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DEC-9A-AMZA-D

1968

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Document:	MACRO-9 ASSEMBLER Programmer’s Reference Manual PDP-9 ADVANCED SOFTWARE SYSTEM
Order Number:	DEC-9A-AMZA-D
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Pages:	84
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OCR Text

MACRO-9 ASSEMBLER
Programmer's Reference Manual
PDP-9 ADVANCED SOFTWARE SYSTEM

Order No. DEC-9A-AMZA-D from the Program Library, Digital Equipment Corporation,

Price $2.00

Maynard, Mass. Direct comment concerning this manual to Software Quality Control, Maynard, Mass.

DIGITAL EQUIPMENT

CORPORATION

MAYNARD

MASSACHUSETTS

1st Edition August 1967
2nd Edition Revised Decembelr 1967
3rd Edition Revised Novembeli 196:3

The following are registered trademarks of Digital
Equipment Corporation, Maynard, Massachusetts:
DEC
FLIP CHIP
DIGITAL

PDP
FOCAL
COMPUTER LAB

PREFACE
It is assumed that the reader is fami liar with the PDP-9 User's Handbook and
Supplement (F-95), and with the Monitors manua I (DEC-9A-MADO-D). In this
manual, frequent references are made to the Linking Loader, which is described
in Utility Programs manual (DEC-9A-GUBA-D).

iii

CONTENTS
Page
CHAPTER 1
INTRODUCTION
1.1

Hardware Requirements and Options

1-2

1.2

Assembler Processing

1-2

CHAPTER 2
ASSEMBL Y LANGUAGE ELEMENTS
2. 1

Program Statements

2-1

2.2

Symbols

2-2

2.2. 1

Evaluation of Symbols

2-3

2.2.2

Variables

2-5

2.2.3

Direct Assignment Statements

2-5

2.2.4

Undefined Symbols

2-6

2.3

2-7

Numbers

2.3. 1

Integer Values

2-7

2.3.2

Expressions

2-8

2.4

Address Assignments

2-10

2.4. 1

Referencing the Location Counter

2-10

2.4.2

Indirect Addressing

2-10

2.4.3

Literals

2-11

2.5

Statement Fields

2-12

2.5. 1

Label Field

2-12

2.5.2

Operation Field

2-14

2.5.3

Address Field

2-15

2.5.4

Comments Field

2-16

2.6

Statement Eva luation

2-17

2.6. 1

Numbers

2-17

2.6.2

Word Evaluation

2-18
CHAPTER 3
PSEUDO OPERATIONS

3. 1

Program Identification (. TITLE)

3-1

3.2

Object Program Output (.ABS and. FULL)

3-1

3.2. 1

3-1

• ABS Pseudo-op

CONTENTS (Cont)
Page

3.2.2

3-2

• FULL Pseudo-op

3.3

Setting the Location Counter (. LOC)

3-3

3.4

Radix Control (.OCT and .DEC)

3-4

3.5

Reserving Blocks of Storage (. BLOCK)

3-5

3.6

Program Termination (. END)

3-5

3.7

Program Segments (. EOT)

3-6

3.8

Text Handling (.ASCII and. SIXBT)

3-6

3.8. 1

• ASCII Pseudo-op

3-6

3.8.2

• SIXBT Pseudo-op

3-7

3.8.3

Text Statement Formal

3-7

3.8.4

Text Delimiter

3-7

3.8.5

Non-Printing Characters

3-7

3.9

Loader Control (. GLOBL)

3-8

3. 10

Requesting I/O Devices (. 10D EV)

3-9

3. 11

Defining a Symbolic Address (.DSA)

3-9

3. 12

Repeating Object Coding (.REPT)

3-10

3. 13

Conditional Assembly (. IF xxx and. ENDC)

3-11

3. 14

Listing Control (. EJECT)

3-13

3. 15

Program Size (.SIZE)

3-13

3. 16

Defining Macros (.DEFIN, • ETC, and. ENDM)

3-13

CHAPTER 4
MACROS

4. 1

Defining a Macro

4-1

4.2

Macro Body

4-2

4.3

Macro Calls

4-3

4.3. 1

Argument Del i miters

4-4

4.3.2

Created Symbols

4-5

4.4

Nesting of Macros

4-6

4.5

Redefinition of Macros

4-8

4.6

Macro Calls Within Macro Definitions

4-9

4.7

Recursive Calls

4-9

CONTENTS (Cont)
Page
CHAPTER 5
ASSEMBLER OPERATION
5. 1

Operating Procedures

5-1

5.2

Assembly Listings

5-1

5.3

Symbo I Tab Ie Output

5-2

5.4

Error Detection

5-3

5.5

Program Relocation

5-4
APPENDIX A
CHARACTER SET
APPENDIX B
PERMANENT SYMBOL TABLE

APPENDIX C
MACRO-9 CHARACTER INTERPRETATION
APPENDIX D
SUMMARY OF MACRO-9 PSEUDO-OPS
APPENDIX E
SUMMARY OF SYSTEM MACROS
APPENDIX F
SOURCE LISTING OF THE ABSOLUTE BINARY LOADER
APPENDIX G
ABBREVIATED MACRO-9 FOR 8K SYSTEMS
APPENDIX H
SYMBOL TABLE SIZES
APPENDIX I
SUMMARY OF OPERATING PROCEDURES WITH KEYBOARD MONITOR

vii

This is a complete sample Program Listing. The last
column {comments} contains the paragraph number in
this manual where full explanations may be found.

,p
MACHO

MD
00101;00102
H
00107
PASS 1 COMPLETED
,p,p
SAMPLE

PAGE

00000
00001
00002
00003
00004
00005
00017
00017
00020
00021
00022
00023
00024
00025
00026
00027
00030
00031
00032
00033
U

R
R
11.
11.
H.

000013
000144
000310

A
A
A

A=II;

• TITLE SAMPLE
• DEC
100;
200

000011
000100
000200
200010

A
A
A
A
A
A
R
A
A
A
A
A
A
A
A
A
A

A=11 ;

.OCT
100;

D
TAG

.ASC I I

'ABC'

/3. (3

.SIXBT 'ABC'
• ASCI I 'ABCD'EFGE

3.8

ADDRES

11.

00034

200107

00073
00073
00074

R
R
R

040400
OLJ0401

A
A

DEP
DEPT

00075
00076
00077

R
R
R

200100
120110
120111

A
E
E

00100
00101
00102

11.
11.

000026
200075
200101

11.
11.

00103
00104
00105

R
R

A
A *RPT
A *hPT

00110
00111

200010
200011
200012
000004
000110
000111

R
R

R
R
R
R
R
R

R
R

3.4

200

LAC 10
.BLOCK 12
.BLOCK 0
LAC TEMP#
0; 0: 0;

STAIn
BUFF
C

200106
000000
000000
000000
406050
300000
010203
LJ06050
342214
LJ34000
000000
406041
100000

/3.1
/3.4
/2.2.3

.ASCII

A
A

/3.5
/2.2.2
/2.2.3

'AB'<11>
/3.13

.IFDEF A
LAC H
.mDC

M
DM

11.

.LOC TAG+50
DAC 400
DAC 401
.GLOBL X6Y6Z
LAC 100
JMS* Y
JMS* Z
• IODEV 1626-36-465
• DSA ADDRES
LAC X
LAC MD
.HEPT 361
LAC 10

MD
MD

SAMPLE

PAGE
000011
00026
00005
00017
00020
00073
00074
00107
00101
00004
00023
00106
00075
00110
00111

MD
START
TAG
TEMP
X
y

2
A
11.

R
11.
R
R

R
R
R

R
k
k
R

E
E

/3.12

E *ETV
3 EhHOH LINES

THERE ARE

A
ADDRES
BUFF
C
D
DEP
DEPT

/3.10
/3.11

/3.6

• END START

11.
E *ETV

/3.9

SAMPLE

PAGE

START
BUFF'
A
C
D
TAG
ADDRES
DEP
DEPT
X
MD
TEMP

00004
00005
000011
00017
00020
00023
00026
00073
00074
00075
00101
00106
00107
00110
00111

H
y
Z

viii

3
R
h

A
R
R
11.

R
R
R

R
R
R
R

E
E

CHAPTER 1
INTRODUCTION

MACRO-9 is the symbolic assembly program for the PDP-9 ADVANCED Software System.
Operating under control of one of the Monitor systems, which handles I/O functions, the MACRO-9
Assembler processes input source programs in two passes, and requires less than 6K* of core memory.
MACRO-9 makes machine language programming on the PDP-9 much easier, faster and more
efficient. It 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.
The standard output of the Assembler is a relocatable binary object program that can be
loaded for debugging or execution by the Linking Loader. MACRO-9 prepares the object program for
relocation, and the Linking Loader 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.
The programmer may direct MACRO-9 processing by using a powerful set of pseudo-operation
(pseudo-op) instructions. These pseudo-ops are used to set the radix for numerica I 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
conditions are met, and other functions which are explained in detail in Chapter 3.
The most advanced feature of MACRO-9 is its powerful macro instruction generator. This
permits easy handl ing of recursive 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 called up to three levels, nested to n levels, and redefined within the program. The technique of defining and ca II ing macro instructions is discussed in
Chapter 4.
An output listing, showing both the programmer1s source coding and the object program
produced by MACRO-9, is printed if desired. This listing includes all the symbols used by the programmer with their assigned va lues. If assembly errors are detected, erroneous I ines are marked with
specific letter error codes, which may be interpreted by referring to the error list in Chapter 5 of this
manua I.
Operating procedures for MACRO-9 are contained in the I/O Monitor Guide (DEC-9AMIPA-D) for paper tape systems, and in "the Keyboard Monitor Guide (DEC-9A-MKFA-D) for bulk
storage systems.
*An abbreviated version, called MACROA, described in Appendix G, is available for 8K PDP-9
systems with DECtape.

1-1

1.1

HARDWARE REQUIREMENTS AND OPTIONS
MACRO-9 operates in PDP-9 systems with the I/O Monitor and the following minimum

hardware configurations:
8K core memory
Console Teletype {KSR33 or KSR35}
Paper tape reader and paper tape punch
With the addition of bulk storage (such as 2 DECtapes, 2 magnetic tapes, a drum I or a disk)
to the hardware configuration, MACRO-9 operates with the Keyboard Monitor, which allows the user
flexibi lity in assigning I/O devices at assembly time and provides true device independence.
With the addition of bulk storage, 8K of memory, the memory protection option, and ()ne
external Teletype, MACRO-9 operates with the Background/Foreground Monitor where assembly may
be accomplished as a normal BACKGROUND job.

1.2

ASSEMBLER PROCESSING
The MACRO-9 Assembler processes source programs in two passes; that is, it reads the same

source code twice, outputting the object code (and producing printed listing, if requested) durin~J the
second pass. The two passes are resident in memory at the same time. PASSl and PASS2 are almost
identical in their operations, but object code is produced only during PASS2. The main function of
PASS 1 is to resolve locations that are to be assigned to symbols and to bui Id up a symbol table. PASS2
uses the information computed by PASSl {and left in memory} to produce the final output.
The standard object code produced by MACRO-9 is in a relocatable format which is accept··
able to the PDP-9 Linking Loader. Relocatable programs that are assembled separately and use identi-·
cal globa I symbols* where appl icable, can be combined by the Linking Loader into an executable
object program.
Some of the advantages of having programs in relocatable format are as follows.
a. Reassembly of one program, which at object time was combined with other programs,
does not necessitate a reassembly of the entire system.
b. Library routines {in relocatable object code} can be requested from the system device
or user library devi ceo
c.

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.

1-2

CHAPTER 2
ASSEMBLY LANGUAGE ELEMENTS

2.1

PROGRAM STATEMENTS
A single statement may be written on a 72-character Teletype line, in which case the

carriage-return line-feed sequence characters del imit the statement. Such a statement actua lIy begins
with a line-feed character and is terminated by a carriage-return character. Since these form-control
characters are not printed, they are represented as ~ (carriage return) and

+(line feed). In the examples

of statements in this manual, only the carriage return is shown:
STATEMENT ~
Several statements may be written on a single line, separated by semicolons:
STATEMENT;STATEMENT;STATEMENT ~
In this case, the statement line begins with a line-feed character and ends with a carriage-return
character, but semicolons are used as internal statement delimiters. Thus, if a statement is followed by
another statement on the same line, it ends with a semicolon.
A statement may contain up 1'0 four fie Ids that are separated by a space, spaces, or a tab
character. These four fie Ids are the labe I (or tag) fie Id, the operation fie Id, the address field, and
the comments field. Because the space and tab characters are not printed, the space is represented by
LJ, and the tab by ...,

in this manual. Tabs are normally set 10 spaces apart on most Teletype machines,

and used to line up the fields in columns in the source program listing.
This is the basic statement format:
LABEL ~ OPERATION +I ADDRESS" /COMMENTS ~
where each field is de I imited by a tab or space, and each statement is terminated by a semicolon or
carriage-return. The comments fie Id is preceded by a tab (or space) and a slash (/).
Note that a combination of a space and a tab wi II be interpreted by the MACRO-9 assembler
as two fie Id del imiters.
Example:
TAG.., OP u -+lADR_
TAG U +I OP ..,ADR ~

}

both are
incorrect

These errors wi II not show on the listing because the space is hidden in the tab.
A MACRO-9 statement may have an entry in each of the four fields, or three, or two, or
only one field. The following forms are acceptable:

TAG~

+I OP ~
TAG -.I OP +I ADDR ~
TAG

2-1

TAG

+I OP +I ADDR

1......1

(s) / comments)

TAG -11'\ OP ....... (s) / comments ~
TAG -+I

-t-I ADDR

TAG ~

-t-I ADDR

(s) / comments

TAG +I (s) / comments ~

-t-IOP~

+I OP +I ADDR ~

+I OP +I ADDR -+I (s) / comments ~
-IJII OP +I (s) / comments ~
+I +I ADDR~

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

+I (s) / comments ~
Note that when a label field is not used, its delimiting tab is written, except for IUnes containing only
comments. When the operation field is not used, its delimiting tab is written if an address field follows,
except in label only and comments only statements.
A label (or tag) is a symbolic address created by the programmer to identify the statement.
When a label is processed by the Assembler, it is said to be defined. A label can be defined only
once. The operation code field may contain a machine mnemonic instruction code, a MACRO-9
pseudo-op code, a macro name, a number, or a symbol. The address field 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. Comments do not affect the object program or assembly processing. They are merely printed in the program listing. Comments must be
preceded by a slash (/ ). The slash must be preceded by:

2.2

Space

Tab

Semicolon

First character of line

SYMBOLS
The programmer creates symbols for use in statements I to represent addresses I operation

codes and numeric va lues. A symbol contains one to six characters from the following set:

2-2

The letters A through Z
The digits 0 through 9
Two specia I characters, period (.) and the percent sign (%).
The first character of a symbol must be a letter, a period, or percent sign. A period may
not be used alone as a symbol. If the first character is a period, it cannot be followed immediately
by a digit. The first character of a symbol must not be a digit.
The following symbols are lega I:
MARK 1

•• 1234

0/050.99

P9.3

INPUT

The following symbols are i II ega I:
TAG:l

L@Bl

:and @ are illega I characters.

5ABC

First character may not be a digit.

.5A

If first character is a period, it cannot be
followed by a digit.

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,
SYMBOLl
SYMBOL2
SYMBOL3
as the symbolic labels on three different statements in his program, the Assembler wi II recognize only
SYMBOL and type error flags on the I ines containing SYMBOL 1, SYMBOL2 and SYMBOL3 because to
the Assembler they are dupl icates of SYMBOL.

2.2. 1

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

it eva luates the symbol by reference to two tables: the user's Symbol Table and the Permanent Symbol
Table. The user's Symbol Table contains all symbols defined by the user. The user defines symbols
by using them as labels, as variables, as macro names, and by direct assignment statements.

A label

is defined when first used '. and cannot be redefined. (When a label is defined by the user, it is given
the current value of the Location Counter, as wi II be explained later in this chapter.)
All permanently defined system symbols, including Monitor commands and all Assembler
pseudo-instructions use a period (.) as their first character. (In some cases the II. II may be used as the
last character of a Monitor I/O symbol). The Assembler has, in its Permanent Symbol Table, definitions
of the symbols for a II of the PDP-9 memory reference instructions, operate instructions, EAE instructions,
and some input/output transfer instructions. (See Appendix A for a complete I ist of these instructions.)
2-3

PDP-9 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 opemtion

-IItI LAC ~ A~

field of a statement causes the Assembler to tre!at it
as an op code rather than a symbol ic address. It
has a va lue of 200000 wh ich is taken from the opera8
tion code definition in the Permanent Symbol Table '.
The user can use instruction menmonics or the pseudo-instruction mnemonics code as symbol
labels. For example,
DZM ~ DZML-l

where the label DZM is entered in the Symbol Table and given the current value of the Location
Counter, and the op code DZM is given the value 140000 from the Permanent Symbol Table. The
user must be careful, however, in using these dual purpose (field dependent) symbols. Symbols in the
operation field are interpreted as either instruction codes or pseudo-ops, not as a symbolic label, if
they are in the Permanent Symbol Table. Monitor command op-code symbols cannot be duplicated by
the user. In the following example, severa I 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 talbles
to form object program storage words.

User Symbol Table

Permanent Symbol Table

Symbol

Value

Symbol

Value

TAG1

100

LAC

200000

TAG2

200

DAC

040000

DAC

300

JMP

600000

If the following statements
are written

the following code is generated
by the Assembler.

TAG1

-+I DAC

TAG2

-+I LAC

~ DAC

200300

DAC

-+I JMP -+t TAG1

600100

~ TAG1

000100

TAG2

040200

2-4

2.2.2

Variables
A variable is a symbol that is defined in the Symbol Table by using it in an address field or

operation field, with the number sign (#). 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 number sign. If
the variable duplicates a user defined label, the variable is flagged as an error during assembly.
Variables are assigned memory locations at the end of the program. The initia I contents of
variable locations are unspecified.
Examples
Location
Counter

Source Statements

Generated
Code

. LOC ...... 100

100

LAC ...... TA#G1

200105

101

+I DAC ..... TAG3

102

040107

LAC ...... TAG2#

200106

103

DAC ..... TAG3#

040107

104

-+I

LAC ..... #TAG2

200106

.END

Storage words can be set to zero as follows:
~A~Oi~Oi+O •

In this way, three words are set to zero starting at A. Storage words can a Iso be set to zero by statements containing only labels

Ai Bi Ci Di E ~
When the programmer defines a macro instruction, the macro name is entered in the Symbol
Tab Ie. Macros are fu Ily described in Chapter 4.

2.2.3

Direct Assignment Statements
The programmer may define a symbol directly in the Symbol Table by means of a direct as-

signment statement, written in the form:
SYMBOL=n
or
SYM1=SYM2
where n is any number or expression. There should be no spaces between the symbol and the equa I sign,
or between the equal sign and the assigned value, or symbol. MACRO-9 enters the symbol in the

2-5

Symbol Table, along with the assigned value. Symbols entered in this way may redefined. These
are legal direct assignment statements:
X=28; A=l; B=2~
A symbol can also be assigned a symbol ic value:
A=4
B=A
The symbol B is given the value 4. Direct assignment statements do not generate storage words in the
object program.
In general, it is good programming practice to define symbols before using them in statements
wh ich generate storage words. The Assembler wi II interpret the following sequence without trouble.
Z=5
Y=Z
X=Y
-+I LAC u Xu/SAME AS LAC 5 ~

A symbol may be defined after use.

For example,

LAC Y"
Y=l,/
This is called a forward reference, and is resolved properly in PASS2. When first encCluntered
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 PASS2, the Assembler finds that Y = 1 in the Symbol Table, and forms the complete
storage word.
Since MACRO-9 operates in two passes, only one-step forward references are allowed. The
following forward reference is illegal:
LAC Y

Y=Z "
Z=l II
In the listing, during PASS 1, the line which contains Y = Z will be printed as a warning.
2.2.4

Undefined Symbols
If any symbols, except global symbols, remain undefined at the end of PASSl 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 fla!gged

as undefined. One memory location is reserved for each undefined symbol with the initial contents
of the reserved location being unspec ified.

2-6

Location
Counter

Generated
Code

Source Statements

Comments

-+I . LaC ..... 100 _
100

-+I LAC -.. UNDEFl _

200106

101

-+I LAC...., TAG# _

200104

102

-+I LAC ...... TAG# 1 Ii

200105

103

-+I LAC ...... UNDEF2 •

200107

Flagged as an error

+I.END~

2.3

NUMBERS
The initia I radix (base) used in a II number interpretation by the Assembler is octa I (base 8).

In order to a lIow the user to express decima I va lues, and then restore to octa I va lues, 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 it as a comment. All numbers are decoded in the current radix unti I a new radix
control pseudo-op is encountered. The programmer may change the radix at any point in a program.
Examples

Source Program

+I LAC

-+I 100

Generated Value (Octal)

Radix in Effect

200100

8 }

initial value is

000025

assumed to be oc ta I

+I LAC --+I 100

200144

+1275

000423

000076

+125

+I .DEC

+I.OCT
+176

2.3. 1

Integer Va lues
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.
18
0 .... 262143
(777777 ) or 2 -1
Unsigned
10
8
17
Signed
±0 .... 131071
(377777 8) or ±2 - 1
10

2-7

An octa I integer* is a string of digits (0-7) I signed or unsigned. If a non-octa I digit i's en-'
countered (8 or 9) the string of digits wi II be assembled as if the decimal radix was in effect and it wi II
be flagged as a possible error.
Examples

--Coded Value

Generated Value (Octal)

-5

777773

3347

003347

3779

007303

Comment
two's complement

possible error I decimal
assumed

A decima I integer** is a string of digits (0-9) I signed or unsigned.
Examples

Coded Value

2.3.2

Generated Value (Octal)

-8

777770

+256

000400

-136098

000000

Comment
two's complement

Error I greater than -2

17
-1

Express ions

Expressions are strings of symbols and numbers separated by arithmetic or Boolean operators.
18
Expressions represent unsigned numeric values ranging from 0 to 2 -1. All arithmetic is performed in
18
unsigned integer arithmetic (two's complement) I modulo 2 • Division by zero is regarded as division
by one and results in the origina I dividend. Fractiona I 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 element (symbol) of the expression and performing the specified operations.
The following are the allowable operators to be used with expressions:

*Initiated by •. OCT pseudo-op and is a Iso the initio I assumption if no radix control pseudo-op wa!;
encountered.
**Initiated by • DEC pseudo-op.

2-8

Character
Name

Function
Symbol

Plus

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

Minus
Asterisk

Multiplication (unsigned)

Slash

Division (unsigned)

Ampersand

Logical AND
Inc lusive OR

Exc lamation point
Back slash

Exc lusive OR

)

Boolean

Operations are performed from left to right (i .e. I in the order in which they are encountered).
For example I the assembly language statement A+B*C+O/E-F*G is equiva lent to the following a Igebraic expression (((((A+B)*C)+D)/E)·-F)*G.
Examples
Assume the following symbol va lues:

Symbol

Value (Octal)

000002

000010

000003

000005

The following expressions would be eva luated.

Expression

Evaluation (Octal)

A+B-C

000007

AlB + A * C

000006

BIA -2* A -1

000003

A&B

000000

2-9

(The remainder of AlB
is lost)

Evaluation (Octal)

Expression

2.4

C+A&D

000005

B * D/A

000024

B*C/A*D

000074

ADDRESS ASSIGNMENTS
As source program statements are processed I the Assembler assigns consecutive memory lo-

cations to the storage words of the object program. This is done by reference to the Location C:>unter I
which is initially set to zero I and incremented by one each time a storage word is formed in the object
program. Some statements I such as machine instructions I cause only one storage word to be generated I
incrementing the Location Counter by one. Other statements, such as those used to enter data I:>r text,
or to reserve blocks of storage words, cause the Location Counter to be incremented by i'he 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,
-II-lJMP ....... -1

which wi II 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 va lue by using the • LOC pseudo-op I
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 immediate Iy fo lIowing the operation fi e Id 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 wi II resu It.
Two examples of lega I indirect addressing follow.
~ TAD*

-+I LAC* -+I B

2-10

The following examples are illegal.
.., LAC

-+I TAD*

The asterisk is not a I lowed in an address field •

.., CLA*~

Indirect addressing may not be specified in nonmemory reference instructions.

2.4.3

Litera Is
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 Iiteral. The
Assembler sets up the address Iink, so one less statement is needed in the source program.

The follow-

ing examples show how literals may be used, and their equivalent statements. The information contained
within the parentheses, whether it be a number, symbol, expression, or machine instruction is assembled
and assigned consecutive memory locations after the locations used by the program. 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 PASS1, are stored only once so that many
uses of the same literal in a given program result in only one (1) memory location being allocated for
that Iitera I •

Usage of Litera I

Equivalent Statements

-til ADD ...... (1)
ONE

TAGAD

-+I LAC ...... (JMP

ADD ...... ONE

-.t LAC

-+I LAC ...... (TAG)

...-.t LAC _ (DAC

..,

~ TAG)

TAGAD

L..-'

INST

-+I TAG
~ LAC

-+I .+2)

L..-'

INST

...-.t DAC ~

HERE

-+I LAC ..... INST

INST

-+I JMP .... HERE+2

TAG

*The opening parenthesis [ ( ] is mandatory while the closing parenthesis [ ) ] is optional.

2-11

The following sample program illustrates how the Assembler handles literals.

Location Counter

Generated Code

Source Statement
~ .LOC ..... 100

100

TAG 1 -., LAC ..... (l 00)

200110

101

----t DAC ~ 100

040100

102

200111

103

-e-t LAC ~ (JMP ...... +5)
-e-t LAC .... (TAG 1)

104

-+I LAC ..... (JMP

TAGl)

200112

105

-+I LAC .... (JMP

TAG2)

20011 3

200110

TAG2=TAGl
...., LAC .... (JMP)

106
107

DAC

-+1 LAC ~ (DAC

200114
~ DAC)

200115

-l1li .END
Generated Literals

2.5

110

000100

111

600107

112

600100

113

600100

114

600000

115

040107

STATEMENT FIE LDS
The follow.ing paragraphs provide a deta i led explanation of statement fie Ids, inc luding how

symbols and numbers may be used in each field.

2 .5. 1

La be I Fie Id

If the user wishes to assign a symbolic label to a statement, 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/line-feed sequence.

2-12

Examples
TAG

......

any value

TAG

'-' (s) any value

TAG -+I

u (s) any value

TAG;

These examples are equivalent to coding

TAG ~

TAG -+I 0 ~

TAG

...... (s) (no more data on Iine)

in that a word of a 1\ Os is output with
the symbol TAG associated with it.

Symbols used as labels are defined in the Symbol Table with a numerical value equal to the
present value of the Location Counter. A label is defined only once. If it was previously defined by
the user, the current definition of the symbol will be flagged in error as a multiple definition. All
references to a multiply defined symbol wi 1\ be converted to the first value encountered by the
Assembler.
Example

Location
Counter

Statement

Storage Word
Generated

100

-+I LAC -+I B

200103

101

-ttl LAC

-+lC

200104

-+I LAC -+I A

200100

102
103

000000

104

-+10

000000

}

Notes

error, multiple definition
first value of A referenced

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

~ LAS.

LOC*2

~ RAR.

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 without causing an
error message. If a user symbol, which was first defined 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.

2-13

Examples

Coding

Generated Value (Octal)

Comments

---A=3

sets current value of A to 3

--t-I LAC

200003

-+I DAC

040003

A=4

redefines value of A to 4

~ LAC

-+I DAC ~

200004
A*

040004

B=A

illegal usage; a label canno
be redefined

-.t DAC

040105

PSF=700201

to redefine possibly incorrec
permanent symbol definition

* Assume that th is instruction wi II occupy location 105.
2.5.2

Operation Fie Id
Whether or not a symbol label is associated with the statement, the operation field must be

delimited on its left by a space(s) or tab. If it is not delimited on its left, it will be interpreted OIS the
label field.

The operation field may contain any symbol, number, or expression which will be eval18
uated as an 18-bit quantity using unsigned arithmetic modulo 2 • 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:

Examples

(1) -+i or
(2) ~
or

L...I

(5)

(field delimiters)
(statement delimiters)

TAG ~ ISZ

-+I .+3

L...I

(s)

u (s)CMA!CML J

-+I TAG/5+TAG2; -Ill TAG3 ~
The asterisk (*) character appended to a memory reference instruction symbol, in the operation field, causes the setting of the Defer bit (Bit 4) of the instruction word; that is, the reference will

2-14

be an indirect reference. If the asterisk (*) is appended on either a non-memory reference instruction
or appended to any symbol in the address field, it will cause an error condition.
Examples
legal

illegal

-+I TAD* .., A

-+I LAC ~ TAD*

-+I LAC* ~ B

CLA*

However, the asterisk (*) may be used anywhere as a multiplication operator.
Examples
legal

2.5.3

illegal

...., LAC -.t TAG* 5

-+I TAG*TAG 1

..., A*

LAC -+I TAG*4+TAD*

Address Field
The address field, if used in a statement, must be separated from the operation field by a tab,

or space(s). The address field may contain any symbol, number, or expression which will be evaluated
18
as an l8-bit quantity using unsigned arithmetic, 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 cause an error message. The address field must be terminated by one of the following characters:

(1)
Examples

-+I or ...... (s)

(field delimiters)
(statement delimiters)

(2) ~

or i

TAG2

-+I DAC ~ .+3
-+I
-...! TAG2/5+3

L...I

(s)

In the last example, the rest of the line will be automatically treated as a comment and ignored by the
Assembler.
The address field may also be terminated by a semicolon, or a carriage-return/line-feed
sequence.
Examples

-+I JMP -+I BEGIN ~
~ TAD ~ Ai

-+I DAC -+I BJ

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.
When the address field is a relocatable expression, an error condition may exist. The size
of a relocatable program is restricted to 8K (8192

words) and cannot be loaded across memory banks.
10
Therefore, any relocatable address field whose value exceeds 177778 is meaningless and will be flagged
in error.

2-15

When the address field is an absolute expression, an error condition will exist if the extende~d
memory bits (3 & 4) of the address do not match the extended memory bits of the bank currently be~ing
assembled into and the extended memory bits of the address are not O.
Examples

Location
(octal)

Instruction

Comments

20000

-+I LAC

20001

-+t DAC ..... 101

20002

-+I J MS I-J 250

)

20005

-+I ISZ ..... 40146

wi II cause an error message

L...I

20100

wi II not cause error messages

The Linking Loader will not relocate any absolute addresses; thus, absolute addresses within
a relocatable program are relative to that bank in memory in wh ich the program is loaded.
Example
Assume that the following source I ine is part of a relocatable program that was loaded into bank 1
(20000 -+ 37777a)
a
Source Statement

-+I LAC

I-J

Effective Address

300 ~

20300

An exception to the above rule is the auto-index registers, which occupy locations lOa - 17a
in memory bank O. The hardware will always ensure that indirect references to lOa - 17a in any bank
will always access lOa - 17a of bank O.
2.5.4

Comments Field
Comments may appear anywhere in a statement. They must begin with a slash (/) that is

immediately preceded by a

I-J

-+I

tab

carriage return/line feed (end of previous line)

(s)

space(s)

semicolon

2-16

Comments are terminated only by a carriage-return/line-feed sequence or when 72

characters have

been encountered.
Examples
-. (s)/THI ~ IS A COMMENT

(rest of Iine is blank)

TAGl -+I LAC '-' /after the; is still a comment
/THIS IS A COMMENT
-.., RTR '-' /COMMENT ~
-.., RTR;.., RTR;/THI SIS A COMME NT
Observe that;-.,

A/COMMENT" is not a comment, but rather an operation field expression. A line

that is completely blank; that is, between two sets of • • (s) is treated as a comment by the Assembler.
Example
1-1

(72 blanks)

A statement is terminated as follows:
~.

or; or rest of line is completely blank.

Examples
..., LAC ~
..., DAC

(the rest of the I ine is blank)

-.., TAG+3
..., RTR; -+I RTR; -.I RTR .l
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
semicolons in order to have the second and third RTR's interpreted as being in the operation field and
not in the label fie Id.

2.6

STATEMENT EVALUATION
When MACRO-9 eva luates a statement, it checks for symbols or numbers in each of the

three evaluated fields: label, operation, and address. (Comment fields are not evaluated.)

2.6.1

Numbers
Numbers are not field dependent. When the Assembler encounters a number (or expression)

in the operation or address fields (numbers are illegal in the label field), it uses those values to form the
storage word. The following statements are equiva lent:
~ 200000u10~
-+I 10+ LAC ~
-+I LACwlO ~

2-17

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 la-bit storage word; for example:
~ 23;L.J 45iw357;w62

This group of four statements generates four words interpreted under the current radix. Zero words are
generated by statements containing only labels. For example,

A·I B·I C'I D·I E_\
..
generates five words set to zero, which may be referenced by the labels defined.

2.6.2

Word Evaluation
When the Assembler encounters a symbol in a statement field, it determines the value olF the

symbol by reference to the user's symbol table and the permanent symbol table, according to the priority
list shown below. The value of a storage word is computed by combining the 18-bit operation field
quantity with the 18-bit address field quantity in the following manner.

l + fOPERATION FIELD&760000~
J L 0 - 17
J

UOPERATION FIELD+ADDRESS FIELD)&017777a
0 - 17
0 - 17

Value
of
Word

The Assembler performs a validity check to verify that meaningful results were produced. As long I:lS

[

l = 760000a or 000000

ADDRESS FIELD & 76000
a
0-17

then meaningful results were produced.
Examples
-t-t TAD -t-t A

Where A can range from 0-+ 777778 and combined
with TAD (340000 ) results in 340000 -.c 357777 •
a
a
a
Where - 1 (777777 a) is combi ned with LAW (760000 )
a
cmd results in 777777a.

If the ADDRESS FIELD & 760000a does not equal 760000 or 000000, erroneous results may have bl3en
a
produced and it wi II be flagged by the Assembler. This va lidity check is performed only if an opel"ations field and an address field is present.

If numbers are found in the operation and address fie Ids, they are combined in the same
manner as defined symbols. For example I
..... 2-t-t5 ..... /GENERATES 000007
The value of a symbol depends on whether it is in the label field, the operation field, or the addrE~ss
field. The Assembler attempts to evaluate each symbol by running down a priority list I depending on
the fie Id I as shown be low.

2-18

Label Field
Current Va lue of
Location Counter

Operation Field

1. Pseudo-op

Address Field

1. User symbol table, (including)

2. User macro in user symbol

direct assignments)

2. Undefined

table

3. System macro table

Direct assignment in user
symbol table

5. Permanent symbol table
6. User symbol table

7. Undefined
This means that if a symbol is used in the address fields, it must be defined in the user1s symbol table before the word is formed during PASS 1; otherwise, it is undefined.
In the operation field, pseudo-ops take precedence and may not be redefined. Direct assignments allow the user to redefine machine op codes, as shown in the example below.
Example:
DAC = DPOSIT
System macros may be redefined as a user macro name, but may not be redefined as a user symbol by
direct assignment or by use as a statement label.
The user may use machine instruction codes and MACRO-9 pseudo-op codes in the label
fie Id and refer to them later in the address field.

2-19

CHAPTER 3
PSEUDO OPERATIONS

In the discussion of symbols in the previous chapter, it was mentioned that the assembler has,
in its permanent symbol table, definitions of the symbols for all the PDP-9memory reference instructions,
operate instructions, EAE instructions, and many 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 or data, direct
the assembler on how to proceed with the assembly.
By convention, the first character of every pseudo-op symbol is a period (.). Th is 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. Pseudo-ops may be used only in the operation field.

3. 1

PROGRAM IDENTIFICATION (. TITLE)
The program name may be written in a • TITLE statement as shown below. The assembler treats

th is statement as a comment.

-+I . TITLE
3.2

L-I

NAME OF PROGRAM

OBJECT PROGRAM OUTPUT (.ABS and. FULL)
The normal object code produced by MACRO-9 is relocatable binary which is loaded at run

time by the Linking Loader. In addition to relocatable output, the user may specify two other types of
output code to be generated by the Assembler.
The following rules apply to the usage of these optional output codes:
a. The pseudo-op specifying the type of output must appear before any coding appears
(excluding title and comments), otherwise it wi II be ignored.
b. Once an optional output code pseudo-op is specified, the user is not a lIowed to switch
output modes. Any subsequent requests are flagged and ignored.
c. Any options provided for in the address field of the pseudo-ops are useful only if the
output device is paper tape .

3.2. 1

• ABS Pseudo-op

Label Field

Operation Field

Address Field

Not Used

.ABS

NLD or

3-1

L-I

The. ABS pseudo-op causes absolute, checksummed binary code to be output (no values are reloccttabIE~).

If no value is specified in the address field I the Assembler wi II precede the output with the Absolute
Binary Loader which will load the punched output at object time. The loader is loaded, via hardware
readin, into location 17720 of any memory bank. (This loader loads only paper tape.) If the address
field contains NLD, no loader will precede the output.

NOTE
. ABS output can be written on fi Ie-oriented devices. The
assembler assumes .ABS NLD for all .ABS output to fileoriented devices and appends an extension of .ABS to the
filename. This file can be punched with PIP, using Dump
mode. (There wi II be no absolute loader at the beginning
of the tape.)

A description of the absolute output format follows.
Block Heading - (three binary words)
WORD 1

Starting address to load the block body which follows.

WORD 2

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

WORD 3

Checksum of block body {two's complement}. Checksum includes Word
and Word 2 of the block heading.

Block Body - (n binary words)
The block body contains the binary data to be loaded under block heading control.
Starting Block - (two binary words)
WORD 1

Location to start execution of program. It is distinguished from the blo,ck
heading 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 :state-·
ment is equal to 0, the provided loader halts before transferring control to the object program, thereb},
allowing manual intervention by the user.
A Iisting of the Absolute Binary Loader is given in Appendix F .

3.2.2

. FU LL Pseudo-op

Label Field

Operation Field

Address Field

Not Used

.FULL

Not Used

3-2

{Only useful if output is paper tape}

The. FULL pseudo-op causes a full mode output to be produced. The program is assembled as unchecksummed absolute code and each physical record of output contains nothing other than 18-bit binary
storage words generated by the Assembler. The Assembler will cause the address of the. END statement
to contain a punch in channel 7, thereby allowing the output to be loaded via hardware Readin Mode.

If no address is specified in the. END statement, a halt (rather than a jump) will be outputted as the
last word.
The following specific restrictions apply to programs assembled in . FULL mode output.
• LOC

Should be used only at the beginning of the program.

.BLOCK

May be used only if no literals appear in the program, and
must immediately precede. END.

Variables and undefined symbols may be used if no literals appear in the program.
Literals may be used only if the program has no variables and undefined symbols.

3.3

SETTING THE LOCATION COUNTER (. LOC)

Label Field

Operation Field

Address Field

Not Used

.LOC

Pre-defined symbolic
expression, or number

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 might occur in PASS2. The. LOC pseudo-op may be used anywhere and as many
times as required.
ExampJes

Location Counter

Instruction

100

-+I .LOC~

100

-+I LAC ...... TAG1

101

-+I DAC~

102

-+I . LOC .......

102

A -+I LAC ...... B

103

-+I DAC ......

107

-+I • LOC ...... A+5

3-3

100

TAG2

Instruction

Location Counter

3.4

107

....... LAC '-' C

110

....... DAC,-,

111

....... LAC...., E

112

....... DAC...., F

RADIX CONTROL (.OCT and .DEC)
The initial radix (base) used in all number interpretation by the Assembler is octal (bas,e 8).

In order to allow the user to express decimal values, and then restore to octal values, two radix s,ettin~J
pseudo-ops are provided.

Pseudo-op Code

Meaning

.OCT

Interpret all succeeding numerical values in base 8 (octal)

.DEC

Interpret all succeeding numerica I 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 unti I a new radix control pseudo-instruction is encountered.
grammer may change the radix at any point in a program.

Source Program
....... LAC

100

Generated Value (Octal)

Radix in Effect

200100

8} initial value is

000025

200144

000423

-tJf76

000076

......... 85

000000

error

..... 25

assumed to be octal

..... DEC
..... LAC
..... 275

100

-+I.OCT

3-4

Th(~ pro··

3.5

RESERVING BLOCKS OF STORAGE (.BLOCK)
• BLOCK reserves a block of memory equal to the value of the expression contained in the ad-

dress field. If the address field contains a numerical value, it will be evaluated according to the radix
in effect. The symbol ic elements of the expression must have been defined previously; otherwise, phase
15
errors might occur in PASS2. The expression is evaluated modulo 2
(77777 ). The user may reference
8
the first location in the block of reserved memory by defining a symbol in the label field. The initial
contents of the reserved locations are unspecified.

Label Field

Operation Field

Address Fie Id

User Symbol

. BLOCK

Predefined Expression

Examples
BUFF -+I . BLOCK ,"-.12 ~

-+I . BLOCK ....... A+B+65_

3.6

PROGRAM TERMINATION (.END)
One pseudo-op must be included in every MACRO-9 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 contains 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:

-+I. END ~ START J
Where START may be a symbol, number, or expression whose value is the address of the first program
instruction to be executed. In relocatable programs, to be loaded by the Linking Loader, only the
main program requires a starting address; a II other subprogram starting addresses will be ignored.
A starting address must appear in absolute or self-loading programs; otherwise, the program
will halt after being loaded and the user must manually start his program.
These are legal • END statements

--.!. END

L....I

BEGIN +5~

~.END L....I 200~

3-5

3.7

PROGRAM SEGMENTS (.EOT)

If the input source program is physically segmented, each segment except the last must
terminate with ('In • EOT (end-of-tape) statement. The last segment must terminat'e with an • END statlemente For example, if the input source program is prepared on three different tapes, the first two are
terminated by . EaT statements, and the last by an • END statement. The. EOT statement is written
without label and address fields, as follows •
...... . EaT,/.

3.8

TEXT HANDLING (.ASCII and .SIXBT)
The two text handling pseudo-ops enable the user to represent the 7-bit ASCII, or 6-bit

trimmed ASCII character sets. The Assembler converts the desired character set to its appropriate nu-'
merical equivalents. (See Appendix A.)

Label Field

Operation Field

Address Field

SYMBOL

{ASCII}

Delimiter - character string - delimiter -

<expression> .....

. SIXBT

Only the 64 printing characters (including space) may be used in the text pseudo-insf'ructkms.
See non-printing characters, Section 2.4.5. The numerical values generated by the text pseud()-ops
are left-justified in the storage word(s) they occupy with the unused portion (bits) of a word zero fillod.

3.8. 1

. ASCII Pseudo-op
. ASCII denotes 7 -bit ASCII characters. (It is the character set that is the inp'ut to and out-

put from Monitor.) 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 w ill a Iways be outputted.

Basic Form

~F-ir-s_t-W-o-r-d------~-----~----~------s-e-c-o-n-d-w~or_d

6 7

.... 0

______________

1st Char.

13 14

2nd Char.

17 0

3rd Char.

3-6

2 3

14th Char.

9 10_______________
15th Char.

2~~107

• SIXBT Pseudo-op

3.8.2

• 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.

Basic Form

56
1st Char.

3.8.3

11 12
2nd Char.

17
3rd Char.

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

MYTAG-.I{: ~1~~li } -.II delimiter Icharacter string Idelimiter I<expression) .....
3.8.4

Text Delimiter
Spaces or tabs prior to the first text del imiter or angle bracket «) wi II be ignored; afterwards,

if they are not enclosed by delimiters or angle brackets, they will terminate the pseudo-instruction.
Also, _ wi II terminate the pseudo-instruction.
Any printing character may be used as the text delimiter, except those listed below.
a.

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

,J - as it terminates the pseudo-i nstruction.

(The apostrophe (') is the recommended text delimiting character.) The text delimiter must be present
on both the left-hand and the right-hand sides of the text string, otherwise the user may get more characters than desired; however, ~ may be used to terminate the pseudo-instruction.

3.8.5

Non-Printing Characters
The octal codes for non-printing characters may be entered in .ASCII statements by enclosing

them in angle bracket delimiters. In the following statement, five characters are stored in two storage
words.

3-7

Octal numbers enclosed in angle brackets will be truncated to 7 bits (.ASCII) or 6 bits
(. SIXBT).

Source Line
TAG -+I. ASCII ..... iABC'
-til. SIXBT '-' 'ABC'
-+I. SrXBT ..... 'ABC'#'/#
~. ASCII '-'

Comments

Recognized Text
ABC
ABC
ABC'/

I ABCD' EFGE

-+I. ASCii ..... 'AB'(ll)
-e.I'. ASCii ..... 'AB(ll )

ABCDFG
AB""
AB(ll )

...,. ASCii ..... ~15)~012>'ABC'
-IIi. ASCII '-' 15) 12)ABC u (s)

• +ABC
~ BC ...... (s)

The # is used as a delimiter in order
that (I) may be interpreted as .~ext.
(11) used to represent tab.
There is no del imiter after B,
therefore, (11») is treated a:; text .
A is interpreted as the text de·
I imiter. Also, since _ was not
used to terminate the text, the U
(s) are interpreted as text
characters.

The following example shows the binary word format which MACRO-9 generates for a given
line of text.
Example:

-+I. ASCII~'ABC'(015)<12>'OEF
Generated Coding
Octal

Word 1

406050

1000001 11 00001 01 1000

Word 2

306424

011 \ 00011 01 \0001 01 0 \ 0

Word 3

422130

10001 00 \ 10001 01

600000

1 10 \ 0000000 0000000 \ 0

Word 4

3.9

Binary

Word Number

I 1 000

LOADER CONTROL (.GLOBL)

Label Field

Operation Field

Address Field

Not Used

. GLOBL

A, B, C, 0, E....

3-8

The standard output of the Assembler is a relocatable object program. The Linking Loader 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.
a.

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 uses this information to load and then link the relocatable programs to each other.
All references to external symbols should be indirect references as memory banks may have
to be crossed.
Examples
-+I. GLOBL-+lA, B, C

A -+I LAC-+l1 00

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

The. GLOBL statement may appear anywhere within the program.

3.10

REQUESTING I/O DEVICES (.IODEV)
The. IODEV pseudo-op appears anywhere in the program and is used to cause the Assembler

to output code for the Linking Loader which specifies the slots in the Monitor1s Device Assignment Table
(DAT) whose associated device handlers are required by the program (see Monitors manual,
DEC-9A-MADO-D) •

3. 11

Label Field

Operation Field

Address Field

Not Used

.IODEV

1,2,3 •••

DEFINING A SYMBOLIC ADDRESS (.DSA)
. DSA (define symbol address) is used in the operation field when it is desired to create a

word composed of just an address field.

It is especially useful when a user symbol is also an instruction

or pseudo-op symbo I .

Label Field

Operation Field

Address Field

User Symbol

. DSA

Any Expression

3-9

Examples
JMP ~ LAC ~TAG
-iIII. DSA-fIII JMP
-iIII JMP

3. 12

Equivalent methods of defining the user symbol JMP
to be in the address field.

REPEATING OBJECT CODING (. REPT)

Label Field

Operation Field

Address Field

Not Used

. REPT

Count I { Increment
or
L....I

The. REPT pseudo causes the object code of the next sequential object code generating
instruction to be repeated Count times. Optiona"y, the object code may be incremented for each timE~
it is repeated by specifying an Increment. The Count and Increment are numerical values (signed or
unsigned) which wi" be evaluated according to the radix in effect. The repeated instruction may conta ina Iabe I, wh i ch wi" be assoc i ated with the fi rst statement generated.
Examples
Generated
Object Code

Source Code

-+I . REPT ..... 5

...,0

000000
000000
000000
000000
000000

~.REPT ..... 4,l

-IloI 1

000001
000002
000003
000004

-IloI .REPT ..... 3, -1

-+15

000005
000004
000003
3-10

Generated
Object Code

Source Code
TAG=50
~

.REPT,-, 4,1

~ JMP _

TAG

600050
600051
600052
600053

NOTE

If the statement to be repeated generates more than one
location of code, the • REPT wi II repeat only the last
location. For example,
~. REPT u3

.... ASCII u IAI
will generate the following:
404000
000000
000000
000000

3.13

5/7 A
last word is
repeated

CONDITIONAL ASSEMBLY (.IF xxx and .ENDC)

It is often useful to assemble some parts of the source program on an optional basis. This is
done in MACRO-9 by means of conditional assembly statements, of the form:
~

. IF. •. ~ 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 symbol ic
elements, such a symbol must have been previously defined in the source program.

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 be low.

3-11

Assemble IF x is:
~

.IFPNZ ...... x

Positive and non-zero

.IFNEG......, x

Negative

-+I .IFZER

......, x

Zero

-+t .IFPOZ ...... x

Positive or zero

-+t .IFNOZ ...... x

Negative or zero

-+i .IFNZR ...... x

Not zero

~ .IFDEF

A defined symbol

..... x

-+t . IFUND ...... x

An undefined symbol

In the following sequence, the pseudo-op .IFZER is satisfied, and the source program c:odin~~
between.IFZER and. ENDC is assembled.
SUBTOT=48
TOTALL=48
-+t .IFZER ..... SUBTOT -TOT ALL

-+I LAC ..... A
-+I DAC ...... B
-+t .ENDC
Conditional statements may be nested.

For each IF statement there must be a terminating

• ENDC statement. If the outermost IF statement is not satisfied, the entire group is not assemb led. If
the first IF is satisfied, the following coding is assembled. If another IF is encountered, however, its
condition is tested, and the following coding is assembled only if the second IF statement is satisfied.
Logica lIy, nested IF statements are I ike AND circu its. If the first, second and third conditions, are
satisfied, then the coding that follows the third nested IF statement is assembled.
Example
~ .IFPOS ......

conditional 1 initiator

-+t LAC -+i TAG
-+t .IFNZR ...... Y

conditional 2 initiator

-+t DAC -+t TAG 1
-+t .ENDC

conditional 2 terminator

-+t .IFDEF ......, Z

conditional 3 initiator

-+lDAC -+tTAG2
-+I. ENDC

conditional 3 terminator

-+t. ENDC

conditional 1 terminator

3-12

Conditional statements can be used in a variety of ways. One of the most useful is in
terminating recursive macro calls (to be described in the next chapter). In general, a counter is changed
each time through the loop, or recursive call, unti I the condition is not satisfied. Th is process concludes assembly of the loop or recursive cal I.

3. 14

LISTING CONTROL (. EJECT)
The following Assembler listing controls are effective only when a listing is requested by

Assembler control keyboard request.

Label Field

Operation Field

Address Field

Not Used

. EJECT

Not Used

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

3.15

PROGRAM SIZE (. SIZE)

Label Field

Operation Field

Address Field

User Symbol

• SIZE

Not Used

When the Assembler encounters .SIZE, it outputs, at that point, the address of the last location plus
one occupied by the object program. Th is is normally the length of the object program (in octal).

3. 16

DEFINING MACROS (. DEFIN, . ETC, and. ENDM)
The. DEFIN 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 the list
of dummy arguments will not fit on the same line as the .DEFIN pseudo-op, it may be continued by
means of the. ETC pseudo-op in the operation field and additional arguments in the address field of the
next line. The coding that is to constitute the body of the macro follows the .DEFIN statement. The
body of the macro definition is terminated by an . ENDM pseudo-op in the operation field.
Chapter 4 for more detai Is on the use of macros.)

3-13

(See

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 necessary 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.
-.t LAC -.t A
~ TAD-.tB

-.t DAC-.t C
~ LAC --.t D

--.t TAD -+I E
--.t DAC --.t F
The sequence
--.t LAC -.t x
~ TAD--.ty

-+I DAC --.t 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

DEFINING A MACRO
Macros must be defined before they are used. The process of defining a macro is as fo"ows.
(Macr~ Name)

(Definition Line)
(Body)

~ ~:rN:: :i~NME'ARGl

~DAC

(Terminating Line)

~Dum~y A~uments}

,ARG2,ARG3

/comment

~ ARG3

~. ENDM

The pseudo-op • DFIN in the operation fi eld 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.

4-1

space

(L.J)

tab

(-.t)

c•

carriage return

(.)

The macro name, as well as the dummy arguments must be legal MACRO-9 symbols. An)'
previous definition of a dummy argument is ignored whi Ie in a macro definition. Comments after th,e
dummy argument list in a definition are legal.

If the list of dummy arguments cannot fit on a single line (that is, if the .DEFIN statement
requires more than 72 10 characters) it may be continued on the succeeding line or lines by the usage of
the .ETC pseudo-op, as shown below.

-t-I. DEFIN-t-I MACNME,ARG1, ARG2, ARG3
-t-I. ETC

-t-I ARG4, ARG5

/comment

/argument continuation

-t-I. DEFIN -t-I MACNME

4.2

..... ETC

-t-I ARG1

..... ETC

.... ARG2

~. ETC

-Ilol ARG4

-t-I. ETC

.... ARG5

MACRO BODY
The body of the macro definition follows the .DEFIN statement. Appearances of dummy

arguments are marked, and the character string of the body is stored 5 characters per 2 words in the
macro definition table, unti I 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 e><pression. They may appear in the label field, operation field, or address field. Dummy arguments may
appear within a literal or defined as variables. They will not be recognized if I'hey appear within (:1
comment.
The following restrictions apply to the usage of the 'OEFIN, ·ETC and ·ENDM pseudo-ops:
a.

If they appear in other than the operation field within the body of a macro definition,

they wi II cause erroneous results.
b.

If ·ENDM or 'ETC appears outside the range of a macro definition, they will be

flagged as undefi ned.

4-2

If .ASCII or .SIXBT is used in the body of a macro, a slash (/) or number (#) must not
appear as part of the text stri ng or as a del i miter (use <57> to represent a slash and <43 > to represent
a number sign). Also a dummy argument name should not inadvertently be used as part of the text string.
Definition

Comments

-+I. DEFIN -+I MAC, A, B, C, D, E, F

-.t LAC--.t A#
-+I SPA

--.t J MP -.t B
-+lISZ -+lTMP -+I

E is not recognized as an argument

-+I LAC-.t (C
-+I DAC-+I D + 1
-+I F
-+I . ASCII -+I E

B=.
-+I. ENDM

4.3

MACRO CALLS
A macro ca II consists of the macro name, whi ch must be in the operation field, followed, if

desired, by a list of real arguments separated by commas and terminated by one of the characters listed
below.
a.

space

L~)

tab

(-+I )

carriage return

( ~)

If the real arguments cannot fi't on one Iine of coding, they may be continued on succeeding
I ines by terminating the current line with a dollar sign ($). When they are continued on succeeding
lines they must start in the tag field.
Example:
-+lMAC -+lREALl,REAL2,REAL3,$
REAL4,REAL5

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, which will be
assigned to the current value of the locatnon counter.

4-3

Example:
-+I • DEFIN -till UPDATE, LOC, AMOUNT

(Definition)

---+I LAC ---+I LOC
---+I TAD ---+I AMO U NT
-+I

DAC---tIII LOC

---+I • ENDM

(Call)

TAG-+I UPDATE -+I CNTR,(5

/TAG ENTERED INTO SYMBOL TABLE
/WITH CURRENT VALUE OF LOCATION COUNTER

(Expansion) TAG

-+I LAC ---+I CNTR

-+I TAD -+I (5
-+I

DAC -till CNTR

The prevailing radix will be saved prior to expansion, and restored after expansion takes
place. Default assumption will be octal for the macro call. It is not necessary for the macro definition
to have any dummy arguments associated with it.
Example
---+I • DEFIN '----+I CMA

TWOS

---+I TAD '-'

(Call)
(Expansion)

4.3.1

(1
-+I .ENDM
---+I TWOS
-+I CMA
--JIll TAD -+I (1

Argument Delimiters
It was stated that the list of arguments is terminated by any of the following symbols.

comma

(

space

( L-J )

tab

(-+I )

carriage return

(I )

)

These characters may be used within real arguments only by enc losing them in ang Ie bnJckets.
Angle brackets will not be recognized if they appear within a comment.
Example
(Definition)

---+I • DEFI N ......
-+I LAC......,

MAC, A, B, C

---+I TAD '-'

B
---+I DAC,-, C
-+I.ENDM

4-4

~MAC ..... TAG1,(TAG2

(Ca II)
(Expansion)

~TAD '-'

(1», TAG3

-+I LAC '-'

TAG1

/comment

~TAD '-' TAG2

(1)
-+I DAC,-, TAG3

-+I TAD '-'

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.
MACRO-9 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
-+I . DEFIN -+I ERRMSG, TEXT

(Definition)

-+I J MS -+I PRI NT
-+I . ASCII -+I TEXT

-+I . ENDM
(Call )

-+I ERRMSG -..(/ERROR

(Expansion

-+I JMS -+I PRINT
-+I . ASCII -+I /ERROR

4.3.2

IN
IN

L1NE/ (15)>
L1NE/ (15)

Created Symbols
Often, it is desirable to attach a symbolic tag to a line of code within a macro definition.

As this tag is defined each time the macro is called, a different symbol must be supplied at each call
to avoid multiply defined tags.
This symbol can be explicitly supplied by the user or the user can implicitly request MACRO-9
to replace the dummy argument with a created symbol which will be unique for each call of the macro.
For example,
-+I. DEFIN -+lMAC, 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 •• 0000+ .. 9999. As they are required they are
entered into the symbol table like any other symbol.
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.

4-5

Example
(Definition)

~ . DEFIN -+I MAC, A, B, ?C, ?D, ?E

..... LAC-+lA
-+I SZA

-+I JMP -+I D
~ LAC -+I B

.... DAC-+I C#
-+I DAC-+I E
D=.
...... ENDM
(Call)

-+I MAC-+I X#", I MYTAG

(Expansion)

-+I LAC -+lX#
-+I SZA

-..t J MP -+I .. 0000
-+I LAC
..... DAC -+1 •• 0001
-+I DAC -+I MYTAG

.. 0000=.

If one of the elements in a real argument string is not supplied, that element must be re!placed
by a comma, as in the call above. A real argument string may be terminated in several ways as shown
below:
Example
-+I MAC -+I A, B, --+I MAC -+I A, B,

-+I MAC -+I A, B '-'
-+I MAC -+I A, B~

-+I MAC -+I A, B,,J
4.4

NESTING OF MACROS
Macros may be nested; that is, macros may be defi ned withi n other macros. For ease of

discussion, levels may be assigned to these nested macros. The outermost macros (those defined directl~/)
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.

4-6

Example:

Levell
-+I . DEFIN -+I LEVEL 1, A, B

-+I LAC -+lA
-+I TAD -+lB

Level 2

-+I . DEFIN -+I LEVEL2, C, D

-+I ISZ -+I C
-+I DAC-+lD

Level 3
-+I. DEFIN -+I LEVEL3, E, F

-+lAND -+IE
-+lXOR -+I F
-+I.ENDM

LEVEL 3

.ENDM

LEVEL 2

.ENDM

LEVEL 1

.ENDM

-+I DAC -+I X
-+I • ENDM

--.r DAC -+lY

-..

-+I . ENDM

At the beginning of processing, first-level macros are defined and may be called in the normal manner.

Second and higher level macros are not yet defined. When a first-level macro is called,

all its second-level macros are defined. Thereafter, the level of definition is irrevelant and macros
may be called in the normal manner. If the second-level macros contain third-level macros, the thirdlevel macros are not defined until the second-level macros containing them have been called.
Using the example above, the following would occur:
Call

Expansion

-+ LEVEL 1 -+I TAG1, TAG2

-+I LAC-+I TAGl

-+I TAD -+I TAG2

Comments
Causes LEVE L 2
to be defined

-+I DAC-+I Y
-+I LEVEL 2 -+I TAG3, TAG4

-+I ISZ -+I TAG3
-+I DAC -+I TAG4
-+I DAC -+IX

-+I LEVEL 3 -+lTAG5, TAG6

-+I AND -+I TAG5

Causes LEVEL 3
to be defi ned

-+I XOR -+lTAG6

If LEVEL 3 is called before LEVEL 2 it would be an error, and the I ine would be flagged as undefined.
When a macro of level n contains another macro of the level n + 1, to call the macro of
level n 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.

4-7

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 el iminated.

For example,

--IIi. DEFIN -.tINDXSV
--IIi J MS --IIi SA VE

-+I JMP -~ SAVXT

SAVE -+I 0
-+I LAC -+110
-+I DAC -+I TMp#
-+I LAC -+111
-+I DAC -t-I TMP1 #
-+I JMP*-IIoI SAVE

SAVXT=.
-+I. DEFIN -+lINDXSV
-+I JMS -+lSAVE
--IIi. ENDM
-t-I. ENDM

When the macro INDXSV is called for the first time, the subroutine call ing sequence is generated and followed immediately by the subroutine itself.
that contains the name INDXSV is encountered.
original macro INDXSV.
generated.

After the subroutine is generated, a . DEFIN

This new macro is defined and takes the place ,::>f the

All subsequent calls to INDXSV cause only the calling sequence to be

The original definition of INDXSV will not be removed until after the expansion is complete.
Call
-t-IINDXSV

Expansion
-+I J MS -+I SAVE

-t-I J MP -+I SAVXT
SAVE -+I 0
-+I LAC -+110
-+I DAC -+I TMP #

-t-I LAC-+l11
.... DAC -+I TMP1 #
-t-IJMP*~

SAVE

SAVXT=.
.... INDXSV

-t-IJ MS --IIi SAVE

4-8

4.6

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 defined before a call is issued to the macro which
contains the embedded call. Embedded calls are allowed only to three levels.
Example
-+I . DEFIN ~MAC1, A, B, C, D, E
-+I LAC ~A
-+I TAD -+lB
-+I MAC2 -+I C, D

/EMBEDDED CALL

-+I DAC -+I E

...-t. ENDM
-+I . DEFI N ...-t MAC2, A, B

/DEFINITION OF EMBEDDED CALL

-+I XOR -+lA
-+I AND -+I B
-+I. ENDM

The call

-+I MACl -+lTAG1, TAG2, (400, (777, TAG3
ca uses generati on of
.... LAC ~TAGl
.... TAD .... TAG2
.... MAC2--.t (400, (777
--.t XOR .... (400
.... AND -". (777
--.t DAC .... TAG3

4.7

RECURSIVE CALLS
Although it is legal for a macro definition to contain an embedded call to itself, it must be

avoided because the expansion wi II cause more than three levels to occur.
Example
~. DEFIN ~MAC, A, B, C

-+I LAC -+lA

-+I TAD -+lB
-.t DAC-+I C
-+I MAC -.tA, B, C

/RECURSIVE CALL

-+I. ENDM
When a call for MAC is encountered by the Assembler, it 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 definition and this process would never cease, if more than three

4-9

levels were allowed. A conditional assembly statement could be used, however, to limit the number
of levels as in the following example.
Example
A =0
B=3
~ .DEFIN~MAC,C,D
~LAC

~DAC

A =A + 1
..... IFNZR-toIB-A
~SAVE,TEMP

.... MAC

/RECURSIVE CALL

~.ENDC
~.ENDM

Names and arguments of nested macros and arguments of imbedded calls may be substi'tuted
and used with perfect genera lity.
Example
-liIi . DEFIN -liliMAC1, A, B, C, D
~ LAC -liIi A

-+I ADD-+! B
-+I DAC-+I C
-+I . DEFIN -+I D, E
-+I AND -liIi A
-+I DAC -+IE
-+I. ENDM
-liIi. ENDM
-liIi. DEFIN
~ ISZ

-+I MAC2, 'M, N, 0, P, Q, ?R

-+1M

-+I JMP -+I R
-liIi MAC1 -+I N, 0, P, Q
R=.

-+I. ENDM

4-10

The call
~ MAC2 ~COUNT, TAG1, TAG2, TAG3, MAC3

causes the generation of
~ ISZ ~COUNT
~JMP-.t .. 0000
-.t LAC -.t TAGl
~ADD~ TAG2
~DAC~ TAG3
.. 0000=.
It also causes the definition of MAC3

4-11

CHAPTER 5
ASSEMBLER OPERATION

5. 1

OPERATING PROCEDURES
Operating procedvres for MACRO-9 are contained in the Vo Monitor Guide (DEC-9A-

MIPA-D) for paper tape systems, and in the Keyboard Monitor Guide (DEC-9A-MKFA-D) for bulk
storage systems.

5.2

ASSEMBLY LISTINGS
If the user requests it, via the Monitor command string, the Assembler wi II 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 Monitor command string. The body of the listing will be
formatted as fo II ows •
ERROR FLAGS

LOCATION

xxx

xxxxx

ADDRESS
MODE

OBJECT CODE

{1}

xxxxxx

LOCATION

SOURCE STATEMENT
x

where
FLAGS

ADDRESS
TYPE

Errors encountered by the Assembler (see paragraph 5.5)
Relative or absolute location assigned to the source

ADDRESS MODE = Indicates the type of user label address
A = Absolute
R = Relocatable
OBJECT CODE

The contents of the location (in octal)

ADDRESS TYPE

Indicates the classification of the address portion of the object code
A = Absolute
R = Relocatable
E = Externa I symbol

Locations and object codes assigned for literals and external symbols are listed following
the program. The program name may be written in a • TITLE statement, as shown. This is treated as
a comment.

5-1

Sample Listing
MACR09

PAGE
. TITLE

u
u

00000 R
00001 R
00002 R
00003 R
00004 R
00005 R
00006 R
00007 R
00010 R
00011 R
00012 R
00013 R
00014 R
00015 R
00016 R
00017 R
00020 R
00021 R
00022 R
00023 R
00024 R
00036 R
00037 R
00040 R
00041 R
00042 R
00043 R
00044 R

5.3

200025 R
200002 R
000014 R
000033 R
000002 R
200036 R
000037 R
000037 R
000040 R
000041 R
000042 R
000043 R
200042 R
200043 R
000026 R
000027 R
000030 R
000034 R
000031 R
000035 R
000032 R
000002 R
000001 A
000002 A
000003 A
000004 A
600002 R
600014 R
600014 R

~TAGl
TAG2

MACR09

TEST

PROGRAM

A#
LAC
LAC
TAG2
TAG3
TAG4#
TAG2
LAC
{l

(2
(2

TAG3

(3
(4
(JMP
TAG2
(JMP
TAG3
LAC (JMP
TAG2
~tc (JMP
TAG3
C#
D#
E

G
H#
.END

TAG2

*L1T
*L IT
* LIT
* LIT
*L1T
*L1T
*L1T

SYMBOL TABLE OUTPUT
After the assembly listing is printed, the Assembler outputs a symbol table, if requested,

which lists all user-defined symbols. There are two symbol lists. The first is an alphabetically ordered
list of the symbols, and the second is a list in order of numerical value. The symbol table listing is
useful in tracing or debugging a program for which the programmer does not have an assembly listing.
The symbol table listing shows which symbols are:
A = Absolute
R = Relocatable
E = Externa I symbol

5-2

5.4

ERROR DETECTION
MACRO-9 examines each source statement for possible errors. The statement which contains

the error will be flagged by one or several letters in the left-hand margin of the line. The following
table shows the error flags and their meanings.

Flag

Meaning

Error in direct Symbol Table assignment, assignment ignored (see paragraph 2.5. 1).

Memory Ba nk error (progra m segment too large).

The statement contains a reference to a multiply defined symbol. It is assembled
with the first value defined.

Erroneous results may have been produced (see paragraph 2.5.3). Wi II also occur
on undefined .END value.
Line ignored. (Redundant Pseudo-op)

Litera I phasing error. Litera I encountered in PASS2 does not equa I any I itera I
encountered in PASS 1•

An attempt is made ,to define a symbol which has already been defined.
The symbol retains its origi na I va lue •

Error in number usage.

Phase error. PASS 1 va lue does not equal PASS2 va lue of a symbol.
PASS 1 va I ue wi II be used.

Questionable Line.

Possible relocation error.

Symbol error. An i II ega I character was encountered and ignored.

An undefined symbol was encountered.

Line overflow during macro expansion.

Illega I usage of macro name.

In addition to flagged lines, there are certain conditions which wi II cause assembly to be
terminated prematurely.

Message

Pass

Cause

TABLE OVERFLOW

1 or 2

Too many symbols and/or macros.
Too many embedded macro calls.

CALL OVERFLOW

5-3

5.5

PROGRAM RE LOCA TION
The normal output from the MACRO-9 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, theaddress portion of some instructions must have a relocation constant added to it.
This relocation constant, which is added at load time by the Linking Loader, is equal to the difference
between the memory location that an instruction is actua lIy loaded into and the location that was (3Ssigned to it at assembly time. The Assembler determines which storage words are relocatable (marking
them with an R in the listing) and which are absolute (marking these non-relocatable words with an A).
The rules that the Assembler follows to determine whether storage word is absolute or relocatable are as follows.
a.

If the address is a number (not a symbol), the instruction is absolute.

b. If an address is a symbol which is defined by a direct assignment statement (i.e. ,=) and
the right-hand side of the assignment is a number; all references to the symbol wi II be abso!ute.
c.

If a user label occurs within a block of coding that is absolute, the label is absolute.

d. Variables, undefined symbols, external transfer vectors, and literals get the same relocation as was in effect when oEND was encountered in PASSl •
e.

.gets current re locatabi I ity •

All others are relocatable.

The following table depicts the manner in which the Assembler handles expressions which
contain both absolute and re locatable 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 flagged as possible error

R- R =A

If multiplication or division is performed on a relocatable symbol, it will be flagged as a
possible error.

5-4

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
014
015
177

B
C
D

E
F

G
H
I

J
K
L
M
N

0
P
Q
R
S
T
U
V

W
X
Y
Z

J*
t *
*

Null
Horizontal Tab
Line Feed
Vertical Tab
Form Feed
Carriage Return
Rubout

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

Printi ng
Character

7-bit
ASCII

6-bit
Trimmed
ASCII

(Space)
I

040
041
042
043
044
045
046
047
050
051
052
053
054
055
056
057
060
061
062
063
064
065
066
067
070
071
072
073
074
075
076
077

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

$
%

&
I

(
)

-*
+

0
1
2
3
4
5
6
7

8
9

:*
;

<
=
>
?

Notes:

(l)
(2)

All other characters are illegal to MACRO-9 and are flagged and ignored.

* = Illegal as source, except in a comment or text.

A-1

APPENDIX B
PERMANENT SYMBOL TABLE
Operate

EAE Type KE09A

Memory Reference

OPR

740000

EAE

640000

CAL

000000

NOP

740000

OSC

640001

DAC

040000

CMA

740001

OMQ

640002

JMS

100000

CMl

740002

CMQ

640004

DZM

140000

OAS

740004

DIV

640323

LAC

200000

RAl

740010

NORM

640444

XOR

240000

RAR

740020

lRS

640500

ADD

300000

HlT

740040

llS

640600

TAD

340000

740040

AlS

640700

XCT

400000

SMA

740100

LACS

641001

ISZ

440000

SZA

740200

LACQ

641002

AND

400000

SNl

740400

ABS

644000

SAD

540000

SMl

740400

DIVS

644323

JMP

600000

SKP

741000

ClQ

640000

SPA

741100

FRDIV

650323

SNA

741200

lMQ

652000

lOT

700000

SZl

741400

MLJl

653122

10RS

700314

SPl

741400

IDIV

653323

RTl

742010

FRDIVS

654323

RTR

742020

MLJlS

657122

Cll

744000

IDIVS

657323

DBK

703304

STl

744002

NORMS

660444

DBR

703344

CCl

744002

lRSS

660500

SPI

705501

RCl

744010

llSS

660600

ISA

705504

RCR

744020

AlSS

660700

CLA

750000

GSM

664000

ClC

750001

LAS

750004

LAT

750004

GlK

750010

lAW

760000

Interrupt
IOF

700002

ION

700042

CAF

703302
B-1

I/O States

Automati c Prioritl
Interrupt Type KF09A

Me m0!:l Exte ns ion
Control Type KE09B
SEM

707701

EEM

707702

lEM

707704

APPENDIX C
MACRO-9 CHARACTER INTERPRETATION
Character
Name

Function
Symbol

Space

Field delimiter.

Designated by

Horizontal tab

Field delimiter.

Designated by ~ in this manual.

Semicolon

Statement termi nator

Carriage return

Statement terminator

Plus

L...I

in this manual.

Addition operator (two1s complement)
Subtraction operator (addition of two1s complement)

Minus
Asterisk

Multiplication operator or indirect addressing indicator

Slash

Division operator or comment initiator

Ampersand

Logical AND operator
Inclusive OR operator

Exclamation point
Back slash

Exclusive OR operator

Openi ng parenthesis

(

Initiate literal

C losi ng parenthes is
Equals

)

Terminate literal
Direct Assignment

Opening angle bracket

<
>

Argument delimiter

Closing angle bracket

Argument delimiter
Argument delimiter

Comma
Question mark

Create symbol designator in macros

Quotation marks

Text string indicators
Text stri ng i ndi cator

Apostrophe
Number sign

Variable indicator

Dollar sign

Real argument continuation

C-l

Character
Line feed
Form feed

Function
}

Ignored if preceded by a carriage return; otherwise they
are considered as illegal characters.

Vertical tab
Null
Delete

Blank character. Ignored by the Assembler
Rubout character. Ignored by the Assembler

Illegal Characters
Only those characters listed on the preceding table are legal in MACRO-9 source programs,
all other characters wi II be ignored and flagged as errors. The following characters, although they are
illegal as source, may be used within comments or in .ASCII and .SIXBT pseudo-ops.
Character Name

Symbol

Commercial at

Opening square bracket

C losi ng square bracket

Up arrow

Left arrow

Colon

C-2

APPENDIX D
SUMMARY OF MACRO-9 PSEUDO-OPS
Pseudo-op

Section

.ABS

3.2.1

Format

Function

~ .ABS ~NLD~

Object program is output in absolute,
blocked, checksummed format for
loading by the Absolute Binary Loader

....,

.ASCII

3.8. 1

label ~ .ASCII ..... /text/<octal>~

Input text strings in 7-bit ASCII code,
with the first character serving as
delimiter. Octal codes for nonprinti ng control characters are enc losed
in angle brackets.

.BLOCK

3.5

label ~ .BLOCK~exp_

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

• DEC

3.4

~ .DEC~

Sets prevailing radix to decimal •

.DEFIN
.DSA

3.16
3.11

~ • DEFI N L...I macro name, args ~

label ~ • DSA ...... exp,

Defines macros.
Defines a user symbol which is to be
used only in the address field.

• EJECT

3.14

~ .EJECT •

Skip to head of form on listing device.

.END

3.6

-+I .END ...... START ~

Must termi nate every sou rce program.
START is the address of the first instruction to be executed •

• ENDC

3.13

~ .ENDC.

Terminates conditional coding in .IF
statements.

.ENDM

3.16

~ .ENDM~

Terminates the body of a macro
definition.

.EOT

3.7

~ .EOT ~

Must terminate physical program segments, except the last, which is terminated by .END.

.ETC

3.16

~ • ETC ...... a rgs, a rgs _

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

.FULL

3.2.2

-+I .FULL ~

Produces absolute, unblocked, unchecksummed binary object programs.
Used on Iy for paper tape output.

.GLOBL

3.9

~. GLOBL ..... sym,sym,sym ~

Used to declare all internal and external symbols which reference other
programs. Needed by Linking Loader.

.IFxxx

3.13

-+I.IFxxx ...... exp ~

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

.IODEV

3.10

-+I.IODEV ...... ~ DAT numbers ~

Specifies. DAT slots and associated
I/O handlers required by this program.

.LOC

3.3

~.LOC ..... exp ~

Sets the Location Counter to the value
of the expression.

D-1

Pseudo-op

Section

.OCT

3.4

~ .OCT J

Sets the prevai ling radix to oc:tal.
Assumed at start of every program.

.REPT

3.12

~ .REPT ..... count, n ~

Repeats the object code of the! next'
object code generating instruc:tion
Count times • Optionally, the! generated word may be incremented by n
each time it is repeated.

.SIXBT

3.8.2

label -t-I.SIXBT ..... /text/<octal> ~

Input text strings in 6-bit trimmed
ASC II, wi th first character ,as delimiter. Numbers enclosed in angle
brackets are truncated to one 6-bit
octal character.

.SIZE

3. 15

~ .SIZE~

MACRO-9 outputs the address of IOlst
location plus one occupied by the
object program.

• TITLE

3. 1

~ • TI TLE ..... any comments ~

Optional, typed on listing as a comment. (The program name given in
the command string is printed at thE~
top of each listing page, and used by
the Loader.) May be used to (lnnotate
logical sections of a program.

Format

Function

D-2

APPENDIX E
SUMMARY OF SYSTEM MACROS
System macros (Monitor commands) are defined in the Monitor manual, and summarized here
for the convenience of the PDP-9 programmers.
System macros are predefined to MACRO-9. To use a system macro, the programmer writes
a macro call statement, consisting of the macro name and a string of real arguments.
To initialize a device and device handler
~ .1 N ITwa, f, r

where

a = • DAT slot number in octal
f

0 for input files;

1 for output files

user restart address*

To read a line of data from a device to a user's buffer
~ .READwa, m,l, w

where

• DAT slot number in octal

a number, 0 through 4, specifying the data mode:

1 =
2
3
4 =

lOPS binary
Image binary
lOPS ASCII
Image a Iphanumeri c
Dump mode

Ii ne buffer address
w

word count of the line buffer in decimal, induding the
two-word header

To write a line of data from the user's buffer to a device
-+I • WRITE u a, m,l, w

where

a
• DAT slot number in octal
m = a number, 0 through 4, specifying the data mode:
lOPS binary
1
Image bi nary
2
lOPS ASCII
Image alphanumeric
3
4 = Dump mode
I = line buffer address
w = word count of line buffer in decimal, including the twoword header

* Meaningful only when device associated with. DAT slot a is the Teletype. Typing CTRLP on the keyboard
wi II force control to location r.

E-l

To detect the avai labi lity of a Ii ne buffer
~.WAITL..Ia

where

= • DAT slot number in octal. After the previous .READ,
• WRITE, or • TRAN command is completed;
returns control to the user at LOC+ 2

• WAIT

To detect the avai labi lity of a I ine buffer and transfer control to ADDR if not avai lable.

-+ .WAITRwa, ADDR
where a = DA T slot number {octa I radix}
ADDR = Address to which control is transferred if buffer is not avai lab Ie.
To close a fi Ie
-+I .CLOSE ..... a

where

= • DAT slot number in octal

To set the real-time clock to n and start it
-.t • TIMER ..... n, c

where

n = number of clock increments in decimal. Each increment
is 1/60 second {in 60-cycle systems} or 1/50 {in 50-cycle
systems}
address of subroutine to handle interrupt at end of interval
c

To return control to Keyboard Monitor, or halt in I/O Monitor environment

-+I .EXIT ~
Mass Storage Commands for DECtape, Magnetic Tape, Disk and Drum only
To search for a file, and position the device for subsequent .READ commands
-.. .SEEK ...... a,d
where
a
d

• DA T slot number in octal
address of user directory entry block

To examine a file directory, find a free directory entry block and transfer the block to the devict3
-+I .ENTER L...I a, d

where

a
d

• DAT slot number in octal

= address of user directory entry block

To c lear a fi Ie directory to zero
~ .CLEAR .... a

where

• DA T slot number in octal

E-2

To rewind, backspace, skip, write end-of-file, or wrJte blank tape on nonfile-oriented magnetic tape

-.t .MTAPE ...... a, xx
where

a
xx

• DAT slot number in octal
a number 00 through 07, specifying one of 'the functions
shown be row
00
Rewind to load point*
02
Backspace one record*
03
Backspace one fi Ie
04 = Wri te end-of-fi Ie
05
Sk i p one record
06 = Skip forward one file
07 = Skip to logical end-of-tape
or a number, 10 through 16, to describe the tape configuration

10 =
11
12 =
14 =
15 =
16 =

Even pari ty, 200 BPI
Even parity, 556 BPI
Even parity, 800 BPI
Odd parity, 200 BPI
Odd pari ty, 556 BPI
Odd parity, 800 BPI

To read from, or write to any user file-structured mass storage device
-.. • TRAN ...... a,d,b,l,w
where
a = •DAT slot number in octal
b

= transfer direction:
o Input forward

1
Input reverse
2
Output forward
3 = Output reverse
b = device address in octal, such as block number for DECtape
= core starti ng address

w = word count in decimal
To delete a fi Ie

-.t • DLETE ...... a, d
where

a = • DAT slot number in octal
d

starting address of the 3-word block of storage in user area
containing the fi Ie name and extension of fi Ie to be deleted
from the device.

To rename a fi Ie
-.. .RENAM ...... a,d
where

• DAT slot number in octal

d = starting address of two three-word blocks of storage in user
area containing the file names and extensions of the fi Ie to
be renamed, and the new name, respectively.

* May be used with any nonfile structured mass storage device.

E-3

To determine whether a fi Ie is present on a device
~ .FSTAT ~ a,d

where

= •DA T s lot number

d = starting address of three-word block in user area containing the fi Ie name and extension of the fi Ie whose
status is desired.
Background/Foreground Mon itor System Commands
To read a line of data from a device to a user's buffer in real-time
~ .REALR~a, n, I, w, ADDR, p

where a = DAT slot number in octa I
m = Data mode specification;

o = lOPS binary
1 ~ Image binary
2 = lOPS ASCII
3 = Image Alphanumeric
4 = Dump mode
I = Line buffer address
w = word count of line buffer in decima I, including the two-word leader
ADDR = 15-bit address of closed subroutine that is given control when the relques1"
made by • REA LR is comp Ieted •
p = API priority level at which control is to be transferred to ADDR:

= mainstream
4 = level of .REALR
5 = API software leve I 5
6 = API software leve I 6
7 = API software level 7

To write a line of data from user's buffer to a device in real time
-JII • REALW~a, m, I, w, ADDR, p

where a = DAT slot number in octa I
m = Data mode specification;

o = lOPS binary

1 = Image binary
2 = lOPS ASCII
3 = Image Alphanumeric
4 = Dump mode
I = Iine buffer address
w = word count of Iine buffer in decima I, including the two-word leadel~
ADDR = 15-bit address of closed subroutine that is given control when the
request made by .REALW is completed
p = API priority level at which control is to be transferred to ADDR:

E-4

o = mainstream
4 = level of .REALR
5 = API software leve I 5
6 = API software level 6
7 = API software leve I 7
To indicate, in a FOREGROUND job, that control is to be relinquished to a BACKGROUND job
..... IDLE
To set the real-time clock to n and start it
..... TIMERL-In, c, p
where n = number of clock increments in decimal. Each increment is 1/60 of
of a second (1/50 in 50 Hz systems)
c = address of subroutine to hand Ie interrupt at end of interva I
p = API priority leve I at which control is to be transferred to c:

o = mainstream
4 = leve I of • TIMER
5 = API software level 5
6 = API software level 6
7 = API software level 7

E-5

APPENDIX F
SOURCE LISTING OF THE ABSOLUTE BINARY LOADER

/
/***ABSOLUTE BI NARY LOADER ***
/
LDSTR T=17720
BINLDR
CAF
CLOF
IOF
CLA
ISA
MPLU
EEM
RSB
LDNXBK=17730
DZM LDCKSM
JMS LDREAD
DAC LDSTAD
SPA
JMP LDXFR
TAD LDCKSM
DAC LDCKSM
JMS LDREAD
DAC LDWDCT
TAD LDCKSM
DAC LDCKSM
JMS LDREAD
TAD LDCKSM
DAC LDCKSM
LDNXWD=17746
JMS LDREAD
DAC* LDSTAD
ISZ LDSTAD
TAD LDCKSM
DAC LDCKSM
ISZ LDWDCT
JMP LDNXWD
SZA
HLT
JMP LDNXBK
LDXFR=17760
DAC LDWDCT
ISZ LDWDCT
JMP LDWAIT
HLT
LDREAD=17764

RSF
JMP LDREAD+1
RRB
RSB
JMP* LDREAD
LADWAIT=17772
RSF
JMP LDWAIT
JMP* LDSTAD
JMP LDSTRT
ENDLDR
LDC KSM=17775
LDSTAD=17776
LDWDCT=17777

/C LEAR FLA GS
/CLOCK OFF
/1 NTERRUPT OFF
/TURN OFF API
/TURN OFF MEMORY PROTECT
/SET EXTENDED MEMORY LOAD
/START READER UP
/CHECKSUMMING LOCATION
/GET STARTING ADDRESS
/BLOCK HEADING OR
/START BLOCK
/ACCUMULATE CHECKSUM
/WORD COUNT (2 1 S COMPLEMENn

/PROGRAM CHECKSUM (2 1 S COMPLEMENT)
/ADDED TO ACCUMULATED CHECKSUM
/LOAD DATA INTO APPROPRIATE
/MEMORY LOCATIONS
/ADD IN TO CHECKSUM
/FINISHED LOADING
/NO
/LDCKSM SHOULD CONTAI N 0
/CHECKSUM ERROR HALT
/PRESS CONTINUE TO ~GNORE

/WAIT FOR READER
/NO ADDRESS ON .END STATEMENT
/MANUALLY START USER PROGRAM

/.-1

/EXECUTE START ADDRESS
/HARDWARE READIN WORD

F-l

APPENDIX G
ABBREVIATED MACRO-9 FOR 8K SYSTEMS

A shorter version of MACRO-9, called MACROA (for MACRO-9 ~~bbreviated), is available
on the system tape, especially for user's with 8K machines who are using DECtape for input and output.
The following features have been removed in this shorter version:
.ABS
. FULL
Conditional pseudo-ops
.REPT
. DEFIN

(User-defined macros are not allowed, but system macro calls are legal.)

This reduces the assembler by about 850 locations, which is about the same number required
by the DECtape I/O service routine. The user's Symbol Table cannot exceed 275 symbols.

If the user of MACROA uses DECtape input and paper tape output, the Symbol Table may
contain up to 550 symbols.

Calling MACROA
In response to
MONITOR

$
the abbreviated assembler is called by typing, after $,
MACROA
Both versions of MACRO-9 are available on the system tape. If macro definition and/or conditional
capabilities are desired, MACRO with DECtape input and paper tape output can be used, allowing up
to 275 user defined symbols.

G-l

APPENDIX H
SYMBOL TABLE SIZES
The following symbol table sizes are for 8K systems with the full cQ,mplement of skip lOT's
in the skip chain.

NOTE
Handlers listed are for DAT slots -11, -12, -13, and -10,
respectively.
MACRO
a.

PRB, TTA, PPC, TTA - 317 symbols (decimal)

DTC, TTA, PPC, TTA - 189 symbols (decimal)

for .ABS or .FULL output PPB must be used - delete 60 symbols (decimal) from above
counts.

MACROA
a.

PRB, TTA, PPC, TTA - 610 symbols (decimal)

DTC, TTA, PPC, TTA - 482 symbols (decimal)

DTB, TTA, DTB, TTA - 261 symbols (decimal)

H-l

APPENDIX I
SUMMARY OF OPERATING PROCEDURES WITH KEYBOARD MONITOR
These procedures are described in the Monitor Manual and are summarized here for the
convenience of PDP-9 programmers.
To assem bl e a program:
a.

Mount the system tape on DECtape 0 (Set selector switch to 8)

Load paper tape bootstrap (HRM), which loads the Monitor, which types out

MONITOR

$
c.

The user may check the Device Assignment Table by typing:

REQUEST MACRO
after which Monitor types out f'he table showing all current device assignments for
MACRO-9 I s logical assignments:
DAT Slot

1. . Secondary input

-10

Input source program

-11

Listing

-12

Output binary program

-13

Command string

-2

Error messages

-3

At this point, the user may assign devices, if none are assigned to any of the 6 slots used by
MACRO-9, or he may change assignments, using the ASSIGN command. If the input source
program is on DECtape .1, and he wants to use DECtape handler A, he types,
ASSIGN

DTAI

-11

To verify this change, he may type REQUEST MACRO again, and Monitor will type out the
specified MACRO-9 DAT, showing that DECtape 1 is now assigned to DAT slot -11 •
d.

To obtain typed out operating instructions for MACRO-9, the user may type

INSTRUCT MACRO
e.

To load MACRO-9 after Monitor types $, the user types

MACRO
After MACRO-9 is loaded and self-initialized, MACRO-9 types MACRO and the user types;
P, B, L, S +program name (or ALT MODE)

1-1

where B requests that MACRO-9 output a binary object program, L requests a listing, and S
requests that the user's symbol table be printed out. These three letters are all optional, and
may be written in any order, but they must be separated by commas. If none of these letters
are written, error messages are output on the Teletype.
Whether or not any letters are written, the reverse arrow (+-) must follow. This is fol-·
lowed by the program name, identifying the source program to be searched for by the loader
on the input fi Ie, and this name is written at the top of the first listing page.
When the input medium is fj Ie-oriented, MACRO-9 expects the fi Ie name extension SRC
(source). The Editor in the PDP-9 Advanced Software System provides SRC to a fi Ie name
automatically if the output medium is file-oriented.

If the SaJ rce is originally on paper tape (or cards), the file name extension SRC must
be included in the command string to PIP, when transferring to a fi Ie-oriented medium.

If another program is to be assembled following this one, the command string is terminai'ed
by a carriage return. At the conclusion of PASS2, control returns to MACRO-9, whi cy tyPt~S
MACRO,

>
and the user may then type another command string for the next program to be assembled.

If the user wishes to return control to the Keyboard Monitor after the program is assemblled,
he terminates the command string by typing ALT MODE.

1-2

MACRO-9 PROGRAMMERS
REFERENCE MANUAL
DEC-9A-AMZA-D

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