0 00 00 0 ~ ¥~
. '-'_ 1'

,',

, , '.:: i::',,\,
J ,. .,

o .- ~':, ::? r: (,() ( ! .; > h' ::~::p
I:)

(>:L 3 r;.: (:.' I.,}i. ,I

"i :,:,.;

r;~

;,) t.'; !")

() ( )

( 'I

:.:< h'

o 014 R 600 14 ~ AP
8

.:. :::: i"'·~ f:

NOTE
If the statement to be repeated generates more than
one location of code, the .RFPT will repeat only the
last location.
For example,
-/. REPTL...I3
-/. ASCII L...I A
I

will generate the following:
404000
000000
000000
000000

5/7 A

last word is
repeated

3-27

Pseudo Operations

3.18

REQUEST PROGRAM SIZE (.SIZE)
Label Field

Operation Field

Address Field

user symbol

.SIZE

not used

When the assembler encounters .SIZE, it outputs one word which contains
the address of the last location plus one occupied by the object program.

This is normally the length of the object program (in octal) .

Bowever, if a given program is 1218 words long and has a .LOC 4¢¢
statement at the head of the program, the value of the .SIZE word will
be 521 .
8

3-28

CHAPTER 4
MACROS

When a program is being written, it often happens that certain coding
sequences are repeated several times with only the arguments changed.
It would be convenient if the entire repeated sequence could be generated by a single statement.

To accomplish this,

it is first nec-

essary to define the coding sequence with dummy arguments as a macro
instruction, and then use a single statement referring to the macro
name along with a list of real arguments which will replace the dummy
arguments and generate the desired sequence.
Consider the following coding sequence.
-I LAC-.lA
-I TAD-I B
-I DAC-/C

-I LAC...jD
-/ TAD-/E
-/DAC-/F

The sequence
-I LAC-I x
-/ TAD-I y
-/DAC--/ Z

is the model upon which the repeated sequence is based.

The characters

x, y, and Z are called dummy arguments and are identified as such by
being listed immediately after the macro name when the macro instruction is defined.

4-1

Macros

4.1

DEFINING A MACRO

Macros must be defined before they are used.

The process of defining

a macro is as follows.

(Definition Line)

(Macro Name)
(DuwroyArguments)
\
II'
~"
-\.DEFIN-\MACNME,ARGl,ARG2,ARG3-\
/comment
-I LAC

-\ ARG1

(Body)

-\TAD

-IARG2

-\DAC

-\ARG3

(Terminating Line)

-I. ENDM

The pseudo-op .DEFIN in the operation field defines the symbol following it as the name of the macro.

Next, follow the dummy arguments,

as required, separated by commas and terminated by any of the following
symbols.
space

(~)

tab

(-\ )

carriage return ())

The macro name and the dummy arguments must be legal assembler symbols.
Any previous definition of a dummy argument is ignored while in a
macro definition.

Comments after the dummy argument list in a defini-

tion are legal.
If the list of dummy arguments cannot fit on a single line (that is,
if the .DEFIN statement requires more than 72

characters) it may be

continued on the succeeding line or lines by the usage of the .ETC
pseudo-op, as shown below.

-I DEFIN-\ MACNME, ARG1, ARG2, ARG3
-I.ETC -\AP.G4,ARG5

/argument continuation

-I. DEFIN -\ MACNME
-\. ETC

-\ ARG1

-\. ETC

-IARG2

-\. ETC

-\ ARG3

-\. ETC

-I ARG4

-I. ETC

-\ARG5

/comment

4-2

Macros

4.2

MACRO BODY

The body of the macro definition follows the .DEFIN statement.

Appear-

ances of dummy arguments are marked and the character string of the
body is stored, five characters per two words in the macro definition
table, until the macro terminating pseudo-op . ENDM is encountered.
Comments within the macro definition are not stored.
Dummy arguments may appear in the definition lines only as symbols or
elements of an expression.

They may appear in the label field, opera-

tion field, or address field.

Dummy arguments may appear within a

literal or they may be defined as variables.

They will not be recog-

ni z ed if they appear within a comment.
The following restrictions apply to the usage of the .DEFIN,

.ETC and

.ENDM pseudo-ops:
a.

If they appear in other than t h e operation field within the
body of a macro definition, they will cause erroneous results.

If .ENDM or .ETC appears outside the range of a macro definition, it will be flagged as undefined.

If index register usage is desirable, it should be specified in the
body of the definition, not in the argument string .
. DEFIN

XUSE,A,B,C

LAC A
DAC B,X
LAC C
.ENDM
If .ASCII or .SIXBT is used in the body of a macro, a slash (I) or
number sign ( # ) must not appear as part of the tex t string or as a d e limi ter (use < 57 > to represent a slash and < 43 > to represer.t a number
sign). Be careful when using a
text string. For example,
.DEFIN

TEXT A

.SI XBT

,A,

.SIXBT

.A •

du~my

• ENDM

4-3

argument name as part of the

Macros

followed by the macro call,
TEXT XYZ
will generate the following code
.SIXBT

,XYZ,

• SIXBT

.A •

In the first .SIXBT statement, A is recognized as a dummy argument resulting in the substitution of XYZ.

In the second statement, A is not

recognized as a dummy argument because the string delimiter, period,
is itself a legal symbol constituent.
Comments

Definition
-I • DEFIN
-I LAC

-I MAC,A,B,C,D,E,F
-I A#

-I SPA
-IJMP
-IISZ
-I LAC
-IDAC

-I B
-I TtvlP

E is not recognized as an argument

-I (C
-I D + 1

-IF
-I.ASCII

-IE

B=.

-I. ENDM
4.3

t.1ACRO CALLS

A macro call consists of the macro name, which must be in the operation
field,

followed by a list of real arguments separated by commas and

terminated by one of the characters listed below.
a.

space

(~)

tab

(-I )

carriage
return

( ) )

If the real arguments cannot fit on one line of coding, they may be
continued on succeeding lines by terminating the current line with a

4-4

Macros
dollar sign ($).

When they are continued on succeeding lines they must

start in the label field.
Example:
~MAC-/REALI, REAL 2 , REAL 3 ,$

REAL 4 , REAL 5

If there are n dummy arguments in the macro definition, all real arguments in the macro call beyond the nth dummy argument will be ignored.
A macro call may have a label associated with it; this label will be
assigned to the current value of the location counter.
Example:

::s

i (lD
(;(:"iC:

I,}

0 ()
0 0 I..)
0 ('I 0

(..

I'';

()

.1.

b T ,. , F;: T

r"',

() 0 ()

..,
.. 0

/"\

,':

F'
r;.:

;:} ,-:'f
() "{.

0 () (~':, F'
() .I. :L
h'
() 0 ,.... ;:;.:

:.~: L.:

>~" c}
>:.:. c:;

:10

00003 R 200007 R tG
COO () ·4

..;~ .,<} ( :; (! .I. 0

r;~

:.;.: : 'i

i.,ij::·D(::'I'r'!::'

('j'J

!.. (:jC

{:';

C·;

(:,
:~.

r'o

!..:?

I.)',.\i... "{"

"1.4

:.:':; 0 0 i,) "/ ,::.:
() 0 (> J 0 r;,:

0' I::

.l .....!

() (I (.I t) .:.:::

1.1 ....·

[::'1

()()O< (,C)

(:l

I ! I I ~, ( ,

The prevailing radix will be saved prior to expansion and restored
after expansion takes place.
macro call.

Default assumption will be octal for the

It is not necessary for the macro definition to have any

dummy arguments associated with it.
Example:
I::~ ;--'i :...

, r:::i\~DjVj

00000 R 20000~ R

I... 1"] ~ •.,

:"'-:·IUCt:~:.::

00001 R 723023 A *G
00002
74.1.100 A tG
00003 K 740(0) A *G
00004 R 04000~ R
10
l.l

:1.2

00005

000567 A
O()O()OO (:-,

~:) I ZE::::OOOO(:'j

4-5

i"li"

cr-";: ...
J)(:,c

': )

Macros
4.3.1

Argument Delimiters

It was stated that the list of arguments is terminated by any of the
followin g symbols.
a.

space

tab

carriage return ( )

These characters may be used within real arguments only by enclosing
them in angle brackets

«».

Angle brackets are not recognized if

they appear within a comment.
Example:

'I ',

.\:'
." -...

:::: ~ ;.....:

(I () () C' <>

0<) <)0:1.

h. .: .-:(.: <) <>() '.:.i'
i :.: ~'::~ . :':; () () J ()

"j' .,(
.;

....,.

'•• J

:.:

~.: .. y . {

i... (, c:.

<> (~.: r:'" i'.> ~:5

r;~

. :'} <> (:. 3 () (>i ::f:: (:.:;

0 000 6

040 0 1 1 R *G

,,/ ,.,.;.

..;

....

.i. .,'::

00010 R 000065 A
0001 1 R 000 000 A

/2:

All characters within a matching pair of angle brackets are considered
to be one argument, and the entire argument, with the delimiters

«»

removed, will be substituted for the dummy argument in the original
definition.
The Assembler recognizes the end of an argument only on seeing a terminating character not enclosed within angle brackets.
If brackets appear within brackets, only the outermost pair is deleted.
If angle brackets are required within a real argument, they must be
enclosed by argument delimiter angle brackets.
Example:

4-6

.DEF IN

ERRMSG,IE< T

ERRMSG

('ERRO R IN

LI NE'~ 15)

~-1acros

00000
00001
00002
0 00 03

I'
.. !

R 600007
R 426 45 2
R 247644
R 2 02 23 1

1'1':; 1 i·1 r
" C17: h: Uh: ::: r.. ~

R *G
A *G
A *G
A *G

:. I I\! [: <: :!. ~:.:.; .,:'
I

00005 R 4 46350 A 1G
0 00 06 R 5 06 40 0 A *8
/

4.3. 2

Created Symbols

Often, it is desirable to attach a label to a line of code within a
macro definition.

As this label is defined each time the macro is

called, a different symbol must be supplied at each call to avoid
multiply defined symbols.
This symbol can be explicitly supplied by the user or the user can
implicitly request the As sembler to replace the dummy argument with a
created symbol which will be unique for each call of the macro.

For

example,
-/.DEFIN-jMAC,A, ?B
The question mark (?) prefixed to the dummy argument B indicates that
it will be supplied from a created symbol if not explicitly supplied
by the user when the macro is called for.
The created symbols are of the form •. 0 0 00+ •. 999 9 .

Like other symbols,

they are entered into the symbol table as they are defined.
Unsupplied real arguments corresponding to dummy arguments not preceded
by a question mark are substituted in as empty strings; and supplied
real arguments corresponding to dummy arguments preceded by a question
mark suppress the generation of a corresponding created symbol.
Exampl e :
.,
.i.

,.,
",','.

..1:':1'"
L(:,C
D{:",C:

6
D::::,;.

·,. ENXh··:
10

(1 (:., C

4-7

OO() ()O F: 200 00'.1' r;: :>i<:G
O()O O1 I'" 1'40 2 0 0
".

I.J~C
~:)Z{:l

r;: ~1)OO() O(, r'", ):{G
000 03 r;: ::.:~ 0 0 () () 0 (.1 )j(C'i
00004 1';.: 0 4 0 0 1 0 F: *G
00 00 ~."j I'~' 0 4 0006 I'~ *n

00 00::;::

O()()OO6

11
:1.2
1. 3

NO [ 1';: r;: 01'\:

:31/[ "'O()O l :I.

D()C

~ "O()(>::.:::jj·

(l AC

HYT(.lCi

:.~

I' :

()O ')O ') O

L(:)C

*U ,. " () 0 (> ::::

OO(j06 F, 000000

,.JI"i'::'

l"i YT ,~,G

0
;.

I...INF~:)

If one of the elements in a real argument string is not supplied, that
element must be replaced by a comma, as in the call above.

A real argu-

ment string may be terminated in several ways as shown below:
Example:

4.3.3

M(',C

(.:) ,.n ,

rvi(l C
r1(.l C
i"ii",C
1'1 ,:; C

(,?I)" v )

......

,0, y B
(" B

......

( , vB ,,

)

Concatenation

If a dummy argument in a definition line of the macro body i s delimited
by the concatenation operation ' @' a nd immediately preceded or followed
by other characters or another dummy argument, the characters that correspond to the value of the dummy argument (real argument) are combined
(juxtaposed) in the generated statement with the other c h aracters or
the real argument that corresponds to the other dummy argument.

This

process is called concatenation.
The following example illustrate s this operation.
:I.
. DEFIN

C(;L..L.
..JI'iF'

00000 R 60000 3 R *G
/'

C i:·'i.../...
{. D~:;(:I
".1 j·. .i ~:~

COJOl R 1 00004 R *G
000 0 2 I'\: 0000 05 R *G
[0

11
:1.2
:1. :5

OO OC 3 R 740040 A
0 0 004 R 0000 00 A
0000~ R 000000 A

., :0 :::,(,
r;:DUT .:
~;i JE:::::T!.

;<}<.
0)

•[,·m

()O() OOO (;

bIZE"" 00006

4-8

CA LL, TYPL. ADDR

F>;, j:;~::::: U " i 1
F:DUT :1.

Macros
The dummy argument TYPE is used to vary the mnemonic operation code of
the generated statement.

The character P, which is the corresponding

value of TYPE in the first call to the macro, will be concatenated with
the characters JM to form the mnemonic JMP.
a dummy argument (i.e., TYPE)

This action occurs because

is delimited by the concatenation opera-

tor (i.e., is preceded by @ and is immediately preceded or followed
by other characters or another dummy argument).
Of course, in the case where other characters are to be concatenated
with the value of a dummy argument, and the first of the other characters is a delimiter, it is not necessary to further delimit the dummy
with the concatenation operator.

The following example illustrates

this rule.
:I.

. DEFIN

MOV[,FRDM,lO,LV l

.:.!':/ E.T.: :,·:\'C .<')1 .. '.'1...

3
4

:::' ;<1::'
~:;l). ::,'1.. \)1. .

,::'

~:~ t.,.: C ,

,.1

• DL.U CI<

(.;

E i\]1)C

D('lC
i. .. (·\ C

....1

:I.

t'!;...t) L. :;:: :!:
~:,; I) • ~;.)

I. .. ,,'I...

Dtl':::

:to
1. :i.
1 ~::
13

.,: ..
"

/
~

::~,: i:j

() .,-.: ,~>

C <) ,.) ,~) ,.~'.

J ::~

~':~:I. <~,

OO OO~

050)

.." . . ...

,':;

0000 0 R 7 4 iO OO H +0

b\) .~ 0
~.;.:

>;.;. ~ J

i... (~ C

D,:,,:;

R *G

/
h i..J~::, T <) i ><

~..:~;)·i·<) ~'

:... ;' :.i ...

J./
JH
,,0.'

·T - , .,'

:.~.:- G

~::; :.j." '~ . '

,:·' f:.

;.'

1':1;-:" ;1.::.

i. ..i:, ,...

".' I , \ \ .....

L,·: ::
:.. .....
{ .';

.;\

1", i

,.,

A•

• .1.

000 ]2

;41000 A ~G

) :) (::1 /~.

;-.:

(> ·~O C. .. ,,'

)}:. U

CO'.) :i. :

F< ~. .:. :;. I,..' " i.:..: :;.

i"<

,y. t:.;

:... t:c,

R tG

Df:'; 1'::

(j i)O .l. )' 1':: ;:::0 00 :1. :.:) :( *U

:U .i. ,,;<

1...(1 (:;

~:~ ~J " ~:.

',1

VVJ~0

05 00 J5

' :-:, ;
-;
, ,1,.-:, . 1.

4-9

Macros
In this example concatenation is used to test the existence of a named
temporary location, and, if necessary, output code to define it. Then
the concatenation operator - Assembler delimiter rule is presented by
concatenating two dummy arguments and other characters beginning with
a delimiter. In detail, one such concatenation string is a delimiter
(Le.,-.j),· a dummy argument (Le., FROM), the concatenation operator
(i.e . , @), a second dummy argument (i.e. , LVL) , finally followed by
other characters beginning with a delimiter (i.e., ,X).
The general case of real argument for dummy argument substitution performed by MACRO is the application of the "other characters beginning
with a delimiter" rule presented above. In other words, argument substitution may be thought of as concatenation when the dummy argument
is bounded by delimiters, rather than a concatenation operator.
Note that one ambiguous case can arise in use of the concatenation operator when the other character string to be concatenated with an argument
value is the same as a dummy argument name. The following example
illustrates this problem.

;

.. ,..
'

.. ;'

..
'

t,..I rC~:>(;·;' L. i..J;···.i

..;' ~\'i :;: -.. !::. \.-' .:.- '..}

C: (, .

c·.·

This macro was written with the intention of satisfying the following
flow diagram.

4-10

Macros

OUTPUT A
"CAL WTCPlun"

OUTPUT WAITFR
CODE, 16l1/J WITH
LABEL "WTCPlun"

YES

OUTPUT THE ADDRESS
OF LABEL "EVlun"

OUTPUT THE VALUE
OF EV HE SPECIFIED

For instance, if the following call to the WAIT macro were coded (wit h
WTCPl~

unde f inen):
" . j

.' .
"

","

:';"""::

" :::: t· .~ .• : L,·
?

,;, '

F >Z

, ', !,ii l'

4-11

.~ ,,' 1,/ " ... ::

Macros

Note that according to box 6 of the preceding flow chart, under these
conditions it was desired to output:
-! EV1.0
for line 7 of the above expansion rather than what was actually generated.

This discrepancy occurs because the characters EVon the appro-

priate line of the body of the definition are not recognized as "other
characters".

EV is also a dummy argument which is bounded by an Ass-

embler delimiter (i.e.,-!on the left) and the concatenation operator
(i.e.,

@ on the right).

This will cause the concatenation of the value

of dummy argument EV (i.e., null) and the value of the dummy argument
LUN (i.e.,

1.0), thus producing the output shown on line 7 of the ex-

pansion.

The only solution to this problem is to choose the names of

dummy arguments to be different from any character strings to be used
for concatenating.
Following is a comprehensive example of the use of the concatenation
operation in defining user macros:
ERRMSG and MESSAGE.

the definition of two macros,

The purpose of ERRMSG is to cause a subroutine to

be called (named ER.PRO) which will print an error message.
(from .0 to 77 ) and an optional
8
The label of the error message to be output is created

It has as arguments the error number
return address.

by concatenating 'ERM.' with the error number.

(ERM • .0, ERM.l, etc.)

no return address is specified, control is transferred to a label named
ER.NOR by default.

The second macro, HESSAGE, is used to create an

lOPS ASCII line buffer with the error message to be printed, presumably
via the ERRMSG macro.

It also has two arguments:

the error number,

and the message text.

The output of the macro is a properly set up

header word pair labeled 'ERM.xx' where 'xx' is the specified error
number, and a .ASCII statement which contains the text specified, preceded by 'ERR#xx--', where 'xx' once again is the error number.

The

reader should examine the example noting the use of the conditional
assembly parameters to accomplish macro-time error detection.

4-12

Macros

.TITLE

cnNCATE~ATIQN

EXAMPLE FOR

'~Rj:(tIS(;'

Of.Flt'ITION.

fRRQR MESSAGE OUPUT

~ACRO

MANUAL

I
I~Ar~('

I
I

~ALLING

SEQUE~CE:

EF.~~SG

EP~~O[,~F.TURNl

I
I

',:HERE:

MAC~O.

FRO~ ~ TO 77 REPRESENTING
COnE.
~ETURN • (GPTID~AL) THE LOCATION TO WHICH CD~TROL
I S H QULn I ~ E RfT I) RN EI') F DLLn \II I N G 0 UTP lJ T 0 F
I
THE ERROR MESSAGE.
IF NOT SPECIFIED,
I
CONTROL wILL ~E GlVEN TO LOCATION 'E~.NOR'.

I
I
I

I
I

•

~RRNO

OCTAL

THE

NU~8ER

ER~~R

nliTPUT:

I
I

I
I
I
I
I

~~TPUT nF
'E~.PRO',

ERR~SG CO \ SI5TS OF
FOLLO~E0 PY A .DSA

A JMS TO THE ENROR P~OCESSO~
ERM.XX WHERE XX ~ ERRNO.
FR~.XX IS ASSUMED Tn HE A STANDARD lOPS ASCII LINE RUFFER
;HICH CONTAINS THt ['ESIRED MESSAGE.
IT MAY BE [)EfINEn USING
,.HE '~iESSAGE' MAC~O (SEt BELOW).

FRROR

I
I
I
I
I
I
I

('fRRNO') IS CHECKED TO ~E RETIOIEE""
nTHERwlSE AN ASSEMbLER ERROR LINt IS
r~TPUT ~ATHER TrlAN THE CALL TO 'ER.PRO'.
THF ILLEGAL
ASSEM8E~ LINE WILL CAUSt AN 'N' EQR~R (AMONG OTHE~S, TO BE
~ E~ERATEn 9Y THE A5SE~~fR, THUS INDICATING A 'NUMBER'
;:- RROR.
H ; r::
J

DET~CTlnN:

ERROR

NU~~ €\E~

AND 77.

ERNN(1, RTN

• DEFt~.

ERR~iSG,

.IFNEG
.IFpnZ

ERRNO-l~~
E~R~O

/VALIDATE ERROR CODE NUMBER
ITO dE ~ cz ERRNO c_ 77
ISETUP RETURN ADDR. IF SPECIFIED

z lRT ~'C :RnJ+Q\

.!FZER

ZZRTNC

Z Z ~ Tt-.! r • FR. :.0 R

IIF NO RETUQN, SET TO 5TO.

ADDR.

.E ~ DC

Ito'S

EQ.PRO

.DSA

EF'M.~ER~NO

Jf'li='

ZZRTNC

ICALL THE

~RROR PROCESSOR
IPOINT TO RIGHT MESSAGE
IEITHER RETURN TO 510. EXIT, OR

.E NQC
.E NOe
• I F~JEG
9
.HiDC

ERRNO
IPUT OUT ERPQR IF NECESSARY
**ERROR COOF IS < ~ OR > 77**

.IFPOZ

ErRNO-l~"

9
• D,jf)C

**EPRnR

COD~

IS c 0 UR > 77**

• E :'~nM

IMACRO 'MESSAGE' DEFINITION.
I
I
I

CALLING

SfOUE ~ CE:

MESSAGE

Enp~O,<TEXT>

I
I
I
I
I
I

RUlLO AN ERROR MESSAGE LINE BUFFER.

\oIHERE:
ER~NO

<TEXT>

= THE ENROQ NUMBER, FROM ~ TO 77 (OCTAL)
= THE MESSAGE TEXT (ENCLOSED It-.! ANGLE
8~ACKF.TS,

SHO~N)

TO BE ASSUCIATED wITH THIS

'ERPNO'.
4-13

~HERE

I SAID

Macros

I
I

r, UTPUT:

I
I
I
I
I
I
I

STA~DA~~ lOPS ASCII LI~E BUFFER IS CRfATED wITH T~E NA~E
'E~M.XX' WHERE X~ a '~RRNO' (SEE ABOVt).
THE ACTUAL ~ESSAGE

WILL ~AVE THE FOR~AT 'E~R#XX-- Tf~T I , WHE~E X~ AND TEXT ARE AS
A80VE.
OF CO r.J ~SF., T~f LtNE BUFFER ~EAOER PAIR WILL BE. PROVIDED.
EP~OR

DETECTl nN :

'E RRNO' WILL RE CrlECKEn TO BE BET WEfN ~ ANU 77.
IF THE CHECK SHU~S AN FRROR, AN ASSEMBLER E.~ROR
LINE ~ILL BE GE ~ E~ATEO RATHER THE THE MESSAGE CODE, THE ERROR
I P i E WILL CAL.ISE AT LEAST AN 'N' FLAG, INDICATING A 'NU~BER'

I
I
I
I
I
I

FR~OR.

.l'.)fFI~J

MESSAGE,E~R~o,T~Xr,?A

.IfNF.G
.TFPOZ

ERRNO-l 'H~
EPR~O

F.RM,~F~~NO

A-ERM.'ERRNn/2*1~~~+2

AI:,

.ASCII
• E ~i GC
.E"lnc
• I n; F. G

ERR 010

**E~RO~

.IFPOZ
9

ERRNO-1 ~ 0

.ENrc

COOF IS

0 OR > 77**

**EPROR COOF IS < ~ OR

77**

• EtlDC

.E~DM

.EJECT
/OUTP UT FRRQR MESSAGE

ERR /ISG

~4,

TAKE

STANOA~O

E~IT

* C;
.IF NEG
*C;
.IFPQZ
*G ZZRT lliC =+0

• "( FZEI<

or.

JMS

*G
*G
*G
*r,
*G
*G
*G
*r,
*G
*r;

.DSA

ER.PR ()
[RH.AI

JO~p

HR TN C

... (;

zZRHJr=ER.N"R
*G
.ENJ)C
(;

.r,

• EtlD C
.E 'J f)C

.IF NEG

9
• E i~ r. r:

**E PRQR COUE IS <

OR > 77**

.IFPOl

4-1 ~H"
**ERR OR COUF

OR > 77**

• r: t·C C

£RRMSG

45,RECOv

.IFNEG

45-1 e (~

.IFPOZ
*G
*r. ZZRT"' CaRECCV+(f
.IFZEp
*G
*r. ZZ R T NC • E R • "i (HI
*r.
• E ~:D C
* t;
J '"'S
*G
. DSA
J/-:P
*u
*G
.E~t:'C
*r;
.ENDC

IS <

IGlvE ERROR #45, ANU

ER.PR Q
EP M.45
ZZ RT NC

4-14

~ETURN

TO LOC 'RECOV' WHEN DONE

Macros

* (. ., III ~"Fi ••
• E.~JDC

.fNDC

.IF·~ EG

**E~RUR

COD~

IS c

UR > 77**

• -r F ~ 0 Z

4 - 1 (~ Ql

**ERR OR (OO~ IS c

OR > 77**

.E \i DC
• E : ~ O c:

~E5S~r;E

*r,

*G
*G
*e;
*G
*e;
*e;

.IF'NF.G
.IF~OZ
Fr./'I.d~

45, <A ~1BrGuUI ' ~ USE. OF A COMPILER
45-1"'Vl
45

I(EY~ORO>

•• ~~09-ER~.45/2*100~.2

".ASCll

'F~R#45--AM'"TGuOIJS

US~

nF A COMPILE~ KEVWORf)'<15>

*r,
*(;

*e;
*e;
*e;
*e;

* t;

* (;

*r,
.lro ~~EG

**ERRO~

rODf IS <

OR > 77*.

.E N:'lC
.IF~OZ

45-1~(lI

**ERROR

_PR ~~ sG

-34,RECOV

.IF e< EG
.IFPf)Z

-34_1Jl~

• F. 'J 0 c:

*G
*G
*G
*e;
*e;

ISHOW THAT to NEGATIVE ERROR NO. IT ILLEGAL

-34

.IFZER

ZZ~TN(

Zl~T'ICo:E:::. 'l OR

• E ~,i ~ C

.i)SA
J~j:)

.:: tJoc
• E',nr;
.1F'NEG

ER.PRO
E R~l . -:34
ZZRTNC
-34
* .. ERROR CODF IS

0 OR > 77**

.IFP OZ
9

-34-1,;1(1
.. *ERRQR CaDE IS

.( NCC
EkKMSG
.IFNEG
.IFPOZ

456
ISH OW ThAT AN ERROR NO. > 77(8) IS ILLEGAL
456-UIil
456

• E ' J ('\ r:

*e;

IS < ~ OR > 77**

zZRT~r.~~COv.~

JMS

COO~

*e;
.. G Z Z R T ,,!r 0: • '"

*e;
.IFZER
* G Z Z R T "J r:: =E ~ • ' J 0 R

ZZ RT'I C

4-15

77.*

Macros
.G

• E~J 0 C
JMS
.OSA

*G
.G

E~.PRq

E. R ~·l. 456

*G
*G
*C,
*C;
*G
.c;
.G

J ~,~
.F..hJDC
• Et.OC

ZZRTNC

.IFNEG

456
.·ERRi1R CUDf IS < ~1 OR > 77 ••

• r;

.E NDC
.IFP[)Z

455-11HI

**ERROf.? CODf IS < ~ OR > 77 ••

.ENDC

.EJECT

*r.

*G
*r;

FRI'I.4

HESS_GE 4,<ILLEGAL nR
.IFNEG 4-1~0
.!FPOZ 4
•• 0~~b_ERM.4/2.10 ~ ~.2

·G

.ASCII

.c;

U N RECOG N IZA6L~

SYNTAX IN

ST~NT>

'fRR#4--ILLf'GAL OR UNRECOGNIZABLE SYNTAX

IN STMNT'<15>

.r.
·G
*r,

*G
.(;

*G
.G
*G
*G
*G
"G
.. r:.

.r;
*r;

*r;

*G
.G
*r, •• ~"'~9" •

• ENDC
• E ~WC
• JFtJEG

•• ERR8R CODE IS < ~ OR

77 ••

• E i";[lC

.IFPOZ

45"H"~

g
**ERROR CO OF IS < ~ OR > 77 ••
• E ~J DC
MESSAGE -l,<THIS S~rlJLn GIVE A MACRO-DETECTED

*G
*G

.IF "I EG

.. 1-10~

.IFPOZ

-1

*r; EkM._l
.r;

•• 0n12-ER~.-1/2*1 ~ ~P.2

.G
*(;

.ASCII

'FRP~-l--THIS

SHOULO GIVE A MACRO-DETECTED ERRORI<15>

• • ~Ot'211.

.E NOC

.(N OC
.IFNEG
9

-1
•• ERROR ( OOF IS <

OR > 77*.

.E~iDC

*(;

E~ROR>

.IFPOZ

-t"10~

.*ERROR CU Of IS

• Et. CC
.EJE:CT

4-16

0 OR

77**

Macros
4.4

NESTING OF MACROS

Macros may be nested; that is, macros may be defined within other macros.

For ease of discussion, levels may be assigned to these nested

macros.

The outermost macros (those defined directly) will be called

first-level macros.

Macros defined within first-level macros will be

called second-level macros; macros defined within second-level macros
will be called third-level macros, etc.

Each nested macro requires an

.ENDM pseudo-op to denote its termination.
Example:
Level 1

-I. DEFIN-I LEVELl, A, B
-ILAC-j A
-ITAD-j B

Level 2

-I. DEFIN -j LEVEL2, C, D
-jISZ-j C
Level 3

-IDAC-j D

-j.DEFIN-lLEVEL3, E, F
-jAND-j E
-jXOR-j F
LEVEL 3 . ENDM

-I.ENDH
-jDAC-j Z

-I. ENDM

LEVEL 2 .ENDM

-IDAC -jy

-I. ENDM

LEVEL 1 .ENDM

At the beginning of proc e ssing, first-level macros are defined and may
be called in the normal manner.
not yet defined.

Second and higher level macros are

When a first-level macro is called, all its second-

level macros are defined.

Thereafter, the level of definition is irre-

levant and macros may be called in the normal manner.

If the second-

level macros contain third-level macros, the third-level macros are
not defined until the second-level macros containing them have been
called.
Using the example above, the following would occur:
!

.-',.

: j:-::':

:... ::.. "." -.

,"\

. ,~

) i,'),..: '.

,/'::!
')((:1

;::. \/ :':: . ;.:. : ~.' C:: ~.' Ii

i, ;;;,::'
,;:,(,

4-17

,1,.

Macros

,C:,.: .. '

.. ~\ i.:.'

0002 R 04 0016 R
F;; ·.;l 0 0 .i, ...., r;·,
,) 1.) 0 0 4 F\ 0 /1, 0 0 :i. :::~ r;;
"

1.. ..

",r
() 0 ,,)

~:.~

I::'
C() '''!
I''\

; :;~

. ,

....

\"..

e 0 () 1 ,"
/~,

,,' (; " ,.- ,., "
,.::. Of ' , "
"

,~
l:.'

>;< ~3
"t,'
.') \ ~ '

....'<. C::

.:. D1.:: F ...

,ii" G

\-: ;'.". :

>~< t·}

...\!...t, ·,.:

;'\
! ,;

.i:\

1... ;:: .,: :...•. ,:~. :: i::. ~L F

i:::

~. !::. i ·.i :.::1 :' /;

.,<C"
.'

I',

c,.

::::i (I !:,',

.,/
.. \ ' "' .

,;'. ..)
/i',

t ] "!" .i . ,

If LEVEL3 is called before LEVEL2 it would be an error and the line
would be flagged as undefined.
When a macro of level n contains another macro of the level n + 1, calling the level n macro results in the generation of the body of the macro
into the user's program in the normal manner until the .DEFIN statement
of the level n + 1 macro is encountered; the level n + 1 macro is then
defined and does not appear in the user's program.

When the definition

of the level n + 1 is completed (.ENDM encountered), the Assembler continues to generate the level n body into the user's program until, or
unless, the entire level n macro has been generated.
4.5

REDEFINITION OF MACROS

If a macro name, which has been previously defined, appears within
another definition, the macro is redefined and the original definition
is eliminated.

For ex amp le,

,i, '

~: :, ( :;

.,'- .
. .• , .

... -'. :

.•.. ~ ':.

" 0 ,' -,

i ...

When the macro INDXSV is called for the first time, the subroutine calling sequence is generated and followed immediately by the subroutine
itself.

After the subroutine is generated, a .DEFIN that contains the

name INDEXSV is encountered.

This new macro is defined and takes the

place of the original macro INDEXSV.

4-18

All subsequent calls to INDXSV

Macros
cause only the calling sequence to be generated.

The original defini-

tion of INDXSV will not be removed until after the expansion is complete .
O()()OO r;: .I. ()O 002 !? >KG

~:; (:) 'H::

O()OO I. I;:
OOO(:\:~:.:,' F;: 000000 A *G SAVE
() 0 0 (I :'::; F:
\'.:
>:<C:.
00004 p o·~·~·OO:L 0 ;: ;~ >1<(:;
OOO()~:.!j

:::~

r( ()·400J.:!.

::.:< C~

OOOO {,:

>1< C-:;

OO()O)' F:;

, i.)

2 () 0 Co ::'.~ i:~~ >!<G
OO(i(i:l. 0 :'< *G
\~'i

;Hi
*(3
~{.\ Cj

4.6

~:; ( :) ~'I J >< "r'

'.' L F f: .:. r"~
,.i;"i:::,
;. Ei'~D r'-!

i:j··l LiX ~:~ ~)
:'::;(,:),:,:

MACRO CALLS WITHIN MACRO DEFINITIONS

The body of a macro definition may contain calls for other macros which
have not yet been defined.

However, the embedded calls must be de-

fined before a call is issued to the macro which contains the embedded
call.

Embedded calls are allowed only to three levels.

Example:
,1:1;' ,,: : 11i
1." ( ",::

"0'

'1"(.":(1

/ 'Ei·';J:::L .L' t :;:.:{1 C(.\ i..

i'j( ,Cl

1...(, [:
'I" (:',:U

!'()UI.
'f('!C-;:::,::

/ ./ /

)

The call
causes generation of

4-19

Macros
4.7

RECURSIVE CALLS

Although it is legal, avoid making a macro definition, containing an
embedded call to itself because the

expans~on

will cause ~ore than

three levels to occur.
Example:

.DEFIN

MAC,A.B .C

1..,(\(:

r:)

T f:~:O

DA C

f-1(,C

('I,' D~· C

,. F<[f:: UF':::; It)/,'

( I i... !. .. ,

, E:NDi'l

When a call for MAC is encountered, the Assembler searches memory
for the definition and expands it.

Since there is another call for

MAC contained within the definition, the Assembler goes back once again
to obtain the def i nition; this process would never cease if more than
three levels were allowed.

A conditional assembly statement could be

used, however, to limit the number of levels as in the following
example.
Example:

t,,,, (i
F,: ;"· 3

, DEFTN
i...i~C

;-··-i {iC ~,c ~) 11
L

Dt ,C

r::

"IFNIF<

D····,:)

. [Nne
, ENDI"l

Names and arguments of nested macros and arguments of embedded calls
may be substituted and used with perfect generality.

4-20

Macros

(oIlEFIN
Lr,C

h tiCI ,! t~YByC,n

{"[iD

D(:lC
.DCFIhi

{)ND

()

D(:lC

I::.

!:~r

1:1 y 1'::

,Ej··WM

,.[NDM

F~::::

.DEF IN

MAC2,M,N~O,P.Qp?R

I!:;Z

..Ji"l P
i'ii)C:I.

1'::
['i '! U, F'" G

MAC2
... ...
. ~.

.l.:; .....
"".." /". i '~ •
r l t·I\ ... .I.

CDUNT,TAG1,TAG2,lAG3.MAC3

CD UN r
~. y 0 () () ::~i

TAG1.fAG2vTAG3.MAC3

!...(,[:

"T(ICi l

(,[II:!

'r(~I D2

• DEF:!. i'!
(:)r\'f'
:0(,)[

Ii< ()
*G

,. I':: j··i j) i"j

• + ()()O~::.i::::,

4-21

CHAPTER 5
OPERATING PROCEDURES
5.1

INTRODUCTION

Detailed descriptions of the assembler calling procedure, command
string format, general operating procedures, and printouts are given
in this chapter.
5.2

CALLING PROCEDURE

5.2.1

XVM/DOS

In the XVM/DOS systems, the MACRO Assembler is called by typing HACRO)
after the Monitor's $ request.

Hhen the Assembler has been loaded, it

identifies itself by typing:
~~CRO

XVM Vnxnnn or BMACRO XVM Vnxnnn
>

on the teleprinter.

The > character indicates that the Assembler is

waiting for the user to type in a command string.
There are two differences between MACRO XVM (the Page Mode Assembler)
and BMACRO XVM (the Bank Mode Assembler).

MACRO XVM starts each as-

sembly assuming page mode relocation (.DBREL implied) and BMACRO XVM
assumes bank mode relocation (.EBREL implied).

When program sizes

exceed 4096, MACRO outputs the warning message "PROG 4K" in the assembly
listing but Br1ACRO does not.

This message will appear even if the pro-

gram is assembled under influence of .EBREL.

This warning message has

no other effect; the program will be assembled and output will be produced anyway.
5.2.2

RSX/XVM

In the RSX systems, MACRO is invoked by typing in the Assembler's name
and also the command string on the same line following the prompting

5-1

Operating Procedures
message "TDV "

For example:

TDV>MAC BLXR .... FILE)
MACRO XVM Vnxnnn
The Assembler identifies itself, as just shown, only i f the R option is
designated in the command.
ent to BMACRO

The RSX version of the Assembler is equival-

in that i t assumes .EBREL to begin with and does not

print "PROG>4K".
5.3

GENERAL COMMAND CHARACTERS

The following characters are frequently used in the entry and control
of ~~CRO programs.
Character Printout
RUBOUT (Echoes")
CTRL U (Echoes @)
CTRL P (Echoestp)

delete single character
delete current line
If the input source is physically segmented
so that all but the last segment end with .EOT
or nothing, the Assembler will print out the
message
EOT

when the end of a segment is reached.
In XVM/
RSX, the Assembler does not type any such message.
If the source is segmented in such a way that
operator intervention is required to load
another segment, MACRO will print
tP
(MAC-tP in XVM/RSX? and wait for the user to key
in CTRL P (CTRL PI in XVM/ RSX).
Except in
XVM/ RSX, the user response will be printed also
and the line will appear as
t PtP
In XVM/RSX if no other tape is to be ;loaded,
terminate assembly by typing CTRL Q~ .

At the start of PASS 2 or PASS 3 if input is
on paper tape or if the source is segmented on
DECtape or Magtape with segments being read via
the same .DAT slot, the Assembler will request a
CTRL P response as above.

5-2

Operating Procedures

CTRL D (Echoest D)

5.4

If the Assembler is not waiting for more input,
or is not waiting to start the next pass,
typing CTRL P causes the Assembler to restart
at PASS 1. This is true for all systems except
XVM/RSX.
If the user specifies the Teleprinter as the
input parameter device, he can delimit the parameter code by typing CTRL D (tD) (followed by .)
with the XVM/RSX Monitor).
MACRO responds with
EOT.
~ACRO immediately begins assembling the
program from the device assigned to .DAT-ll
(LUN 15 with XVM/RSX) •

COMMAND STRING

The command string format consists of a string of options, followed by
a left arrow, followed by the program name(s), followed by a terminator.
options~filnml,filnm2, •..

The following sections describe the rules for forming proper command
strings and show typical assembly examples.
the command line has significance.

The character terminating

Terminating the line with a carriage

return will cause the Assembler to re-initialize itself to PASS 1 at
completion of the assemblY7 the Assembler is thus ready to accept another command string.

Terminating the command with an ALT MODE will

cause a return to the monitor at the end of assembly.

In the XVM/RSX

systems these line terminators have a different meaning.

Termination

with carriage return causes TDV to be called7 termination with ALT MODE
does not.

In either case, the Assembler exits after executing the com-

mand line.

If a command string error occurs, the entire command must

be retyped.
5.4.1

Program File Name

To the right of the back arrow in the command string, one or more program file names may be required, depending upon the options used and
the type of I/O devices.

Where several names are needed, they are

separated by commas.
Program names are required for files which are to be input from or output to directoried devices.

The two proper forms for a file name are

filnam~ext

or
filnam

5-3

Operating Procedures
where
filnam = 1 to 6 character name
ext

= 1 to 3 character extension

These may be formed from any of the legal printing characters shown in
Appendix A and may appear in any order.
If the file name extension is omitted, the Assembler assumes SRC in
default.

Following are examples of single name command strings.

Examples:
User Command String

Assembler Interpretation

+ L...-'ABCDEFL...-'U~.0)
+ABL...-'.011
+ A,)
+ABCDEFG)
+ABCDEFGL...-'H:)
+ABCL...-'L...-'VIA

Name

Extension

ABCDEF
AB
A
ABCDEF
ABCDEF
ABC

1.0.0
.011
SRC
G
H

SRC

The last three examples illustrate how the Assembler interprets improperly formed file names.

If the file name is longer than six char-

acters but is not followed by a space, the seventh, eighth and nineth
characters are used as the extension.

If it is followed by a space,

characters beyond the sixth and before the space are ignored.

If two

spaces follow the file name, the extension is assumed to be SRC.

general, if too many characters are given the excess characters are
ignored.
The extension name of the main program is output (unless the 0 option
is present) as a special code in the relocatable binary file.

This

enables programmers to easily identify different versions of the same
program by merely assigning unique extension names.

If the P- option

is utilized, the Linking Loader and UPDATE print out the source file
names,

including extension.

Regardless of the source file extension, such as TEST .0.01, the binary
file extension will be either BIN, meaning relocatable binary, or ABS,
meaning absolute binary.
5.4.2

Options

Assembler options direct the course of the assembly.

5-4

They describe

Operating Procedures
the types of input and output desired.
the left of the back arrow.

Option characters are listed to

They may be listed in any order and are

typically not separated one from the other (although commas and spaces,
which are ignored, may be used as separators).

Option characters which

appear more than once and invalid characters are ignored.
Examples:
Meaning

Command
B+FILE)

Assemble FILE SRC and produce a
binary object file.
Assemble NAME SRC and produce a
binary object file and an assembly
listing followed by a symbol table
listing.
Assemble PROG ~lX producing no output except a list of assembly errors, if any, on the listing device
assigned to .DAT -12 (LUN 16 in
XVM/RSX) •

BLS+NAME)

The following table shows the action and the default of the options.
Option
A
B
C

Action

Default Action

Print symbols at end of PASS 2
in alphanumeric sequence on
listing device.
Generate a binary file to DAT -13
with extension BIN or ABS, as required.
(LUN 17 in RSX).
Program areas that fall between
unsatisfied conditionals are
not printed.
It is not necessary to type the L option if
this option is used.
This option enables the user
to have any errors occurring
during assembly printed on the
console pri~ter in addition
to the device assigned to .DAT
-12 (LUN 16 in RSX). The L or
N switch should be used with
the E option. This option is
particularly useful to users
who assign non-printing devices to .DAT -12.
Read macro definition file from
.DAT -14 (LUN 18 in RSX) during
PASS 1. Terminate input with
.EOT or CTRL D if Teletype l
(CTRL D ~ i f RSX).
Print only the source line of
a macro expansion.
It is not
necessary to type the L option.

Symbols are not printed
in alphanumeric sequence.
A binary file is not generated.
All source lines are
printed.

Assembly errors are not
printed on the console
printer.

No macro definition file
is processed.

Generate printouts for
macro expansions and expandable pseudo-ops (e.g.,
.REPT) •
lTeletype is a registered trademark of the Teletype Corporation.

5-5

Operating Procedures

Option

Action

Default Action

The H-option is used in conjunction with the A, V, or S
options. User symbols are
normally printed horizontally
at the end of PASS 2, four
symbols to a line.
If the Hoption is used the symbols
will be printed one to a line.
Ignore .EJECT's. The .EJECT
pseudo-op is treated as a
comment.
Generate a listing file on the
requested output device, DAT
-12.
(LUN 16 in RSX). I f the
output device is directoried,
then the listing file extension
will be LST.
Number each source line (decimal).
If this option is used,
it is not necessary to type the
L option.
Causes the assembler to omit
the source extension and the
linking loader code 33 from the
binary file.
This option must
be used when assembling programs in the DOS or RSX systems
to be run in ADSS or B/F.
Before assembly begins, read
program parameters from DAT -10
(LUN 20 in RSX). Terminate
input with .EOT or CTRL D (if
Teletype). The parameter file
is read only once; for this
reason, only direct assignments
may be used.
Identify the Assembler version
number, print END PASS 1 and
END PASS 2, and print the error count on the teleprinter
(RSX only).
Same as selecting both A and V.

Print symbols four to a
line.

I
L

The T option causes a "Table
of Contents table to be generated during PASS 1. The table
will contain the page number
and text of all assembled
.TITLE statements in the program.
Print symbols at end of PASS 2
in value sequence on listing
device.

5-6

Skip to head of form when
.EJECT is encountered.
A listing file is not generated (see options N,C).

Source lines are not numbered.
Loader code 33 is included
in the binary output.

No parameters, begin assembly immediately after command string termination.

These items are not printed
in order to speed up batch
processing.
Symbols are not printed.
(If neither option V, S
nor A is requested, symbols are not printed.)
A table of contents is not
generated at the head of
the assembly listing.

Symbols are not printed
in value sequence.

Operating Procedures
Option

5.4.3

Default Action

Action
At completion of PASS 2, PASS 3
is loaded to perform the crossreferencing operation. At completion of PASS 3 the Assembler
will call in PASS I and 2, to
continue assembling programs.
If the command string was terminated by an ALT MODE, control will
return to the Monitor at the end
of assembly. Without the N option the user would obtain a
cross reference which would be
effectively useless since the
source lines of the listing are
not numbered. The N option is
automatically entered if you
enter Land X.
The Z option is related to the
macro definition file option F.
Z has no effect if F is not also
specified.
F and Z are used in
combination when the main program
is segmented into two parts.
The first part containing instructions other than simply
macro definitions, must be read
both during PASS 1 and PASS 2.
This is the function of the Z
option.

A cross-reference is not
provided and PASS 3 is
not called in.

The F option, if specified,
causes the Hacro definition
file to be read only during
PASS 1.

Multiple Filename Commands

In the general case a command may require up to three file names, depending upon the options specified, to produce a single binary output
file.

As will be illustrated later on, the Assembler in XVr1/RSX sys-

tems allows multiple assemblies to be specified in a single command,
which may require more than three file names.
systems, the limit is three.

For the other software

Names may be needed to specify parameter

files, macro definition files and program files.

The use of these

names and the manner in which they are interpreted by the Assembler
are described in the following paragraphs.
NOTE
In the following descriptions any file which is
processed by both PASS 1 and PASS 2 of the Assembler is also processed during PASS 3 if the
cross-reference option (xl is specified.

5-7

Operating Procedures
NAME 1:

PARAMETER FILE

If the P option is used and the device assigned to .DAT slot -10 (LUN
20 in XVM/RSX) has a directory, the first name is interpreted as being
the parameter file name.

The name of the file must be explicitly stated

if it is on a directoried device.

If the device assigned to the para-

meter file is non-directoried, the first name typed would follow the
rules for name 2.

The parameter file is passed over only once during

PASS 1.
If the P option is not used, only two names are accepted by the command string processor.

The first name then would follow the rules

for name 2.
NAME 2:

MACRO DEFINITION FILE

If the F option is used, the second name (or the first if the P option
is not used) is interpreted as being the macro definition file or part
one of a two part program (assuming the device assigned to .DAT -14
(LUN 18 in RSX) has a directory).

If the device is non-directoried,

the second file name (or first if the P-option is not used or doesn't
require one) would follow the rules for name 3.

The macro definition

is normally passed over only once, during PASS 1.

However, unlike the

main program file, macro definitions on .DAT slot -14 are recorded in
core during PASS 1.

Hence, PASS 2 is unnecessary.

If the Z option is

used with the F option this file will be passed over twice, allowing
source files in two parts on two different devices.

The Z-switch has

no effect if F is not specified.
If the F option is not used, the first name (second if P option is used)
is interpreted as the file name of the program to be assembled.
The macro definition file may also be used as an additional parame t er
file.

A second parameter file is useful where a program is conditionally

assembled to produce different versions according to many as s embly parameters.
NOTE
The RS X MACRO does not contain definitions of system directives and I/O calls. MACRO definitions
or RSX are in a file called RMC.v SRC, where v
changes with each release.

5-8

Operating Procedures
NAME 3:

PROGRAM FILE NAME (Name of the Program to be Assembled)

This file is processed from .OAT slot -11 (LUN 15 in RSX) and always
by both PASS 1 and PASS 2.

If the P and F options are not used and

multiple names are typed, only ' the first name will be processed.

a binary output file is requested, it will be directed to .OAT slot

-13 (LUN 17 in RSX).

If either of the two devices has a directory,

a file name must be specified.

The binary file will assume the name

of the program file and an extension of either BIN or ABS.
MULTIPLE NAME INTERPRETATION
Before processing, the Assembler uses the .FSTAT function (SEEK in RSX)
to determine whether or not the named files are on the input devices.
If not, the message "NAME ERROR" is typed.

In all but the RSX and

BOSS XVM systems the Assembler then expects the command string to be
retyped.

In RSX, the Assembler exits and calls TOV so that the com-

mand string can be given to TOV.
the monitor.

In BOSS XVM the Assembler exits to

Assuming that enough names have been typed to satisfy

the command string options, t1ACRO interprets the file names as follows:
a.

Current name = NAME 1.

Was the P option used?

Is the device assigned to .DAT slot -10 (LUN 20 in RSX)
directoried? If not, go to step f.

Use the current name (NAME 1) to .SEEK the parameter file
via .DAT slot -10 (LUN 20 in RSX).

Current name = NANE 2.

Was the F option used?

Is the device assigned to .OAT slot -14
directoried? If not, go to step j.

Use the current name (NAME 1 or NAr1E 2) to .SEEK the r'lACRO
definition file via .DAT slot -14 (LUN 18 in RSX).

Current name = NAME 3 (or NAME 2 in P option not used).

Use the current name (NAME 1 or NAME 2 or NAME 3) to .SEEK the
program file via .DAT slot -11 (LUN 15 in RSX).

If not, go to step f.

If not, go to step j.
(LUN 18 in RSX)

RULES FOR MULTIPLE NAMES IN THE COMMAND STRING
1.

Initial blanks positioned after the back arrow are ignored.

Files are processed sequentially. The first name after the
left arrow is the first file read, the second file is next
and so on.

5-9

Operating Procedures

Once a string of legal name characters is started, a space
has the following effect on a name.
a.

The first space delimits the proper name and indicates to
the command string processor that the extension name is
next. The proper name is defined as the first six characters of a file name, excluding the extension.

b. Two consecutive blanks delimit the name. An extension of
'SRC' is implied if no extension was typed.
4.
5.

(Same as 3b
A comma or line terminator delimits the name.
above. )
Any name given after the third name is ignored, except in XVM/
RSX. The XVM/RSX assembler allows multiple assemblies to b e
specified in a single command. Where the options require one,
two or three file names, the command may contain multiples of
one, two or three. Each such group of one, two or three names
represents a single assembly.

RESTRICTIONS CAUSED BY MULTIPLE FILE INPUT (not relevant to XVM/RSX)
The .FSTAT system macro is used by the MACRO Assembler to determine
whether or not the input device has a directory and whether or not the
argument names are on the assigned devices.

For this reason, only

those I/O handlers which honor or which ignore the .FSTAT function may
be used with MACRO.

The "A" handlers for directoried devices (e.g.,

DTA, DKA) honor .FSTAT.

The paper tape punch and reader handlers ig-

nore • FSTAT, but the effect is as if they accept it.

Device handlers

which treat .FSTAT as illegal may not be used.
5.4.4

Examples of Commands for Segmented Programs

Below are typical assembly situations which illustrate the usage of
some of the assembly options and show the resulting teleprinter output.
The output for XVH/RSX differs slightly from what is shown.

That is

explained in section 5.3.
1.

Segmented Program on Paper Tape
A source main program is segmented onto three paper tapes to
make loading in the reader easier. Tapes one and two terminate with an .EOT statement and tape three terminates with
.END. All three segments are read from the primary input,
.DAT -11 (LUN 15 in RSX). The command to MACRO to produce
a binary program is:
> B +- At-1YNAM)

Note that tape 1 must be ready in the reader before the command string is entered. Were it not, the reader would return
an end of tape condition anyway and erroneous results would

5-10

Operating Procedures
be obtained. The resulting teleprinter output is shown below.
The comments to the right are not part of the output; these
are included here as explanatory remarks. User responses are
underlined.
>B +ANYNAM)
lEnd of tape l.
EOT
IReady tape 2.
tP....iR
lEnd of tape 2.
EOT
IReady tape 3.
tP-±..L
END OF PASS 1
IReady tape l.
tP....!...E
lEnd of tape l.
EOT
IReady tape 2.
tP....!..l:.
lEnd of tape 2.
EOT
IReady tape 3.
tP...!....f.
SIZE==.012.03
NO ERROR LINES
2.

Type CTRL P.
Type CTRL P.
Type CTRL P.
Type CTRL P.
Type CTRL P.

Segmented Program on DEC tape
A source main program cannot fit onto a single DECtape.
It is
split in two on two different DECtapes and given the same file
name: MAIN SRC. The tape one file ends with .EOT; the tape
two file ends with .END. The file names must be identical if
both segments are to be read via the primary input, .DAT -11
(LUN 15 in RSX).
Example 3 illustrates an alternate method.
However, example 2 must be used if one also is to include a
MACRO definition file, as in example 4.
The following command to MACRO produces a binary program and the subsequent
teleprinter output:
>B + HAIN
EOT
tP t P

lEnd of file 1. ~lount second
IDECtape on same unit. Type
ICTRL P.
END OF PASS 1
lEnd of file 2. Mount first
tP !...E
IDECtape on same unit. Type
ICTRL P.
EOT
lEnd of file l. Mount second
t P....!..R
IDECtape on same unit. Type
/CTRL P.
SIZE=.0.07.03
NO ERROR LINES
3.

Segmented Program on Disk
This example is a variation of number 2. A two part main
program resides on disk.
It doesn't matter whether the two
files are on the same or separate disk units.
Part one terminates with .EOT; part 2, with .END.
PARTI SRC will be
read via the secondary input, .DAT -14 (LUN 18 in RSX); and
PART 2 SRC will be read via the primary input, .DAT -11
(LUN 15 in RSX).
The resultant binary file, produced by
the following command to MACRO, will assume the name of the
second (primary) file:
PART2 BIN or PART2 ABS, as the case
may be:
>BFZ ~ PART 1 , PART2)
EOT
lEnd of PARTI SRC.
END OF PASS 1
lEnd of PART2 SRC.
EOT
lEnd of PARTI SRC.
SI2E==.02.0.03
NO ERROR LINES

5-11

Operating Procedures
Several pOints can be made about the differences between
examples 2 and 3.
First, note that CRTL P type in is not
required unless input is from a device like paper tape.
Next, note ~hat example 2 is impractical on disk because it
requires physically interchanging disks.
Example 3 is not
restricted to usage with disk, but can be used with other
media as well.
4.

Use of a Macro Definition File
MACDEF SRe, which terminates with .EOT, contains only macro
definitions.
It is read from the secondary input, .DAT -14
(LUN 18 in RSX).
The user has a main program, USEMAC 002,
which terminates with .END and which calls some of these
macros but does not itself define them. This is just an example.
It is perfectly legal for the main program to redefine
macros which also appear in the macro definition file.
USEMAC 11112 is read from the primary input, .DAT -11 (LUN 15
in RSX).
Below is the appropriate command string to produce
a binary program.
Note that the F option without the Z option (see example 3) instructs the Assembler to read the
first file (the Macro definition file) only d u ring PASS 1.
>BF +- MACDEF, USEMAC 11112)
EOT
END OF PASS 1
SIZE=1111114
NO ERROR LINES

lEnd of MACDEF SRC.
lEnd of USEMAC 11112.

Note that EOT is not printed during PASS 2 because MACDEF
SRC is read only during PASS 1. The preceding example assumes that the files are on directoried devices.
5.

Parameter File on Paper Tape
A main program, MAIN SRC, which terminates with .E ND is conditionalized to produce different binary code based on the
values or existence of certain assembly parameters.
It is
read via the primary input, .DAT -11 (LUN 15 in RSX), which,
for this example, is assigned to DECtape. A paper tape containing parameter definitions (direct assignments) terminates
with .EOT and is read via the auxiliary input, .DAT -1~
(LUN 211 in RSX). The following command to MACRO produces a
binary program:
>BP+- l''lAIN)

EOT
END OF PASS 1
SIZE=~~6~2

l End of parameter tape.
lEnd of MAIN SRC.
NO ERROR LINES

Note, although input is partly from paper tape , a CTRL P response is unnecessary because the parameter tape is read only
during PASS 1.
6.

Multiple File Assemblies in x VM/ RSX
Using the Assembler in XVM/RSX, several assemb lies, using
the same set of options for each, may b e specified i n a single command.
Unless the R option is used, no printout o n t h e

5-12

Operating Procedures
teleprinter will occur to signal the various stages of assembly.
Below are listed two typical commands in RSX.
>tJ'.AC BL+ P1,P2&...1.0.03,P3,P4)
This requests four assemblies. A separate binary and listing
are produced for P1 SRe, P2 .0.03, P3 SRC and P4 SRC.
\

> MAC PE + PAR1, FILl, PAR2, FIL2..o1

This requests two assemblies. A separate binary is produced
for FILl SRC and FIL2 SRC. The parameter file PAR1 SRC is
applied to the assembly of FILl SRC and PAR2 SRC to that of
FIL2 SRC.
5.5

ASSEMBLY LISTINGS

If the user requests a listing via the command string, the Assembler
will produce an output listing on the requested output device.

The

top of the first page of the listing will contain the name of the program as given in the command string.

The body of the listing will be

formatted as follows:
Line
No.

Error
Flags

Location

Address
Mode

Object
Code

Address
Type

Line
Type

XXXX

XXX

XXXXX

XXXXXX

R
A
E

*G
*L
*R
*E

Source

Statement

where:
Line Number

Flags

Each source line and comment line is
numbered (decimal); generated lines
are not included.
Lines are not numbered unless the X or N option is
specified.

Errors encountered by the assembler

Location

Relative or absolute location assigned to the object code.

Address Hode

Indicates the type of user address.

A = absolute
R = relocatable
Line Type

*G = Generated
*R = Repeated

Object Code
Address Type

*L = Literal
*E :: External

The contents of the location (in
octal)

Indicates the classification of the
object code.

5-13

Operating Procedures

A
R
E

absolute
relocatable
external

The object codes assigned for literals and external symbols are listed
following the program.
5.6

SYMBOL TABLE OUTPUT

At the end of PASS 2, the symbol table may be output to the listing
.DAT -12 (LUN 16 in RSX) device.

If the A option is used, the table

will be printed in alphanumeric sequence; if the V option is used,
the symbol table will be printed in numeric value sequence; if the S
option is used, the symbol table will be output in both alphanumeric
and numeric sequence.

The format is as follows:

Symbol

Value

Type

SYMBL1
SYMBL2
DIRECT

XXXXX
XXXXX
XXXXXX

E
A

The Xs represent the octal value assigned to the symbol.

This is the

location where the symbol is defined, except for external symbols.
For these, the value is the location of the transfer vector, whose
contents are set at program load time with the actual value of the
symbol.

Note that for SYMBL1 and SYMBL2 there are five Xs but that

there are six Xs for the symbol DIRECT.

Symbols havi ng six octal num-

bers to represent their values are the result of direct assignments.
The symbol table shows the type of symbol:
A
absolute
R = relocatable
E = external
Locations assigned to variables immediately follow the last object
code producing statement in the assembled program.

Locations assigned

for literals not under .LTORG influence and transfer vectors are listed
immediately following the variables; if no variables are used in
the program, literals and transfer vectors immediately follow the program output.

5-14

operating procedures

PAGE

SA~"L~

SAMPLE PROGFIAM

SRC

.TITLE SAMPLE PROGRAM
I
I
I
I
I

I
I

SAMPLE SUB~OUTINE, ~OT CLAIMED TO WORK OR TO ~AVE A~Y PRACTICAL
VALUE, USED TO ILLIJSTRATE THE OL'TPUT ON Atv ASSEM~LV LISTING.
THESE LINES ARE COMMENTS.
THIS LISTI~G WAS OBTAINED USING BMACRO-15 IN 005-15
FOLLOWING COM~ANO ~PTIQNS To ~ACRO: LSX

wIT~

THE

OUT-5
• IODEv
.GLOBL

I.OAT SLOT 5 •
OUT
PRINT, SAVE, RESTOR

WIOTH a 72

.IFUND
• DEC

WIDTH

ICONDITIONAL ASSEMRLY •
IOECIMAL NUMBEr:1 •

• OCT
.ENDC
eUFSIZ.wIDTH+'/~·2+2

IDI~ECT

ASSIGNMENT.

GlOIGlCIIGI

0101"''''

II 111''''116 R

""''''01010 A

~ '''''''123
IlItJI''''I:'' It , 2C1' 122
tJlOItJllI" It 22t1111/!
"''''tJl0I5 It 7412"'0
tJllIltJIlI''' It 1'101",,17
OI01\11G1' It ""11'01",3
"'0I1l11\11 II '2~,'7
tJI\IItIII1 It Cl'15"'1"
""'tJlh ~
"tJI"'PI ~ ".tJlll~

"'Ill "'01 ,

U
,:

PRIIIIT

E
R
A

R
A
A
R

"".O A

"'1Il"1'

'3!'!",,,,0 A

GlIIIGI,!! II
"'tJlGlI" It
UtIII'1t
tJllU2tJ1 II

'2t111'11 0i A
Gl51l1"'~~ R
<14"'115 R

"'01"'"

"0"'tJl24 R

LOOP

""'!llPll~ R

II 2",,,,,2~ II

NOBUF

0I0ItJl2:" II (11''''123 R
"'''''''2' It ,."'tJl0I0 A

CHAIIIGE

tJI"'GI'~

""'''2!'!

I'II'I,,,,OI~

fJlDlGl2'

fJI"'flI3'"

tJlOItJl3'

A .G
~tJI"",01
.G
"I'ItJ1011'10 A .G
t110",,,,CI'0 A .G
,"'''' 12/5 R

flI""'~'

"""'0,4 R

"'",Ill,,,

I/J

DAC
ACSAV.
(SAVeUF)
LAC
JMS.
SAVE
LAC.
ACSAV
SNA
NoeUFF
JMP
OAC
IOIRIT£+3
HC
-I
C10)
OAC*
LAW
-BUFSIZ
CAC
COUNT
CL.X
LAC*
1'"
BUF,l(
DAC
COUNT
ISZ
JMP
LOOP
JMP
CHANGE
CERRMSG)
LAC
OAC
WRIT+3
NOP
.INIT
OUT,I,1Il
CAL+t*I",1Il0 OUT&777

IsueROUTINE ENTRY POINT.
IVARURLE.
ILITI::RAL.
IEXTERNAL CALL.
IBUfFER ADDRESS.
IUNDEFt~ED SYMBOL (~ISSPELLED).
IUNDEFINEO SYMBOL BECAUSE OF
12 FORWARD REFER~NCES.
IAUTOI~OEl( REGISTEr:1.

IINDEX REGISTER REFERENCE.

IUNDEFINEO (MISSPELLED).
ISYSTEM MACRO CALL.

0+0
QI

LAC
OAC

(JMP AROUNO)
CHANGE

.EJECT

5-15

IPAGE £JECT.

Operating Procedures

UMPLfI' SRC:

SAMPL.E PROGRAM

WRITe-AROUND
AROUNO .WRITE OUT,2,~~,,,,
",,,,,pille
CAL+2*11'1r110 OUTA777
"I~1II33
*G
11
111111"'3. D "'1'1",,,,\1
*G
~)(
1lI1II1II3~ C/ 7.111",.0
*G
.Dec
*G
"'111"138 0 "'111",,,,1'10 A *G
-0
"'111"'3~

C/
0

••

IFOR~ARD REFERENCE.
ISYSTEM MACRn CALL.

•

"'11111137

"'(11"'.\

"'(11111.:\

.WAIT
OUT
CAL OUT&777
12
CSAVf'\UF)
LAC
RESTOR
JMS*
ACSAV
LAC
PRINT
JJotP*

•• *G*G
'''''''123 R

"'rIII'I",,,,e
"'(IIIlI.1II D '" 1!1I" III t 2

"'111014' C/ t:!"'121 E

"'III"' •• It

'1'1"'116 R
I'! 2'" 1'1 1'10 R

ISYSTEM MACRO CALL.

IE~TERNAL

CALL.

"''''111.'5

"'1'I1lI!!1II
"'!!JI'I!!'
"'''''''!!'
"'III"'!!'
O.I"'I'II!!'
1lI(I!tII!!'5
1lI"'11 ~

II
II

"'1'1:\1111'12 A

A
"'Ill"'.'" D "'1'1"''''1'10
42 111 452 A
"''''111.'
C/

iii

"'111"'1'11'11O A
A

THE

ERRMSG

NE~T

LINE CONTAINS THREE ATATEMENTS.

00~01/l2'

III,

.LOC
.BLOCK
.BLOCK

• -1
3

.ASCII IERROR/<15>

'.'15
•• A
"'15.1'11'10 A

It
It
It

I
I

•

"'01'11(111'110 A

SAVBUF
BUF
COUNT

LOCATION COUNTER •
XR ANO LR.

ICHA~GE

IMQ,

BUFSIZ

I
I

FOLLOWING THE .END STATEMENT ARE THREE LOCATIONS (NOT SHOwN)
ANO TWO UNDEFINED SYMBOLS (NOBUFF
I AND WRITE, T~E LATTER BECAUSE OF A DOUBLE FORWARD REFERENCE).
I FOLLOWING T~AT (SHOWN) ARE TWO EXTERNAL TRANSFER VECTORS
I AND FOUR LITFRALS.

I FOR ONE VARIABLE (ACSAV)

"'1111'1"'1'10 A
D "'UU1 E *E
"''''' 2 t D
"'1'1"'1'2 E *E
"'0.112:\ 1/ "''''''''''52 R *L.
IIIO.I'U D "'1'1"''''10 A *L
"""12'5 If 1'II1!I"'0.e R *L.
"'lIIt2i1! D il!Ml'I33 R *L
sI,E-0"'130

.END

"''''12'

3 ERROR L.IN!!

5-16

Operating Procedures
SA ,",01 . t

ACSAV
CIotA NG I:.
NOBUF

~Io.' ~

~t."'~\.1:.

PI(OG~."I

'''1'111 ~

1 r~ () '. I~. n

/- rAflJJ

1'1'

~ I )F

c: (11., T

III~~~~

"'0 111 2<1

,,' ,A 1 \ ~

tiU~SIZ

1'\

E~iOI"1~r;

"'~ 'H~

L.OUP

''\IT
SAvE

•

MQlQ!4Q!

~001~

!olR1NT

~Q!0Q10

wIDT~

01001111;

VII'l1ll2')

~ .., "", F ~

0!~1:.!\
11 ~ 12 "

I=:

~ ~ v%F

r, "! 117
t ,~~, 52

10\

', C'r or E

:'h' ;\ ;t ,~~

P~H~T

1I~ ')lI.1t!1

('1 ,' T

~/~ ' ' JI~

1.00~

t'liI'f.11~

CH. ~I Gf.

~, ObUF

011!~2:r?

'" ~ r.' 33

(I:(H'l~J3

'iUFSIZ

COU~T

~UF

~~~es!5

2Iltl 11 II!

..,ILlTH

t'I~0I~40

v''' '~ 5 C?

10110 Ire::

ft ." 0, ' ,\,1"
.~ '. V,~ I) ~

Ef.I~"'SG

"'f'I~24
?I II'~ 4 !II

A~5 ,~V

,':H 10

10(

N('~uFr

1'.01121

~~I17

~ ,I \' ~

. ~ 'A

wRIT

RESTOf(
W~IT

RfS,C\R

SA" PIE. C ,H: C; S

ACSAV

~ '.H 1~

AROU~I D

RUF
eUFSIZ

"~~J'
"' ''' 1115~

:-~

CII'II~"'4'"

1Q.

C~.~Gt:

~e'Ql24

COUP,,'[

1JI~11~

ERRMSG
LODfJ

~""245

:,~

~0I0I1~

~e-

"14.

"'OBUF
NOBUFF
OUT

o;~

~:!>

<I!i_

''1-

III

., 1
ill_

:t('

~2.

0I~"'2?

~Q ..

')7
, ~~ *

11
;>t*

P~H'T

",,,,(HIli

~~SlOFI

9'~121

SAVH'F

12
12

P.'~"5'

,:!o

"\1

\VIOt ..

(I (l\ 122
1')1 01 01 1 1 ,.

wRlT

"''II! :i' .~

\ORIH

~'IIf)I"3'

SAVE.

5.7

.,,,
1Jr>

M122

0~0110

e~121Z1

EFE 10( E~, Ct

(1.rA 117
(l!('I~~0~

iO/

12:2 t:

0~",rA...,~

~\1

'54

'52

, ".

~ '" ''
19

~ 7 ..

RUNNING INSTRUCTIONS

Once the Assembler has identified itself,
assembly.

it is ready to perform an

Proceed as follows:

Place the source program to be assembled on the appropriate
input device.

Type the command string.

5.7.1

Paper Tape Input Only

The following steps are required when the source program is encountered
in the paper tape reader:
a.

At the end of a source tape segment which is not terminated
with a .END statement of at the beginning of PASS 2 or PASS 3,
the Assembler types
tP

Place the proper source tape in the reader.

5-17

Operating Procedures

c.
5.7.2

In XVM/DOS type CTRL P to continue.

For RSX, type CTRL

p).

Cross-Reference Output

At the end of PASS 2, PASS 3 will be performed by the Assembler for the
cross-referencing operation if the X option is requested.

At completion,

the assembler will be restarted (except in RSX systems) to permit additional assemblies if the command string is terminated by a CARRIAGE
RETURN ()

entry.

When a cross reference output is requested, the symbols are listed in
alphabetic sequence.

The first address after the symbol is the location

where the symbol is defined or its 6-digit value if it is a direct
assignment.

All subsequent locations represent the line number (deci-

mal) where the symbol was referenced.

The line number with the

asterisk is that in which the symbol is defined.

Leading zeroes are

suppressed for the cross-reference symbol table.

Nine line numbers

are printed on one line and subsequent line numbers are continued on
the next line.
Example:
PAGE

PRGA

CROSS REFERENCE

xxxxxt ...... XXXXX
xxxxx

B
SYMBOL

5000
100

XXXXX
XXXXX
XXXXX*
XXXXX*

Cross referencing can be a useful tool even without the aid of a line
printer.

It is possible to put the source assembly listing with line

numbers onto a directoried device, such as DECtape, and the cross
reference table (by a separate assembly) on a teleprinter.

Then,

desired lines in the "LST" file can be accessed by using the EDITOR.
LIMITATIONS
A.

Before cross reference output can begin, PASS3 of the Assembler must first have read the entire source file(s) and
stored the reference line numbers in core memory. Should
available core be too limited, the Assembler will output the
following message to the listing:
CORE EXHAUSTED AT LINE DDDD
where D is a decimal digit. Then the Assembler outputs all
the references found up to that point.
5-18

operating Procedures

For programs with more than 9999 lines of source code,
line numbers begin again at 0000 on line 10000.
In the
cross-reference listing, 10000 is represented as :000,
11000 as i000, and so on. These special characters are
simply those which follow the numerals in the ASCII character set (Appendix A).
Below is a list of characters
and their meanings.

10
11
12
13
14
15

<
>

To conserve core space, PASS3 of the Assembler does not
maintain a permanent symbol table. Consequently, if user
defined symbols are identical to permanent symbols, references to the permanent symbols will be included in the
cross reference.
For example:
LAC A
TAD LAC

LAC 5
Three references to LAC will be listed.
D.

Conditionals (.IFxxx through .ENDC) are treated during
PASS 3 as if they are always satisfied. Consequently,
although a conditional might not be satisfied during
PASSl and PASS2, references within to defined u s er symbols will appear in the cross-ref e rence output.
Note that undefined symbols which are referenced in .IFDEF
and .IFUND statements remain undefinedi hence, these do
not appear in the cross reference.

5.8

PROGRAM RELOCATION

The normal output from the MACRO XVM Assembler is a relocatable object
program, which may be loaded into any part of memory regardless of
which locations are assigned at assembly time.

To accomplish this,

the address portion of some instructions must have a relocation constant added to it.

This relocation constant is added at load time by

the Linking Loader, CHAIN or TK Bi it is equal to the difference between the memory location that an instruction is actually loaded into
and the location that was assigned to it at assembly time.

The As-

sembler determines which storage words are relocatable (marking them
with an R in the listing), which are absolute (making these non-relocatable words with an A) and which are external

5-19

(marking these with an E).

Operating Procedures

The rules that the
',';:l'::;

Asse~b l e r

follows to determine whether a storage

is a >so l 1.ite or .cc Ioca t a bl.e ale

ciS

fol J ov,',c, :

If the add r ess is a number (not a symh ol), the address is
absolute.

If the a dd ress is a symbol which is defined by a direct as s ignme nt (i. e ., =) and the righthand side of the assignment is a
number. all references to the symbol will be absolute.

If a user symbol is defined within a block of coding that is
absolut e , the value o f that symbol i s absolute.

Variables , '. lnd efin ed sy:r,'~ ·')ls,. e xt.ernal transfer vector s, and
Ij,terals get the same rr,;lOC C;.t:"on as was in effect when .END
was encountered in PASS 1.

If the location counter (.LOC pseudo-op) references a symbo l
which is not defined in terms of a relocatable address, the
symbol is absolute.

All others are relocatable.

The following table depicts the manner in which the Assembler handles
exp r essions which contain both absolute and relocatable elements.
(A=absolute, R=relocatable)
A+A=A
A-A=A
A+R=R

A-R=R
R+A=R
R-A=R

R+R=R and f lagged as possible error
R-R=A

If multiplication or division is performed on a relocatable symbol.

will be flagged as a possible relocation error.
If a relocatable program exceeds 4K, and the assembler is a page mode
version, the following warning message will be typed at the end of
PASS 2:
PROG > 4K
5 .9
5. 0 .1

SYSTEM ERROR CONDIT I ONS AND RECOV ERY PROCEDURES
XVM/DOS and BOSS XVM

See the XVi'VDOS User r s fllanual, Appendix D or the XVflj/ DOS Keyboard
Command Guide, Appendix C for descriptions of lOPS error messages.

5-20

Operating Procedures
5.9.2

XVM/RSX
Recovery Proced ure

Printout
MAC-I/O ERROR LUN xx yyyyyy

5.9.3

5.10

is produced on LUN 3: xx represents
the Logical Unit Number (decimal)
and yyyyyy the octal Event Variable
value indicating the cause of th e
error.
See the XVM/RSX System Manual for the meaning of the error
Event Variables. Control is automatically returned to TDV.

Restart Control Entries (DOS only)
CTRL P

Restart Assembler, if running

CTRL C

Return to Monitor

ERROR DETECTION BY THE ASSEMBLER

MACRO XVM examines each source statement for possible errors.

Th e

statement which contains the error will be flagged by one or several
letters in the left-hand margin of the line, or, if the lines are numbered, between the line number and the location.

The following tabl e

shows the error flags and their meanings.
Flag

Meaning

Error in direct symbol table assignment - assignment
ignored

Memory bank error (program segment too large)
Page error - the location of an instruction and
the address it references are on different memory pages (error in page mode only)
A .ENDC appears before an unsatisfied .IFxxx.
1.

Statement contains a reference to a multiply-defin e d
symbol - the first value is used.

Symbol not found in user's symbol table during
PASS 2
Operator combined with its operand may produce
erroneous results

Forward reference - symbol value is not resol ved by
PASS 2

Line ignored:
1.

2.
3.
4.

Relocatable pseudo-op in . ABS program
Redundant pseudo-op
.ABS pseudo-op in relocatable program
.ABS pseudo-op appears after a line has been
assembled

5-21

Operating Procedures
5.
6.
7.
8.
9.

A second .LOCAL pseudo-op appears before a
matching . NDLOC pseudo-op
An .NDLOC appears without an associated .LOCAL
pseudo-op
Too many .LTORG p s eudo-ops (more than 8 )
.IODEV pseudo-op in .ABS or .FULL program
Illegal statement within .CBS and . CBE

Literal error:

1.
2.

Phase error - literal encountered in PASS 2 does
not equal any literal found in PASS 1
Nested literal (a literal within a literal)

Multiple symbol definition - first value defined is
used
N

Error in number usage (digit 8 or 9 used under .OCT
influence)

Phase error:
1.
2.

PASS 1 symbol value not equal to PASS 2 symbol
value (PASS 2 value ignored)
A tag defined in a local area (.LOCAL pseudo-op
is also defined in a non-local area

Questiona b le line:

1.
2.
3.
4.

Line contains two or mor e sequential operators
(e.g., LAC A+*B)
Bad line delimiter - address field not terminated
with a semicolon, carriage return or a comment
Bad argument in .REPT pseudo-op
Unrecognizable symbol with .ABS(P) pseudo-op

Possible relocation error

Symbol error - illegal character used in tag field
U

Undefined symbol

w
x

Line overflow during macro e xpansion
Illegal use of macro name or ind e x re g iste r
1.
2.
3.

Unmatched .IFxxx and .ENDC
Unmatched .DEFI N and .ENDM
Unmatched .CBS and .CBE

In addition to flagged lines, there are certain co ndition s which will
cause assembly to h e terminated premature ly.
Message

Heaning

SYNTAX ERR

Bad command string, control returns to TDV
(RSX only)

Bad command string, retype (not RSX)

NM1E ERROR

File name d in command string not found.
In
DOS, the Assembler will restart and accept
another command string.
RSX ~~ CR O will return to TDV.
BOSS will return to the Monitor.

TARLE OVERFLOH

Too many symbols and/or macros

CALL OVERFLOH

Too many embedded macro calls

CORE EX HAUSTED
AT LI NE nnn

PASS 3 error - too many symbol references

5-22

APPENDIX A
CHARACTER SET

Printing
Character

7-bit
ASCII

100
101
102
103
104
105
106
107
110
111
112
113
114
115
116
117
120
121
122
123
124
125
126
127
130
131
132
133
134
135
136
137
000
011
012
013

A
B

C
D
E
F
G

H
I
J
K

L
r1
N
0

P
Q

R
S
T
U

V
W

X
y

"']*
t*
+-*

Null
Horizontal Tab
Line Feed
Vertical Tab

6-bit
Trimmed
ASCII
00
01
02
03
04
05
06
07
10
11
12
13
14
15
16
17
20
21
22
23
24
25
26
27
30
31
32
33
34
35
36
37

Printing
Character

7-bit
"_SCII

6-bit
Trimmed
ASCII

Form Feed
Carriage Return
ALT MODE (ESC)
Rubout
(Space)

014
015
175
177
040
041
042
043
044
045
046
047
050
051
052
053
054
055
0')6
057
060
061
062
063
064
065
066
067
070
071
072
073
074
075
076
077

40
41
42
43
44
45
46
47
50
51
52
53
54
55
56
57
60
61
62
63
64
65
66
67
70
71
72
73
74
75
76
77

#
S
%
&

(
)

0
1
2
3
4
5
6
7
8
9

:*
;

<
=

>
?

*Illegal as source, except in a comment or text. Any characters not
in this table are illegal to HACRO XVr1 and are flagged and ignored.

A-I

APP Ej\'D1X B
PEmilANENT SYMBOL TABLE
Operate

GLK
LAW

7033 04

7 500 10

DBK

760000

DBR

703344

rOF

7000 02

OPR

740000

NOP

740000

CMA

74 0001

EAE

6400( 0

1 01'7

70 0 042

CML

740002

LRS

0 4 O~=, (!O

CAP

70330 2

OAS

7 40004

L8,'5

F,f,r,500

R PS

70 7 74 2

EAE

RAL

74 00 1 0

LLS

6 40600

RAR

740020

LLS3

6 60600

CA L

000000

lAC

74 0 030

ALS

64070 0

Dl·\.C

0 4n ooo

HLT

7 4 0040

ALSS

660700

...T ~~ S

1 00000

740040

NORM

6 4 0444

DZI

14000 0

Memor y Refe r e n ce

SMA

74 0 1 00

NORMS

6604 44

LAC

20 00 00

SZA

740200

MUL

6 5 3122

XOR

240000

SNL

7 40400

MULS

65712 2

JI"DD

30 0 000

SML

7 40400

DIV

640323

TAD

3400n o

SKP

74 1 000

DI VS

644323

XCT

<100000

S PA

74 1100

IDI V

(r:'''''')
") 1
') .. ,' • .1 . J ." ,_

L SI:

SNA

741 20 0

~~'rj l \J~:;

IS ~ ) '7 ') :2 ~~,

AND

4 400 0 n
~; C or t) (

SZL

741400

FRDIV

650323

SAD

<; 40 0 00

3 PL

741 400

FRD IV S

f,543 73

lTiJ P

f, 000 00

RTL

742010

CLAC

64 HI{ ' C,

RTR

7 42020

LACQ

641002

SvTHA

74 2030

LAC S

6 4 1001

CLL

7 44000

CLQ

650000

STL

744 002

ARS

64400 0

,l>,'.l: Oli'at lC

i'::' i o r j ty

Interrup-L
RP L

7 0S S1 2

SPI

705501

I SA

705504

CCL

744 002

GSM

664000

RCL

7440 1 0

OSC

64000 1

Index I nst r u c tio n s
Wh ic h Take an Immen i ate
Nine - bit O D ~rand

RCR

744 02 0

OMQ

6400 02

7 2 30 00

CLA

750000

CMQ

640004

AXR

73700.0,

TCA

7 4003 1

LMQ

652000

AXS

725000

CLC

75 000 1

LAS

75000 4

lOT

700000

EBA

7 07764

LAT

7 .5000 4

IORS

700 3 1 4

DBA

70 7 76 2

lO T

tvlod e Swi tc hincL

B- 1

Permanent Symbol Table

Index and Limit Register
Instructions T'lhich do
not use Operands
PAL

736000
722000

PAX

721000

PLA

730000

PLX

731000

PYA

724000

PXL

726000

CLX

735000

CLLR

Index Register Value

10000

B-2

APPENDIX C
V~CRO

CHARACTER INTERPRETATION

Character
Name

Function
Syrt1bol

Space

Field delimiter.
in this manual.

Designated by L...I

Horizontal tab

Field delimiter.
in this manual.

Designated by ~

Semicolon

Statement terminator

Carriage return

)

Statement terminator

Plus

Addition operator (two's complement)
Subtraction operator (addition of
two's complement)

Minus
Asterisk

Multiplication operator or indirect
indicator

Slash

Division operator or comment
initiator

Ampersand

Logical AND operator

Exclamation point

Inclusive OR operator

Back slash

Exclusive OR operator

Opening parenthesis

(

Initiate literal

Closing parenthesis

)

Equals

~erminate

literal

Direct Assignment

Opening angle
bracket

Argument delimiter

Closing angle
bracket

Argument delimiter

Comrr.a

Question mark

An argument delimiter in macro
definitions or an exclusive OR
operator
?

Created symbol designator in macros

Quotation mark

Text string indicator

Apostrophe

Text string indicator

Number Sign

Variable indicator

Dollar sign

Real argument continuation

Line feed
Form feed

non_printing}
non-printing

Vertical tab

non-printing

COlnmercial At

not applicable
Concatenation operator in macro
definitions
C-l

Macro Character Interpretation

Character
Name

Function
Symbol

Null

Blank Character

Ignored by the Assembler

Delete

Blank Character

Ignored by the Assembler

Illegal Characters
Only those characters listed in the preceding table are legal in ~~,CRO
XVM source programs, all other characters will be ignored and flagged
as errors.

The following characters, although illegal as source, may

be used within comment lines and in text preceded by .ASCII or .SIXDT
pseudo-ops.
Character NaMe

Symbol

Left bracket
Right bracket

[
]

Up arrow

Left arrow
Colon

C-2

APPENDIX D
SUMMARY OF

~~CRO

Pseudo-op
(Section)

Format

· ABS (3.2.1)
· ABSP (3.2.1)

-j. ABS -j NLD)
-j. ABSP-j NLD)

. ASCII (3.3.1)

XVM PSEUDO-OPS

Function
Object program is output
in absolute, blocked,
checksummed forna.t for
loading by the Absolute
Binary Loader.
Not
supported in RSX .

label * -j.ASCII-j /text/ <octal»
Input text strings in
7-bit ASCII code, with
the first character
serving as delimiter.
Octal codes for nonprinting control characters
are enclosed in angle
brackets.

.BLOCK (3.11)

· CBC ( 3 • 5 • 4 )

la bel * -j . BLOCK-j exp)

Reserves a block of
storage words equal to
the expression.
If a
label is used, it references the first word in
the block.

-j.CBC-j displacement, value)
Initialize a word of a
common block to a constant.

· CBD (3. 5 . 1)

label *-j .CBD-jNAME, /size)

Sets up a COMMON area
having the name and size
specified. The first
element in the COMMON
area is also given (base
address) .

· CBE (3. 5 . 5)

End of common block initialization section.
,

· CBDR ( 3 . 5 . 2)

label*-j.CBDR-jdisplacement) Enters the starting
address of the last
common block specified
in a .CED plus the argument into the location
of tre .CBDR.

* All pseudo-ops shown with a label generate binary output code.
D-l

Summary of MACRO XVM Pseudo-ops

Pseudo-op
(Section)

Function

Format

· CBS ( 3 . 5 • 3 )

-j.CBS-jname [, size])

Start common block initialization section.

· DBREL ( 3 . 2 • 3 )

-I.DBREL)

Disable bank mode relocation.

.DEC (3.10)

-I.DEC)

Sets prevailing radix to
decimal.

.DEFIN (3 . 4)

~.DEFIN-:lmacroname, args)
Defines macros .

. DSA (3.16)

label* -I.DSA~exp~

Generates a transfer
vector for the specified
symbol .

. EBREL (3.2.3)

-I.FBREL)

Enable bank mode relocation.

· EJECT (3. 1. 2)

-I. EJECT)

Skip to head of form on
listing device.

· END (3.12)

-I. END-I start)\

· EtmC

(3.6)

-I. END C)

Terminates conditional
coding in .IF statements.

· ENDM (3.4)

-I. ENDM )

Terminates the body of a
macro definition.

· EOT (3.13)

-I. EOT)

Must terminate physical
program segments, except
the last, which is
terminated by .E~D.

· ETC (3.4)

-I. ETC-I args, args)

Used in macro definition
to ~ontinue the list of
dummy arguments on
succeeding lines.

· FULL ( 3 • 2 • 2)
· FULLP ( 3 • 2 • 2)

-I. FULL )
-I. FULLP)

Produces absolute, unblocked, uncheck s ummed
binary object programs.
Used only for paper tape
output. Not supported
in RSX.

.GLORL (3.14)

--j.GLOBL-j sym, sym, sym) Used to declare all
internal and external
symbols which reference
other programs.

terminate every
source program.
START
is the address of the
first instruction to be
executed.

~~ust

*All pseudo-ops shown with a label generate binary output code.
D-2

Summary of

~~CRO

XVM Pseudo-ops

Pseudo-op
(Section)

Format

.IFxxx (3.6)

-.,. IFxxx -j exp)

.IODEV (3.15)

-j. IODEV -j. DAT numbers)

Function
If a condition is satisfied, the source coding
following the .IF statement and terminating with
an .FNDC statement is
assembled.

Specifies .DAT slots and
associated I/O handlers
required by this program. Not supported in
RSX.
. LOC (3.9)

-j. LOC -j exp)

Sets the location counter
to the value of the expression.

.LOCAL (3.7)

-j.LOCAL)

Allows deletion of certain symbols from the
user symbol table.

.LST (3.1. 3)

-j.LST)

continue requested assembly listing output of
source lines. Lines
between . NOLST a.nd . LS'T
are not listed.

.LTORG (3.8)

-j.LTORG)

Allows the user to
specifically state where
literals are to be stored.

.NDLOC (3.7)

-j.NDLOC)

'Terminates deletion of
certain symbols from the
user symbol table contained between .LOCAL
and .NDLOC .

. NOLST (3.1.3)

Terminates requested
assembly listing output
of source lines of code
contained between .NOLST
and .LST .

. OCT (3.10)

sets the prevailing radix
to octal. Assumed at
start of every program.

.REPT (3.17)

-I. REPT-j count, n)

D-3

Repeats the object code
of the next object code
generating instruction
Count times. Optionally,
the generated word may be
incremented by n each
time it is repeated.

Summary of MACRO XVM Pseudo-ops

Pseudo-op
Section)
.SIXBT (3.3.2)

Format

Function
\

label-l.SIXBT-I/text/<octal>,J

Input text strings in
6-bit trimmed ASCII, with
first character as delimiter. Numbers enclosed
in angle brackets are
truncated to one 6-bit
octal character.
.SIZE (3.18)

.TITLE (3.1.1)

MACRO outputs the address
of last location plus one
occupied by the object
program.

label-/. SIZE)

-I. TITLE-/ any text string)
Causes the Assembler to
accept up to 5010 typed
characters. During
source program assembly
operations, a .TITLE
causes a form f e ed cod e
to b e output to place the
text starting with .~ITLE
at the top of a page.

D-4

APPENDIX E
SOURCE LISTING OF THE ABSOLUTE BINARY LOADER

700004
700112
700144
700101
017720
7033 02
700004
70001 2
7055 04
740000
707702
017726
157775
117753
057776
741100
617747
117753
057777
117753
017736
117753

0 77776
457776
457777
617736
357775
740200
740040
617726
017747
'lI57777

457777
617763
740040
017753

I***A BSO LUTE B INARY LOADER ***
I
.FULL
CLOF=700v) 0 4
RR8=700112
RSB=70Vl144
RSF=7vJ0101
LDSTRT=17720
BJNLDR CAF
ICLEAR FLAGS
CLOF
ICLOCK OFF
II NTERRU PT OFF
I OF+10
ISA
ITUR N OFF API
LODMOD NOP
I (E BA ), (DBA), (NOP)
7 0 7702
IPDP-9 CO~PATIBILITY <EE M)
LDNX8K=17726
DZM LDCKSM
ICHECKSUMMING LOCATION
JMS
LDREAD
DAC LDSTAD
IGET STARTING ADDRESS
SPA
IBLOCK HEADING Ok
JMP
LD XFR
ISTART BLOCK
JMS
LDREAD
DAC
LDl~DCT
IWORD COUNT <2'S COMPLE MEN T)
JMS
LDREAD
LDNX l'ID= 17736
JMS
LDkEAO
ILOAD DATA INTO APPROPRIATE
DAC* LDSTAD
LDSTAD
I MEMOR Y LOCATIONS
ISZ
LDWDCT
IFINISHED LOADING
ISZ
LDNXWD
11'10
JMP
LDCKSrv,
TAD
/LDCKSM SHOULD CONTAIN 0
SZA
ICHECKSUM ERROR HALT
HLT
LDI\lXBK
IPRESS CONTINUE TO IGNORE
JMP
LDXFR=17747
DAC
LDl.JDCT
LD \.J DCT
ISZ
IEXECUTE START ADDRESS
LDltJA IT
JMP
INO ADDR ESS ON .END STATE~ENT
HLT
IMANUALLY START USER PROGRAM
LDREAD=17753

E-l

Source Listing of the Absolute Binary Loader

000000
700144
357775
057775
700101
617757
700112
637753
017763
117753
637776
006235
003500
000000
000261
000277
000320
000000
017775
017776
017777

o
RSB
TAD
LDCKSM
DAC
LDCKSM
RSF
JMP LDREAD +4
RRB
JMP* LDREAD
ITHE LAST FRAME OF EVERY .ASS(P} PROG IS GARBAGE.
LDWA IT=17763
JMS
LDREAD
IPASS OVER LAST FRAME (PDP-9
JMP* LDSTAD
ICOMPATIBILITY).
ENDLDR =.
HRMWD 003500; 0
IHEADER
261;

277

320;

LDCKSM=17775
LDSTAD=17776
LD',IDCT = 1 7777
I
.END BINLDR
1*** END OF LOADER

IHRM START

***

E-2

INDEX
AAC, AXR, AXS evaluation, 2-28
Absolute
address, 5-20
format, 3-4, 3-5
mode, 2-22
symbol, 5-20
Absolute Binary Loader (ABL) ,
3"'4
.ABSP pseudo-op, 3-4, 3-5, 3-6
.ABS pseudo-op, 3-4, 3-5, 3-6
Addition operator, 2-12
Address assignments, 2-13
Address field, 2~1, 2-2, 2-21
Addressing,
indexed, 2-15
indirect, 2-14
Angle bracket «» delimiters,
3-9, 3-10, 4-6
Argument delimiters, see
Delimiters
Arguments,
dummy, 3-11, 4-1, 4-2, 4-3
real, 4-4
Arithmetic operators, 2-12
ASCII character sets, 3-8, A-l
.ASCII pseudo-op, 3-9, 4-3
Assembler restart, 5-3
Assembly listings, 5-13
Assembly, optional, 3-15
Asterisk (*) (multiplication
operator), 2-20
Asterisk (*) usage, 2-14, 2-20
At symbol (@) usage, 4-8
Auto-index registers, 2-23

Bank bits, 2-27
Bank mode, 2-22
Bank Mode Assembler, 5-1
Base address, 3-12
Basic statement, 2-1
.BLOCK pseudo-op, 3-22
Boolean operators, 2-12

Calling procedure, 5-1
Carriage-return, 2-1
.CBC pseudo-op, 3-14
.CBD pseudo-op, 3-11
.CBE pseudo-op, 3-14
.CBDR pseudo-op, 3-12
.CBS pseudo-op, 3-13
Characters,
ASCII, A-l
command, 5-2

Characters, (cont.)
MACRO, C-l
nonprinting, 3-10
Command characters, 5-2
Command string format, 5-3
Command string terminators, 5-3
Comma (,) usage in argument
string, 4-8
Comments, 2-1, 2-3, 2-23, 4-2
Common block
definition, 3-11, 3-12
initialization, 3-13, 3-14
pseudo-operations, 3-11
Concatenation, 4-8
Conditional assembly pseudooperators, 3-15
Conditionals, 5-19
Configuration, 1-2
Created symbols, 4-7
Cross-reference output, 5-18
CTRL C, 5-21
CTRL D, 5-3
CTRL P, 5-2, 5-21
CTRL U, 5-2

.DBREL pseudo-op, 3-7
Decimal values, 2-10
.DEC pseudo-op, 3-21
.DEFIN pseudo-op, 3-11, 4-2
Delete current line, 5-2
Delete single character, 5-2
Delimiters,
argument, 4-6
field, 2-2, 2-20, 2-21
statement, 2-2, 2-20, 2-21
text, 3-9
Devices, directoried, 3-5, 5-10
Direct assignment statement, 2-3
Division by zero, 2-12
Division operator, 2-12
Dollar sign ($) used as
terminator, 4-5
.DSA pseudo-op, 3-26
Dummy arguments, 3-11, 4-1, 4-2,
4-3

EAE clasB instructions
evaluation, 2-28
.EBREL pseudo-op, 3-7
.EuECT pseudo-op, 3-3
Embedded macro calls, 4-19
.ENDM pseudo-op, 3-11, 4-3
End of program pseudo-operation,
3-23
Index-l

INDEX (Cont.)
End of program segment pseudooperation, 3-24
.END pseudo-op, 3-23
.EOT pseudo-op, 3-24
Equal sign (=) usage, 2-8
Error conditions, 5-20
Error detection, 5-21
.ETC pseudo-op, 3-11, 4-2
Exclusive OR operator, 2-12
Executable object program, 1-3
Expressions, 2-12
External symbols, 3-25
External transfer vectors, 5-20

Field delimiters, 2-2, 2-20,
2-21
Field-dependent symbols, 2-5
Fields in statements, 2-1
address, 2-21
comments, 2-23
label, 2-17
operation, 2-20
Filename commands, multiple,
5-7
Filenames, 5-3, 5-9
Forward reference, 2-9, 3-17
Fractional remainders, 2-12
.FSTAT system macro, 5-10
Full binary format, 3-6
.FULLP pseudo-op, 3-5, 3-6
.FULL pseudo-op, 3-5, 3-6

Globals, evaluation of, 2-4
Global symbol declaration
pseudo-operation, 3-24
Global symbol definitions,
1-3
.GLOBL pseudo-op, 3-24

Handlers, 5-10
Hardware, 1-2

.IFxxx pseudo-ops, 3-15
Inclusive OR operator, 2-12
Indexed addressing, 2-15
Index register, 2-25, 2-26, 4-3
Indirect addressing, 2-14
Instruction mnemonic symbols,
2-5
Integer values, 2-11
Internal globals, 3-25

Internal .GLOBL symbols, 2-9
.IODEV pseudo-op, 3-26
lOPS ASCII packed format, 3-9

Label field, 2-1, 2-17
Labels, 2-2, 2-4
LAW evaluation, 2-28
Library routines, 1-3
Line numbers, 5-19
Linking Loader, 1-1, 2-23
Listing control pseudo-operations,
3-3
Listing output control, 3-4
Literal origin pseudo-operation,
3-20
Literals, 2-16, 5-20
.LOCAL pseudo-op, 3-17
Local symbols pseudo-operators,
3-17
Location counter, 2-13, 2-14,
5-20
Location counter ~seudooperation, 3-21
.LOC pseudo-op, 3-21
Logical AND operator, 2-12
.LST pseudo-op, 3-4
.LTORG pseudo-op, 3-20

Macro
body, 4-3
call, 4-19
definition, 4-2
definition file, 5-8, 5-12
definition pseudo-operations,
3-11
instructions, 4-1
nesting, 4-17
redefinition, 4-18
MACRO characters, C-l
Memory, 3-17, 3-22, 5-19
Memory references across page
boundaries, 3-7
Memory referencing instruction
format, 2-6
Mnemonics, 2-5
Multiple file assemblies in
XVM/RSX, 5-12
Multiple filename commands, 5-7
Multiplication operator, 2-12

Name of program, 3-3
.NDLOC pseudo-op, 3-17
Nested conditional statements,
3-16
Index-2

INDEX (Cont.)
Nested literals, 2-16
Nesting of macros, 4-17
NLD option, 3-5
.NOLST pseudo-op, 3-4
Non-printing characters, 3-10
NUll'.bers, 2-10
evaluation of, 2-24
Number sign (n usage, 2-7, 4-3

Pseudo-operations (Cont.),
global symbol declaration, 3-24
listing control, 3-3
literal origin, 3-20
location counter, 3-21
macro definition, 3-11
object program output, 3-4
radix control, 3-21
repeat object code, 3-26
request I/O device handler, 3-26
request program size, 3-28
reserve blocks of storage, 3-22
summary, 3-1, D-l
text handling, 3-8

Object code, 1-3
Object program output pseudooperations, 3-4
Octal values, 2-10
.OCT pseudo-op, 3-21
Operating procedures, 5-1
Operation field, 2-1, 2~2,
2-20
Operators,
arithmetic, 2-12
Boolean, 2-12
Options, 5-4
Output, 1-1, 5-19
code, 3-4
listing, 5-13

Question mark (7) usage, 4-7

Page mode, 2-22
Page Mode Assembler, 5-1
Paper tape
input, 3- 6
output, 3-5
source program, 5-17
Parameter file, 5-8
Parentheses usage, 2-16
Passes, 1-2, 2-9, 5-18
Period (.) usage, 2-5, 3-1
Permanent symbol table, 2-4, 3-1
5-19, B-1
Pointer, 1-3
processing, 1-2
Program
end, 3-23
filename, 5-3, 5-9
relocation, 5-19
segment end, 3-24
segment identification, 3-3
size, 3-17
Programs, relocatable, 1-3
pseudo-operations,
common block, 3-11
conditional assembly, 3-15
designate a syrrbolic
address, 3-26
end of program, 3-23
end of program segment,
3-24

Radix, 2-10
Radix control pseudo-operation,
3-21
Real arguments, 4-4
Eeassembly, 1-3
Recursive macro calls, 3-16, 4-20
Redefinition of macros, 4-18
Redefinition of symbols, 2-8,
2-19
Referencing the location counter,
2-14
Relocatable programs, 1-1, 1-3,
5-19
Relocation mode, 3-7
Repeat object code pseudooperation, 3-26
.REPT pseudo-op, 3-26
Requesting an I/O device handler
pseudo-operations, 3-26
Request program size pseudooperations, 3-28
Reserving blocks of storage
pseudo-operations, 3-22
Restart assembler, 5-21
RSX system MACRO call, 5-1
RUBOUT, 5-2
Running instructions, 5-17

Segmented source, 5-2
Segmenting programs, 3-24
Semicolon (;) used as separator,
2-1
.SIXBT pseudo-op, 3-9, 4-3
Size of program, 3-17
.SIZE pseudo-op, 3-28
Slash (/) usage, 2-2, 2-3, 4-3

Index-3

INDEX (Cont.)
Software, 1-2
Source listing of the
absolute binary loader, E-l
Source, segmented, 5-2
Space character (~), 2-1
Spaces in filename, 5-10
Special symbols, 2-6
Statement
delimiters, 2-20, 2-21
evaluation, 2-24
fields, 2-17
format, 2-1
line length, 2-1
terminator, 2-24
Statement, direct assignment,
2-3
Storage words, 2-13
Subtraction operator, 2-12
Symbol
definition, 2-4
evaluation, 2-4, 2-29
redefinition, 2-8, 2-19
Symbolic address pseudooperation, 3-26
Symbolic label, 2-17, 2-18
Symbols, 2-3
created, 4-7
special, 2-6
undefined, 2-10
Symbol table output, 5-14
Symbol tables, 2-4

Undefined symbols, 2-10, 5-20
User's Symbol, 3-26
table, 2-4
Validity bits, 2-28
Variables, 2-7, 5-20
VT15 processor, 3-8

Word evaluation, 2-25, 2-28

X option, 5-18
X used as symbol, 2-6, 2-13

Zero, division by, 2 ~ 12
zeroing a storage location, 2-7

Tab character (-I), 2-1
Tag, 2-2
field, 2-1
symbol, 3-26
Terminators, command string,
5-3
Text delimiter, 3-9
Text handling pseudo-operations,
3-8
.TITLE pseudo-op, 3-3
Transfer vector, 1-3, 3-12
Trimmed six-bit format, 3-9
Two's complement, 2-12

Index-4

MACRO XVM Assembler Language Manual
DEC-XV-LMALA-A-D

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