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PAL-D
DISK ASSEMBLER
PROGRAMMER’S REFERENCE MANUAL

For additional copies of this document, order No. DEC-D8-ASAB-D From Program Library,

Digital Equipment Corporation, Maynard, Mass.

DIGITAL

EQUIPMENT

CORPORATION

01754

Price: $1.50

MAYNARD, MASSACHUSETTS

lst Printing April I968
2nd Printing June I968
3rd Printing March I969

4th Printing (Rev) September I969

Your attention is invited to the last two pages of this
The Reader's Comments page, when filled in

manual.

and returned, is beneficial to both you and DEC. All
comments received are considered when documenting

subsequent manuals, and when assistance is required,
a knowledgeable DEC
representative will contact you

The Software Information page offers you a means of

keeping up-to-date with DEC '3 software

Documents Referenced

(available from DEC's Program Library):

Introduction to Programming, C-l8

Disk Monitor System,

Programmer's Reference Manual, DEC-D8—SDAB—D

Time—Sharing System User's Guide, DEC—T8—MRFB-D
TSS/8 System Manager's Guide, DEC-T8—MBZA-D

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

PDP

FLIP CHIP

FOCAL

DIGITAL

COMPUTER LAB

PREFACE

PAL-D, one oF the PDP-8 Family assembly programs, is designed For use on any P’DP-8 Family computer
with disk or DECtape secondary storage.

It is

loaded/optionally stored

disk as a permanently resident

utility program and reproduced in core image as required, under control oF the PDP-8/I Disk Monitor, or
the TSS/8 Time-Sharing Monitor.

PAL-D produces a binary coded obiect program after two passes of the symbolic coded source program

An optional third pass produces a listing oF the source program and the assembler-generated binary code

expressed as Four-digit octal values.

Along with the standard assembly functions PAL-D offers double precision integers, floating point constants, arithmetic and Boolean operators,

literals, text Facilities and automatic oFF-page linkage genera-

tion as standard Features.

It is assumed that the reader is Familiar with assembly

language programming.

For an elementary

approach to this type oF programming, we recommend DEC's publication, No. C-l8, "Introduction to
Programming" available From the Program Library, Digital Equipment Corporation, Maynard ,.
Massachusetts

CONTENTS

Page
CHAPTER 1

INTRODUCTION
PAL-D Language

Syntax

Legal Characters

LLbbwabL

{nip-l:-

Illegal Characters
Format Effectors
Statements

Labels

szw—t
CON—I
014:-

Operators
Operands
Comments

Symbols

Symbol Distinction
Symbolic Addresses
Symbolic Operators
Symbolic Operands
Symbol Tables
Numbers

1.5.1

Arithmetic and Logical Operators

1.5.2

Evaluating Expressions

1.6

Address Assignments

1.6.1

Current Address Indicator

1.6.2

Indirect Addressing

1.6.3

Autoindexing

1.6.4

Literals

1.7

Instructions

1.7.1

Memory Reference Instructions

1.7.2

Augmented Instructions

C HAPTER 2

PSEUDO-OPERATORS

2.1

Current Location Counter

2-1

2.2

Extended Memory

2-1

2.3

Radix Control

2-2

CONTENTS (Cont)

Page
2.4

Listing Control

2-2

2.5

Text Facility

2-2

2.6

End of Program

2-3

2.7

End of File

2-3

2.8

Altering the Symbol Table

2-3

2.8.I

Internal Representation

2-4

CHAPTER 3

PROGRAM PREPARATION AND ASSEMBLER OUTPUT

3.]

Program Tape

3-I

3.2

Assembly

3-2

3.2.1

Pass I

3-2

3.2.2

Pass 2

3-2

3.2.3

Pass 3

LOADING AND ASSEMBLING PROCEDURES

C HAPTER 4

4.]

Disk Monitor System

4—1

4.1.]

4-1

4.1.2

Saving

4-2

4.1.3

Assembling

4-2

4.2

TSS/8 Monitor System

4-5

CHAPTER 5

ERROR DIAGNOSTICS

APPENDIX A

USA SCII CHARACTER SET

APPENDIX B

SYMBOL LIST

CHAPTER I
INTRODUCTION

PAL-D, the acronym forfirogram Assembly _|_._anguage for the _D_isk, is the symbolic assembly
program designed primarily for the 4K PDP-8 family of computers with disk or DECtape secondary storage

operated in either stand-alone or time-shared mode.
The PAL-D Assembler makes machine language programming easier, faster, and more efficient.

Basically, the Assembler processes the programmer's source program statements by translating mnemonic
operation codes to the binary codes needed in machine instructions, relating symbols to numeric values,
assigning absolute core addresses for program instructions and data, and preparing an output listing of the
program, which includes notification of any errors detected during the assembly process.

The PAL-D Assembly language is the same under both the Disk Monitor System and the TSS/8
Monitor (time-sharing) System.

The assembly system includes the disk version of the Symbolic Tape

Editor for altering or editing the source language tape, the Disk Debugging technique for debugging the

obiect program by communicating with it in the source language, and various other utility programs.
PAL-D requires the minimum configuration for disk or DECtape systems (see Disk Monitor

System, DEC-D8-SDAB-D) or time sharing systems (see Time-Sharing System User's Guide,
DEC-T8-MRFB-D), and additionally can utilize the high-speed reader/punch and up to three additional
D532 disk units.

I .I

PAL-D LANGUAGE

The PAL-D Assembler is compatible with the PAL III Assembler.
fol lowing additional features

However, PAL-D has the

Operators

Symbols and integers may be combined by
using the operators
+Addition

—Subtraction
Literals

8. Boolean AND
l Boolean Inclusive OR

Symbolic or integer literals (constants)
automatically assigned

are

Text Facility

Text facilities exist for single characters
and blocks of text.

Indirect Linkage
Generation

I .2

Indirect links are automatically generated for
off-page referencing.

SYNTAX

Programs processed under PAL-D are written using USA SCII characters.
a

complete list of these characters with their octal code equivalents.

I-I

Appendix A contains

1 .2.1

Legal Characters
The following characters are acceptable to PAL-D.
a.

The alphabetic characters
ABCD.

.XYZ

The numeric characters
0123456789

The special characters
1_

Space

Separates symbols and numbers
(see Section 1.5.1)

Plus

Combines symbols or numbers

Minus

Combines symbols or numbers

Exclamation Mark

Combines symbols or numbers

Carriage Return

Terminates a line

Tabulation

Formats Symbols or numbers or source

Comma

Assigns Symbolic address
Direct assignment of symbol values
Terminates coding line
(will not terminate comments)

(add)
—

(subtract)
(inclusive OR)

tape output

Equal Sign
Semicolon
Dollar Sign

Indicates end of pass

Asterisk

Sets current location counter,- redefines origin

Point

Has value equal to current location counter

(Period)

Slash

Ampersand

Indicates start of comment
Combines symbols or numbers

Quote

(AND)

( )

Parentheses

Generates USA SCll constant
Defines literal on current page

I I

Brackets

Defines page 0 literal

Ignored characters
Form-Feed

Indicates the end of a
source

logical page of

program

Blank Tape

Used for

Code 200

Used for

Rubout

Follows tabulation characters for

Line—Feed

Follows carriage return and causes tele-

leader/trailer
leader/trailer

timing purposes
printer paper to roll upward one line
Since certain characters are invisible

(i.e., nonprinting), the following symbols are used

throughout this manual to represent their presence.
L—J

—4
J

Space
Tabulation

Carriage Return

1-2

Illegal Characters

1.2.2

All characters other than those listed above are illegal when not in a comment or TEXT field

and, being illegal, their occurrence causes the error message IC (Illegal Character) to be printed by
PAL—D

l .2 .3

Format Effectors

Tabulations are usually Used in the body of a source program to provide a neat page; they can

separate fields from one another, as between a statement and a comment.

For example,

line written

GO, TAD TOTAL/MAIN LOOP
is much easier to read if tabs are inserted to form

GO, -*l TAD TOTAL—ii /MAIN LOOP
Either the ”;"
statement terminator.

(semicolon) or "J

”

(carriage return—line feed) character may be used as a

The semicolon is considered identical to carriage return-line feed except that it

will not terminate a comment.

Example:

TAD A
The entire expression between the

/THIS IS A COMMENT;

TAD B J

"/” (slash) and J (carriage return) is considered a comment.

The semicolon also allows the programmer to place several lines of coding on a single line.

If, for example, he wishes to write a sequence of instructions to rotate the contents of the accumulator
and link six places to the right, it might look like

RTR a!
RTR J

RTR)

The programmer may place all three RTRs on a single line by separating them with the special character

";" and terminating the line with a carriage return.

The above sequence of instructions can then be

written

RTR; RTR; RTRJ
This format is particularly useful when setting aside a section of data storage for a list.
l2-word list coUld be reserved by

LIST,

For example,

specifying the following format.
0;

O J

A neat printout (or program listing) makes subsequent editing,

much easier than when the coding is laid OUl' in a haphazard fashion.

debugging, and interpretation

STATEMENTS

i .3

PAL—D source programs are usually prepared on a Teletype, with the aid of the Editor,
sequence of statements.

Each statement is written on a single line and is terminated by

return-line feed sequence.
are

not

as a

carriage

PAL-D statements are virtually format free; that is, elements of a statement

placed in numbered columns with rigidly controlled spacing between elements, as in punched-card

oriented assemblers.

There are four types of elements in a PAL-D statement which are identified by the order of
appearance in the statement, and by the separating,

delimiting, character which follows or precedes

the element.
Statements are written in the general form

label, operator operand/comment
The Assembler interprets and processes these statements, generating one or more binary instructions or
data words,

performing an assembly process. A statement must contain at least one of these elements

and may contain all four types.

1.3.1

Labels
A label is the symbolic name created by the source programmer to identify the position of the

statement in the program.

l .3 .2.

If present, the label is written first in a statement and terminated by a comma.

Operators
An operator may be one of the mnemonic machine instruction codes (see Appendix B),

pseudo-operation (pseudo-op) code which directs assembly processing.

codes are described in Chapter 2.
a

The assembly pseudo-op

Operators are terminated with a space if an operand follows or with

semicolon, slash, or carriage return.

i .3 .3

Operands
Operands are usually the symbolic address of the data to be accessed when an instruction is

executed, or the input data or arguments of a pseudo-op.
a

statement depends on the statement operator.

comment

1 .3.4‘

In each case,

interpretation of operands in

Operands are terminated by a semicolon, a slash if a

follows, or a carriage return-line feed.

Comments

The programmer may add notes to a statement following a slash mark.
affect assembly processing or program execution, but are useful in the program
or

debugging

l -4

Such comments do not

listing for later analysis

1.4

Symbols
The programmer may create symbols to use as statement

labels, as operators, and as operands.

A symbol is a string of one or more alphanumeric characters delimited by

punctuation character.

symbol contains from one to six characters from the set of 26 alphabetic characters and ten digits 0 through
9; however, the first character must be alphabetic.

1.4.1

Symbol Distinction
The PAL-D Assembler makes a distinction between the types of symbols it is processing. These

types are
0.

Permanent symbols
JMS

symbol whose value of 4000 (octal) is taken from PAL—D's permanent

operation code symbol table.
b.

User—defined symbols
HERE

user-defined symbol; when used as a symbolic address tag, its value is

the address of the statement it tags (this value is assigned

l .4.l .1

Permanent

Symbols

by PAL-D).

PAL-D has in its permanent symbol table definitions of its operation codes,

operate commands, and many input—output transfer (IOT) microinstructions (see Appendix B).

PAL-D's

permanent symbols may be used without prior definition by the user.

1.4.1.2

User-Defined Symbols

User-defined symbols are composed according to the following rules.

The characters must be

The first character first be

Only the first six characters of any symbol are meaningful to PAL—D; the remainder,

alphabetic (A-Z) or numeric (0-9).

alphabetic.

ifany, are ignored.
Note that because of the third rule above,
since the seventh character is

symbol such as INTEGER would be interpreted as INTEGE

ignored. Remember, if symbols of more than six characters are used, the

programmer must avoid defining two apparently different symbols whose first characters are identical.

For example, the two symbols GEORGE] and GEORGE2 differ only in the seventh character, thus the

Assembler treats them as being the same symbol, GEORGE.
When the symbol

field delimiter.

following the space is a user-defined symbol, the space acts as an address

Example:
"2117-l

CLAJ

JMP,__,A J
l -5

where A is user—defined symbol with the value 2117.

Address

JMP

101

000

000 (binary representation of permanent symbol

000

Oil

001

iii

The operation codes (op codes) are

written more concisely in octal

JMP)

(binary representation of address A)

inclusively ORed to form
101

JMPA
or

The expression JMP A is evaluated as follows.

001

Oil

ill

5317.

Symbolic Addresses

l .4.2

A symbol used as a label to specify a symbolic address must appear first in the statement and
must be

immediately followed by a comma.

defined symbol

can

When used in this way,

symbol is said to be defined.

reference an instruction or data word at any point in the program.

A symbol

can

defined as a label only once.

If a programmer attempts to define the same symbol as a label again, the

second or successive attempt is

ignored and an error is indicated.

definition.

The Assembler recognizes only the first

These are legal symbolic addresses:

ADDR,
TOTAL,
SUM,
The following symbolic addresses are illegal:

7ABC,

LAB-—,

T .4.3

(first character must be alphabetic)
(comma must immediately follow label)

Symbolic Operators
Symbols used as operators must be predefined by the Assembler or by the programmer.

statement

space,

has no ,label, the operator may appear first in the statement, and must be terminated by a

tab, semicolon, or carriage return.
TAD
PAGE
ZIP

1.4.4

If a

The following are examples of legal operators:

(a mnemonic machine instruction operator)
(an Assembler pseudo-op)
(legal only ifdefined by the user)

Symbolic Operands
Symbols used as operands must have a value defined by the user.

These may be symbolic

references to previously defined labels where the arguments to be used by this instruction are to be found,
or

the values of symbolic operands may be constants or character strings.

TOTAL,
The first operand, ACT
ACT

by the user.

TAD AC1

TAG

specifies an accumulator register, determined by the value given to the symbol

The second operand references a memory location whose name or symbolic address is TAG.

1—6

1.4.5

Symbol Tables
.The Assembler processes symbols in Source program statements by referencing its symbol tables

which contain all defined symbols along with the binary value assigned

Initially,

to each

symbol.

the Assembler's permanent symbol tablescontains the mnemonic op codes of the machine

instructions and the Assembler pseudo—op codes,

listed in Appendix B.

As the

source

program is

processed

symbols defined in the source program are added to the user's symbol table.
\
1.4.5.1

Direct Assignment Statements

—

The programmer

inserts

new

symbols with their assigned values

directly into the symbol table by using a direct assignment statement of the form
symbol: value
where the value may be

number or expression.

For example,

ALPHA:
BE TA=1 7
A direct assignment statement may also be used to give a new symbol the same value as a

previously defined symbol.
BETA=17

GAMMA=BETA
The new symbol, GAMMA, is entered into the user's Symbol table with the value 17.
The value assigned to a symbol may be changed.

ALPHA=7

changes the value assigned to the first example from 5 to 7.
The user may also define symbols by use of the comma.

When the first symbol of a statement is

terminated by a comma, it is assigned a value equal to the current location counter

*100

TAG,

(CLC).

For example,

/set CLC (origin) to 100:)

CLAJ
JMP A.)

On)

DCA B)

The symbol TAG is assigned a value of 0100, the symbol B a value of 0102, and the symbol A a value of
0103.
Direct assignment statements do not generate instructions or data in the obiect program.
statements are

1.5

These

used to assign values so that symbols can be conveniently used in other statements.

NUMBERS

Any sequence of numbers delimited by a punctuation character is interpreted numerically by
PAL—D.

i
12

4372
The radix control

pseudo—operators (pseudo-tops) indicate to the Assembler the radix to be
The pseudo—op DECIMAL indicates that all numbers

used in number interpretation (see Chapter 2).
are

be interpreted as decimal until the next occurrence of the pseudo-op OCTAL.

The pseudo-op

OCTAL indicates that all numbers are to be interpreted as octal until the next occurrence of the pseudo—op
DECIMAL.
The radix is initially set to octal and remains octal unless otherwise specified.

1 .5.l

Arithmetic and Logical

Operators

The arithmetic and logical operators are:
+

Plus

25 complement addition

(modulo 4096)
-

2s complement subtraction

Minus

(modulo 4096)
!

Exclamation Mark

Boolean inclusive OR

(union)
&
2.

Boolean AND (intersection)

Ampersand

Interpreted as inclusive OR when used

Space

separate two symbolic operators.

TAG,

l .5.2

Example:

CLA HCLL J

Evaluating Expressions

Symbols and numbers (exclusive of pseudo-op symbols) may be combined by using the arithmetic
and

logical operators to form expressions.

1.6

Expressions are evaluated from left to right. Example:
A! B

A+B

Value

0002

0003

0005

7777

0003

0002

Value
Value

0007

0005

0014

0002

0007

0005

0700

0007

0707

0671

0707

0000

A—B

A&B

ADDRESS ASSIGNMENTS
The PAL-D Assembler sets the origin,

starting address, of the source program to absolute

location (address) 0200 unless the origin is specified by the programmer.

As source statements are processed,

PAL—D assigns consecutive memory addresses to the instructions and data words of the object program.
is done by

incrementing the location counter each time a memory location is assigned.

l-8

This

A statement which

generates a single object program storage word increments the location counter by one.

Another statement

may generate six storage words, thus incrementing the location counter by six.

Direct assignment statements and some Assembler pseudo-ops do not generate storage words
and therefore do not affect the location counter.

1 .6.1

Current Address Indicator
The special character

current location counter.

(point or period) always has a value equal to the value of the

It may be used as any integer or symbol (except to the left of an equal sign).

Example:
*200J
JMP
is equivalent to JMP 0202.

+ 2.)

Also,
*3001
+2400!
.

will produce in location 0300 the quantity 2700.

Consider

*2200l
CALL=JMS |

00271
The second line, CALL

JMS I

does not increment the current location counter,

therefore, 0027 is

placed in location 2200 and CALL is placed in the user's symbol table with an associated value of 4600
(the octal equivalent of JMS 1.).

1 .6.2

Indirect Addressing

When the character 1 appears in a statement between a memory reference instruction and an oper-

and, the operand becomes the address containing the address of the statement to be executed. Consider
TAD 40

which is a direct address statement, where 40 is interpreted as'the address containing the quantity to be
added to the accumulator.

Thus, if address 40 contains 0432, then 0432 is added to the accumulator.

Now consider

TAD I 40

which is an indirect address statement, where 40 is interpreted as the address of the address containing
the quantity to be added to the accumulator.

Thus, if address 40 contains 432, and address 432 contains

456, then 456 is added to the accumulator.
When a reference is made to an address not on the same page as the reference, PAL-D sets
the indirect bit (bit

3)Iof the machine instruction, generating

indirect address linkage to the off—page

reference (see Paging and Off—Page Referencing, Sections 1 .7.1 .1 and 1.7.1 .2).

1-9

In the case of several

off-page references to the same address, the indirect address linkage

will be generated only once.

Example:
A,

*2ll7u)
CLA J

*2600 I
TAD _.A

DC.A__.A
The space preceding the user-defined symbol A acts as an address field delimiter.

PAL-D will recognize

that the address tag A is not on the current page (in this case 2600-2777) and will generate a link to it
ln location 2600, PAL-D will place the word

in the following manner.

(octal equivalent of TAD l 2777)

1777

and in location 2777 (the last location on the current page) the word 2ll7 (the actual address of A) will

be placed.
a

When it sees the second reference to A it will

use the previous link word rather than creating

new one.

PAL—D will recognize and generate an indirect address linkage only when the address referenced
is to a location on another page, not the current page.

The programmer must use the character I to

indicate an explicit indirect address when indirectly addressing to a location on the current page.
PAL-D cannot generate a link for an instruction that is already specified as being an indirect
address.

In this case, PAL—D will type the error message |l

(Illegal Indirect),- the error message is ignored

and assembly is continued.

l .6.3

Autoindexing

lnterpage references are often necessary for obtaining operands when processing large amounts
of data.

The PDP—8 computers have facilities to ease the addressing of this data.

When absolute locations

10 to 17 (octal) are indirectly addressed, the content of the location is incremented before it is used as
an

address and the incremented number is left in the location.

This allows the programmer to address

consecutive memory locations using a minimum of statements.
It must be remembered that initially these locations (10 to 17) must be set to one less than the

first desired address.

Because of their characteristics, these locations are called autoindex registers.

No incrementation takes place when locations 10 to l7 are addressed directly.

Example:
Statement is in location 500
Data is on the page starting at 5000

Autoindexing register 10 is used for addressing

0476

1377

DCA 10

l4lO

TAD l 10

0500

/ set up auto
/ index with 4777
/ C(l 0) is incremented to 5000 before

TAD (5000-l)

0477 30l0

use as

0577 4777

address

literal generated by PAL—D

When the statement in location 500 is executed, the content of location 10 will be incremented to 5000
and the content of location 5000 will be added to the content of the accumulator.

If the instruction

TAD l 10 is re-executed, the content of location 5001 is added to the content of the accumulator, and so on.

1.6.4

Literals

Symbolic and integer literals (constants) may be defined as shown below.
CLA J
TAD (2) J
DCA INDEX J

Operator and operand must always
be separated with a space.

The left parenthesis is a signal to the Assembler that the
in the table at
are

stored.

the top of the' current page.

integer following is to be assigned a location

This is the same table in which the indirect address linkages

In the above example, the quantity 2 is stored in the first free location in a list beginning at

the top of the current page (relative address 177), and the statement in which it appears is encoded with
an

address referring to that location.
A literal is assigned to storage the first time it is

encountered; subsequent references will be

the same location.
If the programmer wishes to assign literals to page 0 rather than the current page, he must use

square brackets,
or

[ l, in place of parentheses. Whether using parentheses or square brackets, the right

closing member is optional and may always be replaced with a carriage return.
TAD (777 1

1.6.4.l

Nesting

Literals may be nested as shown below.
*200 J
TAD (TAD (30 J

will generate
0200

l276

0376

1377

(literals assigned to locations

0377

0030

0377 and 0376; top of current page)

This type of nesting may be carried to many levels.

Literals are stored on each page starting at relative address 177 (only
may be placed on page 0)

l27IO

I778 literals

If literals are being generated for some nonzero page and then the origin

is set to another page, the current page literal buffer is punched out during pass 2.
to the previously used page, the same

If the origin is reset

literal will be generated if used again.

If a single character is preceded by a quote (") , the 8-bit value of the USA SCII code for that

character is inserted instead of taking the letter as a symbol.
CLAJ

Example:

TAD ("A I

will place the constant 0301 in the accumulator.

INSTRUCTIONS

l.7

There are two basic groups of instructions: memory reference and augmented.

Memory

reference instructions require an operand; augmented instructions do not require an operand.

Memory Reference instructions

l .7.l

In PDP—8 computers,

some

instructions require a reference to memory.

They are appropriately

designated memory reference instructions, and take the following format.

OPERATION
CODES 0‘5

MEMORY
PAGE

,——_._.ag_.___‘

r—H

b-~.r--—’
INDIRECT
ADDRESSING

4“

‘
v

ADDRESS

Memory Reference Instruction Bit Assignments
Bits 0 through 2 contain the operation code of the instruction to be performed (AND,
or

JMP)

Bit 3 tells the computer if the instruction is indirect, that

TAD, DCA, JMS, or

is, if the address of the instruction

specifies the location of the operand, or if it specifies the location of the address of the operand.
tells the computer if the instruction is referencing the current page or page zero.

through ll ( 7 bits) to specify an address.

This leaves bits 5

In these 7 bits, 200 octal or l28 decimal locations may be

specified; the page bit increases accessible locations to 400 octal or 256 decimal.
The address field of a memory reference instruction may be any valid expression.

Example:

Bit 4

=270 J
*200 J
TAD A-20 J

l-l2

produces, in location 200, the word
-

1250
001

which in binary is

010

101

000

which is also TAD 250.

l .7.l .l

P_ag_i_n_g_

—

To ease the programmer's addressing problems,

divides memory into sectors called pages.
0 to l77 (octal) on that page.

convention has been defined that

Each page contain 200 octal locations (1 28 decimal) numbered

There are 40 octal or 32 decimal pages numbered 0 to 37 (octal)

examples of page numbers and the absolute and relative locations (addresses):are shown below.
be borne in mind,

Some

It must

however, that there is no physical separation of pages in memory.
Absolute

Page

Address

200

400

7400

7600

Relative
Address

177

377

577

7577

7777

—

177
177
177
177
177

The following table offers a comparison of specific absolute and relative addresses on the
same

page

Absolute

Page

Address

Relative
Address

3
l2

617
2577

l 77

6255

7777

l 77

Since only seven bits are necessary to address 200 octal

for this function

l .7.l .2

l 7

locations, bits 5 to ii are reserved

Off-Page Referencing

from bit 4 of the instruction.

The page on which an absolute address is contained can be determined

If bit 4 is a 0, the address refers to a location on page 0,- if bit 4 is a i,

the address refers to a location on the current (same) page, that is, the some memory page as the instruction.

l .7.2

Augmented Instructions
Augmented instructions are divided into two groups: operate and input—output transfer

microinstructions

1 .7.2.1

Operate Microinstructions

Within the operate group there are l'WO groups of microinstructions.

Group 1 microinstructions are principally for clear, complement, rotate, and increment operations and
are

designated by the presence of a O in bit 3 of the machine instruction word.

OPERATION
CODE?

CLA

PW.“

,_A_fi

(See Appendix B.)

CMA

ROTATE
AC ANDL
RIGHT

ROTATE t
POSITION IF A O,
2POS|TIONS
IFA I

’__»...3

,__.&__‘

\_y__..1

b-v—‘J

\_V—.J

\_.,_.I

CONTAINS
A 0 TO
SPECIFY
GROUPI

CLL

CML

ROTATE
AC AND L
LEFT

IAC

Group 1 Operate Microinstruction Bit Assignments

Group 2 microinstructions are used principally in checking the content of the accumulator and
link and, based on the check,

continuing to or skipping the next statement. Group 2 microinstructions are

identified by the presence of a l in bit 3 and a 0 in bit ll of the machine instruction word (See
Appendix B).

REVERSE
SKIP
SENSING OF

OPERAYION
CODE 7

CLA

SZA

BITS 5,6,7

r———-&-———-\

r—*—\

r—H

CONTAINS AI
TO SPECIFY
GROUP 2

SMA

SNL

HLT
F‘fi

OSR

CONTAINSAO
TO SPEC‘CY
GROUPZ

Group 2 Operate Microinstruction Bit Assignments

Group 1 and group 2 microinstructions can not be combined because bit 3 determines only one
or

the other.
Within Group 2, there are two groups of skip instructions.

OR group and the AND group.

They may be referred to as the

OR Group

AND Group
'

SMA

SPA

SZA

SNA

SNL

SZL

The OR group is designated by a 0 in bit 8, the AND group by a i in bit 8.

OR and AND group

instructions cannot be combined because bit 8 determines only one or the other.

If the programmer does combine
under which

legal skip instructions, it is important to note the conditions

skip may occur.
CR Group

If these skips are combined in a statement, the inclusive OR of the conditions

determines the skip.

SZA

SNL

The next statement is skipped if

the accumulator contains 0000,

the link is a l, or
both conditions exist.

b.
determines the

AND Group

—

If the skips are combined in a statement, the

logical AND of the conditions

skip.
SNA

SZL

The next statement is skipped only if the accumulator differs from 0000 and the link is 0.

1 .7.2.2

Input-Output Transfer Microinstructions

These microinstructions initiate operation of

peripheral equipment and effect information transfer between the central processor and the input-output
device

(5).

This is the principal function of the input-output transfer (IOT) microinstructions.

B lists all valid IOT

microinstructions, and each is discussed in detail in the User's Handbook.

Appendix

CHAPTER 2
PSEUDO-OPERATORS

The programmer may use pseudo-operators (pseudo—ops) to direct the Assembler to perform
certain tasks or to interpret subsequent coding in a certain manner.

Some pseudo-ops generate storage

words in the obiect program, other pseudo-ops direct the Assembler on how to proceed with the assembly.

Pseudo-ops are maintained in the Assembler's permanent symbol table.
The function of each PAL-D pseudo-op is described below.

2.]

CURRENT LOCATION COUNTER
The programmer may

use

the PAGE pseudo-op to reset the current location counter (CLC) to

the first location on a specified page.

PAGE

without an argument, the CLC is reset to the first location on the
next succeeding page.

Thus, if a program is being assembled into

page i and the programmer wishes to begin the next segment of his

program on page 2, he need only insert PAGE,

JMP

.-7J

follows.

(Last location used on page 1)

PAGE I

CLAJ
PAGE n

resets the CLC to the first
a

(First location on page 2)
location of page n, where n is an integer,

previously defined symbol, or a symbolic expression. Example:
PAGE 2

(sets the CLC to location 400)
(sets the CLC to location 1400)

PAGE 6

2.2

EXTENDED MEMORY

When using more than one memory bank, the pseudo-op FIELD instructs the Assembler to output
a

field setting.
FIELD n

where n is an integer,
defined symbol,

or a

previously

symbolic

expression within the range 0 S n 57.
This pseudo—op causes a field setting (binary word) of the form
11 XXX 000
to be output on the binary tape

where 000 §XXX S I II

during pass 2. This word is interpreted by the Loader, which then begins

loading information from the Loader into the new field.
2-1

RADIX CONTROL

2.3

Integers used in a source program are usually taken as octal numbers. If, however, the
programmer wishes to have certain numbers treated as decimal, he may use the pseudo-op DECIMAL.

DECIMAL

all integers in subsequent coding are taken as decimal until
the occurrence of the pseudo-op OCTAL.

OCTAL

2.4

resets

the radix to its original octal base.

LISTING CONTROL

During pass 3, a listing of the source program is printed (punched).

The programmer may,

however, control the output of his pass 3 listing by use of the pseudo-op XLIST.
XLIST

Those portions of the source program enclosed by XLIST will
not appear in

the pass 3 listing.

TEXT FACILITY

2. 5

The pseudo-op TEXT enables the user to represent a character or string of characters in USA SCII
code trimmed to six bits and packed two characters to a word.
are

The numerical values generated by TEXT.

left—justified in the storage words they occupy, with the unused bits of the last word filled with 05.
A string of text may be entered by giving the pseudo—op TEXT Followed

by a space, a delimiting

character, a string of text, and the same delimiting character.

Example:
TEXT ATEXT STRINGA
The first

printing character following TEXT is taken as the delimiting character, and the text string is

the characters which follow until the delimiting character is

again encountered.

If the example above were at location 0200, the
pass 3

200

2405

20l

3024

202

4023

203

2422

204

l I I6

205

0700

listing would be as follows.

(.__. denotes a space)

NOTE
With TEXT, any printing character
may be used as a delimiting character;

the delimiting character cannot be
used in the text string.
2-2

2 .6

END OF PROGRAM

The special symbol $ (dollar sign) indicates the end oF a program.
counters the

2.7

When the Assembler en-

$, it terminates the pass.

END OF FILE

The pseudo-op PAUSE signals the Assembler to stop processing the current input File.
current pass is not terminated, and processing

The

continues when the user types CTRL/P.

When processing a segmented program, the programmer must use the PAUSE pseudo-op as the
last statement oF each segment (tape or File) to halt processing, giving him time to call (or insert, iF
paper tape is being used) the succeeding segment oF his program.

The PAUSE pseudo-op should be used only at the physical end oF a tape or File.

2.8

ALTERING THE SYMBOL TABLE
PAL-D has a permanent symbol table which contains all instructions (symbols and their octal

values) required by the Disk Monitor System

They are referred to as PAL-D's basic instructions or

symbols, and are listed in Appendix B.
When the symbolic program to be assembled requires instructions not already in the table

(e.g., card reader IOT's), the table must be altered to include those instructions.

PAL-D has two

pseudo-ops that are used to alter the permanent symbol table:
EXPUNGE

deletes the entire permanent symbol table, except pseudo-ops.

FIXTAB

appends symbols to the table For duration oF the assembly. All symbols deFined before the occurrence oF FIXTAB are temporarily made part oF the permanent symbol table.

These pseudo-ops can be used to eliminate unneeded symbols From the table, thus providing more storage
For user symbols

To append the Following card reader IOT's to the symbol table, the programmer generates an

ASCII tape oF:

RCSF=663I
RCSP=667I

RCRD=6674
FIXTAB
PAUSE

The ASCII tape is then read into core ahead oF the symbolic program tape during pass I

The PAUSE

pseudo-op stops assembly, and the Loader waits For the programmer to put the symbolic program tape
into the tape reader and press CONTinue

AFter each assembly, PAL-D's permanent symbol table is restored to contain only the basic

symbols

2-3

Internal Representation

2 .8 1
.

Each permanent and user-defined symbol occupies four words (locations) in the symbol table
storage area, as shown below.
O

Word I

Word 2

C3 458

+ C

Word 3

+ C

first 2 characters

458 C2

458

second 2 characters

l'l'lll'd 2 characters

octal code or address

Word 4

where

C] C2,
,

6 represent

the first character, second character,

ly. (Symbols may consist of from one to six characters.)
system flags.

sixth character respective-

Bits 0 and l of word 1 and bit 0 of word 2 are

With a permanent symbol, word 4 contains the octal code of the symbol; with a user-

defined symbol, word 4 contains the address of the symbol.

represented as fol lows

For example: the permanent symbol TAD is

Wordl

Word2

248x458+0l
04

x45

Word 3

0000

Word 4

1000

+00

l3458
224

+4000

4224

flag blt

(octal code for TAD)

Note that the first digit of the USASCII octal code for each character is always trimmed by the assem-

bler so that the character is represented using six bits of a word

324, it was trimmed to 24; A is 30l

it was trimmed to 0]; etc.

For example, USASCII code for T is

CHAPTER 3
PROGRAM PREPARATION AND ASSEMBLER OUTPUT

The source language tape (symbolic tape) is prepared using the Editor or an off-line ASR-33

Teletype
3.I

PROGRAM TAPE
Since the Assembler

readable

ignores certain characters, these may be used freely to produce a more

symbolic source tape.

These useful characters are tab and form—feed.

The Assembler will also ignore extraneous spaces, carriage return-line feed combinations,

rubouts, and blank tape.
The program body consists of statements and pseudo-ops.

dollar sign ($).

The program is terminated by the

If the program is large, it may be segmented by use of the pseudo-op PAUSE.

This often

facilitates editing the source program since each section is physically smaller.

The Assembler initially sets the origin (current location counter) of the source program to 0200.
The programmer may reset the current location counter by use of the asterisk.
The following two programs are identical except that format effectors were used in the second

printout.
*200

/EXAMPLE OF FORMAT
/GENERATOR
BEGIN, O/START OF PROGRAM
KCC

KSF/WAIT FOR FLAG
.—I/FLAG NOT SET YET
KRB/READ IN CHARACTER

JMP

DCA CHAR

TAD CHAR
TAD MSPACE/IS IT A SPACE?

SNA CLA

HLT/YES
JMP BEGIN + 2/NO:

INPUT AGAIN

CHAR, O/TEMPORARY STORAGE
MSPACE, -240/-ASCII EQUIVALENT

/END OF EXAMPLE
$
*200

/EXAMPLE OF FORMAT
/GENERATOR
BEGIN,

/START OF PROGRAM

0
KCC
KSF

JMP

.-1

/WAIT FOR FLAG
/FLAG NOT SET YET
3-I

/READ IN CHARACTER

KRB

DCA CHAR

TAD CHAR

/IS IT A SPACE?

TAD MSPACE

SNA CLA

/YES
/NO: INPUT AGAIN
/TEMPORARY STORAGE

-24O

/-ASCII EQUIVALENT

HLT
JMP BEGIN+ 2

CHAR,
MSPACE,

/END OF EXAMPLE
$
Both of these programs will

3 .2

produce the same binary code. The second, however, is easier to read.

ASSEMBLY
PAL-D is a two-pass assembler with an optional third pass which produces a side-by-side

assembly listing of the symbolic source statements, their octal equivalents, and assigned absolute
addresses.

When used with the TSS/8 time-sharing monitor the passes are invisible to the user.

However,

the user determines whether or not the third pass will be made by his response to PAL-D's OPTION:
every (see Section 4.3.2).

3.2.]

Pass 1

During pass i, PAL-D processes the source tape (or file) and places in its user's symbol table
the definitions of all symbols used.

The user's symbol table is printed (or punched) at the end of pass 2.

If any symbols remain undefined at the end of pass

I, the US (Undefined Symbol) diagnostic is printed

during pass 2 when the undefined symbol is encountered (see Error Diagnostics).

The symbol table is

printed (or punched) in alphabetical order on either the teleprinter or high—speed punch. The punched

symbol table may be used to expand DDT-8s symbol table for use in program debugging.

If the program

listed above were assembled, PAL—D would output the following symbol table.

BEGIN

3.2.2

0200

C HAR

021 3

MSPACE

0214

Pass 2

During pass 2, PAL—D processes the source tape (or file) and generates binary output using the

symbol table equivalences defined during pass I

The binary output may be loaded in core by the Disk

Monitor System Binary Loader.
The binary coded tape

(or file) consists of leader code, an origin setting, and data words.

Every occmrence in the source program of an asterisk causes a new origin setting in the binary output.
At the end of the binary coded tape,

binary checksum is produced and trailer code is generated.
3—2

When using the low speed paper tape punch,
and will be preceded and followed by rubouts.

rubouts

diagnostic messages are both typed and punched

The Binary Loader will

ignore everything enclosed within

3.2.3

Pass 3

During pass 3, PAL-D processes the source tape (or tile) and prints out a side-by-side listing
of the generated octal code and the original source language.

the pass 3

If the program shown above were assembled,

listing would be
*200

/EXAMPLE OF FORMAT
/GENERATOR
0200

0000

0201

6032

BEGIN,

/START OF PROGRAM

KCC

/WAIT FOR FLAG
/FLAG NOT SET YET
/READ IN CHARACTER

0202

6031

KSF

0203

5202

JMP

0204

6036

KRB

0205

3213

DCA CHAR

0206

1213

TAD CHAR

0207

1214
7650

TAD MSPACE
SNA CLA

/IS IT A SPACE?

0210

/YES

.-1

0211

7402

HLT

0212

5202

JMP BEGIN+2 /NO:

0213

0000

0214

7540

CHAR,
MSPACE,

INPUT AGAIN

/TEMPORARY STORAGE
/-ASCII EQUIVALENT

-240

/END OF EXAMPLE

3-3

CHAPTER 4
LOADING AND ASSEMBLING PROCEDURES

The PAL-D Assembler is furnished on punched paper tape and is loaded and stored on the disk

during system build time. Loading PAL-D in a TSS/8 system, is performed by the system manager and is
described in detail in the TSS/8 System Manager's Guide, DEC-T8-MBZA-D.

However, the user can at

any time build a new system in a Disk Monitor system; therefore, complete loading procedures are detail-

ed below.

4.l

DISK MONITOR SYSTEM
If the Disk Monitor is not present on your disk or DECtape, build it according to instructions

in the Disk Monitor System manual, DEC-D8-SDAB-D.

4. l .l

Loading
The assembler is incorporated in the system by loading the paper tape into core using the disk

Loader.

Then the assembler may be saved on the disk or DECtape

PAL-D is loaded into core in two passes as explained below.

Disk system responses are under-

lined; non-underlined characters represent user-supplied data.

_._LOAD 1

call Loader from disk ( J indicates carriage return)

*IN-R: J

input to be from high speed reader; T: would indicate input from
Teletype reader

Loader found device R: valid

*OPT-2 J

two-pass load is specified

i: J

control is to be returned to the Monitor after loading tape into
care; 7600 J would also transfer control to the Monitor after
loading the tape

Loader is waiting for user to put paper tape in reader and type lP.
I

After reading tape into core, Loader waits for user to remove tape
and type lP.

If checksum error occurs, Monitor types ? in place

of 1.

Loader is waiting for user to put paper tape in reader for second
pass and type lP.
|—--—---—

l< W >_1 < 1P >_l_< lP >_i<lP >

After reading tape on second pass, Loader is waiting for user to
remove tape and type TP.
Again, checksum error will cause ? to

be typed in place of 1.
NOTE

lP indicates CTRL-P, and < > indicates
that the enclosed portion is not echoed
(printed when the user types).
4-1

4.1.2

Saving
PAL-D may be saved on the system device as a system program.

This is done by typing the

following:

LSAVE PALD!0-7577;6200

Multipll Entry

Program

Page Save

Name

System Program

User Program

Point

The programmer may now

The PAL-D Assembler is now saved as a system program on the system device.

type PALD J which brings the Assembler into core for use with symbolic source programs.
The user's core resident symbol table can hold
Monitor System;

16010 user-defined symbols under the Disk

24510 under the TSS/8 Monitor System. This may be expanded by saving

device a user file named .SYM which can be used by PAL-D to store extra symbols.

symbol occupies four words.

The symbol table can be expanded by

12810

the system

Each user-defined

2008 locations (one

core

page) by saving a file with the Following statement.

_._SAVE .SYM:0-l77;0 .J

(T92 user symbols)

If a larger symbol table area is needed, simply specify additional pages, where each page saved provides

storage for 32 additional symbols.

For example:

LSAVE .SYM:0-377;0 J

(224 user symbols)

LSAVE .SYM:O-i777;0 .2

(416 user symbols)

will save two core pages, and

will save eight core pages for symbol storage

The preceding procedures are illustrated in Figure l

4.] .3

Assembling
PAL-D is transferred from the system device into core using the Monitor.

One of the following

methods is used depending upon the monitor type.
3.3.1 Disk Monitor System

The user begins by typing

.LPALD J
PAL-D requests on output file by typing

fQLlL‘
The user selects the output device by typing
T: J

for the Teletype (low speed reader/punch), or

R: J

For the high speed reader/punch, or

Szname J

for output to the system device as file name

RESPOND TO DISK
MONITOR AS SHOWN
BELOW
'

LOAD )

iIN-R:
——

R== HIGH-SPEED READER

Ti= LOW- SPEED READER

)

HIGH-SPEED READER

LOW SPEED READER
WHICH READER
P

PLACE PAL-D TAPE
IN READER"

SET TAPE READER
TO FREE

TYPE CTRL /P

PLACE PAL-D TAPE
IN READER"

I
LOADER TYPES

TAPE READS IN AND
STOPS AT TRAILER CODE

LOADER TYPES

TYPE CTRL /P

TYPE CTRL/P

SET TAPE READER TO
START

I
WAS THIS
THE SECOND PASS

TAPE READS IN,STOPS
AT TRAILER CODE,AND
COMPUTER HALTS

I
SET TAPE READER
TO FREE

PRESS CONTINUE

LOADER TYPES

WAS THIS
THE SECOND PASS

TYPE
*

CTRL / P

PLACE LEADER CODE
OVER READER HEAD.
MONITOR TYPES

_'-

TYPE

LSAVE PALD !O-7577;6200)

TYPE

LSAVE.SYM=O-1777;O )

THIS SAVES PAL-D AS
A SYSTEM PROGRAM

THIS CREATES THE SYMBOL
TABLE FILE ON THE DISK

PAL-D IS LOADED
AND READY FOR USE

Figure I

Loading and Saving PAL-D Using the Disk Moni’ror Sys’rem

4-3

PAL-D now types

*_IL~I__and waits for the user to select the input files.

Up to five input files may be specified (e.g., R:, R:,

S:name, R:, R: .2 ), but in this example the user selected
R: 1

input from the high speed reader/punch
NOTE

PAL-D checks the validity of each selected file (i .e.,
valid only if the file was declared when building Moni—
*
tor), and types for each valid file and ? for an in-

valid file. When PAL-D finds an invalid file it returns
control to the Monitor, in which case, the user must
start

again by calling PALDJ

When PAL-D is satisfied that the input file(s) is valid, it will request third pass listing Option by typing
*OPT-

The user may type
T

meaning listing and symbols are to be produced
on

R J

the Teletype, or

meaning listing and symbols are desired on high
speed punch, or

meaning symbols only (any other character means
no

third pass)

When the high speed punch is selected as a listing device, the alphabetic symbol table produced at the
end of pass 2 is also produced on the high speed punch.
PAL-D will now proceed with the assembly, pausing only when user intervention is required

(i .e., placing a new paper tape in the reader, turning on the punch, etc.).

On these occasions,

PAL-D will type an up-arrow (i) on the Teletype to indicate user intervention is required
user

When the

has performed the necessary function and is ready to continue with the assembly, he types CTRL-P

(which does not echo).
At the end of pass 2, PAL-D outputs the user's symbol table in alphabetical order (in addition
to the assembled

binary output).

This symbol table listing may be terminated at any time by typing

CTRL-P, and PAL-D will proceed to initiate pass 3, if requested.

Assembly may be terminated and control returned to the Monitor at any time by typing
CTRL-C

When the assembly is complete, control will automatically be returned to the Monitor.

*With the low-speed reader: set reader to FREE, place tape in reader, type CTRL/P, and then set reader
to

START.

With the high-speed reader: place tape in reader and then type CTRL/P.

4-4

4.2

TSS/8 MONITOR SYSTEM
Assembling with PAL-D in TSS/8 requires no operator intervention between passes. The sym-

bol table is typed out at the end of pass two and the listing at the end of pass three.
be terminated at any point by typing CTRL/C

The assembly may

Control will revert from PAL-D to the Monitor program

which will type out a dot
and wait for the next instruction from the teletype.

In the illustrations which follow, underlined

characters are those typed out by the system; non-underlined characters represent user-supplied data.
Time sharing assemblies are requested as follows.
In response to the monitor's dot

the user types the RUN (or simply R) command, a space and the name of the system program
_.

R PALD J

PAL-D is brought into core and signals its readiness by requesting an input file name

MM: BIN2 J
The user reply in this case was BIN2, a user symbol for a source program to be assembled.
PAL-D next requests the name of an output file.

O_Lljf_l.fl': TYPE2 l
The user response was TYPE2, the name under which the assembled program will be stored.

Optionally, the user may type the RETURN key to specify no output file.
OUTPUT: J

This is useful in debugging.

A program may be corrected and reassembled any number of times with

production of an output file postponed until a satisfactory version is achieved

PAL-D's final query is whether the user wants a program listing.
OPTION:

There are two effective responses only: N signifying No and I (RETURN key) signifying Yes.

When it

receives the final response, PAL-D reads in the user source program from disk (source programs are stored

prior to assembly) and proceeds with the assembly

After assembly, PAL-D returns control to the Monitor

which types
and waits for the user to supply the next command.

NOTE
When running under the Disk Monitor system PAL-D
requires a dollar sign ($) as the last entry in a source
program.

Under the TSS/8 Monitor PAL-D does not

require one but if it does not find one it types a message
to warn

the user that his program may not be assembled

properly by an assembly program other than time-sharing
PAL-D.

4-5

The following listing was reproduced from a time sharing run.

It illustrates the initial dialogue,

the symbol table produced at the end of pass 2 (any error messages would also appear at this point) and
the listing, in octal notation, produced at the end of pass 3.

"QHTAL

DIALOGUE

PALD

INPUT:BIN2
OUTPUT:TYR2

_OPT ION:
kOUNT

O415

CRLF

O417

SYMBOL

LOOP

O4O6

TABLE

OUT

O425

REG

O416

@TART

O4OO

/RROGRAM

TYPE

OUT

"123456789"

*w4wfl

PROGRAM
USTHQG

LITERALS

O4OO

72OO

O4O1

4217

JMS

O4O2

1377

TAD

(-12

O4O3

3215

DOA

COUNT

O4O4

1376

TAD

<26O

O4O5

3216

DCA

REG

TAD

REG

START:

LOOP:

CLA
CRLF

O4O6

1216

O4O7

4225

JMS

OUT

O41O

2216

ISZ

REG

O411

2215

152

COUNT

O412

52O6

JMP

LOOP

O413

4217

JMS

CRLE

O414

74O2

O415

OOOO

COUNT,

O416

OOOO

REG,

O417

OOOO

GRLE,

1375

TAD

(215

4225

JMS

OUT

O422

1374

TAD

(212

O423

4225

JMS

OUT

JMP

5617
OOOO

OUT,

CRLF

O426

6O46

TLS

O427

6O41

TSF

O43O

5227

JMP

O431

72OO

CLA

_O432
'O574

5625

JMP

.-1

OUT

O212

O575

O215

@576

026i?)

O577

7766

ZERO

HLT

O421

O425

FOR

O42O

O424

/ASGII

385

4-6

/ASCII

FOR

CARRIAGE

/A5011

FOR

LINE

FEED

RETURN

CHAPTER 5
ERROR DIAGNOSTICS

PAL—D makes many error checks as it processes source

detected, the Assembler prints an error message.

language statements.

When an error is

The format of the error messages is

ERROR CODE

ADDRESS

where ERROR CODE is a two-letter code which specifies the type of error, and ADDRESS is either the

absolute octal address where the error occurred or the address of the error relative to the last symbolic
tag (it there was one) on the current page.
The programmer should examine each error indication to determine whether correction is

required.
PAL-D's error messages are listed and explained below.
Error
Code

Explanation
Two PAL—D'internal tables have overlapped

can

—

This situation

usually be corrected by decreasing the level of literal

nesting or number of current page literals used prior to this

point on the page.
DE
7

Systems device. error

An error was detected when trying to

read or write the system device; after three failures, control is re—
V

turned to the Monitor.
.

Systems device full

The capacity of the systems device has been

exceeded; assembly is terminated and control is returned to the Monitor.
IC

Illegal character
.a

An illegal character was encountered in other than

comment or TEXT field; the character is ignored and the assembly

continued
ID

—

Illegal redefinition of a symbol

—

An attempt was made to give a

previously defined symbol a new value by other means than the
equal sign; the symbol was not redefined.
IE

Illegal equals

—

An equal sign was used in the wrong context.

Examples:
TAD A +=B

(the expression to the left of the equal sign is not
single symbol or, the expression to the right of
the equal sign was not previously defined)

A +B=C
II

Illegal indirect
not be

—

An off—page reference was made; a link could

generated because the indirect bit was already set.

5—l

Error

Explanation

Code

Example:
*200

TAD I A 1!

PAGE :1

7240 :1

A,
ND

The program terminator, $, is missing (with TSS/8 only).

Current nonzero page exceeded

An attempt was made to

override a literal with an instruction, or

override an instruction with a literal; this can be

corrected by

(l) decreasing the number of literals on the page or
(2) decreasing the number of instructions on the page.
PH

Phase error

PAL-D has received input Files in an incorrect order;

Assembly is terminated and control is returned to the Monitor.
SE

Symbol table exceeded

Assembly is terminated and control is

returned to the Monitor; the symbol table may be expanded to
contain up to ”84 user symbols by saving a File named .SYM
on

the system device.

Undefined

symbol

A symbol has been processed during pass 2

that was not defined before the end of pass I
ZE

Page 0 exceeded

Same as PE except with reference to page 0.

APPENDIX A

USA SCII CHARACTER SET

Character

Code

Character

Code

Character

Code

301

302

260

241

261

303

262

242
243

304

263

244

305

264

245

306

265

246

307

266

247

(
)

310

31 1

267
270

312

271

31 3

250
251

252

253

254

314

315

316

31 7

320

321

322

275

323

277

324
325

[
]

333

U
V

326

BELL

207

327

TAB

21 1

X
Y

330
331

LINE FEED

212

332

CARRIAGE-RETURN
SPACE
RUBOUT

215

,
-

255

256

257

272

;

273

335

240
377

APPENDIX B

SYMBOL LIST
Mnemonic

Code

Operation

Event Time

MEMORY REFERENCE IN STRUCTION S
AND

0000

TAD

1 000

ISZ

2000

DCA

3000

JMS

4000

JMP

5000

logical AND
complement add
increment & skip it zero
deposit & clear AC
jump to subroutine
iUmP
25

GROUP 1 OPERATE MICROINSTRUCTIONS
NOP

7000

IAC

7001

increment AC

RAL

7004

rotate

RTL

7006

rotate AC &

link left two

RAR

7010

rotate AC &

link right one

RTR

7012

rotate AC &

link right two

CML

7020

complement link

CMA

7040

complement AC

CLL

7100

clear link

CLA

7200

clear AC

operation
AC & link left one

GROUP 2 OPERATE MICROINSTRUCTIONS

halts the computer

HLT

7402

OSR

7404

inclusive OR switch register with AC

SKP

7410

skip unconditionally
skip on nonzero link
skip on zero link
skip on zero AC
skip on nonzero AC
skip on minus AC
skip on plus AC (zero is positive)

SNL

7420

SZL

7430

SZA

7440

SNA

7450

SMA

7500

SPA

7510

COMBINED OPERATE MICROINSTRUCTIONS
CIA

7041

complement & increment AC

STL

71 20

set

GLK

7204

STA

7240

get link (put link in AC, bit 11)
set AC
-1

LAS

7604

load AC with switch register

link to 1
=

PSEUDO-OPERATORS
DECIMAL
EXPUNGE

FIELD
FIXTAB
I

OCTAL
PAGE

—L-—L—t—-l_l

PSEUDO-OPERATORS
PAUSE
TEXT
XLIST
Z

Mnemonic

Code

Event Time

Operation

IOT MICROINSTRUCTIONS FOR DISK MONITOR

Program Interrupt
ION

6001

turn

[OF

6002

turn

KSF

6031

skip if keyboard/reader flag

KCC

6032

clear AC & keyboard/reader flag

KRS

6034

read keyboard/reader buffer

KRB

6036

clear AC & read keyboard buffer, & clear

interrupt on
interrupt off

Keyboard/ Reader

keyboard f lag

Teleprinter/Punch
TSF

6041

TCF

6042
6044

TPC

skip if teleprinter/punch flag
clear teleprinter/punch flag

load teleprinter/punch buffer,
select & print

TLS

6046

load teleprinter/punch buffer,
select & print, and clear teleprinter/punch

flag
High-Speed Reader (Type PC02)
RSF

6011

skip if reader flag

RRB

6012

read reader buffer & clear flag

RFC

6014

clear flag & buffer & fetch character

-"=

High-Speed Punch (Type PC03)
PSF

6021

PCF

6022

PPC

6024

PLS

6026

1
skip if punch flag
clear flag & buffer
load buffer & punch character
clear flag & buffer, load & punch
==

Disk File and Control (type DF32)
DCMA

6601

DMAR

6603

clear disk memory request & interrupt flags
load disk from AC, clear AC, read into care,

DMAW

6605

clear interrupt flag
load disk from AC, write onto disk from core,

DC EA

6611

clear disk extended address & memory address
extension register

DSAC
DEAL

6612

skip if address confirmed flag

6615

clear disk extended address & memory address

DEAC

6616

extension register & load same from AC
clear AC, load AC from disk extended address
1
register, skip if address confirmed flag

clear interrupt flag

DFSE

6621

skip if parity error, data request late, or
write lock switch flag
0 (no error)
=

B-2

Mnemonic

Code

DF SC

6622

DMAC

6626

Event Time

Operation
skip if completion flag I (date
transfer completed)
clear AC, load AC from disk memory
=

address register

DECtape Transport (Type TU55) and Control (Type TCOI)
DTRA

DTCA
DTXA
DTSF
DTRB
DTLB

676i
6762
6764
6771
6772
6774

read status register A

clear status register A
load status register A

(ON—ICON"

skip on flags
read status register B

load status register B

Memory Extension Control (Type 183)
62nI
62n2

change to data field n
change to instruction field n
read data field into AC 6-8

RMF

6214
6224
6244

RIB

6234

read interrupt buffer

CDF
CIF
RDF
RIF

read instruction field into AC 6-8
restore memory field

IOT MICROINSTRUCTIONS FOR TSS/8 MONITOR

Program Interrupt
IOT

6000

(See Time-Sharing System User's Guide

DEC-TB-MRFB-D .)

Keyboard/Reader
603i
6032
6034
6036

skip if keyboard/reader flag

6400
640]
6030

set

skip if teleprinter/punch flag
clear teleprinter/punch flag

TPC

6041
6042
6044

TLS

6046

SAS

6040

KSF

KCC
KRS
KRB
K58

SBC
KSR

clear AC & keyboard/reader flag
read keyboard/reader buffer
clear AC & read keyboard buffer, & clear

keyboard flag
keyboard break

set buffer control

flags

read keyboard string

Teleprinter/Punch
TSF

TCF

load teleprinter/punch buffer,
select & print
load teleprinter/punch buffer,
select & print, and clear teleprinter/punch

flag
send a string

High-Speed Reader (Type PC02)
RSF
RRB

RFC
RRS

601 I
6012

6014
6010

skip if reader flag

read reader buffer & clear flag
clear flag & buffer & fetch character
read reader string

Mnemonic

Event Time

Operation

Code

High-Speed Punch (Type PC03)
PSF

6021

PCF

6022

PPC
PLS

6024

PST

6020

skip if punch flag 1
clear flag & buffer
load buffer & punch character
clear flag & buffer, load & punch
punch string
=

6026

DECtape Transport (Type TU55) and Control (Type TCOl)
DTSF

6764
6771

DTRB

6772

DTXA

load status register A
.

skip on Flags
read status register B

Program Control
URT

6411

user run

TOD

6412

time of day

RCR

6413

return clock rate

DATE

6414

Date

SYN

6415

quantum synchronization

STM

6416

set timer

T55

6420
6421
6430

skip on TSS/8
set switch register

CKS

6200

check status

ASD

6440

assign device

REL

6442

release device

DUP

6402

duplex

CON

6422

console

REN

OPEN

6600
6601

Open File

CLOS

6602

Close File

RFILE

6603

Read File

P‘ROT

6604

Protect File

WFILE

6605

Write File

CRF

6610

Create File

EXT

6611

Extend File

RED

6612

Reduce File

FINF

6613

File Information

SIZE

6614

SEGS

6406

Segment Size
Segment Count

ACT

6617
6616

Account Number
Who

USE

SSW

time

user

File Control

WHO

Rename File

N—IOJ

PAL-D

Absolute location IO to I7, I-IO

INDEX
Arithmetic and Logical Operators, I-8

Absolute and relative addresses, I-I3

Ampersand, I-8

Accumulator, I—I5

Boolean AND, I-8

Accumulator Register, I-6

Boolean inclusive OR, I-8

Additional features, I-I

Exclamation Mark, I-8

Addition/Subtraction, 2's complement, see 25
complement, addition/subtraction

Minus, I-8

Address Assignments, I-8

Autoindexing,

I-IO

Indirect Addressing, 1-9

Literals, 1-“

25 complement addition/subtraction, I-8

ASCII, 2-3

Assembler, I-I, 1-4, 3—2

Location counter, 1-8

I-8

Assembly, 3-3, 4—2
Listing, 4-2

Starting address, I-8

Pass

Address Field, I-IZ

I, 4-2

Pass 2, 4—2

Address Indicator, Current, see Current Address
Indicator

Alphabetic Characters

1-2

Altering Symbol Table, 2-3

Pass 3, 4-3

Third pass, 4-2

Asterisk, 4-I

4-2

Augmented Instructions, I-I4

ASCII, 2-3
Basic instructions, 2-3

CONT, 2-3

Input-Output Transfer Microinstructions, I—I4,
I-I5

Operate Microinstructions, I-I4

Disk Monitor System, 2-3

EXPUNGE, 2-3

Autoindexing, I-IO
Absolute location IO to I7, I-IO

FIXTAB, 2-3

Autoindex registers, I-IO

IOT's symbol table, 2-3
Pass

Plus, I-8

Space, 1-8

Current Address Indicator, I-9

Origin,

Modulo 4096, 1-8

I, 2-3

Incrementation, I—II

Interpage references

Permanent symbol table, 2-3

AND group,

1-14,

Basic instructions, 2—3

1—15

Autoindex registers, I-IO

Symbolic program, 2-3
Ampersand, I—8

BE, 5-I

PAL-D INDEX (Cont)

Binary coded tape, 4-2
Binary Loader, 4-3

Point or period, l-9

Current Location counter, 2-l, 4-l

Binary representation, l-6

CLC, 2-l

Binary word, 2-l

Integer, 2-l

Boolean AND, 1-8

n, 2-l

Boolean inclusive OR, l—8

PAGE n, 2-l

Build Monitor, 3-l

PAGE, 2-l
Current page, l-l2

Carriage Return (J ), l-3

Current page literal, 5-l

Carriage return-line feed (as terminator), l-3

Current page literal buffer, l-l2

Central processor, l-l5

Characters, Alphabetic, see Alphabetic
Chraacters

ignored, see ignored characters

Legal, see Legal Characters

Numeric, see Numeric characters

Special, see Special Characters
Symbols for nonprinting, see Symbols

For nonprinting characters

Checksum, 4-2

DDT-8, 4-2
DE, 5-l

Debugging, 4-2
DECIMAL, 2—2

DECtape, 3-l, 4-]
Defined symbol, 1-6

Checksum error, 3—1

CLC, 2-l

Delimitor, 2-2
Device error, 5-l

Clear, l-l4

Device full, 5-l

Combined Operate Microinstructions, B-l

Combining symbols and numbers, l-8
Comma, l-6

DF, 5-l
DF32 Disk, 1—]
D532 Disk, l-l

COMMENT, l-3

Direct Assignment, l-7

Comments, l-4

Symbols, l-7

Notes, 1-4

Symbol Table, l-7

Complement, l—l4
Condition, skip,

Data words, 4-2

l-l5

CONT, 2-3

Disk Debugging Tape, l-l
Disk Monitor System, 2-3, 3-l

Dollar Sign (33), 2-3, 4-], 5-2

CTRL/C (iC), 3-3
CTRL/P (1P), 3—3
Current Address indicator, l-9
Incrementation , 1—9

Editor, 1-4, 4-l
Elements of statement, l-4

PAL-D INDEX (Cont)

End of File, 2-3

Program terminator, 5-2

PAUSE, 2-3

SE, 5-2

PAUSE pseudo-op, 2-3

Source language, 5-I

Segmented program, 2-3

.SYM, 5-2

End of Program, 2-3

Dollar Sign ($), 2-3

Symbol table exceeded, 5-2
Undefined symbol, 5-2

Error checks, 5-I

US, 5-2

Error code, 5-l

ZE, 5-2

Error Diagnostics, 4-2, 5-I

Error message, 5-l, 5-2

BE, 5-l

Error messages format, see Format of error messages

Current page literals, 5-l

Evaluating Expressions, l-8

DE, 5-I

Arithmetic operator, l-8

Device error, 5-l

Combining symbols and numbers, I-8

Device full, 5-l

Expression evaluating, l-8

DF, 5-l

Logical operator, l-8

Dollar Sign ($), 5-2

Evaluation, l-6

Error checks, 5-l

Exclamation mark, l-8

Error code, 5-I

EXPUNGE, 2-3

Error message, 5-I

Extended Memory, 2-]

Error message format, 5-l

Binary word, 2-l

IC, 5-I

FIELD, 2-]

ID, 5-I

FIELD n, 2-]

IE, 5-l

Field setting, 2-]

II, 5-l

Loader, 2-]

Illegal character, 5-l

Pass 2, 2-]

Illegal equals, 5-I
Illegal indirect, 5-l

FIELD, 2-l

Illegal redefinition, 5-I

FIELD n, 2-]

Literal nesting, 5-l

Fields, I-3

Nonzero page, 5-2

File, End of, see End of File

Page 0 exceeded, 5-2

FIXTAB, 2-3

PE, 5—2

Format Effectors, 1-3, 4-]

PH, 5-2

Carriage Return ( J ), l-3

Phase error, 5-2

Carriage return-line feed (as terminator), I-3

PAL-D INDEX (Cont)

COMMENT, I-3

Indirect Addressing, 1-9

Fields, I-3

I, I-9, I—IO

List, I-3

II, I-IO

Semicolon (as terminator), I—3

Illegal indirect, I-IO

Slash (/), 1-3

Indirect address linkage, l-9, l-IO

Statement terminator, I-3

Indirect bit, I-9

Tabulations, I-3

Off-page reference, I-9, l-IO

Format of error messages, 5-l

Indirect address linkage, I-9, l-IO

Format memory reference instruction, I-IZ

Indirect bit, I-9

Input file, 3-3
General Form of statement, l-4

Input-output device, l-l5

Group I microinstructions, l—l4

Input-Output Transfer microinstructions, I-I5

Group 2 microinstructions, l-I4

Central processor, I-I5

Group I operate microinstructions, 3-]

Input-output device, I-I5

Group 2 operate microinstructions, 8-]

IOT, l—I5

Operation of peripheral equipment, 1-15
I, 1-9, 1-10

Instructions, I—I2

IC, 5-I

Augmented instructions, l-I4

ID, 5-I

Memory reference instructions, I—I2

IE, 5-l

Integer, 2-I

Ignored characters, I-2, 4-]

Interpage references, I-IO

II, I-IO, 5-I

IOT, 1-5, 1-15

Illegal characters, l-3, 5-I

IOT microinstructions, B-2

Comment field, I-3

IOT's symbol table, 2-3

Error message, I-3

IC, I-3

Labels, I-4, also see Symbols I-5

TEXT field, 1-3

Language, 1-]

Illegal equals, 5-I

Leader code, 4-2

Illegal indirect, 5-I

Left parenthesis, 1-”

Illegal redefinition, 5-I

Legal characters, I-2

Inclusive OR, l-I5

Alphabetic characters, I-2

Increment, I-I4

Ignored characters, I-2

Incrementation, 1—9, I—II

Nonprinting characters, I-2

PAL—D INDEX (Cont)

Numeric characters, l-2

Off-page referencing, 1—13

Special characters, l-2

Page zero, l-lZ

Link, l-l5

Paging, l-l3

List, l-3

Minus, l-8

Listing, 2-2, 4-2, 4-3

Monitor, 3-l, 3-2

Listing control, 2-2

n, page, 2-l

Pass 3, 2-2

Names file, 4-l

XLIST, 2-2

ND, 4-6, 5-2

Literal buffer, current page, see Current Page
literal buffer

Literal nesting, 5-l

1-12

Nonzero page, l-l2

Left parenthesis, l-ll

Pass 2, l-l2

Nesting literals, l-ll

Quote,

Square brackets, l-ll

1—12

Relative address 177, 1—12

Loader , 2—l, 3~l

Nonprinting characters, 1-2

Loading PAL-D, 3-l

Nonzero page, 1-12, 5-2

Checksum error, 3-]

Notes, l—4

CTRL/P (1P), 3-]

Numbers, l-7

Loader, 3-]

Arithmetic and logical operators, 1—8

Question Mark (?), 3-1

Evaluating expressions, l-8

Two-pass load, 3-]

Logical

Current page literal buffer, l-lZ

Literals,

Literals, l-ll, l-l2

Location counter,

Nesting literals, 1-“

Pseudo-operators, l-8

l-8, 1-9

Radix, l-8

AND, l—l5

Radix control, l-8

Logical Operator, 1-8

Numeric characters, l-2

Low speed paper tape punch, 4-3

OCTAL, 2-2
Machine instruction, l-l4

Memory, Extended,

see

Octal code, 4-3

Extended Memory

Memory page, 1—13

Memory Reference instructions,

Off-page referencing, l-9, l-lO, l-l3
Current page, 1—13

1-12,

3-]

Address Field, l-12
Current page, l-l2
Format memory reference instruction, 1-12

Memory page,

Operands, 1-4

l-l3

PAL-D IND EX (Cont)

Operate microinstructions, l-l4
Accumulator, l-l5
AND group,

l-l4, l-l5

Clear, l-l4

Complement, l-I4
Condition skip, l-l5

Group I microinstructions, l-l4
Group 2 microinstructions
Inclusive OR, l-l5

Increment, l-l4

Logical AND, l-l5
Machine instruction, l-l4

l-l4, l-l5

Rotate, i-l4

Skipping, l-l4
Operation of peripheral equipment, l-l5
Operators, l-4
Operators, Arithmetic and Logical, see
Arithmetic and Logical Operators
OR group,

PAL III Assembler, l-l

Paper tape, 3-]
Paper tape punch, low speed, see Low speed paper
tape punch
Pass I,

2-3, 4-2

Debugging, 4-2
DDT-8, 4-2
Error Diagnostics, 4-2
Source tape, 4-2
US (Undefined Symbol), 4-2

Link, l-l5

OR group,

PAL-D, definition, 1-]

l-l4, l-l5

User's symbol table, 4-2
Pass 2,

1-12, 2-l, 4-2

Asterisk, 4—2

Binary coded tape, 4-2
Binary loader, 4-3
Checksum, 4-2
Data words, 4-2

Diagnostic messages, 4-3
Leader code, 4-2

Low speed paper tape punch, 4-3

ORed operation codes, l-7

Origin setting, 4-2

Origin, 1-8, 4-]

Rubouts, 4-3

Origin setting, 4-2

Trailer code, 4-2

Output device, 3-2
Output file, 3-2

Pass 3,

2-1, 2-2, 4-3

Listing, 4-3
Octal code, 4-3

PAGE, 2-]

Source language, 4-3

PAGE n, 2-]

Source tape, 4-3

Page zero, 1-12

PAUSE, 2-3, 4-l

Page 0 exceeded, 5-2

PAUSE pseudo-op, 2-3

Paging, l-l3

PE, 5-2

Absolute and relative addresses, l-l3
PAL-D Assembler, 3-2

Period or point, l-9
Permanent symbol table,

l-5, l-7, 2-l, 2-3

PAL-D INDEX (Cont)

Saving PAL-D, 3-2

PH, 5-2
Phase error, 5—2

PAL-D Assembler, 3-2

Plus, l-8

Expanding user's symbol table, 3-2

Point or period, 1-9

Program, End of

see

SE, 5-2
End of Program

Program tape, 4-l

Segmented program, 2-3
Semicolon (as terminator), 1-3

Asterisk, 4-]

Skipping, l-l4

Current location counter, 4-]

Slash( /), 1-3

Dollar sign ($), 4-]

Source language, 4-3, 5-]

Format effectors, 4-1

Source language tape, 4-]

Ignored characters, 4-]

Source programs, 1-4

Origin, 4-]

Source tape, 4-2, 4-3

PAUSE, 4-]

Space, 1-8

Program terminator, 5-2

Special characters, 1-2

Pseudo-op codes, l-7

Square brackets, l-ll

Pseudo-operators, 1-8, 2-l, 3-1

Statements, 1-4

Pseudo-ops

2-l , 2-2

Assembler, l-4
Comments, 1-4

Question Mark ('2), 3-]

Editor, 1-4

Quote, 1-12

Elements, l-4
General Form, 1-4

Labels, l-4

Radix, 1-8, 2-2
RADIX Control,

1-3, 2-2

Operands, l-4

DECIMAL, 2-2

Operators, 1-4

OCTAL, 2-2

Source programs, l-4

Pseudo-op, 2-2

Teletype, 1-4

Radix, 2-2

Statement terminator, 1-3

Relative address l77, 1-12

Starting address, 1-8

Relative addresses, Absolute and, see Absolute

String, l-5

and relative addresses

Requirements,
Rotate, l-l4

Rubouts, 4-3

1-]

String of text, 2-2
.SYM, 3-2, 5-2

Symbol Distinction, l-5
Permanent symbols , l-5

PAL-D INDEX (Cont)

User-defined symbols, l-5

String, l-5

Symbol Distinction, l-5

Symbol list, 3-]
Combined operate microinstructions, 3-]

Symbolic Addresses, 1-6

Group 1 operate microinstructions, B-l

Sy'mbolic Operands, 1-6

Group 2 operate microinstructions, B-l

Symbolic operators, 1-6

IOT microinstructions, B-2

Symbol tables, 1-7

Memory reference instructions, 3-]

Symbols for nonprinting characters, 1—2

Pseudo-operators, 3-]

Symbols, User-defined, see User-defined symbols

Symbol table, Altering, see Altering symbol table

Syntax, l-l

Symbol table exceeded, 5—2

Illegal characters, 1-3

Symbol Tables, 1-7

Format effectors, l-3

Direct assignment statements, l-7

Legal characters

l-2

Mnemonic op codes, l-7
Permanent symbol table, l-7

Tables, Symbol, see Symbol tables

Pseudo-op codes, l-7

Tabulations, l-3

User's symbol table, l-7

TCOl

Value assigned, 1-7

Teletype, 1-4

Symbol table, User's, see User's symbol table

Terminator, l-6

DECtape, l-l

Symbol used as a label, 1-6

TEXT, 2-2

Symbolic addresses, l-6

Text Facility, 2-2

Comma, 1-6

Delimitor, 2-2

Defined symbol, 1-6

String of text, 2-2

Symbol used as a label, 1-6

TEXT, 2-2

Symbolic Operands, l-6

USASCII, 2-2

Accumulator register, 1-6

Third pass, 4-2

Values of symbolic operands, 1-6

Trailer code, 4-2

Symbolic operands, Values of, see Values of
symbolic operands

Transferring PAL-D, 3-2
25 complement addition/subtraction, l-8

Symbolic operators, 1-6
Terminator, 1-6

Symbolic program, 2-3
Symbolic tape, 4-]
Symbolic Tape Editor, 1-]
Symbols, l-5, l—7

Undefined symbol, 5-2
US

(Undefined symbol), 4-2, 5-2

USASCII, 2-2,4-l
USASCII Character Set, A-l

PAL-D INDEX (Cont)

User-defined symbols, l-5
User infervenfion, 3-3

User's symbol fable, 1-7, 3-2, 4-2

Using PAL-D, 3-2

Assembly, 3-3
CTRL/C (TC), 3-3
CTRL/P (1P), 3-3
Input File, 3-3
Monitor, 3-2

OUl'pUl' device, 3-2
Output file, 3-2
Transferring PAL-D, 3-2
User inferven’rion, 3-3

Value assigned, l-7

Values of symbolic operands, l-6

XLIST, 2-2

ZE, 5-2

PAL-D ASSEMBLER

DEC-D8—ASAB—D
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