Digital PDFs

DEC-D8-SDAB-D

December 1969

120 pages

Original

3.0MB

Document:	PDP-8/1 DISK MONITOR SYSTEM PROGRAMMER'S REFERENCE MANUAL For additional copies specify
Order Number:	DEC-D8-SDAB-D
Revision:
Pages:	120
Original Filename:	https://svn.so-much-stuff.com/svn/trunk/pdp8/src/dec/dec-d8-sda/dec-d8-sdab-d.pdf

OCR Text

Digital

Equipment Corporation

Maynard, IVIassachusetts

SHIinnSn
UIILIUII6JIJ

DISK MONITOR

SYSTEM

PROGRAMMER'S REFERENCE MANUAL
PDP-8 FAMILY

PDP-8/1

DISK MONITOR SYSTEM

PROGRAMMEF^'S REFERENCE MANUAL

For addifional copies specify Order NIo.
Library, Digital Equipment Corporation,

DIGITAL

DEC-D8-SDAB-D to Program

Maynard, Mass.

EQUIPMENT CORPORATION n MAYNARD

Price:

$2.75

MASSACHUSETTS

1st

Printing May 1968

2ncl Printing

Rev. July 1968

3rd Printing January 1969
4th Printing Rev. April 1969

Revised July 1969

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

1968, 1969 by Digital Equipment Corporation

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

DEC

PDP

FLIP CHIP

FOCAL
COMPUTER LAB

DIGITAL

CONTENTS
Pa£(

CHAPTER

INTRODUCTION
1.1

Equipment Requirements

1-1

CHAPTER 2

MONITOR OPERATION
2.1

General Description

2-1

2.1.1

Monitor Residence

2-1

2.1.2

System Modes

2-1

2.2

Bootstrapping the Monitor

2-2

2.3

Starting the Mlonitor

2-3

2.4

Command Strings

2-3

2.4.1

Command String Format

2-4

2.4.2

Examples of Command Strings

2-6

2.5

Loading- Disk System Binary Loader

2-7

2.5.1

Binary Loader Operating Procedures

2-7

2.5.2

Binary Loader Error Messages

2-9

2.6

Saving Programs (Save Command)

2-10

2.6.1

Save Command Format

2-10

2.6.2

Save Command Processing

2-12

2.7

Calling a Program (Call Command)

2-12

2.8

System Error Messages

2-13

CHAPTER 3
SYSTEM PROGRAM LIBRARY
3.1

PIP

3-1

3.1.1

Loading and Saving

3-1

3.1.2

Operating Procedures

3-2

3.1.3

Examples

3-7

3.2

Editor

3-10

3.2.1

Loading and Saving

3-12

3.2.2

Operating Procedures

3-13

3.2.3

Example

3-14

3.3

PAL-D Disk Assembler

3-15

CONTENTS (Cont)
Page
3.3.1

Loading and Saving

3-15

3.3.2

Operating Procedures

3-16

3.3.3

Examples

3-18

3.4

FORTRAN--D

3-18

3.4.1

Compiler

3-21

3.4.2

Operating System

3-27

3.4.3

Examples

3-36

3.5

DDT-D

3-38

3.5.1

Loading and Saving

3-41

3.5.2

Operating Procedures

3-42

3.5.3

Examples

3-42

APPENDIX A
SYSTEM GENERATION

A-1

APPENDIX B
SYSTEM FORMATS

B-1

APPENDIX C

COMMAND DECODER

C-1

APPENDIX D
BINARY LOADER

D-1

APPENDIX E
SYSTEM PROGRAMS

E-1

APPENDIX F
I/O PROGRAMMING

F~l

TABLES
Page
2-1

System Error Messages

2-13

3-1

Special

Key Functions

3-10

3-2

Summary of Editor Commands

3-11

3-3

PAL-D Pseudo-Operators

3-15

3-4

PAL-D Error Messages

3-17

3-5

Summary of FORTRAN Statements

3-19

3-6

Compiler Systems Diagnostics

3-24

3-7

Compiler Compilation Diagnostics

3-25

3-8

Operating System Diagnostics

3-30

3-9

DDT-D Commands

3-41

ILLUSTRATIONS

B-1

Disk Storage Layout

B-2

DECtape Storage Layout

B-3

Directory Name (DN) Block Format

B-4

Storage Allocation Map (SAM) Block Format

B-6

B-5

Contiguous-Page Save File Format

B~8

B-6

Noncontiguous-Page Save File Format

B-9

B-7

Sample PIP Directory Listing

B-10

B-8

Monitor-Time vs User-Time Core Usage

B-1

B-9

Core Usage During SAVE Command Execution

B-1

B-10

Core Usage During CALL Command Execution

B-13

B-11

Monitor Flov/ Chart (Part 1)

B-1

B-11

Monitor Flow Chart (Part 2)

B-1

B-11

Monitor Flow Chart (Part 3)

B-1

C-1

Output List Produced by Command Decoder

C-4

C-2

Command Decoder Core Usage

C-5

C-3

Command Decoder Flow Chart (Part 1)

C-6

C-3

Command Decoder Flow Chart (Part 2)

C-7

C-3

Command Decoder Flow Chart (Part 3)

C-8

C-3

Command Decoder Flow Chart (Part 4)

C-9

C-3

Command Decoder Flow Chart (Part 5)

C-10

C-3

Command Decoder Flow Chart (Part 6)

C-11

D-1

Binary Loader Flow Chart (Part 1)

D-3

D-1

Binary Loader Flow Chart (Part 2)

D-4

D-1

Binary Loader Flow Chart (Part 3)

D-5

CHAPTER

INTRODUCTION

The PDP-8 Disk/DECtape Monitor System is designed for any PDP-8 computer having at
least one

DECdisk or one DECtape.

This system consists of a keyboard -oriented Monitor,

which en-

ables the user to efficiently control the flow of programs through his PDP-8, and a comprehensive soft-

ware package, which includes a FORTRAN Compiler, Program Assembly Language (PAL-D),

Edit pro-

gram (Editor), Peripheral Interchange Program (PIP), and Dynamic Debugging Technique (DDT-D)
program.

Also provided is a program (Builder) for generating a customized monitor according to the

user's particular machine configuration

(amount of core, number of disks or DECtapes, etc.).

The system is modular and open ended, permitting the user to construct the software required
in his environment,

device —

and allows the user full access to his disk (or DECtape) — referred to as the system

for storage

and retrieval of his programs.

By typing appropriate commands to the Monitor,

the user can load a program (construct it from one or more units of binary coding previously punched out

on paper tape or written on the disk by the Assembler, and assign it core), save it (write it out, with an
assigned starting address, on the system device), and later call

(read

back into core from the sys-

tem device) for execution

. 1

EQUIPMENT REQUIREMENTS
The minimum equipment requirements of the PDP-8 Disk/DECtape Monitor System are as

follows.

A basic PDP-8/I, -8/L, -8/S, or -8
4K of core
Teletype
3 -Cycle Data Break (Option required with PDP-8/S)

At least one DF32 Random Access DECdisk File or a TCOl Automatic Control
The DECtape must have timing and mark

with a TU55 DECtape transport.
tracks written on it prior to use.

NOTE
The system will recognize up to 32K of core, up to
up to
(1 Type DF32 and 3 Type DS32's),
eight DECtapes (TCOTs only) and a high-speed paperfour disks

tape reader.

1-1

CHAPTER 2

MONITOR OPERATION
This chapter contains a discussion of the operation of the Monitor.

Succeeding chapters

contain descriptions and operating procedures for the system programs.

GENERAL DESCRIPTION

2.1

The PDP-8 Disk Monitor System permits the user to control the flow of programs through his

computer and takes full advantage of the extended memory capabilities of disk or DECtape.
tion to the Monitor, the system also contains a library of system programs.

addi-

Together, they provide the

user with the capabilities of compiling, assembling, editing, loading, saving, calling, and debugging
his own

programs.

2.1.1

Monitor Residence
Monitor, as well as system and user programs,

system device

stored on and retrieved from the user's

To obtain a working Monitor, the user must first build his own customized version, via

the easy-to-use dialogue technique of the System Builder program and store this version on his system

device.

Following this, the user then creates his System Program Library on the system device.

Both

of these procedures are described in Appendix A.
In

core, the resident part of Monitor (called head of monitor )

tions 7600 through 7777) of field 0.

the system

The starting address of Monitor is 7600;

7642 is entry address to

I/O routine, which performs all reading and writing on the system device.

portions of Monitor, such as those routines which perform
in as

resides in the top page (loca-

Nonresident

SAVEs and CALLs, are automatically called

needed, and in core, they share the area from location 7000 through 7^77

(These portions

disappear after use, leaving this area for the user.)
Specific diagrams showing the allocation of the system, both on the system device and in

core, are given in Appendix B.

2.1.2

System Modes

At any point in time, the system is running in one of tv/o modes:

Monitor mode or user mode.

Monitor mode is entered (1) whenever the Monitor is started (see Paragraph 2.2) or (2) when

CTRL/C (tC) is typed while running any system program. Monitor mode is signalled by the Monitor
typeout of a dot ( •)•

At both Monitor and system program time. Monitor is able to sense a tC typein,

causing the system to enter Monitor mode, return to Monitor at location 7600, and respond with a dot
(

•)

typeout.

At this point, the user can issue any Monitor command via the Teletype keyboard.

User mode is present whenever the system is executing a system or user program.

grams signal user mode by responding with an asterisk (*) typeout.

^See Appendix F.

2-1

System pro-

2.2

BOOTSTRAPPING THE MONITOR
The following discussion assumes that the user has built a customized Monitor and has stored

on his system device, according to the procedure described in Appendix A.

The bootstrapping of Monitor into core is necessary only when the resident Monitor area
(locations 7600 through 7777) has been cleared or its contents otherwise destroyed.

System Builder

Turning the computer off and subsequently

leaves the resident portion of Monitor in core after building.

turning it on again does not normally destroy the contents of core.

The bootstrap procedure is as follows.
a.

Toggle in one of the following boolstrap routines, depending upon the type of system

device.
Disk
Location

Conf-ents

0200

6603

DMAR

0201

6622

DFSC

0202

5201

0203

5604

JMP .-1
JMP .+1

0204

7600

7750

7576

7751

7^7b

Symbolic

DECtape
Location

Symbolic

Contents

*200

7600

BEG,

0200

7600

0201

1216

TAD MVB

0202

4210

JMS DO

0203

1217

TAD

0204

3620

DCA

0205

1222

0206

4210

0207

5600

TAD RF
JMS DO
BEG
JMP

0210

0000

0211

6766

DTXA DTCA

0212

3621

DCA

0213

6771

DTSF

0214

5213

0215

5610

JMP .-1
JMP DO

0216

0600

/V\201
1

DO,

0000

MVB,

2-2

0600

DECtape

Symbolic

Location

Contents

0217

7577

M201,

-201

0220

7755

CA,

7755

0221

775A

WC,

7754

0222

0220

RF,

0220

After toggling in one of the above bootstrap routines, set the switches to 200 and press
Monitor should respond with a dot (•) after it has been brought into

LOAD ADDress and START.
core.

2.3

STARTING THE MONITOR

A jump to this location can be made by either (1) stopping the machine, setting the switches to 7600, and pressing LOAD ADDress and START, or (2) typing
Monitor start is at location 7600.

tC when in Monitor mode or when a system program (or any user program which includes coding to sense
a t C typein) is running.

Monitor start performs the following actions.
Saves the coding from location 7200 through 7577 in the first two scratch blocks on the
a.
system device.
b.

Reads blocks 1 and 2 (containing the rest of Monitor) from the system device into these

Transfers control to Monitor,

locations.

which responds with a carriage return,

line feed,

and a

dot.

A monitor restart can be performed by typing RUBOUT to Monitor. A Monitor restart performs
the same actions as described above except for Subparagraph a, A common use for RUBOUT is to terminate a command string when the operator has discovered that he has made a mistake.
string is ignored,

and A/\onitor responds as described in Subparagraph c.

The command

The user core image on the

system device is not changed by RUBOUT (it is changed, however, by tC).

2.4

COMMAND STRINGS
The user types commands in the form of command strings to direct Monitor, or a system pro-

gram, to perform some action.,

Command strings are simple in format and afford the user an easy means

of communicating with the system.

Monitor indicates its readiness to accept a command string by typing a dot, and at this point,
the user can type some Monitor command, such as CALL or

SAVE.

A start instruction (ST=7600) is issued when running Loader causes a |ump to 7600 after loading has
been performed.

Certain errors ahio cause a jump to this location.

2-3

System programs indicate their readiness to receive information by typing either an asterisk

The most common queries are as follows.

or a query.

*OUT-

Requests that the us€)r specify one output device name. In the case of
disk or DECtape the filename to be assigned to the output data must
also be specified.
'

Requests that the user specify one or more (up to 5) input device names.
For disk and DECtape, filenames of input files must also be specified.

*IN-

*OPT-

Requests that the user specify one option or switch, entered as a single
see Chapter 3 for options available in each

alphanumeric character;
system program.

This communication between the system and the user is handled by a portion of Monitor

known as the Command Decoder.

Command Decoder is called into core by the system when needed

and occupies any four contiguous pages of core.

A description of its core allocation and calling pro-

cedure, plus a flow chart, is given in Appendix C.
listed in

Paragraph 2.8.

Error

messages produced by Command Decoder are

Messages unique to individual system programs are given in Chapter 3.

Command String Format

2.4.1

Command strings are composed of a few basic elements and follow certain rules of punctuation.

Their basic elements are as follows.
a.

Device names

Filenames

Punctuation

Special characters

Each of these elements is described in the following paragraphs.

2.4.1 .1

Device Names - Device names permitted in command strings are as follows.
Dn:

DECtape unit, if both disk and DECtape are present in the system
(n

= unit number,

through 7)

System device (disk or DECtape unit 0)

High-speed paper tape equipment (reader or punch)

Low -speed paper tape equipment on the Teletype (reader or punch)

Device names and filenames are explained in Paragraph 2.4.1

Command Decoder is a system program ( .CD.) which is saved on the system device at build time

2-4

2.4.1 .2

Filenames - Filenames are limited to four characters in length and can be composed of any

combination of alphanumeric characters or special characters

with the following exceptions,

Imbedded spaces cannot appear in a filename (they are ignored).
a.
spaces are permitted.
b.

However, trailing

A filename cannot be one of the following words or symbols.
CALL

SAVE

;

Extensions to the filenames specified by the user are automatically appended by the system.
3
They are used internally by the system and cannot be referred to or modified by the user.

SYS
USER

(n)

Saved system program file in core bank n.

Saved user program file in core bank n.

ASCII

Source language program file (input to PAL-D Assembler or FORTRAN
Compiler)

BINARY

Binary program file (output from

FTC BIN

Interpretive binary/ file (output from

PAL-D Assembler).

FORTRAN Compiler).

Filenames (and extensions) are meaningful only for file structured devices (disk and DECtape).
If

they are specified for other devices, they are ignored.

on directory listings produced by the list feature in

NAME

Example:

Both the filename and extension name appear

PIP."^

TYPE

BLK

.SYS(O)

0015
0007

8D
PIP

SRCl. ASCII
BINARY
BIN
SRCl.USER(O)
.

2.4.1.3

Punctuation ,

(comma)

Punctuation within commond strings is as follows.

Used to separate device names, when more than one is given in a
command string. The comma is also used to separate core references
in a SAVE command string, when more than one contiguous area of core
is

;

0001
0001

specified.

Precedes the entry point specification in a SAVE command.
Terminates each device name. The colon is also used following the
filename in a SAVE command to indicate that the file is to be saved as
a user program.

Although both printing and nonprinting keyboard characters are allowable, printing characters are

recommended.
2

Note that Monitor is given the filename EX C; one reason for this unconventional use of an imbedded
blank is to protect Monitor from accidental destruction by the user (e.g., deletion via PIP).
The data structure of these files is described in Appendix B under "Data Structure. "

"8D" in example means VERSION 8, change D.

2-5

Separates the beginning and ending addresses of a contiguous core area
specification in a SAVE command.

Follows the filename in a SAVE command when a file is to be saved as
a system program.

2.4.1.4

Special Characters -

Special characters are used as described below.

if given while the system is in Monitor mode or a system program is running,
control is returned to Monitor start (location 7600). Monitor responds with a dot,

^C is typed by holding down the CTRL key and striking C.
not echo (does not print).
tp

tC does

Typed in response to a t typeout. Instructs the system to proceed with
tp |s typed by holding down the CTRL key and
the next operation. 1
tp doe:; not echo (does not print).
striking P.
Carriage return terminates current command string input. When typed
alone, in response to a system query, it indicates that the user does
not desire to specify the item (e.g., device name) requested.

RUBOUT

Causes the current command string to be ignored, and the system
returns to the beginning of the command string and is ready to receive
a new command.

2.4.2

RUBOUT does not echo.

Examples of Command Strings
These examples illustrate the elements and rules explained above.

Samples of both Monitor

commands and system program commands are given.
Monitor Commands:

^CALL PRGl J
.

Call the user program file, PRGl , from the system
device into core for execution.

SAVE PALD! 0-7577; 6200 J

Save a program, previously loaded by Loader into
locations
through 7577 of core, on the system
device as a system program (!). Assign a starting
address of 6200 and a filename, PALD.

System Program Com m and s

*IN- S:PR02 J

Use the file PR02 on the system device as the
input file.

*IN- S;TST1,R:^

Use the file TSTl on the system device and one file
From the high-speed paper tape reader as the input
Files.

*OUT-D5:SPEC J

Write the output file on DECtape unit No. 5 and
assign it the filename SPEC.

tP can also be used to prematurely terminate certain
operations while in progress (e.g., the typing
out of a file directory by the list option in PIP).
2
In all

examples, system response (typeout)

underlined for clarity.

2-6

*OUT- T: J

Punch the output on the Teletype paper tape punch.

*OPT-M

Select option M.

Spaces in command strings are ignored.

Thus, both examples below are equally correct and

perform the same function.

^SAVE PALD
._SAVE PA LD

0-7577} 6200 J
-7577;

6200 J

LOADING PROGRAMS - DISK SYSTEM EilNARY LOADER^

2.5

The Disk System Binary Loader takes as input the binary coding produced by the PAL-D Assembler and loads it intocore inexecutable form.
first

When loading is completed. Loader "disappears" after

entering the loaded program at the starting address typed by the user just prior to loading (see Para-

graph 2.5.1).

Loader accepts input from the system device or paper tape.

Loader requires one pass for any program which does not load above location 6777 (field

0).

Loader uses core from location 167 through 177 and 6000 through 7577, and the resident
portion of

Monitor occupies the remainder of field 0.

One -pass loading reads input files only once.

Two passes are required for all other programs (i.e., programs loading above 6777).

."^
two -pass loading, programs can be loaded in all of field 0, except locations 7600 through
7777

Two -pass loading requires that input paper tapes be read through the reader iwice.
2.5.1

Binary Loader Operati ng Procedures

A.OAD J

Direct Monitor to bring Binary Loader from the
system device into core for execution.

*IN-

Loader requests source of input(s). Type one or
more device names, separated by commas. If an
input device
filename(s).

a file-structured device, include

Up to five files can be specified.
Exomples

*IN-R: J

Input one tape from the paper tape reader.

*IN-R:,R:,R: J

Input three tapes from the paper tape reader.

An automatic carriage return occurs after user response to an OPT-request.
2

The Disk System Binary Loader is a system program saved on the

disk at build time. It is called by the user
occupies locations 7000-7577and hasastartingaddress of 7000,

the same manner as any system program.

8K and larger systems. Loader sets up locations 7574 through 7577 to
perform a start in fields other

than U.

An E or

the user s responsibi lity to protect these locations if he wants

to start in other than field 0.

error message (see Table 2-1) may appear following the entry of an IN

command.

Regardless of whether R: or T: is used to specify paper tape input, the high-speed
equipment is used
if it was indicated as present in the system
at System Builder time, otherwise the Teletype equipment
is used.
This convention is unique to Binary Loader.

2-7

INPT from the system device.

*IN-S:INPT^

Input the file

*IN-S:BIN2,R: J

Input the file BIN2 from the system device and one
tape from the paper tape reader.

*IN-S:BIN1,S:BIN2 J

Input

the files BIN! and

BIN2 from the system

device.
if device(s) are valid and filenames (if any) are
actually found on the system device. Loader responds with one asterisk for each correct input.

Loader requests mode desired (one -pass or two-pass).

*OPTExamples

*OPT-

One pass loading desired; no programs are loaded
above location 6777.

*OPT_2

Two -pass loading desired; programs can be loaded

(or anything else)

above location 6777.

*ST=

Loader requests the starting address to which control
be transferred when loading is completed. The
address is typed in the form
is to

fnnnn
'here
f

field

number

(omitted if field 0)^

and

nnnn = location within field
Examples
*ST=*'
*ST=7600i.^

Load into field 0,
Return to Monitor after loading.

*ST=0*'

ST=30225w^
'ST=10000./'

Load into field 3.

Jump to location 255, field 3, after loading.
Load into field

Return to Monitor after loading into field

Loader now types a series of up -arrows, one at a
time, as explained below.

Following each up -arrow typeout, the user is required to perform one or more actions.

Regardless of whether R: or T: is used to specify paper tape input, the high-speed equipment is used
was indicated as present in the system at System Builder time, otherwise the Teletype equipment
is used.
This convention is unique to Binary Loader.
if it

The f-digit forces Loader to start loading into the specified field until a
input file or tape.

2-8

"field setting"

found in the

^ ^ ^ ^

First

Loader is ready to load. If paper
up -arrow:
tape input, put the tape in the reader.

Type tP.

Second up -arrow: End of pass 1
If operating in
one-pass mode, type tP to jump to previously
.

specified starting address.
If operating in

two-pass mode, type ^P.

The next two up -arrows appear only if operating
two -pass mode.

Third up -arrow:
Type tP.

Reload paper tape input for pass 2.

Fourth up -arrow:
End of pass 2. Type tP to jump
to previously specified starting address.

Multiple Input Files

An up -arrow is typed out as the processing of each
input file is completed. If paper tape input,
insert the next file in the reader and type tp.

Repeat the above step until all files given in response to the *IN- request have been processed.
If in

two -pass mode, each tape must be entered

twice,

in the order

T1,T2,T3,....T1,T2,T3,....
After all files have been entered the required number of times, type tP to jump to the previously
specified starting address.

NOTE
After each input paper tape is read, the high-speed paper
tape version of Loader loops until the user types tP to continue.
However, the low -speed paper tape version halts . Thus, when
using the Teletype paper tape equipment for input, the user
need not type t P but press
N T on the console and start
the paper tape reader.

At this point. Binary Loader disappears and control is transferred to the previously specified
starting address.

A flow chart of Binary Loader can be found in Appendix D.
2.5.2

Binary Loader Error Me ssa ges

An illegal checksum error condition causes Loader to type
?

and return to A/bnitor after the user types t P or tC.

Error messages for illegal filenames or devices are

as specified in Paragraph 2.8.

Teletype paper tape equipment is used, type t P before turning on the reader.

2-9

2 6
.

SAVING PROGRAMS (SAVE COMMAND

)

The SAVE command enables the user to write core images of system or user programs from
core onto his system device for subsequent call-in (CALL) and execution.

For example, a program

which has been loaded by Binary Loader can be stored on the system device by the SAVE command.
Or, a previously saved program which has been called in and modified by DDT can be stored in its updated version on the system device, overlaying the old version if desired.

Core images can be saved in units of one or more pages, each page occupying one block on
the system device.

page is written out.

a core specification (see below) addresses only a portion of a page, the entire

For example, the core specification 45-150 is treated as though

Core areas to be saved may be contiguous or noncontiguous as desired by the user.

were 0-177.

Up to 32, q core

specifications, in any combination of monotonically increasing single -page or multiple -page requests,

can be entered in a single SAVE command.

2.6.1

SAVE Command Format
.SAVE

filenames

.'> core -specifications, .. .;

entry-pointy

SAVE

Directs Monitor to call in the nonresident SAVE routine.

filename

The filename (program name) to be assigned to the file on the
systems device. This name will be used to call the file later
when the user wants to read in and execute the program.
Restrictions on the formation of filenames can be found in
Paragraph 2.4.1.2. Any previously saved program with the
same "filename" and having the same extension will be automatically overwritten.

is typed immediately after the filename of a file if the user
desires to save it as a system program (e.g., PIP). A program
!

saved in this manner can be called in by simply typing its

name to Monitor (the word CALL is not required).
.filename^

An extension name of ,SYS is automatically appended to the
filename.
:
is typed immediately after the filename of a file if the user
desires to save it as a user program . A program saved in this

manner can be called in and executed later via the CALL

command.

.CALL filename ,;

An extension name of .USER is automatically appended to the
filename.

core -specifications

Up to 32 core specifications can be entered in a single SAVE
command. Each core specification is separated from the follow
ing one by a comma. The last core specification in the series
is

followed by a semicolon.

2-10

Addresses are expressed in octal.

Single -page core specification

fnnnn

where
f

field number (can

be omitted if field 0).

nnnn = any location within the page which the user
desires to save.

Saves page

Examples

through 177)

(locations

of field 0.

3570

Saves locations 3400 through 3577
of field 0.

30100

Saves page

through 177)

(locations

of field 3.

Multiple -page core specification

When a user wishes to save a core area of several contiguous
pages, he can t>/pe a multiple -page core specification in the
format
fnnnn i-nnnn«

where
f

field number (can be omitted

field 0).

nnnn, = any location within the first page of the series
of contiguous pages to be saved.

nnnn^ = any location within the last page of the series
of contiguous pages to be saved.

The following rules apply.
a. The beginning address of a multiple -page request must be
smaller than the ending address (nnnn, must be smaller than

nnnn2).
b.

Both addresses must be in the same field.

c. The field number (f) must be within the range of your
system; however, no check for the validity of this number is
performed at SAVE time.

Examples

Q)-'7^77

Saves all of field 0.

0000 -:7777

Saves all of field 1 .
the same as typing

Note that this is

10000-17777
See below for explanation of how the
field number (5th significant digit to
the left of the decimal point) is

"remembered

2-11

30425-745

Saves locations 400 through 111
(pages 3 and 4) of field 3.

NOTE
Only one field can be saved by each SAVE command.
If

multiple fields are to be ;>aved, a separate

SAVE com-

mand must be given for each.

The entry point of the saved program,

entry -point

the format

Fnnnn (see explanation above)
causes a return to Monitor at CALL time,
regardless of the field into which the program was saved.

An entry point of

NOTE
The last nonzero field number encountered in a SAVE
command string is remembered and prefixed to all other
addresses in the command string. (Remember:
only
one field can be referred to in each command string.)

Example:

The following entries are identical in meaning.

SAVE PRGA:
SAVE PRGA:
SAVE PRGA:
SAVE PRGA:

10000-10777, 11400, 1600-17777; 10200
30000-777, 51400, 26000-7777; 10200
10000-777, 1400, 6000-7777; 200
0-777, 1400, 6000-7777; 10200

In each of these examples, all addresses are treated as
being in field 1, because the last five-digit entry seen
contained a most significant digit 1
.

2.6.2

SAVE Command Processing

A list of the required pages is constructed from the information typed by the user and a block
requirement count is kept.

When the user types the terminating carriage return (J ), allowing

SAVE process to begin, a directory name search on the system device is initiated.
same name as the filename in the SAVE command i«i found,
If

no such file is found, a new file is created.

it is

a file having the

replaced by the file now being saved.

Next, a storage availability search finds a sufficient

number of available blocks on the system device to satisfy the block requirement count.
These block numbers are stored in a corresponding block list;
tents of the pages to be saved.

2.7

the

(See above.)

the blocks are then filled with the con-

When the SAVE process is completed, control returns to Monitor (7600).

CALLING A PROGRAM (CALL COMM/vND)
Once a file has been loaded and saved, it can be called into core as desired.

types of CALL command strings:

There are two

one for system programs and the other for user programs.

The CALL command string format for ^stem programs (programs saved by a SAVE command
string in which the filename was followed

by a

i;5

.filename ^

where filename is the same as the one used in the SAVE command string which saved it.

2-12

The CALL command string format for user programs (programs saved by a SAVE command
string in which the filename was followed

by a

.CALL filename j

When a program is called, a directory name search is performed on the system device.
Associated with the directory entry is the entry point of the program and information concerning file
protection and memory extension.

the appropriate directory name entry is found and the file has the

proper extension (.SYS or .USER), calling proceeds.

not, the calling process is terminated,

? is

typed and control is returned to A/lonitor.

2.8

SYSTEM ERROR MESSAGES
As an input command string is being typed. Monitor recognizes any incorrect syntax and

remembers it.

When the user types a carriage return. Monitor responds with a ? to indicate invalid

input.
Error messages output by

Command Decoder are given in Table 2-1
Table 2-1
System Error Messages

Message

Meaning

Illegal syntax or miscellaneous error condition

Directory on the systems device is full

Too many inputs or outputs were entered

No such inputs
System I/O failure

Local errors in each system program are given in Chapter 3.

Monitor time read or write errors cause a halt to occur.

Persistence of this condition indi-

cates a hardware failure, as the system I/O routine attempts to read or write three times before halting,

2-13

CHAPTER 3

SYSTEM PROGRAM LIBRARY

The Monitor System's library of programs presently consists of the Peripheral Interchange
Program (PIP), Disk System Editor (Editor), PAL-D Disk Assembler (PAL-D), 4K Disk FORTRAN

(FORTRAN-D), and Dynamic Debugging Technique for Disk (DDT-D), and this list is destined to

A section of this chapter is devoted to each program in the library.

lengthen with time.

To load a program using the Monitor System, the Loader makes certain queries to which the
user must type a reply.

The queries are the same for all programs.

The user's replies will vary, how-

ever, depending on the particulars of the program being loaded.

When loading a program into core, the user should first check to see whether Monitor is in
core.

This is done by typing tC (CTRL key and then the C key).

the teleprinter).

teleprinter paper.

Monitor is in core,
If

The tC will not echo (not print on

will respond by typing a period (*) at the left margin of the

a period is not typed in response to tC, Monitor is not in core.

Therefore, the

user should refer to Chapter 2 of this manual for information on building Monitor and putting it into

core.

The library system includess the Binary Loader (LOAD) which is automatically saved on the
disk at build time.

(For Loader operating procedures see Paragraph 2.5.)

The user may save any program on the disk by responding to the last period typed by Monitor
with the word SAVE, a four character name of the program, the type of program (user or system),

whether it's a one or more page save, and the location of its starting address, as is thoroughly described in Paragraph 2.6.

After each program is saved on the system device,

may be called (i.e., transferred from

the disk into core) merely by responding to Monitor (to a period) with the four characters designated as

the name of that program, as explained in Paragraph 2.7.

3.1

PIP
PIP (Peripheral Interchange Program) performs general utility operations, such as listing the

contents of specified directories, deleting unwanted files from the system device, and transferring files

between devices, and copying specified files.

PIP enables the user to do any of the above operations

merely by typing commands from the teleprinter keyboard

3-1

3.1.1

Loading and Saving
PIP is loaded into core as indicated in Appendix E.

Core requirements, starting address, and

number of passes through the Binary Loader (hereafter frequently referred to merely as Loader) are also
found in Appendix E.

To load PIP into core, the user calls LOAD, using Monitor, and replies to the system responses as explained in Chapter 2.

When in core, PIP may be saved on the system device as a system program by Monitor, as
indicated in Appendix E.

(See Paragraph 2.6.1 for a detailed description of the SAVE format.)

When loading and saving PIP, the printout will take approximately

the follov/ing format:

A.OAD J
*IN- R:

*OPT-l
*ST= J
_n

(type CTRL/P)

.SAVE PIP! 0--51 77; 1000 j

3.1.2

Operating Procedures
PIP has now been loaded into core and saved on the disk.

PIP via Monitor which can be done only in response to a period.

To use PIP, the user must call
a period is not present as the last

system response, the user must type tC, which should cause Monitor to type the needed period.
printout should appear as follows:

^PIP^
which transfers PIP from the disk into core.

PIP now responds with

*OPTand waits for the user to select and specify one of the following options.
L

List entire directory of device to be specified

Delete a file to be specified

Move copy of directory to write-locked area of disk (See below)

Protect blocks 0-176 of disk

Restore the previously moved directory

A or ^

Copy ASCII file (destination and origin(s) to be specified)

Copy binary file (destination and origin to be specified)

3-2

The

Copy FORTRAN binary file (destination and origin to be specified)

Copy user file (file structured origin and destination to be specified)

Copy system file (file structured origin and destination to be specified)

The user types only the option character, to which Monitor immediately responds with a carriage return
and line feed.
If

The user does not terminate the line with the RETURN key, it is a meaningful option.

the user selects an option using any character other than one of those listed above, the

option is illegal, and PIP ignores the request, types ? (question mark), and asks for another option

character.

The output would appear as follows:

*OPT- G
?

*OPT~
The L option lists the entire directory of the system device or DECtape on which a directory
exists.

For example.

^PIP

User calls PIP

*OPT-L
*IN- S: J

list

option of the

system device directory

FB=2426

PIP types number of free (unused)
blocks remaining on specified

device

NAME

TYPE

8D
PALP .SYS

BLK
followed by filename and des-

LOAD. SYS

(0)

.CD

.SYS

(0)

0037
0015
0003
0006

PIP

^YS

(0)

ooifr

DDT

.ASCII

EDIT

.SYS
.

(0)
(0)

PAL-D is a system

program in field

and occupies

37p blocks of storage

0062

FOO .USER (0)

0001

BAR

0037

.SYS

cription; e.g.,

(0)

When the user specifies the D (delete a file) option, PIP responds with
*FILETYPE (A,B,F,U,S) where A, B, F, U, and S are the legal options from which the user may choose; indicating ASCII,
binary, FORTRAN binary (compiler output), user (see Section 2.6.1), and system program (see Section

2.6.1), respectively.
If

the user's reply is S i ^ indicating a system file, PIP asks

REALLY?
User and system files may not be copied onto paper tape as they are core images and have no defined
paper tape format

3-3

F*IP

will not delete a system file unless the user answers by typing

(meaning yes)

to the question.

types Y^

Any reply other than Yj

causess PIP to repeat the FILE TYPE request.

When the user

PIP responds with

*INand waits for the user to specify the device and filename of the system file to be deleted.

The printout

would appear as:

*OPT -D
*FILETYPE (A,B,F,U,S) - S j
REALLY N J
*FILE TYPE (A,B,F,U,S) - S^
REALLY Y ^
*IN- S:BAR J
*OPT-

delete option specifying system file,
user must reply with Y^ ,

PIP repeats request,

user replied correctly,
PIP needs device and filename,
file

deleted and PIP asks

for the next option

When the file has been properly identified and deleted PIP returns to ask for another option.

filename BAR, in the example above, had not been on the specified device, PIP would have ignored the
request and typed a ? before asking for another option.

For example,

*IN- S:BAR J

BAR is not the name of a

file on the specified

*'OPT-

device

The user should not try to delete the system files .CD. or LOAD.
Options M, P, and R, in conjunction with the hardware write-lock switch, allow the user
to protect the lower

system software.

16K of his disk (1/2 of disk

for users with more than one disk) while using the

The user may specify either the system device or a DECtape unit numbered 0-7.

Since

only input is requested, the action specified by the option is performed solely on the device specified.
For instance,

it is

not possible to use the

M option to move the system directory to another device.

The M option will move a copy of the first directory block (the first 25,^ filenames),
block 177, of the device specified to block 3 of the same device.

also moves a copy of the first

SAM (storage allocation map) block, block 200, of that device to block 4 of that device.

the user

were to move a copy of the system file directory, the printout would appear as follows:

*OPT-M

move option specifying

*IN- S; J

the system device

*OPT-

PIP asks for another option

The P option searches the first SAM block, block 200, for free or unused blocks in the lower
half of the first disk.

All unused blocks are marked as being used by Monitor, thus the lower half of

the disk appears to have no unused space

—

it is

protected.

3-4

The user may now activate the write-lock

switch on the disk control unit and Monitor will not attempt to write on the protected portion.
blocks in the lower half of the first disk are already used, the P option does nothing.
function independently of the

M option.

If all

This option will

Unless the user has previously moved a copy of the true

directory which he can later restore however, there is no way (short of rebuilding the disk) to recover

the space used by the P option.

The printout would look as follows:

*OPT- P
*IN- S: J
*OPT-

protect option specifying

the system device
PIP asks for another option

The R option restores the copy of the directory name block (DN block 1) from block 3 back
onto block 177 and the copy of the SAM block from block 4 back onto block 200.

SAM blocks above the first one (if any) as well as directory name blocks 2 and 3.

The R option will

then zeros all

do nothing until a Move has been done on the specified device, so that a system may not be destroyed
by inadvertently requesting the R option.

The printout would look as follows:

*OPT-R
*IN- S: i
*OPT-

restore option specifying

the system device
PIP asks for another option

The directory which is moved should be one which does not contain files likely to be
deleted from the working directory after the move.

Some typical uses for the M, P, and R options

are:

M to save a specific disk (or DECtape) status and later R to effectively erase all scratch

a.
files created

subsequent to the M, thus restoring the device to its status prior to the M.

M, P, set write-lock switch, and operate protected.

L to determine the

number of unused blocks and for a report on the status of the system

device
Files
files used

.SYM and .DDT should not be in the protected area of the disk. They are scratch

by DDT-D and PAL-D during their operation and require output to the disk.

(See PAL-D

DISK ASSEMBLER, DEC-D8-ASAA--D, and Section 3.5.1 of this manual.)
Options A, B, F, U, and S are used to transfer files from one device to another.

When

the user has requested any of these five options PIP responds with

*OUTand waits for the user to specify the destination or output file, and if the destination Is disk or DECtape, the name of the file.

For example,

*OPT- A

copy an ASCII file option

*OUT- S:ASCI ^

specifying the destination and

filename

3-5

Only one destination is legal, and if the user specifies more than one, PIP will ignore the
response, type the error message E, and return control to Monitor.

For example,

*OPT-A

copy an ASCII file option

*OUT-S:ASCI, E

PIP recognizes the comma,

which

used to separate file and device

names; control returns to Monitor

NOTE
The L and D options return to PIP's option request (*OPT-)
when the user responds illegally, and all other options return control to Monitor.

PIP indicates acceptance of the user's destination by responding with *, carriage return/line

feed, and *IN-, and waits for the user to specify the input, that is, to state from where the input is to
originate.

An attempt to specify more than one input to any but the A option will cause PIP to ignore

the response, type the error message E, and return control to Monitor.

For example,

copy a FORTRAN file option

*OPT-F
*OUT-S:FORT J

specifying system device and filename

PIP accepts user's destination

comma is

*IN-S:, E

input to system device,

used to separate device names

control returns to Monitor

The A option will allow any combination of up to 11 ASCII input files to be merged into one
output file in the order specified by the input list.

The user therefore, may write generalized sub-

routines as separate files to do his often repeated operations and then, by combining these with each

specialized program before assembly, eliminate the need to rewrite such operations for each program.
PIP acknowledges each legal input file by printing an *.

If,

however, the input file specified to oiiy

option is not found on the specified device, PIP prints I in place of the * and returns to the Monitor.
For example,

*IN-S:FIL2 ^

the file does exist; when the user types CTRL/P,

copying begins

*IN- S:FIL3 J
I

the file does not exist

control returns to Monitor

If the

user requests the B option, indicating he wishes to copy a binary file but the filename

he has specified appears as an ASCII file. It is not acceptable, therefore, PIP prints an I and control
returns to Monitor.

The user can ascertain file types by using the L option and checking the file

directory.

3-6

A summary of the copy features of PIP is presented in the following table.

Option

Number of
Input Fil es

ASCII

Binary

High Speed
Disk

DECtape

Reader/Punch

Teletype

Yes
Yes

Yes
Yes
Yes

Yes

No
No

FORTRAN
Binary

User

System

3.1.3

Examples
_.PIPj

User calls PIP

and requests the list option

*OPT" L
*IN- S: J
FB=2426

of the system device directory
PIP types number of free (unused)
blocks remaining on specified device

NAME TYPE
8D
PALD

followed by filename and des-

SYS
EDIT .SYS
LOAD. SYS
.CD. .SYS
PIP
SYS
.

DDT

BLK

(0)
(0)

(0)

ASCII

0037
0015
0003
0006
0015
0062

FOO .USER

(0)

0001

BAR

(0)

0037

.SYS

cription; e.g.,

PAL-D is a

system program in field

and
occupies 37o blocks of storage

*OPT-D

User requests the delete option

*FILETYPE (A,B,F.U, S)--U ^

and specifies type of file, U(user)
and device and filename; file is

*IN-S:FOOj
*OPT-D
*fMIYPi(A,B,F,U,S)-S J
REALLY ? Y J
*IN-S:BAR j

deleted
User requests the delete option

and specifies type of file, S
(system) (PIP double checks); Y
is the only meaningful answer
User specifies file and filename;
file

deleted

*OPT" L

User requests list option

*IN- S; J
FB=2466

and system device directory.

Note increase of 40g free
blocks (see above)

3-7

NAME TYPE
8D
PALD

SYS
EDIT .SYS
LOAD. SYS
.CD. .SYS
SYS
PIP
.

BLK
(0)
(0)
(0)
(0)
(0)

DDT .ASCII
*OPT-D

0037
0015
0003
0006
0015
0062

Note removal of two deleted files
User requests delete option

*FILETYPE (A,B,F,,U,S)-Sj
REALLY ?N J
*FILETYPE (A,B,F,,U,S)-S J
REALLY ?W J
*FILETYPE (A,B,F..U,S)-SJ
REALLY ?Y J
*IN-S:EXC J

Y is only response for deletion of
a system file; other responses
cause PIP to repeat the file type
request

Even if user responds to REALLY?
with Y, PIP will not delete the
Monitor file

*OPT-D
*FILETYPE (A,B,F,,U,S)-U

NONE

not an existing

*IN-S:NONE i

PIP knows

user filename on the system device

*OPT-D

and indicates by typing ?
User requests ASCII file option
PIP also knows when the filename
and file type don't match; EDIT is
a system program

*FILETYPE (A,B,F rU,S)-A J
*IN-S:EDIT J
?

*OPT-D

*FILETYPE (A,B,F ,U,S)-Bj
*IN-S:EDIT J
?

*OPTMerge into an ASCII file on disk 'ASCI", one tape from the reader, one tape from the
'

Teletype, one file from disk called SRC, and one file from DECtape 7 called SRCl

*OPT- A
*OUT-S:ASCI

^IN-R:,T:,S:SRC,D7:SRC1 J

*111 1

(type CTRL/P after each f le)
i

*OPTCopy the system file PIP from disk to DECtape 3 using filename PIPX.

*OPT- S
*OUT-D3:PIPX J
*IN-S:PIP J

11
*OPT-

(type CTRL/P)

3-8

Try to merge two binary files onto disk called BIN from paper tape.

*OPT- B
*OUT-S :BIN J
*

*IN-R:,E

(list

exceeded)

Try to copy an ASCII paper tape from high-speed reader, a non-existent file from DECtape

5, and a paper tape from Teletype fo high-speed punch.

*OPT-A
*OUT- R: J
*

*IN- R:,D5:FOO,T:^

_
I_
:_

accepted as legal)
([)5:FOO rejected, no such file
on 05:)
(R:

3-9

EDITOR

3.2

Editor (Disk System Editor) enables the user to generate and edit symbolic programs on-line

from the teleprinter keyboard.

The symbolic program may be either printed on the teleprinter, punched

on paper tape using the high- or low-speed punch, or saved on the system device as a user program.
Editor operates either in command or text mode.

command mode, all typed input is in-

terpreted as a command instructing Editor to perform a certain operation or to allow the user to perform

an operation on the text stored in the buffer.

text mode, all typed input is interpreted as text to

replace, to be inserted into, or to be appended to the contents of the text buffer.

The command language of the Disk System Editor is identical to that of the PDP-8 Symbolic
Editor

(DEC-08-ESAB-D) but with the following exceptions.
a.

Special characters:

During output, progress stops and control is returned to command

mode.

tC
b.

Always returns control to AAonitor.

Commands:
P

Proceed, and output entire contents of the buffer followed by a form
feed and return fro command mode.

Output line n, followed by a form feed, return to command mode.

m,nP

Output lines m through n, followed by a form feed, return to com-

mand mode.

command

Illegal

Process entire file (perform enough

remaining

NEXT commands to transfer the

input to the output file) and

create an end-of-file indicator

(legal only for output to the system device).

Certain keys have special operating functions.
listed in

These keys and their associated functions are

Table 3-1

Table 3-1
Key Functions

Special

Key
^ (carriage return)

Functions

Text mode:

Enter the line in the text buffer.

Command mode: Execute the command.
*-

(back arrow)

Text mode: Cancel the entire line of text and
continue typing on same line.

Command mode:

\ (rubout)

Text mode:

cancel command.

Delete from right to left one charac(is not in effect during

ter for each rubout typed

a READ command).
Command mode: Delete entire command.

FORM FEED

Text mode:

3-10

End of input, return to command mode.

Table 3-1 (Cont)
Special Key Functions

Key

Functions

Command mode:

(period)

Current line counter used as

argument alone or in combination with + or and a number.

Command mode:

/ (slash)

Value equal to number of last

line in buffer and used as argument.

Used in SEARCH command to insert a
Text mode:
carriage return/line feed combination into the line
being searched.
Command mode: List the next line.

(line feed)

ALT MODE

Command mode:

List

the next line.

ESCape

Command mode:

List

the next line.

< (left angle bracket)

Command mode:

List

the previous line.

= (equal sign)

Command mode:

Used in conjunction with
(. = 27).

and /

to obtain their value
:

Command mode:

(colon)

Lower case character, same func-

tion as = .

—

»|

On output, is interpreted as
Text mode:
a tab/rubouf combination.

(tabulation)

Table 3-2 is a summaPi^ of Editor commands.

Table 3-2
Summary of Editor Commands

Command

Meaning

Format(s)

READ

Read incoming text and append to buffer until a
form feed is encountered.

APPEND

Append incoming text to any already in the buffer
until a form feed is encountered.

LIST

L J

List the entire buffer.
List the line
List lines

m,nP J

Proceed and output the entire contents of the
buffer and return to command mode.
Output line n, followed by a form feed.
Output lines m through n, followed by a form feed.

PROCEED

TRAILER

KILL

DELETE

m through n.

m,nL J

Punch four inches of trailer.

Punch the entire buffer and a form feed;
buffer and read next page.
Repeat the above sequence n times.

KJ
nD J

m,nD J

Kill the buffer.

Delete line n.
Delete lines m through n.

3-n

kill

the

Table 3-2 (Cont)

Summary of Editor Commands

Command

Forma t(s)

Meaning

INSERT

Insert before line one all text until a form feed

encountered.
nl

CHANGE

«f

Insert before line n until a form feed is encountered.

nC J

Delete line n and replace it with any number of
lines from the keyboard until a form feed is en-

m,nC J

Delete lines m through n, replace from keyboard
as above until form feed is encountered.

m,n$kM J

Move and insert lines m through n before line k.

cour>tered.

MOVE
GET

GJ
nG J

Get and list the next line beginningwith a tag.
Get and list the next line after line n which begins
with a tag.

nS i

m,nS J

END FILE

E i

Search the entire buffer for the character specified
(but not echoed) after the carriage return;
allow modification when found.
Search line n, as above, allow modification.
Search lines m through n, allow modification,
Proce:>s the entire file (perform enough

NEXT com-

mands to pass the remaining input to the output file)
and create an end-of-file indication; legal only
for output to the system device.
If the lowspeed paper tape reader is used for input while
performing an E command, the paper tape reader
will eventually run out ot tape, and at this point
typing a form feed will allow the command to be

completed.

Editor will print an error message consisting of a question mark whenever the user requests

nonexistent information or uses an inconsistent or incorrect format in typing a command.

The question

mark will be followed by a carriage return/line feed and the command will be ignored.

halts at location 2330, a system error has occurred while reading from the disk.

the computer

You should, therefore,

run the disk maintenance tests to determine the cause of the error.

Loading and Saving

3.2.1

Editor is loaded into core from punched jpaper tape in one pass using the Loader.

core,

When in

occupies locations show in Appendix E.

To load Editor into core, the user calls LOAD, using Monitor, and replies to the system responses as explained at the beginning of this chapter and in Paragraph 2.5.

When in core. Editor may be saved on the system device as a system program by Monitor whthe user types the command indicated in Appendix IE.

(See Paragraph 2.6.1 for detained description of the SAVE format.)

3-12

When loading and saving Editor, the printout should appear approximately as follows.
^LOAD*^'
*IN- R: v'

*OPT-l
*$T = 7600 J
tt

(See Appendix E.)

.SAVE EDITIO-3177; 2600 k*

3.2.2

Operating Procedures
Editor is transferred from the system device into core by Monitor when the user types

EDIT v^
Editor

now in core and responds by typing

*OUTThe user selects one of the following output devices: (T:) for low-speed reader/punch;

(R:)

for high-speed

reader/punch; (Srname) for output to the systems device on a file called name and types his choice

immediately after OUT-.

the specified device

not valid, that is, not declared when building

Monitor, Editor will respond with an error message (see Paragraph 2.8) and return control to Monitor.
Thus the user must call EDIT and respond to *OUT- with a valid device.

When Editor recognizes a valid device, it responds with *J (asterisk,

carriage return/line

feed) and *IN-, as shown below,.
*

*iNThe user now specifies the input device by typing T:^

R: i/

or Siname*' or*' in the same manner as

when replying to *OUT-, above.
The Editor responds with

*OPTasking the user to specify one of the following options.
B

Preserve blanks. Editor normally replaces
multiple blanks (spaces) with tabs, resulting
in considerable saving of space on the system

device.

Enter dynamic deletion mode if input is from the system
device. As the file is read, it is deleted from the system
device, thus allowing space for output if desired. (File
name remains on the directory but without any assigned blocks.)

Combine the functions of B and D options.

None of the above options; assume conversion of
two or more blanks to tabs, and not D.

With a System Device output, the user must type E J to properly close the output file.

3-13

After the user has specified one of the options listed above. Editor responds with a carriage
return/line Feed and asterisk.

The entire printout night appear as follows.
^EDIT*'

*OUT-R:i^
*

^IN-T:i/
~

*OPT-B

The appearance of the last asterisk in the example above indicates that Editor is ready to
accept and operate on the user's symbolic program.

The user may now read the symbolic progjram into core by using the R command or he may
type the symbolic program directly into core by using the A command (see Table 3-2).

3.2.3

Example

^LOAD ^

Call Loader using Monitor
Inpui" to be

^OPT-

Inpuil"

from high-speed reader

device valid

One -pass load

*ST= ^

.SAVE EDIT!0-3177;2600 i
^EDIT^

Return to Monitor after loading
Editor is loaded
and ;>aved on the system device
Call Editor using Monitor

*OUT-S:SRCW

Output to be on system device, file named SRCl

*IN-R: i

Input to be from high-speed reader

*OPT- ^

No blanks, no dynamic deletion mode

Inpuii" device

valid

*R,/

Read incoming text

Process entire file

.EDITJ

Call Editor using AAonitor

*OUT- ^

No output, no dynamic deletion mode, i.e., no option
desired.

*IN-S:SRCU

Inpuir from

filename SRCl

Filename valid
f OPT-

No option desired

IR^

Read incoming text

*74Q0

/STARTING ADDRESS OF PROGRAM

List J-he

ODUM

entire buffer

CLA
/GET LOWER LIMIT

DCA LOCK
HLT

OSR

CMA

/GET UPPER LIMIT
(t P

v/as typed here, stopped listing of buffer)

*/L
"$

(tC was typed here)

3-14

PAL-D DISK ASSEMBLER

3.3

PAL-D, the acronym for Program Assembly JLanguage for the Disk system, is the symbolic
assembly program designed primarily for the 4K PDP-8 family of computers with disk or DECtape.

The PAL-D Assembler performs many useful functions, making machine language program-

ming easier, faster, and more efficient.

Basically, the Assembler processes the user's source program

statements by translating mnemonic operation codes into 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 user may use pseudo -operators (pseudo-ops) to direct PAL-D to perform certain tasks or
to interpret subsequent coding in a certain manner.

Instead of generating instructions or data, pseudo

ops direct the Assembler on how to proceed with the assembly.

Pseudo-ops are maintained in the

Assembler's permanent symbol table.

The following is a summary of PAL-D's pseudo-ops.
Table 3-3

PAL-D Pseudo-Operators
PseudoOperator

Explanation

PAGE

Set current location counter to first location on next page.

PAGEn

Set current location counter to first location on page n.

FIELD n

Load subsequent data in field n.

DECIMAL

Interpret subsequent integers as decimal.

OCTAL

Interpret subsequent integers as octal.

XLIST

Data enclosed is not to appear on third pass listing.

TEXT

Input text strings in USA SCII code trimmed to six bits.

End of symbolic program, terminate current pass.

PAUSE

End of file or paper tape, suspend processing, proceed to next file
or paper tape and resume processing.

EXPUNGE

Erase permanent symbol table, except pseudo-ops.

FIXTAB

Append to permanent symbol table all symbols defined before the
FIXTAB.

The Assembler is thoroughly documented in PAL-D Disk Assembler Programming A/\anual
(Doc. No.

DEC-D8-ASAA-D).

3.3.1

Loading and Savin g

PAL-D is loaded into core from punched paper tape in two passes using Loader. When in
core,

occupies locations, as shown in Appendix E.

To load PAL-D into core, the user calls LOAD using Monitor and replies to the system
responses as explained at the beginning of this chapter.

3-15

When in core, PAL-D may be saved on the system device as a system program by Monitor
as described in Appendix E.

(See Paragraph 2.6.1 for a detailed description of the

SAVE format.)

When loading and saving PAL-D, the printout should appear approximately as shown below.
(See Paragraph 2.5.)

A.OADJ
*

"*OPT-2
ST = 7600 k'
ft f t

_^SAVE PA LD 10-7577; 6200*'

3.3.2

Operating Procedures

PAL-D is transferred from the system device to core using Monitor. The user begins by
typing

^PALD V

PAL-D responds with a request for the output device by typing

*OUTThe user selects the output device by specifying one of the following.
T:

for the low -speed

punch

for the high-speed

punch

for output to the <;ystem device as a file called name

S:name J

PAL-D then responds with
*I

N-

and waits for the user to select the input device(s).

example,

R:, T:,

R:, R:, T:,^), but in this example the user selected

R: ^^

Up to five input devices may be specified (for

input from the high-speed reader

the user had specified the devices in the parenthetical

example above, PAL-D would have

typed an asterisk for each input device that it found valid.

When PAL-D is satisfied that the input device is valid (i.e., the device does exist or the
file is present on the file -structured device), it will

request the third-pass listing option by typing

*OPT-

3-16

The user types one of the following.
T

meaning listing and symbols are to be produced on the teleprinter

meaning listing and symbols are to be produced on the high-speed
reader/punch

meaning no third pass desired, symbols are printed on the teleprinter
(any other character means no third pass desired)

The entire printout might appear as follows.

PALD J
*

"*IN- R:i^
*

"*OPT- T

PAL-D is now ready to proceed with the assembly, pausing only when user intervention is
required (i.e., placing a new paper tape in the reader, turning off the punch, etc.).

PAL-D will type on an up-arrow (t) on the teleprinter and wait for the user to type tP, indicating

sions,

that the user is ready to continue with the assembly.
(

On these occa-

*IN-T

;

When using the low-speed reader on input

an tP must be typed before turning the reader on.

Assembly may be terminated and control may be returned to Monitor at any time by typing
tC.

When assembly is complete, control is automatically returned to Monitor.

PAL-D makes many error checks as it processes source language statements. When an error
is detected

the Assembler prints an error message.

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

(if

there was one) on the current page.

PAL-D's error messages are listed and explained below.
Table 3-4
PAL-D Error Messages
Error Code

Explanation

Two PAL-D internal tables have overlapped.

DE
DF

System device error

Illegal character

Illegal redefinition of a symbol

Illegal equal sign

System device full

Illegal indirect address

Current nonzero page exceeded

Phase error

Symbol table exceeded

US
ZE

Undefined symbol
Page zero exceeded

3-17

Examples

3.3.3

The following example shows the entire process covered in this section.

^LOAD 4

Call Loader

*IN- R; i

Input to be from high-speed reader

Loader found input device valid

*OPT-2

Two -pass load

*ST= J

Return to A/\onitor after loading

PAL-D is loaded

tttt

TS^E PA LD 0- 7577} 6200 J

PAL-D is jiaved on disk (see Appendix E)

J'ALD J

Call

* OUT- S:BIN

Output to Filename BIN on system device
Filename and system device valid for output

PAL-D

Input from high-speed reader

*IN-R: ^

Reader is valid input device
Output listing and symbols on high-speed punch
tP should be typed after inserting source tape in reader for each
pass (If both input and output are to system device, no t's are

*OPT-R
ill

typed

user called

finished; control returns to Monitor;
Assembly
the Loader.
Input from filename BIN on system device
Filename and system device valid for input

*OPT- 2

Two -pass load required

*ST=7636 J

Transfer control to the HALT in the Monitor after loading the

_^LOAD

i:5

*IN- S:BIN ^

user program
tP typed four times in response to each

tttt

User program is loaded; the computer halts with user program in
core

3.4

FORTRAN-D

FORTRAN-D (FORm ula TRANslation for the _Disk System), is an expanded version of standard
PDP-8 FORTRAN designed for PDP-8 computers with disk or DECtape units.
FORTRAN-D contains a compiler and an operating system. The FORTRAN compiler is used
to convert a source

program into an object program..

The FORTRAN operating system is used to execute

the object program.
This version of FORTRAN is designed to Facilitate user/system communication by typing

appropriate commands from the teleprinter keyboard, eliminating the need to toggle input using the
switch registers.

FORTRAN statements specify the computiations required to carry out the processes of the
FORTRAN program. There are four types of statements provided for by the FORTRAN language:
a.

Arithmetic statements define a numerical calculation.

Control statements determine the sequence of operation in the program.

Specification statements define the properties of variables, functions, and arrays ap-

pearing in the source program.
d.

They also enable the user to control storage allocation.

Input-output statements are used to transmit information between the computer and re-

lated input-output devices.

3-18

A summary of the FORTRA,N statements Is given in Table 3-5.
Table 3-5

Summary of FORTRAN Statements
Statement and form
1.

Explanation

Arithmetic Statements
V is a variable (possibly subscripted);
an expression.

e is

2. Control Statements

GO TOn
GO TO (n^,n2,...n^),i

a statement number.

n , , . . .n

are statement numbers;

a non -

subscripted integer variable.
IF (e) n^,n2,n2

e is an expression;

n^^n^An^ are statement

numbers.

DO n

= ki,k«,l<o

a statement number of a CONTINUE;
an integer variable; l<,,k«,ko are

is
i

integers or nonsubscripted integer variables.

CONTINUE

Proceed

PAUSE

Temporarily suspend execution.

PAUSE n

an address;

subroutine execution will

commence at n.

STOP

Terminate execution.

END

Terminate compilation;
program.

last statement in

3. Specification statements

DIMENSION v,(n,),v.,(n^,...v (n )

Vw...v^ are variable names; ni,...n

integers.

are

DEFINE device

Device is DISK or TAPE, system I/O device.

FORAAAT(s^,S2,...s^)

s is

COMMENT

Designated by C as first character on line.

a data field specification.

4. Input -Output Statemen ts

ACCEPT fjist

f is

a FORMAT statement number;
of variables.

list is

list

TYPEfJist

f is a
list

READ u,f,list

FORMAT statement number;

list is a

of variables.

is an integer, representing device from
which data is to be read,
f is a FORMAT statement number; list is a

list

WRITE u,fjist

of variables.

u is an integer, representing device onto
which data will be written,
f is

a FORMAT statement number;
of variables.

list

3-19

list is a

The following functions are allowed:

SQTF(x)

square root of x

SINF(x)

sine of x

COSF(x)

cosine of x

ATNF(x)

arctangent of x (in radians)

EXPF(x)

exponential of x

LOGF(x)

logarithm of X

ABSF(x)

absolute value of X

Certain input-output statements have special characteristics when used with disk or DECtape
units.

The READ and WRITE statements disable the user from performing sequential input and
a.
output either on paper tape or on the system device.

A DEFINE statement must precede the first executable statement in any program by using
b.
the system device to input or output data.
When the operating system is called, the input or output filename must be specified by
c.
if data is to be read from or written on the system device.
S
option
the
using
When a READ statement is used with the teleprinter, the statement differs from the
d.
ACCEPT statement in that the data being read is not echoed on the printer.
e.

A WRITE statement used with the teleprinter differs from a TYPE statement in that it

always terminates by typing a carrige return-line iFeed.
The READ and WRITE statements allow the user to input and output data on either th6
f.
teleprinter, the high-speed reader/punch, or the system device.
g.

When the ACCEPT statement is used, the rubout character deletes the previous number as

shown in the following examples.

Typed and Corrected

Read

Floating-point numbers

Integer Number s:

2 42
+2. 42

+1028
-128
+128

128 1028
128 -28
-128 128

-2.0
42

20E6
2.0E-6

2.0
-42.2
5
5

;

+42.0
+42.0
+2.0
-42.2
.
+2.0 X
+2.0 X 10^

When the READ statement is used, the rubout character is completely ignored.

The device assignments for FORTRAN-D READ and WRITE statements are:
1

2
3

Teletype
High-speed reader/punch
System device

For example,

READ2,f,list
will read from the high-speed reader.

The following examples show how the READ and WRITE statements might be used in a typica'

FORTRAN program.
3-20

EXAMPLE PROGRAM TO READ COORDINATE PAIRS
FROM THE TELETYPE AND STORE THEM ON

C
C
C

THE SYSTEM DEVICE
DEFINE DISK
TYPE TOO
FORMAT ("ENTER THE NUMBER OF COORDINATE PAIRS"/)
ACCEPT 10,N

TOO

FORM/a (I)

TYPE 102
FORAA/vT ("NOW ENTER THE COORDINATES"/)
= 1,

102

DO 20

ACCEPT 30,X,Y
WRITE 3,30,X,Y
20

CONTINUE

STOP
FORM/J(E,E)

END
Several

READ and WRITE statements may occur within a single DO loop and may refer to dif-

The data is written in USA SCI! format regardless of the device used.

ferent devices.

The following

program demonstrates how information previously stored on the disk might be read, processed, and

punched using the high-speed punch,,

FORTR^^N EXAMPLE PROGRAM
DEFINE DISK

DIMENSION X(100),Y(100)
READ DATA FROM THE DISK DEVICE NR3

IDEV = 3

SUMX=0
SUMY-0

DO 10 1=1,100
READ IDEV,20,X(1),Y(1)
WRITE2,20,X(1),Y(1)
SUMX= SUMX + X(1)

SUMY=SUMY + Y(1)
CONTINUE
TYPE 30,SUMX,SUMY

ACCEPT 40,J
IF (J)

12,12,6

STOP

20
30

FORMAT (E,E)
FORMAT ("SUM OF X VALUES = ",E," SUM OF Y VALUES = ",E,"
//"TYPE TO STOP,
TO CONTINUE")
FORMAT (1)
END
1

3.4.1

Compiler
The compiler consists of a loader (FORT) and the main portion of the compiler (.FT.)

version of the compiler differs from the standard
a.

uses the disk or

•

This

PDP-8 4K FORTRAN compiler in the following ways.

DECtape unit during its operation.

It will compile programs which have been stored on the system devices or programs
b.
which have been prepared on punched paper tape.

It will

generate a FORTRAN binary output file either on the system devices or on

punched paper tape.
d.

Significant improvements have been employed with the READ and WRITE statements.

3-21

Input and output devices are determined using the Command Decoder

f..

It is

possible to terminate compilation at any time by typing ^C, thus returning control

to Monitor.

Within certain restrictions, a program compiled on a system device may be executed
g.
immediately when the user types tP after compilation of the program.
h.
Statement numbers need not be delimited by a semicolon, unless the user wishes them to
be employed for appearance.

Statements without preceding numbers must be preceded by a space, a tab, or a semicolon,

3.4.1 .1

Loading the FORTRAN Compiler

— To load the compiler, the following steps must be

performed

Load the compiler loader (FORT) into core using Loader in one pass and save it on
the system device as shown in Appendix E.
a.

Load the compiler (.FT.) into core using Loader in two passes and save it on the sys
b.
The compiler is now loaded and saved on the system device and
tern device as shown in Appendix E.
ready for use. The entire procedure will generate the following printout.

_^LOAD J
*IN- R; J
"*OPT- 1
*ST=76 00i;

^SAVE FORTlO-1777; 200j

(See Appendix E.)

^LOAD J
*IN- R: i
*

*OPT-2
*SJ=7600J
ft ft

^SAVE .FT. 1200-7377; i

(See Appendix E.)

The loader occupies core locations 0-1777 with a starting address at 200.

occupies core locations 200-7377,
calls .FT.

when needed.

3.4.1 .2

Operating Procedures

its

The compiler

starting address is not specified since the loader (not the user)

— The FORTRAN compiler

transferred from the system device into

core when the user responds to Monitor's period with FORT, as shown below.

^FORT i
Command Decoder then types

*CUTand waits for the user to specify one of the followiing:
T:

Output on low -speed punch/printer

S:name J

Output on high-speed punch
Output on system device and assign name

No output desired

3-22

Command Decoder will respond with cm * when it recognizes a valid output device, and then types
*INand waits for the user to specify one of the following:
T: J

Input to be from low -speed reader

Input to be from high-speed reader

Srname j

Command Decoder will type an

Input to be from system device file named
*

when it recognizes a valid input device.

The compiler now assumes control, and if the program to be compiled is on paper tape, the
compiler types

when it is ready to receive the tape for compilation.

When the user is ready to read in his program he should type

which initiates compilation,

At the end of compilation the compiler will type any error diagnostics necessary, a carriage return/line
feed , and

The process described above would produce the following printout.

^FORT i
*OUT- R; J
*

*IN~R: i

(tC typed here;

3.4.1 .3

— Certain errors can make

Compiler Diagnostics

the normal manner.

compilation finished)

These are referred to as system errors.

the compiler, by not having an

impossible for the compiler to proceed in

They may be caused by improperly loading

END statement on a source file, by a machine malfunction, or for

various other reasons.

There are two types of system errors:

those which occur before the compiler has been loaded

into core, and those which occur after the compiler has been loaded into core.

compiler will type a four-digit error code and return control to the Monitor.

the second case, the

compiler will type SYS followed by a four-digit error code.
to return control to the Monitor,

Table 3-6 lists the system error messages.

3-23

the first case, the

At this point the operator must type ^C

Table 3-6

Compiler Systems Diagnostics
Error

Explanation

Code
0227

Could not find Command Decoder on system device

0231

Same as above

0326

Could not find .FT. on «;ystem device

0330

Same as above

1425

READ error during direclory or SAM block search

1521

Same as above

1626

Same as above

1726

WRITE error during SAM block search

3100

Illegal operator on

3417

Pre -precedence error

4737

No input device or invalid input device specified

6141

Attempt to execute a program not compiled onto the system device

6145

Could not find FOSL on system device; if the error occurs, it may
be necessary to reload FORT and FOSL.

6207

READ error while loading FOSL

6211

Error while doing

6223

Error while loading .FT.

6226

Same as above

6257

Same as above

6407

Illegal overlay request

6416

Same as above

6467

System device READ error

6724

No END statement on source device

6746

Same as above

7114

Same as above

7136

READ error on system device source file

7150

System device full

7173

WRITE error on system device output file

compiler stack

SAM block manipulation

Error may be due to a compiler error or a

machine malfunction.

3-24

The example below illustrates the appearance of the error codes.

^FORT J
Command Decoder not on system device

0227
^FORTi/

*OUT- i
*

*IN- S;name J
SYS 6141 <tC>

No output file specified

Error messages for errors which occur during compilation of a program are typed out upon

completion of the compilation.

XXXX

These errors are referred to as compilation errors and take the form:

XX
The error code

The number of statements since the appearance
of last numbered statement (octal)
'

The statement number of the last numbered statement

For example, during compilation of the statements

A=I(J+1)
B = A*(B + SINF(THTA)

the error message

would be printed, indicating that an error exists in a statement which occurs 11 statements (octal) after
the appearance of statement 10.
left and right parentheses in the

The message corresponding to error code 11 shows that the number of
statement is not equal.

The statement is examined and corrected, then

compilation is resumed.
Table 3-7 lists the compilation error
Table 3-7

Compiler Compilation Diagnostics
Error

Code

Explanation

Mixed mode arithmetic expression

Missing variable or constant in arithmetic expression

Comma was found in an arithmetic expression

Too many operators in this expression

Function argument is in fixed -point mode

Floating-point variable used as a subscript

Too many variable names in this program

Program too large, core storage exceeded

3-25

Table 3 --7 (Cont)
Compiler Compilation Diagnostics
Error

Explanation

Code

3.4.1 .4

Unbalanced right and left parentheses

Illegal character found in this statement

Compiler could not idenlrify this statement

More than one statement with same statement number

Subscripted variable did not appear in a DIMENSION statement

Statement too long to process

Floating-point operand should have been fixed -point

Undefined statement number

Too many numbered state;ments in this program

Too many parentheses in this statement

Too many statements have been referenced before they appear in
the program

DEFINE statement was proceeded by some executable statement

Statement does not begin with a space, tab, C, or number

Debugging Aid (Symbolprint)

FORTRAN compiler.

Its

— Symbol print

a program which may be used with the

purpose is to help the user create and debug his FORTRAN programs by pro-

viding certain information about the compiler-generated interpretive code.

Symbolprint may be used

only immediately after a program has been compiled by using the Disk/DECtape FORTRAN

compiler.

Symbolprint provides the following information:
a.

The limits of the interpretive code..

A list of variable names and their corresponding locations (the symbol table).
A list of statement numbers and their corresponding locations (the statement number table),

Symbolprint is loaded into core from punched paper tape and may be saved on the system device approximately as shown below (see Paragraph 2.5).

^LOAD J
*IN- R;j
*

*OPT- 1
*ST= J
U_
\.SAVE STBL!600-777;600 i

(See Appendix E.)

When in core, Symbolprint occupies locations 600-777 with its starting address at location
600.

3-26

When symbolprint is called into core, it types the interpretive code limits, symbol table,
statement number table, carriage return/line feed, and

At this point the user may execute his pro-

gram by typing tP, or he may return to Monitor by typing tC.
In

the following example, a program named SRC is compiled with no output specified.

Sym-

bolprint is then used as shown above.

^FORT J
*OUT- J
*

*IN- S;SR(: J
*

(tC typed here)

_^STBL.,;

6154

1
X

757A

7566

7565
(Symbol Table)

Tsn

0100
0010
0102
0020
0030

6033
6060
6066

(Statement Number Table)

'6U-5

6147

I<tC>
In

the example above, location 615^

the lowest location used for data, indicating that the part of core between 6145 and 7565 is unused.

the highest location used for interpretive code and location 7565

Interpretive code starts at location 600 if a

DEFINE statement appears in the program;

otherwise, the

code starts at location 5200.

3.4.2

Operating System
The FORTRAN operating system consists of a loader (FOSL) and the interpreter and arithmetic

subroutine package (.OS.).

This version of FOSL differs from the paper tape

FORTRAN operating sys-

tem in the following ways.
It will load and execute programs which have been compiled and saved on the system
a.
device or programs which have been compiled on paper tape.

FOSL may be called directly by the compiler when a program has been compiled and
b.
saved on the system device. This; is referred to as compile -and -go mode.
FOSL is able to recognize READ and WRITE statements which may read and write data in
c.
USA sen format on either the low-speed paper tape reader/punch, the high-speed paper tape reader/
punch, or the system device.
d.

typing tC;

The execution of a FORTRAN program may be interrupted by the user at any time by
control will be returrjed to Monitor.

3-27

Loading the FO RTRAN Operating System

3.4.2.1

— To load the operating system, the following

steps are performed

Load the operating system loader (FOSL) using Loader in one pass and save it on the sysa.
tem device as shown in Appendix E.
Load the operating system interpretive and arithmetic package (.OS.) by using Loader
Appendix E. The FORTRAN operating system
The loading process will generate the following printout.
is now loaded and ready for use.
b.

in one pass and save it on the system device as shown in

^LOAD J
*IN- R: J

*OPT-l
*ST- ^
ft

",SAVE FOSL10-1577;200 i
."LOAD,/

*IN- R:

*OPT-

(See Appendix E.)

*ST= J
ttt t

.SAVE .OS. I0-5177;0 J

(See Appendix E.)

The loader occupies core locations 0-1 ')77 with its starting address at 200.

and subroutine package occupies core locations 0-5177;

its

The arithmetic

starting address is not specified since the

loader (not the user) calls .OS. when needed.

Operating Procedures

3.4.2.2

— The FORTRAN operating system may be transferred from the system

device into core in one of two ways:

by typing tP immediately after compiling a FORTRAN program

onto the system device, or by typing FOSL immediately after Monitor types a period.
If

T: «i for

the operating system is called from Monitor, specify the desired input device by t/ping

low-speed reader, R:^

for

high-speed reader, or Smame,;' for system device input.

FOSL.will

type * when it recognizes a valid input device.

FOSL will type *OPT-.

input or output is to be to or from the system device, type S.

other character indicates that the system device is not to be used.

However,

Any

the S option is used,

FOSL will type *OUT-. The user should now specify the desired output filename (if any) by typing
S.-namej (name is the name of the file). FOSL will ask for the input filename by typing *IN-. The
user should respond with S:
If

the

and the name of the file, followed by a carriage return.

FORTRAN program is on paper tape. Loader will type

when it is ready to begin

When the user is ready to load his program, he types tP and the tape will begin loading.
When the FORTRAN program or file is loaded, FOSL will type *READY, followed by a

carriage return/line feed and

cuting the program.

(If the

Place data tapeu in the appropriate reader and type tP to begin exe-

low -speed reader is U!>ed, turn the reader

ON after typing tP.)

When a STOP or END statement is executed, or when an end-of-file is read on the system
device, the operating system will type

and return control to the Monitor.

3-28

The following examplej; show bow the FORTRAN operating system may be used.

Example 1

*IN-S:FBIN^
*OPT- ^
*READY
t

(Program execution occurs here)

Example 2
I

^FOSL*'
*IN- R;,R:J
*

ERROR 01
*READY

(tP typed here)

(Program execution begins here)

Example 3

_^FORTJ

*OUT- S;SMSQ,<>
*

*IN- S:SM$Q J
*

T
*READY

Compile
and

Go
«/

(Program execution begins here)

Example 4

_^FOSLv^
*IN- S;BIN«/
*

*OPT- S

*OUT- S:DAT2 J
*

"*IN- S;DAT1 J

^READY
(Program execution begins here)
In

example 2 a checksum error was detected on the second input tape.

cided to attempt to execute the program in spite of the checksum error.

3-29

In this

case the operator de

3.4.2.3

Operating System Diagnostics

ting system will type

of the error.

— When an error occurs during program execution, the opera

ERROR followed by a two-digit error code number which will indicate the cause

Depending on the nature of the error, it may be possible to continue program execution

by typing tP or it may be necessary to return to the Monitor by typing tC.

The following is a list of the operating system error messages.

Table 3-8
Operating System Diagnostics
Error

Code

Explanation

Checksum error on FORTRAN binary input

Illegal origin or data address on

System device input-output error

High-speed reader error

Illegal

Zero divide error

Floating-point input data conversion error

Illegal

System device input-output error

Non- FORMAT statement used as a FORMAT

Illegal

Floating-point number larger than 2048

Square root of a negative number

Exponential negative number

Logarithm of a number less than or equal to zero

Illegal

System device full, could not complete a WRITE statement

Stack underflow error
2
Stack overflow error

FORTRAN binary input

FORTRAN binary input device

op code
1

FORMAT specification

device code used in READ or WRITE statement

May be caused by machine malfunction or operating system error.
May be caused by source program or liDoding error;

to correct,

do the following

in descending order.

a.
b.
c.

Use Diagnose to determine where the error occurred.
Recompile the source program.
Examine source program (in particular the arithmetic statements and subscripted variables).

When an error occurs, execution will stop and the operating system will wait for the user to
type tP or tC.

3-30

3.4.2.4

Debugging Aid (Diagnose)

the user debug his FORTRAN program.

— Diagnose
It is

a basic system program whose purpose

to help

intended to be used in conjunction with the PDP-8 4K

FORTRAN Operating System and revised FORTRAN Symbolprint.

Diagnose provides the following

information.
If stack overflow or underflow has occurred, it will type a message indicating which of
a.
the five run -time stacks caused the error.

will type a message indicating the contents of the current location counter (CLC).

the counter stack is nonempty, it will type the contents of that stack.

d.
If location zero is nonzero, it will type the contents of that location (minus one), indicating the point at which some FORTI^AN systems error occurred.

Diagnose is loaded into core from punched paper tape and may be saved on the system device
as shown in Appendix E.

_^LOADfc^

*IN-R:^

*OPT-

*ST== J
tt

^SAVE DIAGI200-n77;200<^

(See Appendix E.)

When in core. Diagnose occupies locations 200-1 177 with its starting address at location 200.
Diagnose is called by typing the letters DIAG to the Monitor.

FORTRAN 4K Operating system is in core.

(If it is

may be used any time the

called any other time, the information typed will be

meaningless.)

The use of Diagnose is demonstrated by the ejxample of the following test program which contains a large amount of arithmietic calculations.

Program]:
*L

C
C
C

FORTST
PDP-8 ADVANCED SOFTWARE

FORTRAN TEST 1/2/68
DIMENSION ADIFE(6),AFAC(3),APIPE(6),IMRCD(3),PP(27)
,ACPRI(3)

TYPE 1
1

FORMAT("PDP-8 4-K FORTR/^N TEST'/)
ASPVA = .60
APIPE(1) = 12„09
APIPE(3)=6. 66
APIPE(4)=5.
APIPE(5)=5.0

IMRCD(1)=30
IMRCD(2)=30
ADIFE(1)==47.

AD FE (2) ==47.
I

ADIFE(4)-508.
ADIFE(5)-38,57048.

AF=37.96

3-31

SC=3.1416

AMEAS=9.02
FSUBB^IO.O

ASUVA = 100.98

DO 200 1=1,27
RtEAD2,199,PP(l)
199

FORMAT(E)

200

CONTINUE

AGAST=38
INORU=2
BSPVA=n ./ASPVA)**.5
DO 550 JCB=l,INORU
AVEDE=IMRCD(JCB)
BE=APIPE(JCB+3)/APIPE(JCB)
F(BE-. 75)471, 472, 472
I

472

AK = .731
GO TO 16

471

AG = .075
DO 100 IE = 1,27
AG=AG + .025

100
110

CONTINUE

IF(AG-BE) 100,100,110

991

TOTA=PP(IE)
TOTB=PP(IE-l)
SC = .025-(AG-BE)
WRITE 2,991,TOTA,TOTB,SC,AG,BE,IE
FORMATC/" r',E,E,E,E/" ",E,I)
F(TOTA - TOTB)l 20, 20, 30
1

AK=TOTA
GO TO 16
AK =TOTB +(SC *(TOTA - TOTB))/. 025

FRD=830.-5000.*BE+9000.*BE**2-4200.*BE**3+(530./APIPE(JCB)**.5)

120
1

BMEAS=AMEAS+14.4
FR=1

+((F RD/(12835. *AK))/((BMEAS*AVEDE)**.5))

XSUB2=AVEDE/(27.7*BMEAS)
YTTA = (XSUB2+1.)**.5
YTTB = .35*BE**4. +41.
YTTC=XSUB2/(1 .3*YTTA)
YSUB2 =YTTA - YTTB* YTTC
ACPRI(JCB)=YSUB2*FR*1.0177*FSUBB
AFAC(JCB)=ADIFE(JCB)*BSPVA

3-32

992
550

WRITE 2,992,AK,FRD,AMEAS,BMEAS,FR,XSUB2,YTTA,YTTB,'
YTTC,YSUB2,ACPRI(JCB),JCB
FORAAAT(/"2",E,E,E,E)

CONTINUE
AFTF-(520./(460.+AGAST))**.5
AFPV=(l.+(ASUVA*AMEAS)/((AGAST+460.)**3.825))**.5

FLOW=0
RATE=0

DO 38

= l,INORU

AMWP=(ADIFE(1)*AMEAS)**.5/1000.
RATE = R/aE+ACPRI(l)

FLOW=FLOW+AFTF*(AFAC(l)*AFPV*AMWP)
38

CONTINUE

WRITE 2, 993,AFTFvAFPV,AMWP, FLOW, RATE
TYPE 14, FLOW, RATE
FORMAT(E,E/)

993

FORMAT(/E,E,E,E)

STOP

END
.STBL

6360

ADIF

AFAC
APIP

IMRC
PP

ACPR
ASPV
AF
SC

AMEA
FSUB

ASUV
1

AGAS
INOR
BSPV
JCB

AVED
BE

AG
IE

TOTA
TOTB
FRD

BMEA
FR

XSUB
YTTA
YTTB

YTTC
YSUB
AFTF
AFPV

FLOW
RATE

AMWP

6756
7555
7544
7522
7517
7376
7365
7362
7310
7302
7274
7266
7260
7254
7246
7244
7240

7231

7225
7222
7213
7205

-Q

"1
J;

7201
7171

7166
7153
7124
7116
7102
7074
7063
7047
7041

7032
7016
6///
6773
6766

^
3-33

0001

5203

0199
0200
0025
0472

5411

5414
5426
5507
5515
5547
5550
5615
5650
5656
5676
6147
6162
6323
6342
6350

0471

0100
0110
0991

0120
0130
0016
0992
0550
0038
0014
0993

A
JV
-8
*Z

J
z.

z
5

7
V

Example 1(a)
1

"READY
t

PDP-8^^-K FORTRAN TEST
0.255323E+1

-0.825572E+1

]

DIAG

•

CURRENT LOCATION COUNTER AT 6347
Example 1(b)

.FOSL
*IN-S:BIN
*

*READY
PDP-8 4-K FORTRAN TEST

ERROR 05
.DIAG

(tC typed here)

CURRENT LOCATION COUNTER AT 5407
Example 1(c)

.FOSL
*IN--S:BIN
*

*READY
t

PDP-8 4-K FORTRAN TEST

(tC typed here)

.DIAG

CURRENT LOCATION COUNTER AT 4404

COUNTER STACK...
4733
4716
4673
6024

3-34

example 1(a), the program was run to completion after which Diagnose was called.

Diagnose indicated that the current location counter contained 6347.

By referring to the statement

number table (top of page 3-29, we can see that the CLC was pointing to an address just above statement 993 (address 6350), verifying that the program terminated normally at that point.
In

reader.

example 1(b), program ejxecution was attempted without paper tape in the high-speed

After observing the error diagnostic 05, Diagnose was called, indicating that CLC=5407.

Again referring to the statement number table, we note that the address 5407 must refer to a statement
just before statement number
In

199 which is indeed the READ statement at which the error occurred.

example 1(c), program €;xecution was arbitrarily stopped when the user typed tC.

should be noted that in this case the CLC contained a 4404 which is outside the user's interpretive code

area.

such cases it is necessary to refer to the counter stack in order to determine where the pro-

gram interruption occurred.

The last address on the counter stack points to location 6024, and by

again referring to the statement number table we can determine that the program was interrupted at

some point beiween statements 16 and 992.
Program 2 is a FORTRAN program in which a missing operator appears on the 6th line. When

program execution is attempted a stack overflow (error 71) occurs.

Diagnose indicates that the operand

stack has overflowed, which suggests some noncompiler detected error in the source program.
ferring to the statement number table, which

By re-

typed oftenA^ards, we note that the CLC points just

before statement 10, which happens to be the source of the error.

should be pointed out, however,

that when stack overflow or underflow occurs the CLC will not always point to the source of the error.
It

may be necessary to examine the entire program for errors of this type.

Program 2:

.EDIT

*OUT-S:SRC
*

*IN*

*OPT-B
*l

FORTRAN TEST
B=l

C=2
D=3

DO 10

= 1,160

A=B(C+D)
10

CONTINUE
TYPE 20, A

FORMAT(E)
STOP

END
*p

.FORT
*OUT-S:BIN
*

*IN-S:SRC

3-35

*READY
ERROR 77
(tC iyped here)

.DIAG

OPERAND STACK OVERFLOW
CURRENT LOCATION COUNTER AT 5231
.FORT

*OUT*

*IN-S:SRC
*
t

(tC typed here)

.STBL

7555

5251

757A
7570
7564
7562
7555

0010
0020

5237
5244

C
D
1

When Diagnose finishes typing the appropriate information control returns to the Monitor
since it is impossible to resume FORTRAN program execution.
3.4.3

Examples

^LOAD**
*

"^OPT*ST= J

.SAVEFORT!0-1777;200,;

^LOAD J
*IN- R:^

*OPT-2
*ST- ^
t

ft t

^SAVE .FT.!200-7377;0i^

^LOAD i
*IN- R:^
*

*OPT-

*ST= ^
ft

.SAVE FOSL!0-1577;200,/

Call Loader
Input to be from high-speed reader
Input device is valid
One -pass load
Return to Monitor after loading

Loader-driver is loaded
and saved on the system device
Call Loader
Input to be from high-speed reader
Input device is valid
Two-pass load
Return to Monitor after loading

Compiler is loaded
and saved on the system device
Call Loader
Input to be from high-speed reader
Input device is valid
One -pass load
Return to AAonitor after loading
Operating system loader is loaded
and saved on the system device

3-36

^LOAD*'
*IN- R:.>
"^OPT-

TSAVE .OS.l0-5]77}0J

^LOAD i

Call Loader
Input to be from high-speed reader
Input device is valid
One -pass load
Return to Monitor after loading
Interpretive and arithmetic package is loaded
and saved on the system device
Call Loader
Input to be from high-speed reader
Input device is valid
One -pass load
Return to Monitor after loading

*OPT-l
*ST= J

^SAVE STBL!600-;777;600V

Symbolprint is loaded
and saved on the system device

^EDIT«/

Call Editor

*OUT- S;FORT J

Output to be on system device
Output device is valid
Input to be from high-speed reader
Input device is valid
Leave blanks (spaces) unchanged
Write the program on the system device
then write an end -of -file

*IN- R;;
*

*OPT- B
*E

FORTRAN compiler
FORTRAN binary output to be on system device

.FORT^
*OUT-S:FORTJ

Call

Output device is valid
USA ASCII input to be from system device

^IN-S:FORT,/
*

T<tC>,/

Input device is valid
Compilation is finished, return to Monitor

^STBL«'

Call

6177

M
A
B

ANS
0001

0002
0003
0004
0005
0006
0009
0100
0200
0300
0400
0500
1000
2000
3000
4000
1500
0008
0007

7565
7576
7573
7570
7565
5200
5257
5413
5570
5717
5754
5760
5763
5766
6//1

FORTRAN Symbolprint

Core beliween 6200 and 7564 is unused

Symbol fable (typed by Symbolprint)

Statement number table (typed by Symbolprint)

5774
5777
6027
6040
6051

6062
6071

6077
6123

3-37

±
*READY J
J

Symbolprint is finished, load operating system
and interpretive code
Operating system and interpretive code are loaded
Execute the program

THIS IS A DEMONSTRATION OF PDP FORTRAN.
THIS PROGRAM WAS COMPILED IN ONE PASS

^FOSL *'

(tC typed here)

^
*OPT- J

Call operating system and loader
FORTRAN binary input is on system device
Input device is valid
No input or output to be done on system device

*READY k^

during program execution
Operating system and interpretive code have been

loaded
Begin program execution

*IN- S:FORT>^

THIS IS A DEMONSTRATION OF PDP FORT

^FORT./
*OUT- S:FORT J

^
*IN- S:FORT»^
*
t_

*READY tJ
^

Call

(tC typed here)

FORTRAN compiler

Output to be on the system device
Output device is valid
Input to be from the system device
Input device is valid
Compilation is finished, loading operating system
and interpretive code
Operating system and interpretive code are loaded
Begin program execution

THIS IS A DEMONSTRATION OF

3.5

(tC typed here)

DDT-D

DDT-D (Dynamic Debugging Technique for the Disk/DECtape System) is used for on-line
checking, testing, and altering object programs by typing from the teleprinter keyboard.

When de-

bugging on-line, the user checks his program at the computer, controlling its execution, and making
corrections or changes to his program while it is running on the computer.

When using DDT-D, the user should have a listing of his program and its symbols so that he
can update the program listing as corrections and changes are made to his program.

The user may refer

to variables and tags by their symbolic names or by their octal values.

DDT-D operates as described in DDT Programming A/\anual, DDT-8 (Doc. No. DEC-08CDDA-D), except where that manual differs from this one, in which case this manual has precedence.

DDT-D can be considered as being in three sections.
a.

DDT Proper

A slightly modified version of DDT-8 (Low), occupies core
locations 200-4577 and the three breakpoint locations.

Driver

Resident in core with its origin set above DDT proper
(above 4577); it is a two -page program plus a one -page
once -only program, and it contains breakpoint insertion
and removal logic, overlay routines, continuation iteration
count and control, and breakpoint list.

a-38

User Core Image File

Occupies same storage area as DDT proper and is used for
swapping DDT proper and the user program to and from the
system device.

DDT-D is an expanded version of DDT-8 with the following exceptions.
a.

Three breakpoints (as opposed to only one in DDT-8)

No punching (program may be output on the system device)

No switch options (user direction is via keyboard)

No halts (continues when user types

Variations in commands
a.

[O,

follows.

[S, [Y, [L,

Are temporary modifications to their respective constants;
are reset at every entrance to DDT-D from a G or [C
[

Continue (DDT types t to indicate that it is waiting
for tP)

Restore user core image and return to Monitor

n[Bk

Set breakpoint; where n is the address of the break, [B is
the breakpoint command, and k is 1, 2, or 3

NOTE
If

user tries to set two breakpoints at the

same address, a ?

typed and no action

occurs.
e.

n[B, [T, a;b[P,

Have been removed

[IE

switch independent

The following subroutines have been added.
a.

ADDCHK

ADDMOD

Updates real or virtual core.

DDTB

Updates symbol table pointer, gets value of breakpoint and its
contents, types breakpoint number and a - (hyphen) if a breakpoint,
and goes to TRAP or types nothing and goes to START if breakpoint
number = 0.

STOSYM

WORD

Finds word to be examined and puts it in
2; remembers if
last virtual word referenced was in same buffer as present virtual
word and reads only if required.

Updates DDT proper symbol area (DDT proper must be on unprotected
disk).

READS
and

Input-output routines for disk;

a failure in either types S and goes

to start of DDT.

SYMIO

The ALT MODE key precedes each command character and is echoed as

3-39

[

The following subroutines have been modified as indicafed.

REDTAB

Assumes user wants to add to existing symbol table;

user must type

[X to clear the symbol table.
b.

FINIS

Does not halt, instead,

CHANGE

Allows lookup of values to change limit of search and search mask.

TODDT

Handles breakpoint insertion;

TRAP

Breakpoint handler;

waits for the user to type

^P,.

transferred to DDT driver.

The following subroutines have been removed.
a.

PUNWOR

FSTPUN

FUN

PUNCHK

PUNLDR

WHICH

CHKSUM

From the teleprinter keyboard, the user can automatically stop his program at up to three
strategic points by setting breakpoints,

another breakpoint stop.

which may be set before the debugging run is started or during

To set a breakpoint, the user types the absolute address or symbolic tag of the

location where he wants his program to stop, the ALT

number.

MODE key, the B key, and then the breakpoint

For example,

3400[B1

(absolute address, ALT MODE, B, 1)

HERE[B2

(symbolic tag,

ALT MODE, B, 2)

Locations 3,4, and 5 on page zero are used as the breakpoint locations.

The user may, by

reassembly of the furnished DDT Driver source resei- the breakpoint locations to any three contiguous locations on page zero. Changing the breakpoint locations is done by setting BRKCEL=n, where n is the
lowest of the three locations desired

The following symbols represent certain registers in DDT-D whose contents are available to
the user by typing:

Accumulator storage (at breakpoints)

Link storage (at breakpoints)

Mask used in search

Lower limit of search

Upper limit of search

[

Table 3-9 lists the DDT-D commands available to the user.

3-40

Table 3-9

DDT-D Commands
Character

ActI on

(space)

Separation character

Arithmetic plus
Arithmetic minus

Location examination character; when it follows the
address of a location, it causes the contents of that
location to be printed

J (carriage return)

Make modifications, if any

(line feed)

Make modifications, if any, and print the contents of
the next sequential location

Type last quantity as an octal integer

(period)

Current location

(left arrow)

Delete the line currently being typed

DDT-D to type out in symbolic mode
Sets DDT-D to type out in octal mode

n[W

Word search for all occurrences masked with C([M) of

[

Sets

the expression n

k[Bn
[

Insert breakpoint n at location k

(n=1, 2, or 3)

Remove breakpoint n (n =1, 2, or 3)

n[C

Continue n times automatically;
assumed to be 1

k[G

Go to location k

Append symbol table into external symbol table or define

if n is

absent,

it is

symbols on line

3.5.1

Loading and Saying

DDT-D is loaded into core from punched paper tape. The tape is in two sections. The first
section contains DDT proper which loads in one pass, occupies core locations 200-4577 (Appendix E)
and uses three locations on page

for the breakpoint locations.^

should reserve on the system device a user core image file name

After loading DDT proper, the user

.SYM, which should also be assigned

to core locations 200-4577.'

The next section of DDT (the driver) loads in two passes and occupies two pages in core with
its

origin anywhere above DDT proper, that is,

core.

For setup,

uses five more pages:

anywhere above location 4577.

The driver is resident

one for once -only code plus four for Command Decoder.

Command Decoder expects two inputs to be assigned as files to be used by the driver.

These files are

assigned only once unless the system is changed or destroyed, in which case the user must reassign these

two files.

.SYM is used also by PAL-D to store a'Iditional symbol table entries.
2Binary tape of DDT driver uses locations 3, 4, 5, and 7200-7577.
3-41

The sections of DDT are loaded and saved as described below.
.
"

LOAD J

Call Loader using Monitor
Input to be from high-speed reader
Loader found input device valid
DD f proper loads in one pass
Return to Monitor after loading

*^IN- R:,^
"

^OPT-

*ST= V
11

DDT proper is loaded

^SAVE .DDT:200-4577;0
^SAVE .SYM:200-4577;0i;
li

^LOAD*'
*

*OPT-2
*ST= 7000^
tt ft

*IN- S:<.DDT>,S;<:USER>,/
*IN- S:,DDT,S;.SYM./
*

TSAVE DDT!7200-7577;7200 J

(See Appendix E.)
Saved as a user program
(See Appendix E.)
User core image file also
saved as a user program
Call Loader using Monitor
Input to be from high-speed reader
Loader found input device valid
Driver loads in two passes
Transfer to once -only code after loading
Driver is loaded
DDT Loader expects names of 2 input files saved
above for use by driver
(See Appendix E.)
Inputs to be from DDT proper and user
core image files
Loader found input files valid (an
asterisk for each valid file (device)
(See Appendix E.)
Saved as a system program

The error message DDT? is typed whenever an error is encountered while loading DDT-D.
Errors may be caused by the following.

3,5.2

User file too large

System device read error

No Command Decoder

Operating Procedures

DDT-D is now saved on the system device.
be debugged.

The user must now load into core the program to

This is done as described in Paragraph 2.5.

When the program to be debugged is in core the user types DDT in response to Monitor's
period as shown below.

.DDT
The user may now use DDT-D in debugging this program, directing execution and making
modifications to his program as described above and in the DDT-8 programming manual.

A brief example of using DDT-D is shown in Paragraph 3.5.3.
3.5.3

Example

^LOAD^
*IN- R;,^
*

*OPTST= ^

Call Loader
Input to be from high-speed reader
Loader found input device valid
One -pass load
Return to Monitor after loading

3-42

_^SAVE .DDT:200-4577;
^SAVE .SYM:200-457:^;0,»

^LOAD.;
*IN- R:J
*

*OPT-2
SI = 7000 J

Sk:DDT>,S:<.SYM>V
*IN- S:.DDT,S:.SYM>>>

DDT proper is loaded
DDT proper is saved on disk

(See Appendix E.)
User code image file also saved
Call Loader
Input to be from high-speed reader
Loader found input device valid
Two -pass load
Transfer to once -only code after loading
Driver is loaded
DDT Loader expects names of 2 input files saved
above for use by driver
Inputs from DDT proper and user code image file

3400[B1^^
3400 [Gv^
1 -3400)0000

Loader found both input files valid
(See Appendix E.)
Driver is saved on disk
Call DDT using Monitor
Examine contents of location
3400 and 3401
Set breakpoint No. 1 at location 3400
Start execution at location 3400
Location 3400 contains 0000

[CJ

Continue

-3400)0001
JOOiC**
1 -3400)0701

Pass through location

^SAVE DDl\7200-75T/}7200^
3400/AND 0007 lACi^
3401/AND JMP3400v'

Location 3400 now contains 0001
3400 700 times
Location 3400 now contains 0701
tC was typed here

3-43

APPENDIX A
SYSTEM GENERATION

This appendix describes the creation of a

Disk/DECtape System (Disk/DECtape Monitor and

system programs) on an empty disk or JDECtape (if DECtape,

must have timing and mark tracks previously

written on it).

The steps involved in system generation are as follows.

. 1

Toggling in the Readin Mode (RIM) Loader.

Loading the Binary (BIN) Loader

Loading and executing Disk/DECtape System Builder to create Monitor.

Loading and saving any system programs.

TOGGLING IN THE READIN MODE (RIM) LOADER
The Readin Mode (RIM) Loader is a short program which loads any program in RIM format on

paper tape into core.

Although the RIM LDoder has various uses,

its

sole purpose in the System Building

process is to load the Binary Loader.

There are two versions of the RIM Loader, one for loading programs from the high-speed paper
tape reader and the other for loading from the Teletype paper tape reader.

High-•Speed Reader

Teletype Reader

Location

Instruction

Location

Instruction

7756

6014

7756

6032

7757

6011

7757

6031

7760

5357

7760

5357

7761

6016

7761

6036

7762

7106

7762

7106

7763

7006

7763

7006

7764

7510

7764

7510

7765

5374

7765

5357

7766

7006

7766

7006

7767

6011

7767

6031

///O

5367

///O

5367

777\

6016

7771

6034

j/n

7420

///2

7420

7772

3776

///2

3776

777A

3376

///A

3376

7775

5357

7775

5356

///6

0000

7776

0000

A-1

A detailed description of the toggling and checking procedures for the RIM Loader can be
found in the PDP-8 Console Manual (Doc. No. DE:C-08-NGCA-D).

Acomplete discussion of the

RIM Loader is contained in the PDP--8 Readin Mode Loader Program writeup (Doc. No. Digital-8-1 -U).
A. 2

LOADING THE BINARY (BIN) LOADER
The Binary (BIN) Loader loads any program in binary format on paper tape into core.

pose in the System Building process is to load the Disk/DECtape System Builder.

Its

pur-

The procedure for

loading BIN is as follows.
a.

Check that the RIM Loader is in core.

b.
Place the paper tape containing BIN in the paper tape reader (high-speed or Teletype,
according to version of RIM).

If Teletype

Place the addre ss 7756 in to the SWITCH REGISTER and press LOAD ADD.

reader is to be used, turn it on.

Tape should begin reading (if it does not, check that the SING INST and
(Note: The Teletype reader is always
on line.) If the Teletype begins to print, flip Teletype switch from LOCAL to LINE and back up the
e.

Press

START.

SING STEP switches are down and that the reader is on line).

tape to the leader/trailer.
f.
After paper tape reads in, wait until only bit
of the accumulator is on. Press STOP
on console. If the high-speed reader is used, a 7402 (HLT) appears in the accumulator, and the tape
stops over the leader/trailer (200 code).

A detailed description of BIN and its use can be found in the PDP-8 Console Manual and PDP-8
Binary Loader Program writeup (Doc.

A. 3

No. Digital-8-2-U).

LOADING AND EXECUTING DISK/DECTAPE SYSTEM BUILDER
Next, the Disk/DECtape System Builder program,

by the Binary Loader.
a.

binary format on paper tape,

loaded

Loading procedures are as follows.

Place the address 7171 (starting address of BIN) into the SWITCH REGISTER.

Press

LOAD ADD.
b.

If the

high-speed paper tape reader is to be used, put down (or set to 0) bit

of the

SWITCH REGISTER, place the System Builder tape in the reader.
If the Teletype reader is to be used, leave up bit
of the SWITCH REGISTER, place the
System Builder tape in the reader, put the Teletype to line, and set reader to START.

Press

START on the console.

Tape should read in.

d.
When tape has been read, the accumulator should contain all zeroes (if not, the program has loaded incorrectly; begin the loading procedure from the beginning).
e.
Turn off WRITE PROTECT on the disk (if present). Otherwise, mount a DECtape reel on
one of your DECtape units, set the unit selector to 8, and set the WRITE switch to WRITE.
f.

press

To begin System Builder execution, place the address 0200 into the SWITCH REGISTER,

LOAD ADD, and then START.

As the following questions are typed out, answer them according to your machine
g.
configuration.

A-2

*TYPE SIZE OF CORE (IN K)^
User enters core size of his machine
20, 24, 28, or 32),

{% 8 Jl2, 16,

tr/.^

*HIGH SPEED PAPER TAPE?
*YES J

User answers YES or NO«
;'

*Disc?
*YES^
'^fl^PE

User answers YES or NO.

ji/

<t^

NUMBER OF DISC UNITS

*TAPE?

—

User answers YES or NO.

p l:^ ^f\ ft

^X^A ^
(^

User fypes number of disk units on his machine.

*YES,(I

User types YES if he has DECtape,
if he does
not
Monitor creation is completed, the resident
portion is moved to the appropriate core area

(7600 through 7117) , and the nonresident portions are written on the system device.

NOTE
If

specified as present, the disk is

automatically selected as the system
device; if not, DECtape unit 8 is
selected.

Monitor is loaded and ready.
If

the response

WRITE ERROR
occurs:
a.

If disk, start over at Para. A. 2; there may be
a hardware problem.

DECtape, try a new DECtape and start at
Or, rewrite the timing and mark
tracks and start at Para, A. 2.
If

Para. A. 2.

LOADING AND SAVING SYSTEM PROGR>A.MS
Binary Loader is one of the nonresident portions of Monitor and is used to load system and

user programs into core.

fully described in

.LOAD,/
*IN-R:^

*OPT-l
ST =7600 k

.SAVE PIP! 0-3177; 1000^

Chapter 2.

An example follows.

Calls Binary Loader from the system device.
Input device is paper tape reader (high-speed reader
if specified as present at System Builder time;
otherwise Teletype reader).
Device is valid
One -pass loading mode selected.
Return to Monitor after loading.

After each up -arrow typeout, user types t P to
continue (also must press CONTinue on console
if Teletype reader is being used).
Saves program (in this case, PIP) on system device.
Note that a
must follow name of system program.
The SAVE command is explained in Chapter 2. The
SAVE command program is given in Appendix E.
I

Repeat the procedure above for each system program to be saved.

A-3

If \

APPENDIX B
SYSTEM FORMATS

This appendix contains the following information.

System Device Layouts

Disk Storage Ljayout

DECtape Storage Layout
Directory

Name (DN) Block Format

Storage Allocation

Map (SAM) Block Format

Table of System Device and Core Capacities

Data Structure

Source File (ASCII)
Binary File

(BINARY, FTC BIN)

Saved Files (SYS, USER)
c.

PIP Listing of System Device Map (for Disk)

AAonitor Core Usage Diagrams

SYSTEM DEVICE lAYOUTS

B. 1

Figures B-1 and B-2 illustrate the layout of the system device for both disk and DECtape.

Note that, although the layouts differ in arrangement, they are logically equivalent.

A relatively sophisticated file structure is used for all automatic retrieval of storage by the
system.
tion

Two special types of blocks are required:

Directory Name (DN) Blocks, and Storage Allpca-

Map (SAM) Blocks.

B.1.1

Directory Name (DN) Blocks

The format of a Directory Name Block is illustrated in Figure B-3.
in

Each file has an entry

one of the three DN blocks on the system device.

DN^ - Contains entries for internal file numbers 01 through 31g (25, q) and a link to DN«.

DN2 - Contains entries for internal file numbers 32 through 62o

(50iq)

and a link to DN^

DNo - Contains entries for internal file numbers 63 through 77q (63,^) and an end-of-chain
-^

link of 0.

Thus, the system device can contain up to 63 files.

Each file entry contains the filename,

entry point address, file type, and an internal file number (1 through 77g).

start address,

When a file is to be added

on the system device, an entr/ for the file is created in the first open entry slot found in the DN blocks.

When a file is deleted, its DN entry is cleared and the slot is made available for some other

B-

file.

BLOCK

BLOCK
1

2
3

4
5

7
10
11

MONITOR HEAD
MONITOR (1ST PAGE OF SAVE)
MONITOR (START)
DN (BACKUP - SEE PIP)
SAM (BACKUP - SEE PIP)
MONITOR (2ND PAGE OF CALL)
MONITOR (3RD PAGE OF SAVE)
MONITOR (2ND PAGE OF SAVE)
MONITOR (1ST PAGE OF CALL)
MONITOR (4TH PAGE OF SAVE)

LOADER

COMMAND DECODER
COMMAND DECODER
COMMAND DECODER
COMMAND DECODER

COMAAAND DECODER

COMMAND DECODER

15
16

401

SECOND DISK (OPTIONAL)

1001

vLOWER
/ HALF

SAM3 (USER)

rrwrrwiS'fww^^

THIRD DISK (OPTIONAL)

177

DN] (USER)

200

SAMi (USER)

201

202

DN2 (USER)
DN3 (USER)

373

SCRATCH BLOCK

374

SCRATCH BLOCK

375

SCRATCH BLOCK

1401

UPPER
>HALF

FOURTH DISK (OPTIONAL)

DN = Directory Name Block

376

SAM = Storage Allocation AAap Block

377

AREA AVAILABLE FOR
SAVING CORE IMAGES

FIRST DISK

Rgure B-1

Disk Storage Layout

B-2

BLOCK

2
3

4
5

7
10

n
12

14
15
16

20
21

23
24
25

MONITOR HEAD
MONITOR (1ST PAGE OF SAVE)
MONITOR (START)
DN
SAM
SCRATCH BLOCK
SCRATCH BLOCK
SCRATCH BLOCK
MONITOR (2ND PAGE OF CALL)
MONITOR (3RD PAGE OF SAVE)
MONITOR (2ND PAGE OF SAVE)
MONITOR (1ST PAGE OF CALL
MONITOR (4TH PAGE OF SAVE)
LOADER
LOADER
LOADER
COMMAND DECODER
COMMAND DECODER
COMMAND DECODER
COMAAAND DECODER
COMAAAND DECODER
COMMAND DECODER

DN = Directory Name Block
SAM - Storage Allocation Map Block
AREA AVAILABLE
FOR SAVING CORE
lAAAGES

177

DN] (USER)

200

SAMi (USER)

201

DN2 (USER)

202

SAM2 (USER)

203

SAM3 (USER)

204

SAM4 (USER)

205

206

SAM5 (USER)
SAM6 (USER)

207

DN3 (USER)

2701

Figure B~2

DECtape Storage Layout

B-3

BLOCK NUMBER OF FIRST SCRATCH BLOCK
(DISK = 0373;

DECTAPE - 0005)
)

2-DIGIT VERSION NUMBER

1ST DN BLOCK ONLY; OTHER

BLOCKS CONTAIN ZEROES IN

BLOCK NUMBER OF FIRST SAM BLOCK (0200)

THESE WORDS

DN ENTRY FOR FIRST FILE
(INTERNAL FILE NUMBER == 01)

DN ENTRY FOR SECOND FILE
(INTERNAL FILE NUMBER = 02)

DN ENTRY FOR THIRD FILE

ENTRIES

(INTERNAL FILE NUMBER == 03)

PER DN

DN ENTRY FOR TWENTY-FIFTH FILE
(INTERNAL FILE NUMBER == 31

o
Link to DN

LINK

-JL

(files

through 62 J

FIRST DIRECTORY NAME (DN)

BLOCK

N = 4-CHARACTER
N

FILENAME

DN
ENTRY

START

ADDRESS

ENTRY

POINT

FORMAT
INTERNAL FILE

NUMBER
1

EXTENDED MEMORY BITS

^1 = SYSTEM PROGRAM

PROGRAM TYPE
00 = ASCI
01

= BINARY

Figure B-3

10 = FTC BIN
11

= SIYSOR USER SAVE FILE

Directory Name (DN) Block Format

B-4

Storage Allocation

B . 1 .2

Map (SAM) Blocks

SAM blocks contain a record of which files are occupying which blocks on the system device,
Each

SAM block contains a record of a 377o-block area.
SAM,

contains the map for blocks

(See Figure B-4,)

through 377o and a link to

SAM«.

SAM^ contains the map for blocks 400 through 777o and a link to SAM^.
SAMq contains the map for blocks 1000 through 1377o and a link to SAMi.
SAMi contains the map for blocks 1400 through V777
(if disk)

or a link to

and either an end-of-chain link of

SAM^ (if DECtape).

The next two SAMi blocks are present only if a DECtape is the system device.

SAMc- contains the map for blocks 2000 through 2377o and a link to SAM,

SAM,

contains the map for blocks 2400 through 2701 o and an end-of-chain link of 0.

On disk, one SAM block is present for each disk unit (up to four allowed) and each SAM
block resides on the disk which

maps (SAM, on the first disk, SAM-^ on the second disk, etc.).

When a file is to be added, a search is made through the SAM blocks for an entry containing
is

unoccupied), the internal

file number of the file is placed in that

(block

entry (and in as many other unoc-

cupied entries as are needed for the file), and the storage block linking is adjusted.

When a file is

SAM block entries containing the file's internal file number are set to 0. The block number of the beginning block of the SAM chain (200) is stored in the third word of the first DN block.

deleted,

all

B-5

SPECIAL INTERNAL FILE NUMBERS:

= ALL MONITOR, DN, SAM,

AND SCRATCH BLOCKS
LOADER BLOCKS
COMMAND DECODER BLOCKS

04
05

WORDO
WORD
WORD 2
WORD 3
WORD 4
WORD 5
WORD 6
WORD 7
WORDS
1

^200

^000

^201

^001

^202

^002

^203

^003

nnn
^204

^004

^205

^005

^206

^006

^207

^007

^210

Z' ^^

internal file

number of file
occupying block
nnn (0 =
unoccupied)

—^^^^
''oio

-J

^67

WORD 122
WORD 123
WORD 124
WORD 125
WORD 126
WORD 127
WORD 128 10

''370

^70

''371

^71

^372

^72

^373

^73

^374

^74

LINK TO SAM

^375

^\1^

(BLOCKS 400-777)

^376

^76

^377

'^Ml

LINK

STORAGE ALLOCATION MAP (SAM)

EXAMPLE
FILE #1 - BLOCKS 0,

FILE #3- BLOCKS 5, 6,

FILE #4- BLOCK 10

FILE #13- BLOCKS 201,

202, 206, 207
FILE #15- BLOCKS 200,

203, 205, 210

UNUSED - BLOCKS 3, 4, 7,
204, 211

Figure B-4

10
12

Storage Allocation Map (SAM) Block Format

li-6

Table B--1
System Device and Core Capacities
Highest Page (Block)
Unit

Words

Number (1st Page = 0)

DISK

32,768

(3753)

2 DISKS

65,536

(773g)

3 DISKS

98,303

(1371g)

4 DISKS

131,072

(I767g)

190,146

(2701g)

4K CORE

4,096

(378)

8K CORE

8,192

(773)

12KCORE

12,288

(1373)

16KCORE

16,384

(1773)

20K CORE

20,480

{237g)

24K CORE

24,576

(277g)

28K CORE

28,672

(337g)

32 K CORE

32,768

(3778)

B.2

DECTAPE

DATA STRUCTURE
The data structure of each type of program file is described in the following paragraphs.

B.2. 1

Source File (ASCII) Data Structure
All characters are stored in 6-bit ASCII code as described below.

All nonprinting characters (200 through 237 and 340 through 377) have their two most
significant bits dropped and a 77 prefixed to them. (The one exception to this rule

RUBOUT, 377, which is nonexistent.) All printirig characters are trimmed to six bits,
except for ? (277), which is packed as 7777
B.2 .2

Binary File (BINARY, FTC BIN) Data Structure
All binary (BINARY) and FORTRAN binary (FTC BIN) files are stored as two words per three

paper tape frames.

Frame 1 contains the rightmost eight bits of word 1, frame 2 contains the rightmost

eight bits of word 2, and frame 3 contains

the leftmost four bits of words 1 and 2 (the most significant

bits of frame 3 are those of word 2).

B-7

Example:
Paper tape

200
102
033

Meaning

Disk(Octal)

Leader

5600
0502

ORG

Disk (Binary)

1011

0001

10000000
01000010

Second half
of ORG word

This procedure

B.2 3
.

repeated until a trailer code is found.

Saved File (SYS, USER) Dote Structure
Saved files are stored on the system device as an integral number of pages and each page

occupies one disk or DECtape block.

Storage conventions differ between saved files of contiguous pages

of core and those of noncontiguous pages.

C ontiguous Pages
All system device blocks contain core images (Figure B-5)

The Start Address word in the

Directory Name (DN) entry for the file is set to the starting page address.

SAVE

Block 1

FILC:200-600;433

Contains core

image of locations
200 through 377

Filename
Start Address

4
6

Entry Point

File Type/File

DIRECTORY NAME ENTRY
Contains core
Block 2

image of locations
400 through 511

Block 3

Contains core

image of locations
600 through 111

SYSTEM DEVICE BLOCKS
Figure B-5

Contiguous-Page Save File Format

B-8

Number

Noncontiguous Pages

The first system device block of a saved file composed of noncontiguous pages of core contains a

list

of core page assignments and the core images sotred in subsequent blocks.

this list

set to 7177 (Figure B-6) .

The Start Address word in the Directory Name entry for the file is

set to 7777 to indicate that the first block does not contain a core

SAVE

Block 1

image but a page assignment listing.

FILN: 0,400, 1000;433

0000 List of
0400 page
1000 assign7777 ments

Filename

Start Address

Entry Point

File Type/File

DIRECTORY NAME ENTRY
Contains core
Block 2

image of locations
through 177

Contains core
Block 3

image of locations

400 through ^77

Block 4

Contains core
image of locations

1000 through 1177

SYSTEM DEVICE BLOCKS

Figure B-6

The last entry in

Noncontiguous-Page Save File Format

B-9

Number

B.3

PIP

DIRECTORY LISTING

A directory listing of the system device can be obtained by running PIP (Figure B-7)
sample output is given below.

.PIP

*OPT-L
*IN-S:

FB=ono

110 free blocks remain

8D
PALD.SYS

0030
0015
0003
0006
0020
0010
0035
0024
0006

EDIT. SYS

LOAD. SYS
.CD.. SYS
.SYS
FORT. SYS
.FT.. SYS
.OS.. SYS
PIP

FOSL.SYS
STBL.SYS
.DDT. USER
.USR.USER

0001

0022
0023
0002

DDT^.SYS

Number of blocks used
Field number

Extension name

Filename

Figure B-7

Sample PIP Directory Listing

B-10

B.4

MONITOR CORE USAGE DIAGRAMS
The following illustrations show Monitor usage of locations 7000 through 1117 at
a.

Monitor Time and User Time (Figure B-8)

SAVE Command Processing (Figure B-9)

CALL Command Processing (Figure B-10)

nil

1111

SYSTEMS I/O ROUTINE

MONITOR HEAD

7600

MONITOR
USER AREA

TELETYPE SERVICE

7400

SAVE COMMAND DECODER

AND

USER AREA

PAGE STACK BUILDER

7200

7000

(a)

7000

Monitor-Time Core Usage

Figure B-8

(b)

USER AREA

User-Time Core Usage

Monitor-Time vs User-Time Core Usage

B-11

SAVE filenamercore-specifications,

.;entry-point'

rni
SYSTEMS I/O

SYSTEMS I/O

MONITOR HEAD

PAGE STACK BUILT HERE

MONITOR AND TTY SERVICE ROUTINES
ARE NOW DESTROYED; VARIOUS STATUS
REGISTERS ARE HELD HERE.

7600

TTY SERVICE ROUTINE
7400

DIRECTORY NAME ENTRY BUILT HERI

PAGE STACK MOVED HERE

SAVE COMMAND DECODER

BUFFER FOR DN SEARCH

AND
PAGE STACK BUILDER
7200

CODE HERE IS SWAPPED OUT TO
SYSTEM DEVICE SCRATCH BLOCK;

DN BLOCK SEARCH AND UPDATE
ROUTINE LOADED HERE

7000
(a)

"SAVE filename:"

Processing

(b)

"Core-specifications,

.;entry-point'

Processing

1711

SYSTEMS I/O

MONITOR HEAD

BLOCK STACK

PAGE STACK

7600
7500

7400

SAM BLOCK SEARCH AND UPDATE
ROUTINES LOADED HERE
(CREATE BLOCK STACK)

ACTUAL SAVE ROUTINE LOADED HERE
(RETURNS TO MONITOR START 7600-WHEN FINISHED)

SAM BUFFER

SWAPPED-OUT CODE BROUGHT BACK

7200

7000
(c)

SAM Search

Figure B-9

(d)

Actual Save Time

Core Usage During SAVE Command Execution

B-12

CALL filename^

.filename^

nil
SYSTEMS I/O

MONITOR HEAD
7600

BUFFER FOR DN AND SAM BLOCKS
7400

CALL:

DN AND SAM SEARCH
ROUTINES

7200

(LOCATE FILE AND DEFINE RANGE OF CALL)

X
7000
(a)

"CALL filename" Processing

nil
SYSTEMS I/O

MONITOR HEAD
7600

READ ROUTINE
(PERFORMS ACTUAL CALLING IN OF FILE;
CAN DISAPPEAR AT USER TIME)
7400

CONTIGUOUS-PAGE PROGRAM:
THIS AREA IS NOT TOUCHED.

NONCONTIGUOUS-PAGE PROGRAM:
SCATTER-GET READS CORE
ALLOCATION (BLK 1) INTO HERE

7200

X
7000
(b)

Figure B-10

Actual

CALL Time

Core Usage During CALL Command Execution

B-13

MONITOR START

7600

SWAP OUT CORE
(7200-7577) AND
READ MONITOR

CONSTRUCT
PAGE LIST

SET NONSYSTEM-

YE:S

PROGRAM
MODE IND.

set SYSTEM
MODE INDICATOR

READ AND
SEARCH DN

CONSTRUCT
PA(!E

NAME FOUND -y

^ypE

LIST

"?"

CONSTRUCT
ENTRY POINT
ADDRESS

READ SAM
BLOCK

F IND

-y*<;^FILENO

Figure B-1 1

Monitor Flow Chart (Part 1)

B-14

SET ENTRY
POINT TO 200

READ

BLOCK

SEARCH FOR
FILENAME
READ BLOCK
(CORE

ALLOC. LIST)

INTO

7200

READ BLOCK OF
SAVE FILE INTO
PROPER PAGE

AN OLD VERSION
OF THE FILE
EXISTS AND IS
BEING OVERWRITTEN BY
A NEW VERSION

JUMP

TO ENTRY

POINT

ADDRESS

CONSTRUCT DN

ENTRY

WRITE OUT UPDATED
DN BLOCK

READ IN SAM

Figure B-11

BLOCK

Monitor Flow Chart (Part 2)

B-15

EXTRACT A

SAM ENTRY

y^ REQUIREMENTS^^NO »
\,.

SATISFIED

TYPE

"FULL"

YES

PICK UP

PAGE FROM
PAGE LIST

SET LINK

WORD TO

WRITE BLOCK
PICK UP BLOCK

NUMBER FROM
BLOCK LIST

PLACE FILE NUMBER
OF FILE BEING SAVED
INTO SAM ENTRY

WRITE PAGE

CONTENTS
INTO BLOCK

IF AN OLD FILE IS
BEING OVERWRITTEN
CONTINUE SEARCHING
SAMS FOR OLD FILE

NUMBER AND CHANGE
TO e

Figure B-1 1

Monitor Flow Chart (Part 3)

B-16

7600
J

APPENDIX C
COMMAND DECODER

Command Decoder is a genera -purpose program used by all system programs to read in and
I

interpret

command strings entered by the user via his Teletype keyboard.

Command Decoder is gener-

ated and stored on the system device by System Builder.

Command Decoder uses four pages of core (see Figure C-2) and is called in by a system program in the following way.
a.

The internal file number of Command Decoder (filename = .CD.)

The starting block of the Command Decoder file is obtained.

This block

obtained.

then read into the second of the four pages to be used by Command

Decoder. Command Decoder is position-independent and can be read into any four contiguous pages
of core between locations 200 and 1S71 inclusive.
d.
first

Command Decoder Is then entered by jumping to the second location of page 2 (the

location is an error return)

LOCATIONS USED BY COMMAND DECODER
Locations 167 through 177, page 0, are used as follows.

Table C-1

Page

Locations Used by Command Decoder

Purpose

Location

167

Preloaded with 7171 if input and output filenames and extension names
are different.

170

Scratch location.

171

Scratch location.

172

Points to the first block of Command Decoder.

173

Scratch location.

174

Points to the output list.
is

Information concerning each device request

placed in this list by Command Decoder.

175

Contains the option bits. This location is not left in its original state
upon exit from Command Decoder

176

Scratch location.

177

Contains the address of the return from Command Decoder.

C-1

C.2

INPUT AND OUTPUT REQUIREMENTS F-OR COMMAND DECODER
Location 174 (CDPTRP), the output list fxjinter, must point to a block of code, the length of

which must be 3*n+l, where n is the total number of device requests expected.
with one output file plus three input files requires 13 locations.

The option bit location (175)

(See Figure C-1 .)

constructed as follows.

Contain output file extension code (or input,

and 1

Bits

For example, a program

no output is

requested) J
Bits 2 and 3

Contain the input file extension code.

Bit 4

Output file is expected (Command Decoder will type
*OUT-" query (in addition to *IN-) )

Saved output file is a system program (bit 5 of word 4 in

Bit

DN entry is set to 1)
Bit 6

Option is available (Command Decoder will type *OPT-)

Bit 7

Saved input file is a system program (bit 5 of word 4 in
DN entry is checked for a 1)

Bits 8-11

(Total

number of input files allowed) -1

J
(Number of input files) -1
2

System/user input

OPT- option

— System/user output

— Output

option

Input extension
1

Output extension
This option word must be set up by the system program before calling Command Decoder.

Extension codes:

= System,

ASCII

BINARY

FTC BIN

Saved file (USER, SYS)

= User

C-2

The first block of the Command Decoder Is read into the second of the four blocks into which
it is

to run.

In the

following examples, assume Command Decoder is to be run in locations 2000-2777;

that you have already loaded FBLK with the first block number of the Command Decoder; output list is
in

3000; return is at 203 and you are looking for user file output, system file input, no *OPT- is

desired, and three input files are allowed.

Example

*1700

TAD

(203
177

DCA
TAD

(7622
175

DCA
TAD

DCA

(3000
174

TAD

FBLK

DCA

172

/RETURN
/111 110 010 010 = BITS

/POINTER TO LIST

/BLOCK

OF .CD. (DISK)

CMA
DCA

167

JMSI

{76A2

/READ

2200

/BLOCK OF COMMAND DECODER
/INTO LOCATION 2200

HLT

/LINK
/BAD READ

FBLK,

JMPI

.+1

2201

/ENTER .CD.

Example 2
*2200

TAD

(203

DCA

177

/RETURN

TAD

/111 110 010 010= BITS

DCA

(7622
175

TAD

(3000

DCA

174

TAD

FBLK

DCA

172

/POINTER TO LIST

/BLOCK

OF .CD.

CMA
DCA
JMS
1003

FBLK,
2200
2200

167
{76A2

/READ AND RETURN THRU
/ADDRESS IN ERROR RETURN
/IF ERROR,OR ERROR RETURN
All IF CORRECT RETURN
/NOTE THIS CODE IS OVER-WRITTEN

C-3

FOR DISK OR DECTAPE:

OUTPUT
(OR INPUT
IF

UNIT

CODE

NUMBER

NO OUTPUT)

INPUT
(OR INPUT 2
1

DEVICE

NO OUTPUT)

INTERNAL FILE

NUMBER
0-7

6 = System Device
4 = Not System Device

FOR TELETYPE OR HIGH SPEED READER:
DEVICE

CODE
= Teletype
2 = High Speed Reader
= Null Device
1

END OF LIST
DISK OR DECTAPE (INPUT):

ASCII

CHARACTER ^^
START BLOCK NUMBER
DISK OR DECTAPE (OUTPUT):

PAPER TAPE:

Figure C-1

Output Lisi- Produced by Command Decoder

C-4

«IN-,»»OUT-

COMMAND

TYPEOUTS

DECODER INIT,

TYPE
ROUTINE

READ ROUTINE
FOR PAGES
I

CHARACTER
FETCH AND
Dl S PATCH

DEVICE LOOKUP
AND VALIDITY CHK.

TYPE OUT ¥r

COMMA, CARRIAGE
RETURN HANDLER

I/O DEVICE

READ BLOCK 5
INTO PAGE 2

CHECK ROUTINE

DN CHECK

READ BLOCK

ERROR DISPATCH

DN SEARCH
ROUTINE

DIRECTORY
UPDATE

SAM BLOCK
SEARCH ROUTINE
(INPUT ONLY)

READ

IN BLOCK
INTO PAGE 2
(OUTPUT ONLY)

OPT-READ IN
OPTION CHAR

EXIT TO USER

Figure C-2

Command Decoder Core Usage

C-5

TYPE-OUT RTE

VALI

AND 4

ERROR ROUTINE

DECTAPE I/O

PAGE 2 (BLOCK 1)

MMA FOUND IN
COMMA V,^°j;
T STRING)

STORE la;jt
DEVICE/'

NAME VALUE

PLACE "E"

PAGE

(BLOCK 2)

TYPE "*OUT-

READ IN
DEVICE NAME

TYPE CHARACTER

READ IN
FILENAME

WAIT FOR COMMA
OR CARRIAGE
RETURN

Figure C-3

Command Decoder Flow Chart (Part 1)

C-6

(BLOCK 2) I

^^'''^
)

'^'^^'^ * CHARACTER

FROM THE TELETYPE KEYBOARD)

LINE
>FEED

PAGE
START \
(BLOCK 2)
1

DISPATCH

'carriage
3PTIIDM

\cOMMA

(CARRIAGE

END

RETURN
FOUND
INPUT
STRING)
IN

Figure C-3

Command Decoder Flow Chart (Part 2)

C-7

PAGE 3
(BLOCK 3)

READ BLOCK 5
INTO PAGE
2

PLACE "?"
IN

ERROR

^(PAGE 4)y

(DNSRCH)

DN BLOCK SEARCH
(PAGE 2

BLOCK 5)

(CDNODN)

ATTEMPT TO MAKE
NEW [IN ENTRY
(PAGE 2, BLOCK 5)

FOUND

YES

READ BLOCK 6
INTO PAGE
2

PAGE 2
(BLOCK 6)

Figure C-3

Command Decoder Flow Chart (Part 3)

C-8

DNSRCH

INITIALIZE

AND

(DN BLOCK SEARCH)

POINTERS

COUNTERS

(CDIOX)

READ DN BLOCK
(PG 4 BLK 4)
,

SET INTERN

FILE

»/ FOUND
RETURN
^^
J

NUMBER IN AC

NO (READ NEXT DN BLOCK)

YES (END OF DN CHAIN)

NOT
FOUND

V RETURN

Figure C-3 Command Decoder Flow Chart (Part 4)

C-9

CLEAR OUTPUT
BIT IN

LOCATION 175

SET UP TO READ

BLOCK 1
(CDIOX)

TYPE
'

*OPT-

GET OPTION
CHARACTER

RESET
COUNTER

Figure C-3

Command Decoder Flow Chart (Part 5)

C-10

PAGE 2 (BLOCK 5)

PAGE 4 (BLOCK 4)

SEARCH FOR

DEPOSIT
CHARACTER
FROM AC

EMPTY DN SLOT

V-

TYPE

(DIRECTORY FULL)

fCARRIAGEirLINElKl

LreturnJLpeedJI^J

CREATE NEW DN
ENTRY IN SLOT

WRITE OUT
DN BLOCK
PAGE 4 (BLOCK 4)
GET INTERN.
FILE NUMBER

SIMULATE JMS
DECTAPE I/O

SYSTEM DEVICE

Figure C-3

Command Decoder Flow Chart (Part 6)

C-lll

APPENDIX D
BINARY LOADER

Binary Loader loads binary output from Assembler into one or more fields in core in executable form.

operates in either 1-pass or 2-pass mode (all input files must be read in once for each pass)

A field bit indicator, which determines the field into which loading occurs, is initially set equal to the
field bit of the address typed in response to the

ST= typeout.

This indicator can be changed during

pseudo-op
loading by the occurrence, in any input file, of a FIELD word (generated by the PAL-D
FIELD).
In

all of fields

fields

through 6777 in field

1-pass mode. Binary Loader can load core from locations

through 7.

2-pass mode,

Two-pass loading, then,

through 7.

through 1571 in field

can load core from
is

and

and all of

required when any of the input files require that coding

be loaded into locations 7000 through 1511 in field 0; the reason for this is that Loader occupies
positions and cannot load the information over itself.

these

To handle this situation, 2-pass loading operates

as described in the following paragraphs.

PASS

All input files are read to find those portions of coding residing in the area from 7000 through

ISJl

Such coding is loaded into locations 6000 through 6577 instead.

At the end of Pass

All other coding is bypassed.

the contents of locations 6000 through 6577 are written into three scratch blocks

on the system device.

PASS 2
Normal loading is performied,
to be loaded in the 7000-7577 area

just as in

ignored.

the single pass of 1-pass loading, except that coding

At the end of Pass 2, the contents of the three scratch

blocks written during Pass 1 are read into locations 7000 through 1511

A jump is then made to the

ST= address.

The ST= address has a double significance.
a.

initially sets the field bit indicator for loading

specifies the address (either in the loaded program or Monitor) to which control

be transferred after loading.

1ln 8 through 32K systems it is the user's responsibility to specify existing bank settings.

a 5-digit specification is illegal

D-1

In 4K systems,

Examples

ST-10000

Begin loading in field

and jump to Monitor start (7600) after

ST=31015

Begin loading in field 3 and jump to location 1015, field 3,
after loading.

ST=27600

Begin loading in field 2 and jump to location 7600, field 2,
after loading.

D-2

START

OR 40

7600

CLEAR

SET UP TO INPUT

FROM

SYSTEM

DEVICE

SET UP TO READ
FROM PAPER TAPE

SET UP FIELD INST.
FROM ST- ADDRESS

Figure D-1

Binary Loader Flow Chart (Part 1)

D-3

CHECKSUM

Figure D-1

Binary Loader Flow Charf (Part 2)

D-4

PASS 2
(OR 1-PASS

READ 3 SCRATCH
BLOCKS INTO
7000 -7577

READ A
CHARACTER

RUBOUT

SET RETURN
TO NOT -

LEADER/TRAILER

READ A

CHARACTER

SET UP FIELD

INSTRUCTION

?<^ rubout\1o_

Figure D--1

Binary Loader Flow Chart (Part 3)

D-5

APPENDIX E
SYSTEM PROGRAMS

E.l

LOADING STATISTICS
Name

E.2

Core Limits

Entry Point

Pass

PIP

0-5177

1000

EDIT

0-3177

2600

PALD

0-3377, 3600-4377,
4600, 5200,
6200-6577, 7000-7577

6200

FORT

0-1777

200

.FT.

200-7377

STBL

600-777

600

FOSL

0-1577

200

.OS.

0-5177

—

DIAG

200-1177

200

.DDT

200-45//

.SYM

200-4577

—
—

DDT

7200-7577

7200

SAVE STATISTICS
PIP

SAVE PIP!0-5177;1000

EDIT

SAVE EDIT!0-3177;2600

PALD

SAVE PALD!0-7577;6200

FORT

SAVE FORT!0-1777;200

.FT.

SAVE .FT.!200-7377;0

STBL

SAVE STBL !600;600

FOSL

SAVE FOSLI0-1577;200

.OS.

SAVE .OS.I0-5177;0

DIAG

SAVE DIAG 1200- 11 77; 200

E-1

DDT 200"4577;0

DDT

SAVE

.SYM

SAVE .SYM!200-4577;0

DDT

SAVE DDT! 7200-7577;0

(User may assemble anywhere above
location 4577)

E-2

APPENDIX F
I/O PROGRAMMING

F.l

GENERAL
The modular concept of Input/oui-put (l/O) handling of the disk system provides for easy

maintenance and programming.

The system device l/O is found in the following places (all l/O routines

must be in field 0),

Top page of field
(location 7642) which is the l/O routine used by all system programs
l/O. A copy of this page is on block of the system device. Block
of each DECtape is
the DECtape l/O routine.
a.

for normal

F.2

Interrupt versions of disk and

Paper tape l/O is handled by individual programs.

DECtape routines are found in PIP.

CALLING SEQUENCE FOR BASIC I/O ROUTINE
The basic l/O routine (see Paragraph F. 1 .a.) is called as shown in Figure F-1

It is

called

two ways, as determined by bit 2 of the function word.

a.
Normal - The l/O routine returns to JMS +6 (normal) or JMS +5 (error). For example,
the following routine would read consecutive blocks from a file on the system device. The routine is
initialized by putting the first block number of the desired file into location LINK. If an attempt is
made to read past the last block of the file, an exit will be made to a routine called ENDFIL.

GETBLK,

TAD LINK

/GET LINK FROM LAST READ

SNA
JMP

/IS THIS END OF FILE?
I

(ENDFIL

A'ES

DCA BLOK
JMS
3

/CALL DISK I/O ROUTINE
/FUNCTION - READ

BUFFAD

/BUFFER ADDRESS

JMP
JMP

/ERROR RETURN

(7642

BLOK,
LINK,

(ERROR

GETBLK

Indirect - The l/O routine returns to the 12-bit address in the error return word +1

(normal or the 12-bit address in the error (ERROR)) .

An example of the indirect routine is given on

page C-2a of this manual

F.3

GENERALIZED DISK/DECTAPE I/O ROUTINE
The user or system programs may use the generalized l/O routine in Appendix C.

The calling

sequence to this routine is the same as that used by the basic l/O routine, except for certain restrictions
explained below.
F-1

Calling Sequence

JMS

Explanation

Location SYSIO points to l/O

SYSIO

FUNCT

Function word*

BLOCK

Block to be accessed

CORE

Low-order core address

LINK

Filled by READ, used by WRITE

ERROR

Error return here

Normal return here

*Function word:

Bits 0-1
Bit

unused
=0, normal return

= ], indirect return at end of read/
write to address +1 in error
return

Figure F-1

if DECtape
memory field

Bits

3-5
Bits 6-8

unit no.

Bits 9-1 1

function:

READ = 3; WRITE = 5

Calling Sequence of System Routine

The Command Decoder must be called as shown in Examples 1 and 2 on page C-2a. The
entry point for the generalized l/O routine is the first location of the Command Decoder plus 603g
locations, i.e., in the previously mentioned examples the entry point would be at location 2603.
a.

The generalized l/O routine uses location 0171 on page zero.

This location must con-

tain the address which points to the l/O list created by the Command Decoder. If the JMS instruction
which calls the routine is at an even numbered location, location 0171 must point to Word B (see

Appendix C) of a Command Decoder list entry. If the JMS is at an odd numbered location, location
0171 must point to Word A of a Command Decoder list entry. The contents of Word A then determines
whether the DECtape or system device will be used.
The contents of the function word in the calling sequence determine whether information is to be read from or written on the selected device and DECtape unit (if applicable) as shown in
c.

Figure F-1

The following examples illustrate the use of the generalized l/O routine.

It is

assumed that

the Command Decoder was called and placed in locations 2000-2777, and that its list begins at location 3000.

F-2

3000
3001

3002
3003
3004
^^^^

300
301

4312
0000
6007
0065
1777
0215

4777
0305
0160
7000

302
303
304
305

7402

171

3001

377

2603

0161

(Word A) Output device - DEOape #3,
(WordB) internal file #12
(Word A) Input - system device, internal
(Word B)

file #7, starting at

block 65

Option - carriage return was typed

JMS

(2603

FUNCTION WORD
BLOCK NR
BUFFER ADDRESS
LINK NR
ERROR HALT

ENTRY POINT

The above code will write the contents of locations 7000-7177 onto block 160 of

DECtape unit 3 and

will write link word of 161.

501

502
503
504
505
506
171
^"^"^

4777
0003
0065
7200
0000
7402
3002
2603

JMS

(2603

FUNCTION
BLOCK NR
BUFFER ADDRESS
LINK NR
ERROR HALT

ENTRY POINT

The above code will read the contents of block 65 of the system device into locations
will place the link to the r\eY,\ block of this file in location 505.

F-3

7200-7377 and

INDEiX

Monitor, 2-6

ALT MODE, 3-39

PIP,

Processing, 2-12

Binary File, B-7

SAVE, 2-10

Binary Loader, Disk System App.
Error Messages,

3-2

2-9

Strings,

2-3 to -6

System, 2-6

Examples, 2-8

Compiler,

Flow Charts, D-3 to -5

Core Usage App.

FORTRAN-D, 3-21
B

Operating Procedures, 2-7
Bootstrap Loader, 2-2
Builder, Disk System,

Data Structure

A-2

Binary File, B-7

C
Command Decoder, 2-4, B-2, App. C
Core Usage, C-1 -4
Error Messages,

2-13

Saved File, B-8
Source File, B-7

Device Names, 2-4

DDT-D, 3-38

Flow Charts, C-5 to -10

Commands, 3-39

I/O Requirements, C-2

Core Requirements, 3-38

Output List, C-4

Loading and Saving, 3-41

Command Strings, 2-4

Operating Procedures, 3-42

Device Names, 2-4
Examples, 2-6
Filenames, 2-5

Subroutines, 3-39

Directory Name, B-1

Format, B-4

Format, 2-4

DN, see Directory Name

Monitor Commands, 2-6

Dynamic Debugging, see DDT-D

Punctuation, 2-5
Special Characters, 2-6

System Program, 2-6

Commands

Editor, Disk System

Commands, 3-10 to -12
Example, 3-14

CALL, 2-12

Loading and Saving, 3-12

DDT-D, 3-41

Operating Procedures, 3-13

Editor, 3-11

Special Characters, 3-10

Format, 2-10

Special Keys, 3-10 -11

INDIEX (Cont)

Equipment Requirements, 1-1

Device Names, 2-4

Error Messages

PIP, 3-1

Binary Loader, 2-9

Programming App. F

Command Decoder, 2-13

Routines, F-1
L

FORTRAN -D, 3-23 to -26 -30
Loading and Saving

PAL-D, 3-17

DDT-D, 3-41

t:xamples

3-12

Command Decoder, 2-6

Editor,

Command Strings, 2-6

FORTRAN-D, 3-22 to -31

DDT-D, 3-42

PAL-D, 3-15

Editor,

PIP, 3-1

3-14

System Programs, 2-7, A-3, E-1

FORTRAN-D, 3-36
Monitor Commands, 2-6

Bin,

PAL-D, 3-18
PIP,

Loader

A-2

Bootstrap, 2-2

3-7 to -9, B-10
F

Disk System Binary, 2-7, App.

RIM, A-1

Filenames, 2-5

Flow Chart
Binary Loader App.

Mode

Command Decoder App. C

Monitor, 2-1 -3

Monitor, B-14 to -16

System, 2-1
User, 2-1

FORTRAN-D, 3-18

Monitor

Compiler, 3-21

Debugging Aids, 3-26 -31

Bootstrapping the, 2-2

Diagnostics, 3-23 to -26 -30

Commands, 2-6

Examples, 3-36

Core Usage, B-11

Operating Procedures, 3-28

Flow Charts, B-14 to -16

Operating System, 3-27

Residence, 2-1

Statements, 3-19

Starting, 2-3
I

System Generation App. A

Input/Output
Calling Sequence, F-1 -2

Operating Procedures

INDEX (Cont)

Processing, 2-12

Binary Loader, 2-7

DDT-D, 3-41
Editor,

Statements,

3-13

FORTRAN -D, 3-19

Storage

FORTRAN-D, 3-18

Capabilities, B-7

PAL-D, 3-16

DECtape, B-3

PIP,

3-2

Disk, B-2

System Generation App.

PAL-D Assembler, 3-15
Error Messages,

Storage Allocation Map, see SAM

Symbolprint, see FORTRAN-D

System

3-17

Builder,

A-2

Examples, 3-18

Formats App. B

Loading and Saving, 3-15

Modes, 2-1

Operating Procedures, 3-16

System Programs

Output Devices, 3-16

Loading and Saving, A-3, E-1

Pseudo-Operators, 3-15
Peripheral Interchange Program, see PIP
PIP, 3-1

Directory Listing, B-10

Examples, 3-7

Loading and Saving, 3-1

Operating Procedures, 3-1 to -7
Options, 3-2, 3-7

Program Assembler Language, see PAL-D
R

RUBOUT, 2-3, 3-10
S

SAM, B-5
Format, B-6

SAVE Command
Core Usage, B-12, -13
File Format, B-8, -9

Format, 2-10

READER'S COMMENTS

DISK MONITOR SYSTEM

DEC-D8-SDAB-D
Digital Equipment Corporation maintains a continuous effort to improve the quality and usefulness of its

publications.

To do this effectively we need user feedback - your critical evaluation of this manual.

Please comment on this manual's completeness, accuracy, organization, usabihty, and readability.

Did you find errors in this manual?

How can this manual be improved?.

DEC also strives to keep its customers informed of current DEC software and publications. Thus, the following periodically distributed publications are available upon request.

Please check the appropriate box(s) for a current issue of the

publication(s) desired.

Q Software Manual Update, a quarterly

collection of revisions to current software manuals.

D User's Bookshelf, bibliography of current software manuals.
a

Q Program Library Price

List, a list of currently available software programs and manuals.

Please describe your position.

Name

Organization

Street

Department

City

State ^

Zip or Country

— Fold Here

Do Not Tear - Fold Here and Staple

FIRST CLASS
PERMIT NO. 33

MAYNARD, MASS.
BUSINESS REPLY MAIL

NO POSTAGE STAMP NECESSARY IF MAILED IN THE UNITED STATES
Postage will be paid by:

Digital Equipment Corporation

Software Information Services

146 Main Street, Bldg. 3-5

May nard, Massachusetts 01754

HOW TO OBTAIN SOFiTWARE INFORMATION
Announcements for new and revised software, as well as programming notes, software problems, and documentation corrections are published by Software Information Service in the following newsletters.

Digital Software News for the PDP-8 Family
Digital Software News for the PDP-9/ 1 5 Family
PDP-6/PDP-10 Software Bulletin

These newsletters contain information applicable to software available from Digital's Program Library.

Please complete the card below to place your name on the newsletter mailing list.

Questions or problems concerning DEC Software should be reported to the Software Specialist at your nearest DEC
regional or district sales office. In cases where no Software SpeciaUst is available, please send a Software Trouble
Report form with details of the problem to:

Software Information Service
Digital Equipment Corporation
146 Main Street, Bldg. 3-5
Maynard, Massachusetts 01754

These forms, which are available without charge from the Program Library, should be fully filled out and accompanied by teletype output as well as listings or tapes of the user program to facilitate a complete investigation. An
answer will be sent to the individual and appropriate topics of general interest will be printed in the newsletter.

New and revised software and manuals, Software Trouble Report forms, and cumulative Software Manual Updates
are available from the Program Library.

When ordering, include the document number and a brief description of

the program or manual requested. Revisions of programs and documents will be announced in the newsletters and
a price Hst will be included twice yearly. Direct all inquiries and requests to:

Program Librai-y
Digital Equipment Corporation

146 Main Street, Bldg. 3-5
Maynard, Massachusetts 01754
Digital Equipment Computer Users Society (DECUS) maintains a user Library and publishes a catalog of programs
as well as the

DECUSCOPE magazine for its members and non-members who request it. For further information

please write to:

DECUS
Digital Equipment Corporation

146 Main Street
Maynard, Massachusetts 01754

Send Digital's software newsletters to:

Name.

Company Name.
Address

(zip code)

My computer is a

My system serial number is.

D
LINC-8 D
PDP-9
D
PDP-10 D
PDP-8/I

D
D
D
OTHER D
PDP-8/L
PDP-12
PDP-15

(if known)

Please specify

— Fold Here

Do Not Tear - Fold Here and Staple

FIRST CLASS

PERMIT NO. 33

MAYNARD, MASS.
BUSINESS REPLY MAIL

NO POSTAGE STAMP NECESSARY IF MAILED IN THE UNITED STATES
Postage will be paid by:

SDIDDSD
Digital Equipment Corporation

Software Information Services

146 Main Street, Bldg. 3-5

May nard, Massachusetts 01754

Equipment Corporation
Maynard, IVIassachusetts
Digital

printed

U.S.A.