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DEC-T8-MRFA-D

December 1968

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Document:	Monitor
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OCR Text

TIME-SHARING SYSTEM
TBS/B Monitor
for the
PDP—B
PD P-B/ |

For additional copies order No. DEC-T8—MRFA—D from Program Library,

Price $3.00

Corporation, Maynard, Mass.
DIGITAL EQUIPMENT CORPORATION

Digital Equipment

MAYNARD. MASSACHUSETTS

First Printing,

September l968

The reader's attention is invited to the last two pages of this manual.
The How To Obtain Revisions and Corrections offers the reader a means
of keeping up-to-date with DEC's soFtware.

The Reader's Comments

card, when filled in and returned, is beneficial to both the reader
and DEC. Each card received is considered when documenting subsequent manuals, and where the comments imply or ask For assistance,
a

knowledgeable DEC representative will contact the reader.

ACK NOWLEDGMENT

We wish to thank Dr. John McCarthy and his associates at the
Stanford Computation Center For their permission to use some
parts of the THOR User's Manual which describes a time-sharing
System For the PDP-l computer.

CONTENTS

Page
CHAPTER 1
INTROD UCT ION

1.1

Monitor Functions

1.2

TSS/ 8 User and Console

1.3

System Program Library

1.4

User Programs

1.5

User Files

1.6

System Configuration

1—4

1.6.1

Minimum Hardware Requirements

1-5

1.6.2

Hardware Options

1-5

1.6.3

Data Communication System,

Type 680/1

CHAPTER 2
THE TSS/8 MONITOR

2.1

Monitor Services

2—1

2.2

Character and Data Flow

2—3

2.2.1

Character Transmission

2—4

2.2.2

General Input Routine

2-4

2.3

Permission and Switchboard Tables

2-5

2.3.1

Permission Table

2-6

2.3.2

Switchboard Table

2-6

CHAPTER 3
MONITOR COMMANDS

3.1

Logging In and Out

3—2

3.2

Console Manipulation

3-2

3.3

Device Allocation

3-3

3.4

File Control

3-3

3.5

Control oF User Programs

3-5

3.5.1

Saving and Restoring Binary User Programs

3-6

3.6

Switchboard

3-7

3.7

Inter-System Communication

3-9

CONTENTS (Cont)

Page
CHAPTER 4

INPUT/OUTPUT TRANSFER INSTRUCTIONS
4.1

Program Control

4.2

File Control

4-9

4.3

Input Buffer Control

4—14

4.4

Output Buffer Control

4-16

4.5

High-Speed Paper Tape Reader

4-18

4.6

High-Speed Paper Tape Punch

4—19

4.7

DECtape

4—20

4.8

Automatic Line Printer

4—21

4.9

Incremental Plotter

4-23

4.10

Card Reader

4—24
CHAPTER 5
ERROR DIAGNOSTICS

5.1

User Program

5-l

5.2

System Interpreter

5-I

APPENDIX A

TSS/8 CHARACTER SET
APPENDIX B
SUMMARY OF COMMANDS
APPENDIX C
SUMMARY OF IOT INSTRUCTIONS
APPENDIX D

REQUIRED MODIFICATIONS
APPENDIX E
STORAGE ALLOCATION

ILLUSTRATIONS
1-1

User Console

1-2

Users Console Keyboard

1-2

1-3

System Configuration

1-5

2-1

Character and Data Flow

2-3

2-2

Permission Table

2-5

ILLUST RATIO NS (Cont)

Page
2-3

Switchboard Table

E—I

TSS/ 8 Sforage Map

E—I

E-2

File Directories

E—2

HOW TO OBTAIN REVISIONS AND CORRECTIONS

Notification of changes and revisions to currently available Digital software and of
software manuals is available from the DEC Program Library for the PDP-5, 8,

new

8/5, 8/1, 8/L, LINC-8, the PDP-4, 7, and 9 is currently published in DECUSCOPE,
the magazine of the Digital

Equipment Computer User's Society (DECUS) This inforComputer NewsII
.

mation appears in a section of DECUSCOPE called "Digital Small

Revised software products and documents are shipped only after the Program

Library

receives a specific request From a user.

DECUSCOPE is distributed periodically to both DECUS members and to non-members
who request it. If you are not now receiving this information, you are urged to
return

the request form below so that your name will be placed on the mailing list

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__________________________

To:

Decus Office,

Digital Equipment Corporation,
Maynard, Mass. 0l754
0 Please send DECUS installation membership information.
0 Please send DECUS individual membership information.

0 Please add my name to the DECUSCOPE non-member mailing list.

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(Zip Code)

CHAPTER I
INTRODUCTION

TSS/8 (Time—Sharing System for the PDP-8/l Computer) is a general purpose stand-alone,
time-sharing system offering each of up to 32 users a comprehensive library of system, utility, and
service programs which provide facilities for compiling,

assembling, editing, loading, saving, calling,

and debugging user programs on-line, and also two conversational

languages, FOCALI and BASIC-82.

The minimum hardware configuration is designed for eight users and includes the Following:
a

modified PDP-S/I or PDP-8 with 8K words of core memory, a RF08 Disk,

PT8/l high-speed paper

tape reader, and Teletype control units for data communication (either four PTOSs or one 680/1 per

system).

See Section 1.6 for a complete list of possible optional devices and for the configuration for

systems accommodating up to 32 users.

By segregating the central processing operations from the time—consuming interactions with
the human users, the computer can in effect work on a number of programs simultaneously.

Giving

only a fraction of a second at a time to each program or task, the computer can deal with many users
seemingly at once, as if each had the computer to himself.

The execution of various programs are

interspersed without interfering with one another and without detectable delays in the responses to the
individual users.

MONITOR FUNCTIONS

The heart of this time-sharing system is a complex of subprograms called Monitor.

Monitor

coordinates the operations of the various units, allocates the time and services of the computer to users
and controls their access to the system.

The allocation function includes scheduling the user's requests,

transferring control of the central processor from one user to another, moving (swapping) programs in
and out of core memory, and managing the user's private files.

1.2

TSS/8 USER AND CONSOLE
A TSS/8 user is any person running a computer program within TSS/8.

He has an account

number assigned to him by the person responsible for the system which determines his identity for TSS/8
and identifies his files on a permanent basis.

When he is using the system this number also identifies

l FOCAL

(FOrmula CALculator) is an on-line conversational interpretive program developed
by Digital Equipment Corporation.
2 BASIC-8 is a modified version of the elementary algebraic language developed at
Dartmouth College.

1-]

his console, his individual disk swapping track (a contiguous 4K section of disk) For temporary storage

of active programs, and whatever other Facilities he may be using at any given time.

While the user is logged into the system, he owns at least one console (Figure l—l) and one
4K disk track.

The console consists of a keyboard (Figure l-2), which allows the user to type infor-

mation to his user programs and Monitor, and an output device,

usually a Teletype printer, which Fur-

nishes typed copy of program and Monitor output and user input.

Figure l-l

Figure 1-2

User Console

Users Console

1-2

Keyboard

SYSTEM PROGRAM LIBRARY

1.3

A comprehensive library oF programs is available to all TSS/8 users.

Facilities For assembling,

The library provides

compiling, editing, and debugging user programs. Any oF the system, utility,

and service programs can be called into use by typing, in response to the dot typed by Monitor, the
command R and the assigned name oF the programs.
.

For example,

R FOCAL

brings FOCAL into core From the disk and automatically executes FOCAL so that it begins typing out
its lnitial

Dialogue.
The System Program Library contains the following programs:
a.

Binary (BIN) Loader

Symbolic Tape Editor

used to load user programs into core memory From the console.
-

used to prepare, edit, and generate symbolic (source) programs

and program tapes From the console.
c.

PAL III Symbolic Assembler

used to translate source programs written in the PAL III

language into obiect programs.
d.

MACRO-8 Assembler

used to translate source programs written in the MACRO-8

language, containing macros and literals, into obiect programs.
e.

Dynamic Debugging Technique (DDT-8)

used to aid the user in correcting errors in

stored user programs by allowing him to execute small sections at a time, to stop execution where he
wishes, and to change portions oF his program, using the symbolic language oF the source program or

machine language.

The user may create an octal program using the DEPOSIT command.

Octal Debugging Technique (ODT-81- used For the same purpose as DDT-8 (above)
F.
that
the
user communicates in the octal
except
representation oF his program. ODT-8 requires less
core area than DDT-8, and can be loaded in either the upper or lower portion oF core, depending
upon where the user's program is loaded.
g.

used to compile and operate a user program written in the 4K version
compilation
language;
requires only one pass through the compiler.

FORTRAN (4K)

oF the FORTRAN

FOCAL (FOrmula CALculator)

BASIC-8

an on-line, conversational,
interpretive program used to
solve complex numerical problems; used as a programming tool by students, engineers, and scientists.
—

elementary algebraic language, is an on—line, service program similar
problems.

to FOCAL used to solve complex numerical

1.4

USER PROGRAMS
A user program is any program being run in user mode by TSS/8.

When a user program is

being run by TSS/8 it is swapped into core memory From the user's disk track. Several programs may
be run by a regular process oF bringing a program into core From the disk, allowing it to execute For a
short time,

marking the state in which its execution is stopped, returning it to the disk, and picking up

the next user program.

User programs are serviced regularly on a "round-robin" basis.

executed, it is placed last in the order oF user programs waiting to run.
one

quantum oF time and then it is exchanged For the next user program.

AFter a user program has been

Each program is allowed to run
IF only one program is in a

condition to run, it is allowed to run without interruption.
There are three ways in which a user can place a binary program on his disk track.
a.

He may prepare an octal program at a console using a debugging program such as DDT-8,

He may load a previously saved core image, or

He may load the binary output File oF a previous assembly or compilation.

USER FILES

l.5

Disk storage is divided into logical areas called Files.
new

Files and extending,

contracting, and destroying old Files.

binary core images, or data in any standard Format.

Facilities are available For creating
Files may contain textual inFormation,

The user can also protect his Files against unau-

thorized access.
A user File directory (see Appendix E) is assigned to each user by the person responsible For

the system beFore the user First logs into the system.

The user File directory is associated with the iob

number assigned to the user by the Monitor each time the user logs in.
Files are composed oF segments oF disk storage.

20008 words. Files

are

A segment can consist oF From

2008 to

least one segment long and grow by adding additional segments to the end

oF the File.

Each user may have access to up to Four active Files at any time.

An internal File number,

0 through 3, is associated with each oF the user's active Files, and commands then operate in terms oF

the internal File numbers.

With this Feature, a user may attach one oF his Files to an internal File num-

ber and then load system and utility programs which operate on his File without having to explicitly

call the File For each system or utility program used.

1.6

SYSTEM CONFIGURATION

Depending upon the hardware conFiguration oF a particular TSS/8, there can be From 1 to
32 users working with the system simultaneously.

Following resources:

Each user has, in addition to system soFtware, the

least 4K words oF core memory For execution oF programs, and a corresponding

4K disk track For temporary storage oF his core image.

l.6.l

Minimum Hardware Requirements

The minimum equipment requirements of the system are listed below (see Figure 1-3).

PDP-8/l or PDP-8 with KT08/I Time—Sharing Modifications
MC8/I-A Memory Extension Control and 4096 words
RF08 Disk Control
R508 Disk

PT08 Asynchronous Line Interfaces, Dual (4)
PT8/I High—Speed Paper Tape Reader
KE8/I Automatic Multiply—Divider
CAB 8/IA Option Cabinet

(TELETYPE

MODEL

33 OR

35)

Califooggf

(TELETYPE

MODEL

OR 35)

CORE

X I f
CONSOLE
680/1

CONTROL

PT08’S

E
O
C
K

CPU

EXTRA
4K

CORE

RF08

Figure 1-3

1.6.2

System Configuration

Hardware Options
The system can have a maximum of 32K of core memory.

As additional fields of core mem-

ory are added they permit overlapping the running time of one user program with the swapping time of

another, expanding the resident Monitor to buffer a larger number of consoles, and reducing the amount
of Monitor overlay required.

With a minimum of 12K of core memory, the following options are available.
a.

Up to three DECdisks can be appended to increase the number of active users and their

file storage.
b.

Up to eight DECtapes can be appended for the use of private DECtapes by users.

l.6.3

Memory Parity

Extended Arithmetic Element (PDP-8/I only)

Power Failure

l Card Reader

l Incremental Plotter

I Line Printer

l DAIO Interface (PDP—lO)

I Bit Synchronous Communication Unit (Type 637)

I Line Frequency Clock (required with PTO8's)

32 Teletype Controls (PTO8's or 680/I)

High-Speed Paper Tape Punch

Data Communication System,

Type 680/I

The Data Communication System, Type 680/I, is used in full duplex mode.
Data Line Interface Unit (DL8/I),
to form a data

It consists ofa

Serial Line Multiplexer Unit (685), and other devices connected

link and message switching system between the user consoles and the central processor.

CHAPTER 2
THE TSS/8 MONITOR

MONITOR SERVICES

2.1

The TSS/8 Monitor is composed of the Following routines:
IOT Trap Handler

Error Message Handler

Scheduler

Buffer Handler

Storage Allocator

680 Service

Overlay Control

Disk Service

System Interpreter

Optional Device Service

File Control
With the above routines, Monitor provides services which may be divided into three broad categories:
a.

Device Service

Scheduling and Activation

Communication

On an interrupt basis the Device Service routines receive information from all input devices,

parcel that information out to the appropriate buffers, and inform the Activation routine when a user
program must be activated to receive its information.
user

The Device Service routines accept output from

programs, buffer it, and send it to output devices whenever they are able to receive it.

Activation is handled by a "round-robin'I scheduling algorithm with the exception that programs with disk requests pending are run out of turn to optimize disk usage.

The Activation routine

decides whether to remove the current program from core, and if so, which program is to be run next.
A user program is, at any point in time, in one of the following states.
a.

Running

—

The user program is in execution.

It continues execution until its quantum

has expired or until it issues an input/output (I/O) request that cannot be satisfied immediately.
The user program is ready to run and will be swapped into core when its turn
b.
Active
A program can become active when
—

comes.

(I) An output buffer is almost empty, thus assuring continuous output of information,
(2) An input buffer is almost full,
(3) Input requested by a user has arrived,
(4)

A user determined activation condition has been satisfied,

(5) When the user commands the system to begin execution.

Waiting In this state, the program would be active except that it is waiting for the
of
some
I/O request or special condition.
completion
c.

”

The user may be
Dormant
The program is not being entered into the "round-robin.
communicating with Monitor or the program may be dismissed for a variety of user determined reasons.
d.

2—]

A program may be swapped out oF core memory For any oF the Following reasons.
a.

The quantum has expired; the program moves From the running state to the active state.

The program has requested the quantum be terminated; the program moves From the

running state to the active state.
The program has Filled an output buFFer, has requested input and the input buFFer is
empty, or has requested a special dismissal condition; the program moves From the running state to
the waiting state.
c.

The program has tried to execute an illegal instruction; the program moves From the

running state to the dormant state.
Monitor checks all

incoming characters For the SEE (CTRL/B) character. When the call

character is encountered, Monitor routes all subsequent characters up to and including the First carriage
return

(CR) to its System Interpreter's input buFFer. Monitor's System Interpreter routine perForms the

Following services.
VeriFies the user's name and account number when he logs in and provides him with a
a.
disk track to store user programs. It releases Facilities oWned by the user when he logs out.

Parcels out extra consoles and input/output devices.

Provides commands For creating,

Allows the user to save all or part oF his binary user program For Future use and reFerence,

opening, and maintaining the user's Files.

and restores it with its state unchanged.

Provides accounting oF console time and user program run time.

Provides the user with inFormation about the state oF his program while running, as well

inFormation about the state oF the character control tables.
9.

Provides commands For calling the various utility programs.

Communications to the System Interpreter are automatically duplexed.
From a keyboard to the System Interpreter appear on that console's printer,

setting.

That is, all characters

regardless oF the switchboard

(See Section 2.3.)
The System Interpreter may be receiving messages From many keyboards and user programs,

thereFore, it must be run oFten. Consequently, it occupies its private position in the "round-robin,

being activated whenever there are characters in its input buFFer.
Monitor has two Phantom routines:

Error and File Control.

which run in place oF a regular user program in the "round—robin.

Phantoms are privileged routines

The time the Phantom takes to

perForm its service is charged to that user program upon which it is servicing.
The Error Phantom prints all error messages For running user programs.
error

Printing a lengthy

message may require several quanta; the use oF the Error Phantom punishes the user responsible

For the error and no one else.

The File Control Phantom handles such modiFications to the File directory as creating,

lengthening, renaming, and destroying Files. This Phantom is brought into operation when a user program executes certain IOT instructions or when Monitor is acting For the user program.

2—2

CHARACTER AND DATA FLOW

2.2

When a user logs into the system his account number is associated with a job number, and

iob number is then associated with a disk swapping track and the console(s) he owns. The account

that

number establishes ownership oF the input buffer attached to the user program on his disk track and the

output buffers attached to the printers oF his consoles.
Monitor provides For communication among the users,
communication is illustrated in

Figure 2-l

programs, and Monitor.

user

Data

Communication is provided through the [OT instructions.

When a program executes certain IOT instructions, Monitor picks up locations in the user program as

parameters to service routines.
or

These routines may simulate input/output to the on-line device, control

release ownership of devices, handle character communication, or return information to the user

program by filling registers within the program.

Through IOT instructions, the user program can make

its wants known and Monitor can inform the

program oF any variation in the time-sharing system.

user

SWAPPING

REQUEST FOR
SPECIAL
SERVICE OR I/O

usrn
nupnc

“%

CHARACTER
USER

CONTROL

CONSOLE

GENERAL
KEYBOARD

--|NPUT-

SWITCHBOARD
—

ROUTINE

‘3

+~——9U—T—p91—
BUFFER

BUFFER
0

3
PRINTER

INPUT

————————————————————————————

———~

TABLES

I/O

CONTROL

3
._

3
0

_-_

l—

I
'

GENERAL

--~-

PERMISSION

—————~—>.=.._

—INPuT——

——————

ROUTINE
COMMAND
LANGUAGE

AND

SERVICE

RFOHFQT
sIOI-. :W

FOR
SERVICE

PHANTOM
SERVICE
OTHER

Figure 2-1

110

Character and Data Flow

2-3

0st

FILES

Character Transmission

2.2.]

The input/output transfer instructions provide character transmission.
ated by users typing at keyboards or by user programs typing out.

Characters go into input buffers to be

read by user programs or to output buffers to be printed on Teletype printers.
Up useful character transmission

Characters are gener—

A switchboard device sets

paths, whereby any character source (keyboard and program) may, with

permission, send to any character sink (input and output buffer). To insure that unwanted connections
are

not made,

using the appropriate command to Monitor the user owning any character sink may grant

deny permission for connection into that sink.
A console may be thought of as two disassociated devices,

keyboard and a printer.

To each

printer there is an associated character output buffer numbered like the consoles, O-K. When a character is

placed into output buffer number n, Monitor causes that character to be printed on printer

number n.
Each iob has an associated character input buffer numbered like the iob, O-P.

When user

program number n executes a keyboard input IOT, the next character waiting in input buffer number
n

placed in the user program's accumulator (AC).

the

source

of the last data

character,

This character may be

data

the time that the last data character was

character,

placed in the

input buffer.

2.2. 2

General Input Routine
The General Input Routine (GI R) provides and controls character input to user programs.

Programs vary in how promptly they must pay attention to incoming characters.
a

In the preparation of

file, characters are added to the input buffer when typed; when the input buffer gets full the program

receives all the characters at once and transmits them to the disk.
is activated only when the input buffer gets full.

In this case, the user's program

With a program whose operation is controlled from

the keyboard, however, every character typed goes directly to and influences the program's action.

Through IOTs, the user program can specify under which conditions the input characters
will cause the program to be activated.
some

These conditions are called delimiters.

A delimiter may be

specific type of character appearing in the input or it may be a change in the source of characters;

the input buffer becoming full is always a delimiter.
GIR places all

incoming characters in the user's input buffer until a delimiter is encountered.

When a delimiter appears, the user program is always alerted and usually activated to receive all the
characters in the input buffer.

This is done by setting the delimiter bit (status register I) to one.

the Wait Mask (see Chapter 4, Set Wait Mask) is set to one, the user program will be activated.

2.3

PERMISSION AND SWITCHBOARD TABLES
Characters originating From any keyboard or From any user program typing out can, with

permission, be placed in any or all of the K output buffers or any or all of the P input buffers.

The

Permission Table is the device with which a user controls which character sources may place characters
in which oF his buffers; the Switchboard Table controls the actual

routing of these characters.

The Permission and Switchboard Tables are organized as matrices (see Figures 2-2 and 2-3).

The rows represent character sources, that is, keyboards and programs typing out. The columns represent
character sinks, that is, input and output buffers.

Along the rows are the K keyboards and P programs.

Along the columns are the P input buffers and the K output buffers.

INPUT

IurrEns

ITIVTIIIIIII

OUT'UT

Iurrens

llI'lTlllllllllllllltlll'Ill'YY

‘

KEVIOARD
nwur

n.z

5.1

PROGRAM
ouwur

—

Permission Table

Figure 2—2

mPuY

IurrEns

IlllIlTl'l'

OUTPUY

nurrsns

'I‘l'TI"Vl'll'VIYTIIllll'l'TT‘

KEVBOAHD

INPUT

‘

moan

‘

OUYPuY

Figure 2—3

Switchboard Table

2-5

2.3.]

Permission Table
The Permission Table acts as the matrix of permitted connections.

For example, if the bit R,

Y is a one, it means that the owner of input buffer number Y allows keyboard number R to place characters in it.

Similarly, if bit S,Z is a one, it means that the oWner of output buffer number Z (printer

Z) has agreed to allow iob number S to type out characters onto printer Z.

In general, if a bit in the

Permission Table is a one, the owner of the entity specified by the column has granted permission for

the entity specified by the row to place characters in his sink.
The fact that permission for a given character routing has been established does not neces-

sarily mean that characters automatically flow along that route.

A route to a buffer is not established

unless the owner of the keyboard or program sets the Switchboard Table.

2.3. 2

Switchboard Table
The Switchboard Table acts as a matrix of requests by the oWner of a character source that

characters emitted by that source appear in some sink.

If bit Q,W is a one, characters coming from

program number Q typing out will appear in input buffer number W.

Similarly, if bit P,X is a one,

characters typed on keyboard number P will appear in the output buffer of printer number X.

In general,

if a bit in the Switchboard Table is a one, characters emitted by the source specified by the row will
appear in the sink specified by the column.

Attempts to set bits in the Switchboard Table are automati—

cally checked against the Permission Table. Only if the corresponding bit in the Permission Table is a
one

will the system allow that bit to be set in the Switchboard Table.

The Switchboard Table may be

regarded as the final arbiter of character routing.
Bits in the Permission and Switchboard Tables may be set, reset, and read by using Monitor
commands or by an IOT instruction which the system executes interpretively.

The Permission and Switchboard Tables are automatically set up for normal use when a user

logs into the system. This configuration is:
a.

The user gives permission for his keyboard to send characters to his user program's input

buffer.
The user gives permission for his keyboard to send characters to his printer's output
b.
buffer (this condition is known as duplexing). Whether the characters actually appear depends upon
the corresponding Switchboard setting. Normally, the Switchboard is not set to handle the input before it is printed.

The user gives permission for his program to type characters to its own input buffer.
c.
(The Switchboard determines whether characters typed out will in fact be sent to the input buffer.)
d.

The user gives Permission for his p r 09 ram to send characters to his pr inter's out P ut buffer.

2-6

e.
user

The Switchboard is set so that characters from the user's keyboard will be placed in the

program's input buffer.
f.

The Switchboard is set so that characters typed out by the user program will be placed

in the program's output buffer.

The user is, of course, free to modify and add to these settings.

The Switchboard generality finds application in:
a.

Duplexing

Characters typed at a keyboard can be printed on any console without user

program intervention.

b.
Interprogram Communication User programs can communicate with each other and
with Monitor. Thus, several user programs may run as one system coordinating their separate tasks
through character communication.
-

Interconsole Communication
Users at consoles can set up general links for conferences,
or
for
other
reason.
teaching, monitoring,
any
c.

d.
Multiple Consoles User programs may receive characters from and send characters to
than one console. This allows a user program to act as a time-sharing system within TSS/8, con-

trolling its own set of consoles, as in teaching machine monitors.

CHAPTER 3
MONITO R COMMANDS

A Monitor command is a string of characters terminated by a semicolon (;) or a carriage
return

(RETURN key). Commands to Monitor are typed on the Teletype keyboard by the user or output

by the user program, with each command beginning with a command name.
name

In some cases, the command

is the entire command, in which case it is followed directly by a terminator.

command name is followed by a space,

one or more

parameters, and then a terminator.

(requesting the time of day.

.TIME

In other cases, the

For example,

This command was terminated by the

RETURN key)

(requesting the processing time used by job Cl.

.TIME Cl

Terminated by the

RETURN key)

Only enough characters need be typed in the command name to uniquely identify the command name.
For example,
LOGI

for LOGIN

LOGO

for LOGOUT

More than one command may be typed on a line, with all but the last command being ter-

minated by a semicolon; the last command is terminated by the RETURN key.
5]

.OPEN Cl

For example,

C2; LOAD Cl 51; START Cl

(The abbreviated parameters are explained below.)

NOTE
Commands are executed when the RETURN key is typed,
which explains why the last command on a line must be
terminated by the RETURN key.
As shown in the above examples, each command or line of commands is typed after the dot

typed by Monitor.

The dot is typed by Monitor when it is ready and available to accept commands

from the user.
Parameters may be typed as octal numbers, decimal numbers, character strings,

letters.

single

In the following descriptions of Monitor commands the parameters are coded as follows.

Cl,

C2,

represent octal numbers

Dl ,

D2,

represent decimal numbers

Sl ,

$2,

represent character strings

Ll ,

L2,

represent single letters

3-]

3.]

LOGGING IN AND OUT

Logging in and out of TSS/8 is a function performed by Monitor's System Interpreter routine.
When a console is in the free state, a prospective user may attempt to log into the system.
LOGIN

Si;

This is a request by a user to log into the system.

If the console from
which the command is typed is free, there is an available disk track,
and the two parameters following the command LOGIN form a legitimate account

number and password, then the user will be logged into

the system.
Cl is the user's account number
Si is the user's password

At the time of login, the Switchboard is initialized to the normal

operation setting. However, Monitor diverts all characters typed to
the System Interpreter until the user gives a command that indicates
otherwise.

LOGOUT;

This is a request by a user to logout of the system.

consoles and disk tracks that he owns,

It disconnects all

places his programs in the free

state, and resets the Switchboard. It also writes an account record
on the disk showing how much computing time
(processing time) and

console time was used by the user's program(s).
TIME C];

This is a request for Monitor to type out the computing (processing)
time used since

console is assumed.

If iob Cl is not specified, the job owning the

If requested before login and if no iob is speci—

fied, the time-of—day is typed. If, at any time, job 0 is specified,
the time-of-day is typed.

3.2

CONSOLE MANIPULATION

ASSIGN K C];

This is a request for console number Cl to be added to those consoles

already owned by the requesting user.
K denotes console

Cl is the console number
If the console is free, it will be given to the user and the user's

Switchboard settings will be augmented by those additional entries
which put the new console in the normal state with respect to its
oWn printer and the program on the user's disk track.
Cross settings
for inter—console connections are left to the user's discretion.
SLAVE c1;

This command causes console number CT to be slaved. This means
that console number Cl will be unable to communicate with Monitor,
and the system will ignore the call (CTRL/B) character from that

console.

However, the console may serve as an input/output device

for the user's program.

Monitor checks to make sure that the request-

ing user owns the console he wishes to slave.
every console that a user owns.

3-2

It is illegal to slave

UNSIAVE c1;

This command restores a slaved console to normal status.

After this

command, console number Cl will be able to communicate with
The user must own the console to unslave it.

Monitor.
RELEASE K

C];

This command releases console number Cl and puts it in the free
Monitor checks to make sure that the requesting user owns

state.

the console he wishes to release.

When the console is released,

the Switchboard is reset and the input and output buffers are cleared.

The user must own the console to release it.

3.3

DEVICE ALLOCATION
ASSIGN Ll;

This is a request for access to the device specified by L].
L]

for paper tape reader

for paper tape punch
for card reader

C
L

for line printer

for incremental plotter

If device Ll is not busy, it will be allocated to the user program

issuing the command. Ifdevice Ll is busy, the iob number of the
having possession is returned. A RELEASE L]; or LOGOUT;

user

will release the device.
ASSIGN D c1,-

This command is the same as ASSIGN Ll;
D denotes DECtape unit

Cl is the unit number of the DECtape unit
RELEASE L1;

RELEASE K C];
RELEASE D C];

3.4

Each of these commands will annul the current assignment of the

specified device.

FILE CONTROL

OPEN C] S]

C2;

This command establishes association between an internal file num—
ber and a file. After this command is given, the file of account
C2 with the name 51 is associated with internal file number Cl
The internal file number specified must be between zero and three
.

inclusive.

If C2 is not specified, the account number of the cur-

rent user is assumed.

CLOSE S];

This command closes the files specified by S]

S] is a list of internal file numbers separated by spaces

After this command is given, no writing can be done on the files

specified, and the associations between the internal file numbers
and the files are broken.

This command causes Monitor to create a new File which is to have

CREATE $1;

the name Sl, iF there is available File storage. At the time oF
creation, Monitor will enter the name oF the new File and the date
oF creation into the owner's File directory (see Appendix E) and set

the protection mask to 17.

Example:
asks Monitor to create a new File

CREATE NEWF;

named NEWF. IF there is no more
File storage, Monitor will so inform
the user (see Chapter 5).

RENAME c1

51,-

This command renames a File.

The File to be renamed must be al—

ready open and associated with internal File number Cl.
name

will become 5]

Its new

Example:

RENAME 1 F00;

that File NEWF has been
opened to internal File number l;
this command will change the name
assume

oF that File From NEWF to FOO.

REDUCE C]

Di ;

This command reduces the length oF a File. The File which is to be
shortened must be open and associated with internal File number Cl
D1 is the number oF segments to be removed From the end oF
the File.
IF D] is greater than or equal to the number oF segments in the File,

the File is deleted From the directory.
REDUCE 2

Example:

File TTl3 is opened to internal
File number 2; this command then reassume

moves

2 segments From its end and

returns those

EXTEND C]

Di;

segments to Free storage.

This command extends the length oF a File. The File which is to be
lengthened must be open and associated with internal File number
C].
D] is the number oF segments to be added to the end oF the

File.
IF there is space available, Monitor will

lengthen the File as

requested.
PROTECT C1

C2;

This command changes the File protection mask oF a File. The File
protected must be open and associated with internal File
number Cl.

to be

C2 is the new File protection mask.
For File protection, the 12—bit account number is partitioned into
project number (high order 7 bits) and a programmer number (low

order 5 bits).
C2

Examples:
read protect against users whose proiect number
diFFers From OWner's

write protect against users whose project number

differs from owner's

read protect against users whose project number is
same as

OWner's

ID write protect against users whose project number is
same as owner's

C2 can be the sum of any of the above values.

This command is illegal for all users except the owner.
PROTECT l

Example:

read and write protect internal file 1

against access by any user whose proiect number differs from the owner's.
F

This command causes Monitor to print out the current state of the
The

Cl;

association of the user's internal file number Cl with the file.
response format is

where
Cl is the owner's account number
Si is the file name

C2 is the protection mask
D] is the number of segments

3.5

CONTROL OF USER PROGRAMS
START

This command begins execution of a user program at location Cl.
In addition, the command resets the Switchboard so that all characters typed from either a keyboard or program directed into the
user program's input buffer are no longer intercepted
by the System
Interpreter. The accumulator (AC) and link are cleared and the
user's interrupt system is turned off.

Cl;

This command restarts a user program.

START;

If Monitor has been called

during the execution of the user program, the complete state of the
program is saved including the location of the next instruction to
When the START command is given, the program's

be executed.

state is restored and the program continues execution where it

left

As in the START Cl; command, characters intended for the
user program's input buffer are no longer intercepted by the System
off.

Interpreter.
DEPOSIT Cl C2

Cn;This command stores C2 in location Cl, C3 in location Cl+l,

..,

Cn in location Cl+n-l.
n

is equal to or less than 10 decimal.

A user can load a binary user program using the DEPOSIT command,

although it is much easier using DDT-8. This command is useful
when making small patches to stored programs.

EXAMINE Cl

This command causes Monitor to type the contents of the Dl locations
starting at location Cl.

Dl;

Dl is equal to or less than l0 decimal.
If Dl is not specified, the contents of location Cl is typed.

3.5.l

Saving and Restoring Binary User Programs
The SAVE, LOAD, R and RUN commands leave file Sl open on internal file 3, turn the

user's interrupt system off, and reset the Wait Mask to its initial value.
SAVE Sl;
SAVE Sl

Cl;

SAVE Sl

C2;

SAVE Sl

C3;

These commands write portions of the user's core image onto a file
whose name is Sl

is the file address of the first word to be written; if

not

specified, the entire 4K is written on the first

4096 words of the file.
C2

is the core address of the first word to be written; if

all 4096 words are written.

not specified,

is the core address of the last word to be written; if
not specified, 7777 is assumed.

Example:
SAVE NEWF;

writes core words 0 through 7777 on

words 0 through 7777 of file NEWF.

LOAD Cl

Sl;

LOAD Cl Sl

C2;

LOAD Cl 51

C3;

LOAD Cl Sl C2 C3 C4; These commands read certain portions of the file whose owner's
account

number is Cl, and whose file name is Sl into core.

is the file address of the first word to be read; if not

specified, words 0 through 7777 are read into words
0 through 7777.
C3

is the core address of the first word to be loaded; if

all 4096 words are loaded.

not specified,

is the core address of the last word to be loaded; if
not specified, 7777 is assumed.

Example:
LOAD NEWF 5 l0 l7; loads words 5 through l4 into words
l0 through l7 respectively.
R S];

This command is equivalent to
OPEN 3 Si

2; LOAD 2 51; START 0

which loads program Sl from the System Library (account 2) and
starts the program running. The accumulator (AC) and link are

Cleared.
3—6

RUN $1;

This command is equivalent to
OPEN 3 Si; LOAD Sl; START 0

The accumulator (AC) and link are cleared.
RUN c1

51,-

This command is equivalent to
OPEN 3 Si

Cl; LOAD Cl Sl; START 0

The accumulator (AC) and link are cleared.
This command stops the execution of the user program, saves its
complete state, and sets the Switchboard so that all characters
directed to the program's input buffer will be intercepted by

System Interpreter.
WHERE;

This command causes Monitor to type out the current state of a user
program's location counter, accumulator, link, and switch register.

USER;

This command causes Monitor to type out the number of the job and
devices owned by the user.

USER Cl;

This command causes Monitor to type out the numbers of the devices
owned by user Cl. If job 0 is specified, the numbers of unassigned
devices are typed.

SWITCH Cl;

3.6

This command sets the user's switch register to Cl

SWITCHBOARD

Using Monitor commands the user may set, reset, and read any given bit in either the Permission Table or the Switchboard Table.

See Section 2.2.l Character Transmission and Section 2.3

Permission and Switchboard Tables for a description of the meaning of bits in these tables.
SET Ll L2 Cl L3 C2;

This command sets a bit in either the Permission or Switchboard
Table to a one.
Ll
L2

denotes Permission Table

denotes Switchboard Table

denotes keyboard

denotes user program

denotes input buffer

denotes output buffer

is the octal number of the keyboard or program

Cl
L3

is the octal number of the buffer which is to receive

the characters from the character source.
Monitor checks for appropriate ownership to decide whether it will

allow the connection to be made.
source

The ownership of the character

is used to determine legality in setting the Switchboard Table

while the ownership of the character sink is used in setting the Permission Table.

Examples:

3—7

SET P K 13 0 12;

requests that keyboard number 13 be

given permission to write on the printer

(output buffer) of console 12.
SET S P 41

16;

informs Monitor that job number 4
would like to type out characters into
the input buffer of user program 16.
This request will be granted only if
user 16 has previously given permission
by SET P P 41 16; or by the equivalent
IOT instruction (SSP).

RESET L1 C2 C1 L3 C2;

This command is identical in all respects to the SET command above

except that the bit indicated by the parameters will be set to zero
instead of one.

READ L1 L2 C1 L3 C2;

This command uses the same parameters to specify a bit in either the
Permission or Switchboard Table as in the SET and RESET commands

above.

DUPLEX;

Monitor will type out the value of the bit.

This command is a shorthand command to set the Switchboard Table
so that characters typed on the keyboard from which this command
is issued will appear on the printer of that console. Example:

DUPLEX;

if the keyboard issuing this command
is number

16, then this command is

equivalent to SET S K 16 0 16;
ALLOW c1;

This command is shorthand to indicate that a user is given permission
for keyboard number C1 to place characters in the output buffer of

his console.

Example:

ALLOW 4

assume

that this command was issued

from keyboard number 27, then it is

equivalent to SET P K 4 0 27;
UNKCb

This command is given by a user who wishes to communicate with a
console other than the one at which he is setting. This command is
legal only if the owner of the console has set the Permission Table
so that he will accept characters from the requesting console into
his printer's output buffer. The command is shorthand for the command ALLOW C1; followed by the command to set the Switchboard
so

that characters from the requesting console will be placed in

output buffer number C1.
LINK 32;

Example:
assume

that the console which issued

this command was number 7, then this
command would be legal only if the
owner

of console number 32 had pre—

viously set the Permission Table to
allow keyboard 7 access to that output
buffer. He could have done this with
ALLOW 7; or by SET P K 7 0 32; or by

equivalent IOT instruction executed
by his program. If that permission has

been granted, the LINK command is

equivalent to the following two Switch—
board commands:

SET P K 32 0 7;
and
SET
S K 7 0 32;
32)
(ALLOW

3.7

INTER- SYSTEM COMMUNICATION
In those TSS/8 systems having a local connection to a PDP-lO Time-Sharing System or a

Synchronous Data Communication System (Type 637), the input to the user's input buffer and program
output is scanned for the character sequences CTRL/B CTRL/X and CTRL/B CTRL/Y, respectively. All
characters up to the next CTRL/ B are diverted to the PDP—lO or 637 System, whichever the case may be.
Characters from the PDP-lO and 637 System are directed into the user's input buffer.

CHAPTER 4

INPUT/OUTPUT TRANSFER INSTRUCTIONS

Whenever a user program executes an input/output transfer (IOT) instruction (an instruction
of the form 6XXX) the system traps the instruction and transfers control to a system service or simulation

These routines accomplish special tasks, set up parameters for the system, and perform input/

routine.

output for the user program.
IOT instructions may be separated by function into three types:
a.
Input/output instructions available on the standard PDP-8/I without a time-sharing
when a user program executes one of these IOTs, TSS/ 8 simulates an input/output function
similar to the function of the IOT instruction on the standard PDP-8/I. Some standard PDP-8/I IOT

monitor

instructions are illegal in TSS8

(see Appendix C for a summary of legal IOTs).

IOT instructions to request input/output service from TSS/8 unavailable on the standard
b.
these include requests for DECdisk, DECtape, high-speed paper tape reader and punch,
card reader, and console character handling.

PDP—8/I

IOT instructions which call subroutines to set user parameters or to alter the time—sharing

environment for a particular user program
or

an alteration may, for example, include requests to add
release facilites or to change mode of character handling.
-

An IOT instruction usually acts as a subroutine call.

Therefore, depending upon the specific

IOT instruction, parameters may be loaded into the accumulator (AC) before execution of the IOT.
some

cases,

the parameter in the AC acts as a pointer to a parameter block in the user's program.

the system has to return information to the user's program, it returns that information in the AC or in a

block of locations in the user's program (the beginning address of this block is in the AC).

4.l

PROGRAM CONTROL

Check Status (CKS)

Octal Code: 6200

Operation: There are three status registers, STRO, STRI, and STR2.

All three registers are

read by the CKS instruction, and the accumulator (AC) is cleared.

Before executing CKS,

load the AC with the address ofa 3-word block.
Word l:

STRO

Word 2:
Word 3:

STRI
STR2

Executing CKS will store in

The formats of these registers are:
STRO Bits
0

Run Bit

Unconditional run (this bit is turned on when the program is
started by the System Interpreter)

PI Enable

ION has been executed by user program

Source

Input buffer source is being recorded

4-!

ST R0 Bits

Binary

JSIOT

JSIOTC

Input buffer time is being recorded
Card reader mode: alphanumeric (0), binary (T)
Non-resident IOT call (system use only)
Copy IOT results to user (system use only)

Error Code

Bits 7 through Tl specify a system error code

Timer

Time is up

File 0

Internal file 0 is not busy

File 1

File 2
File 3
Delimiter

Internal file l is not busy
Internal file 2 is not busy
Internal file 3 is not busy
There is a delimiter in the input buffer
There is a character in the input buffer
Output buffer is not full

Time

through
H

STR]

Bit_s_

4
5
6
7

Keyboard
Teleprinter

Reader

Punch

Character in reader buffer
Punch buffer is not full

Error

System error detected, code in bits 7 through ll of STRO

Wait

Job is not waiting

Plotter

Plotter flag

DTO Flag

DTO Error

DTT

DTl Error

DECtape flag unit 0
DECtape error flag unit 0
DECtape flag unit 1
DECtape error flag unit 1

STR2 Bits

Flag

Unused
Card Reader

Character in card reader buffer

CR No Ready

Card reader not ready

CR End File

LP Error

Card reader end of file
Line printer error

LP Done

Set Interrupt Mask (SIM)

Line printer done
Unused

Octal Code: 6000

Operation: TSS/8 simulates the PDP—8 program interrupt system for the user.
may request this mode of operation by executing the ION instruction.

will cause an immediate transfer to location i of the user program.

A user program

A simulated interrupt

The user's current loca-

tion (Program Counter) before the interrupt, is stored in location 0 and the interrupt system

is disabled

(bit I of STRO= 0). Ifthe instruction following the ION is a JMP or JMS in-

struction, it is simulated by the system before returning control to the user's program.
The SIM instruction enables the user program to set those conditions which will
result in simulated program interrupts.

The system provides a mask called the Program In-

terrupt Mask, which has the same format as the two status registers STRI and STR2 (see CKS).
Before executing the SIM instruction, load the AC with the address of a 2-word

After executing the SIM instruction, a bit match between the

block containing the mask.
status registers and the

Program Interrupt Mask will result in a simulated interrupt if the

interrupt system is enabled.
cause

The user's program may do a CKS instruction to determine the

of the interrupt.

The Program Interrupt Mask is normally set to

0074
7677
and is reset only on LOGOUT.

Read Interrupt Mask (RIM)

Operation:

The AC is cleared by SIM.

Octal Code: 6003

The Program Interrupt Mask is read into two locations starting at the location

whose address is in the AC, and the AC is cleared.

Interrupt Turn On (ION)

Octal Code: 6001

Operation: This instruction enables TSS/ 8 to respond to a user program interrupt request by
setting bit 1 of STRO

If the user interrupt is disabled (bit 1 of STRO

0) when this in-

struction is given and the following instruction is a JMP or JMS instruction,

it, then enables the interrupt by returning control to the user program.
no

TSS/8 executes

This instruction has

effect if given when the user interrupt is enabled.

Interrupt Turn Off (IOF)

Operation:
STRO

Octal Code: 6002

This instruction disables the user program interrupt system by setting bit I of

Set Wait Mask

Operation:

(SWM)

Octal Code: 6005

The user program may request to be dismissed until some condition has been met.

This is done by setting a mask through which the system will observe the status register of the
user

program.

Load the AC with the address of a 2-word block containing 1 bits in the desired

4-3

wait conditions.

cleared.

The two words are inclusively ORed with the wait mask and the AC is

In general,

flag test IOTs whose skip condition is not met and requested [/0

operations which cannot be performed immediately, cause the program to be dismissed until
the condition is met.
For example, suppose it is desired that the user program be dismissed until any

character is typed, then
TAD MASK
SWM
KSF

MASK

0040

0000

would have the desired effect.
The normal setting of the Wait Mask is

0001
7767
and is reset on LOGIN,

Clear Wait Mask (CWM)

SAVE, LOAD, R and RUN commands.

Octal Code: 6006

Same as Set Wait Mask (SWM) except that the selected bits are cleared and

Operation:

the AC is cleared.

Read Wait Mask (RWM)

Operation:

Octal Code: 6007

The contents of the user's Wait Mask are read into two successive locations be—

ginning at the word whose address is in the AC, and the AC is cleared.

Wait (WAIT)

Operation:

Octal Code: 6410
The user's program is dismissed until it is re-scheduled by some status bit/Wait

Mask match.

The user may read the status registers to determine the restart conditions.

User (USE)

Octal Code: 6421

Operation:

Return in the AC the number of the current iob.

4—4

Octal Code: 6422

Console (CON)

Return in the AC the smallest unit number of the unslaved consoles assigned to

Operation:

the job whose number is in the AC.

If the AC is 0, the number of an unassigned console is

returned; if it does not exist, —l is returned.

Octal Code: 64]]

User Run Time (URT)

Returns the total run time of the user program in the two locations starting at the

Operation:

location whose address is in the AC.

Time—Of-Day (TOD)

Octal Code: 64l2

Returns the value of the System Clock in the two locations starting at the loca—

Operation:

tion whose address is in the AC.

Return Clock Rate (RCR)

The AC is cleared.

Octal Code: 64l3

The number of milliseconds per clock tick is returned in the AC.

Operation:

Date

The AC is cleared.

Octal Code: 6414

(DATE)

Operation: Returns the date in the AC. The format of this 12-bit number is

DATE=((YEAR-i964)*12*(MONTH-i ))*3]+DAY—i

Skip On TSS/8 (TSS)

Octal Code: 6420

Operation: This instruction is used by programs which run under both TSS/8 and a standard

PDP-8/l.

Under TSS/8, the instruction following TSS will be skipped.

On a standard

PDP—8/I, the IOT has the effect of a NOP instruction.
Halt (HLT)

Octal Code: 7402

Operation: This instruction is used to stop the user program and to pass control to the System
Interpreter.

Executing HLT is exactly equivalent to typing CTRL/B S RETURN.

micro-coded with other group 2 IOT's (see Small

Computer Handbook, C-800).

HLT may be

Octal Code: 6415

Quantum Synchronization (SYN)

Operation: Upon execution of this instruction, the system will dismiss the user program and
set it in the

run

state so that it will

be run again next time through the "round—robin.

Ordinarily, this instruction is used to insure a full time quantum to perform some critical
operation

Octal Code: 6416

Set Timer (STM)

The system provides a clock time for each user program.

Operation:

By means of this IOT,

the timer may be set to "fire" after a specified number of clock ticks have elapsed.
Load the AC with the time in ticks to prime the timer.

Upon execution of the STM

instruction, the system sets the timer to IIfire" in the specified number of ticks, and turns the
timer bit (bit 0) in status register 1 to 0 and clears the AC.

After the specified time has

elapsed, the system turns bit 0 back to l.
The timer mechanism may be used three ways:
and use the CKS IOT to find out when the time is up
feature

i) The user may set the time going

2) The timer may be used with the Wait

/Prime timer with 5000 8 ticks

TAD C5000

STM

/Set the Wait Mask to check bit 0
/of status register 1

TAD MASK
SWM

MASK ,

4000

C5000,

5000

0000

Here the user program will be dismissed until 5000 ticks have elapsed 3) The time may also
be used in coniunction with the interrupt system.

In this case, an interrupt will occur after

the specified number of ticks.

Assign Device (ASD)

Operation:

Octal Code: 6440

If the device specified by the contents of the AC is available, it will be assigned

to the user program and the AC cleared.

the device is placed in the AC.

Otherwise, the number of the user program having

If the device does not exist, 7777 is returned in the AC.

The left half of the AC specifies the device type and the right half specifies the
unit number.

AC Bits 6—ll

AC Bits 0—5

Device

Console K

Paper tape reader
Paper tape punch
Line printer

Plotter

Card Reader

N+5

DECtape unit N

This assignment is in effect until a corresponding REL instruction or LOGOUT is encountered.

Release Device (REL)

Octal Code: 6442

Operation:

The device specified by the contents of the AC is released.

not assigned

by ASD, the release is a NOP. Otherwise, the device is made available to

other users.

The AC is cleared.

Octal Code: 6402

Slave A Console (SLV)

Operation:

SLV enables a user program to slave a console belonging to the user.

console is slaved, the call
as

If the device was

When a

(CTRL/B) character is treated as an ordinary character rather than

the System Interpreter call character.

This means that the slaved console may not call the

System Interpreter.
Load the AC with the number of the console to be slaved, then execute SLV.

the console specified does not belong to the user, this IOT will be considered illegal and the
AC will be non—zero.

Otherwise, the AC is cleared.

Unslave A Console (UNS)

Operation:

Octal Code: 6403

UNS removes a slaved console from the slave state.

its power to call the

The call character resumes

System Interpreter.

Load the AC with the number of the console to be released from the slave state,

then execute UNS.

If the console specified is not a slave or does not belong to the user,

this IOT will be considered a NOP.

The AC is cleared.

Set Switchboard and Permission Tables (SSP)

Operation:

Octal Code: 6404

SSP is used to set, reset, and read bits in the Switchboard and Permission Tables.

Its use mirrors the format of the Monitor commands for the same purpose.
Load the AC with the beginning address of a 3-word block:

Bits 0 and l contain 0, l, 2,

Word 1:

reset the bit in the table

read the bit in the table

—

the value of the bit is

returned in the AC after executing SSP
2

set the bit in the table

link

set both

tables

Bit 9 contains 0 or T
0

reference the Switchboard Table

reference the Permission Table

Bit 10 contains 0 or T

reference the keyboard rows of the table

reference the programs typing out rows of the table

Bit ll contains 0 or T
0

reference the input columns of the table

reference the output columns of the table

contains the number of the keyboard or program typing out

Word 2:

to be

referenced

contains the number of the input or output buffer to be

Word 3:

referenced
If SSP is executed, the AC is set to 0, otherwise, to 7777.
use

As an example of the

of SSP to duplicate the effect of the Monitor command SET P K 13 0 7; (set the Permission

Table to give permission for the keyboard of console 13 to type into the output buffer of con—
sole 7) execute the fol lowing sequence:
TAD ARRAY

SSP

ARRAY, .+l
4005
13
7

As an example of console linking, the Monitor command LINK 3;
to

(set the Permission Table

give permission for the keyboard of console 3 to type into the output buffer of this job

and set the Switchboard Table to route keyboard

console 3) is equivalent to:

input to this job to the output buffer of

USE
CON

DCA TABLE+2
TAD TABLE
SSP

TABLE,

.+1
6000
0
3

Set Switch Register (SSW)

Operation:

Octal Code: 6430

Each user program has a switch register corresponding to the PDP-8/ I switch

OR With Switch Register (OSR)

Octal Code: 7404

Operation: The contents of the user's switch register are inclusively ORed into the AC.
OSR may be micro-coded with other group 2 IOT's (see Small Computer Handbook,

FILE CONTROL

4.2

All bulk data storage for user programs is on file on the disk.

lectively as file storage.
or

C-800).

This area is referred to col-

A user program may read or write a file to handle bulk input/output of text

binary information.
Files are composed of sequential segments of file storage.

The size of a file segment is an

integer multiple of disk records specified at system initialization time.
machine words.
of the file.
not

A record consists of 128 12-bit

Files are at least one segment long and grow by adding additional segments to the end

Each file is registered in the OWner's file directory by a name which may be any string of

than six 6—bit characters.

Each user may refer to four files simultaneously.
associated with each of the user program's active files.

numbers.

An internal file number (0, l, 2, or 3) is

All references to file storage is by internal file

The act of assodating an internal file number with a file referenced by an account number

and name is called

l'opening" the file.

All file IOTs that are successfully completed return to the user with the AC cleared.
zero

AC indicates that an error was detected and the IOT was not performed.

follows:

A non-

The error messages are

4000

4400

The internal file specified is not open
The file is open to another user

5000

The directory is full

6000

File protection violation

7000

7400

File not found
Disk is full

AC
AC
AC

Read File (RFILE) and Write File (WFILE)

Operation:

Octal Codes: 6603 and 6605

Once the association of a file with an internal file number has been made, these

IOTs allow the actual file reference to be made.

They are illegal on a file that has not been

opened (associated with an internal file number).
To read or write a file, load the AC with the address of a 6—word block, then
execute the IOT.

The format for the 6-word block is:

Word 1:

contains the high—order file word address

Word 2:

contains the internal file number

Word 3:

contains the negative of the number of words for the operation.

This number will be either the number of words to be read or

the number of words to be written.
Word 4:

contains a pointer to the beginning address —l of a buffer lo-

cated in the user program. On a read operation this buffer
will receive the information from the file; on a write operation this buffer holds the information that is to be sent to the
file.

Word 5:

contains the least significant 12 bits of the initial file word

address to begin the operation.

Word 6:

contains an error code:

if no error

if parity error

if file shorter than word count

if file not open

if protection violated

The read or write begins at the word specified by words i and 5.

For example:

TAD X
WFI LE

,+1
0
i
-200

6477
200
means, write 200 words starting at word 200 of the file that is associated

file number i from a buffer starting at location 6500.

4-10

with internal

After the IOT is given, the file request is placed in the file request queue, and the

corresponding file-inactive bit is cleared in status register 1 for the user program.

Execution

of the user program continues immediately without waiting for the file request to be com—

pleted.

If the Wait Mask contains a i in the bit corresponding to the inactive bit for that

file, however, the user program will be dismissed until the file request has been completed.
The file queue is one deep for each of the user program's internal file numbers,

therefore, four different file requests may be overlapped if they refer to the four different
internal file numbers.

An attempt to overlap a file request on the same internal file number

will result in the user program being dismissed until the first request on that internal file
number has been completed.

After completion of any file request, the corresponding file

inactive bit in status register 1 is set to i and the word count

(word 3) and core address

(word 4) are updated, and the error code is set in word 6.

Octal Code: 6600

Rename A File (REN)

REN is used to change the name of a file.

Operation:

Load the AC with the beginning

address of a 4-word block, where
contains the internal file number associated with the file
whose name is to be changed, that is, to rename a file one
must first open it, otherwise, REN is illegal.

Word 1:

Words 2 through 4:

contain the new name.

This name is in 6—bit characters

packed two to a word.
Open A File (OPEN)
Operation:

Octal Code: 6601

OPEN is used to assOciate a file with an internal file number.

This process,

called "opening", is necessary since all file operations are in terms of the internal file
numbers.

Before executing the OPEN IOT, load the AC with the beginning address of a

5-word block, Where

Word 1:

contains the internal file number.

Word 2:

contains the account number of the owner of the file.
the account number of the current user is specified.

Word 3 through 5:

contain the name of the file to be opened.

If 0,

This name is in

6—bit characters packed two to a word.
If there was another file associated with the internal file number before the execution of

the OPEN IOT, it will be closed automatically before the new file is associated with the

internal file number.

4-H

Close A File (CLOS)

Operation:

Octal Code: 6602

CLOS terminates the association between files and their internal file numbers.

Before executing CLOS, load the AC with a selection pattern for the internal file numbers

whose associated files are to be closed.

The file is closed if bit I is l, where l

bit 0, l,

2, or 3.

Octal Code: 6604

Protect A File (PROT)

Operation:

The owner of a file may protect his file from unauthorized attempts to access it

by using this instruction.

Before executing PROT, load the AC with

Bits 5 through 6

Internal file number of the reserved file to be protected.

Bit 7

Write protect against owner.

Bit 8

Write protect against users whose proiect number is same as

owner's.
Read protect against users whose project number is same as

Bit 9

owner's.
Bit 10

Write protect against users whose proiect number differs from

owner's.
Read protect against users whose proiect number differs from

Bit it

owner's.
A file must be opened before it can be protected.

PROT is legal only when performed by the

file owner, that is, the user who created the file.

All attempts to access the file which

violate any of the protection flags will be considered illegal.

File Information (FINF)

Operation:
an

Octal Code: 6613

FINF enables a user program to determine what file, if any, is associated with

internal file number.
Word 1:

Load the AC with the beginning address of a 7-word block, where
contains the internal file number for which the user program
wishes information.

Words 2 through 7 will contain the information that the system returns after executing FINF.
Word 2:

contains the account number of the owner or zero if no file
is associated with the internal file number, that is, the file
is not open.

Words 3 through 5:

contain the name of the file in 6-bit code.

Word 6:

contains

Means

Bit=i
7

write protected against OWner

write protected against users whose proiect number
is same as owner's

read protected against users whose proiect number
is same as owner's

write protected against users whose proiect number

differs from owner's
ll

read protected against users whose proiect number

differs from OWner's
Word 7:

contains the number of segments that the file contains.

Create A File (CRF)

Octal Code: 6610

Operation: The user may request the system to create a new file of one segment.
program provides the new name for the file.

The user

Load the AC with the beginning address of a

3-word block, where

Words 1

through 3:

contain the 6-character name.

If there is some reason why the request cannot be granted, the system will return a non-zero
error

code in the AC.

The protection of a newly created file is 17.

Extend A File (EXT)

Operation:

Octal Code: 66'”

To extend the length of an existing file, that file must be currently open.

Load

the AC with the beginning address of a 2-word block, where
Word l:

contains the internal file number of the file to be extended.

Word 2:

contains the number of segments the system should append to

the file.
If for some reason the request to extend a file cannot be granted, the AC will contain 4000,

4400, 6000, or the number of segments it failed to append.

RedUce A File (RED)

Operation:

Octal Code: 6612

To reduce the length of an existing file, that file must be currently open.

Load

the AC with the beginning address of a 2-word block, where
Word 1:

contains the internal file number of the file to be redUced.

Word 2:

contains the nUmber of segments to be removed.

This request will always be granted.

Octal Code: 6614

Segment Size (SIZE)

Operation:

The number of words per segment is returned in the AC.

Octal Code: 6617

Account (ACT)

Operation:

The account number of the job whose number is in the AC is returned in the AC.

If the AC is 0, the current iob is assumed.

If 0 is returned in the AC, the specified iob does

not exist.

Octal Code:

Who (WHO)

Operation:

6616

The account number and password of the current job are returned to the three—

word block whose address is in the AC, and the AC is cleared.

4.3

INPUT BUFFER CONTROL
Set Keyboard Break (KSB)

Operation:

Octal Code: 6400

Rather than activate the user program to receive each character as it is placed

in the input buffer,

TSS/8 saves time by activating the program only on certain conditions

specified by the user. These activation conditions are called delimiters.

Before executing

KSB, load the AC with a 12—bit delimiter table. The format of the table is as follows:

(where each bit

Specifies

EL
0
1
2

3
4

change of character source
all letters
all numerals
horizontal tab
vertical tab

space
line feed
form feed

carriage return

;

[
&

(

RUBOUT
ALT MODE
all characters not specified in bits 1 through 10

6
7

10
11

)

4-14

When a bit in the table is set to 1, the user's program is activated if the condition the bit

represents is met by the incoming character, or if the input buffer becomes full.
table is initialized to 3777 on LOGIN and ASSIGN.

Set Buffer Control Flags (SBC)

Operation:

The delimiter

KSB clears the AC.

Octal Code: 6401

SBC permits the user program to clear his input and output buffers and control

the recording of character time and source in his input buffer.

Before executing SBC, load

the AC with the desired flags whose functions are
Bit

Clear output buffer

Clear input buffer
Record character source
Record character time

2
3

If bit 2:1, the source of each character in the input buffer is recorded in the following

character position.

The source from which the character was generated is indicated by the

8-bit character as follows:
OXX
1XX

Console XX keyboard
User program XX typing out

172

637 typing out

174

PDP—10 typing out

177

System Interpreter typing out

Bit 2 of status register 0 is set to 1.

If AC bit 2:0,

source

recording in the input buffer is

suppressed and bit 2 of status register 0 is set to 0.
If AC bit 3=1, the time of receipt of each input character is recorded in the two
sUccessive character positions following the character or following the source.

If the time

is being recorded, bit 3 of status register 0 is set to 1.

If AC bit 3:0, time recording in the input buffer is suppressed and bit 3 of status

Skip On Keyboard Flag (KSF)
Operation:

Octal Code: 6031

The keyboard flag is sensed, and if it contains a binary 1, the contents of the

PC is incremented by one so that the next sequential instruction is skipped.

The keyboard

flag is bit 6 of status register 1, and it has a value of 1 whenever the input buffer is not
empty. If the keyboard flag is 0 and the keyboard wait flag (bit 6 of wait register 1) is 1,
the iob is placed in the active state until the keyboard flag is 1.
is 0, control returns to the calling program immediately.

4—15

If the keyboard wait flag

Clear Keyboard Flag (KCC)

Octal Code: 6032

Event Time: 2

Operation:

The AC is cleared, and if the input buffer is empty, the keyboard flag is cleared.

Read Keyboard Buffer Static (K RS)

Octal Code: 6034

Event Time: 3

Operation:

If the input buffer is not empty, the next character from the input buffer is

inclusively ORed into bits 4 through ll of the AC.
the AC nor the keyboard flag is cleared.

This is a static command in that neither

If the input buffer is empty and the keyboard wait

flag is 0, no operation is performed and control returns immediately to the user's program.
If the keyboard wait flag is l, the iob is placed in the active state until the keyboard flag

isl.

Read Keyboard Buffer Dynamic (KRB)

Octal Code: 6036

Event Time:

2, 3

Operation:

Identical to KCC followed by KRS.

Read Keyboard String (K SR)

Operation:

Octal Code: 6030

Before executing KSR, load the AC with the address of a 2—word block, where

Word 1:

contains the negative of the number of characters to read.

Word 2:

contains the address —l of the first word of the buffer.

If the keyboard wait flag is 1, control does not return to the user program until a break
condition

(see KSB) is satisfied or until the word count in Word 1 is reduced to zero.

If the

keyboard wait flag is 0, control returns to the user program immediately; control returns to
the location following the KSR, the negative of the number of characters remaining to be
transferred is in Word 1, and word 2 points to the last character stored.

4.4

The AC is cleared.

OUTPUT BUFFER CONTROL
Send A String (SAS)

Operation:

Octal Code: 6040

To send a string, load the AC with the address of a 2-word block, where

4-16

Word l:

contains the negative of the number of characters to be sent.

Word 2:

contains the address -1 of the first word of the string.

The characters are stored one per word right iustified starting at the address specified by
word 2.

Upon execution of SAS, the system takes only as many characters as will fit in the

output buffer. It then makes the appropriate adjustment to word 2 to indicate a new starting
address and to word 1 to indicate the reduced character count; it returns to the instruction

following the SAS.
SAS is skipped.

If the character count is reduced to zero, the instruction following the

The instruction following the SAS may contain a JMP .-l to continue the
In this case, the user program will dismiss until the

block transfer of Teletype characters.

Teletype output buffer is nearly empty.
a

If the user wishes to avoid dismissal, he can place

jump to another part of his program in the instruction following SAS. The AC is cleared

by SAS.
Skip on Teleprinter Flag (TSF)
Event Time:

Octal Code: 6041

Operation: The teleprinter flag is sensed, and if it contains a binary l, the contents of the
PC is incremented by one so that the next sequential instruction is skipped.

The teleprinter

flag is bit 7 of status register 1, and has a value of T if the output buffer is not full.

If the

teleprinter wait flag is 0, control returns to the user program immediately, otherwise, control returns when the teleprinter flag is 1.

Clear Teleprinter Flag (TCF)
Event Time:

Octal Code: 6042

Operation: The teleprinter flag is cleared to zero.
Load Teleprinter And Print (T PC)
Event Time:

Octal Code: 6044

Operation: The character in bits 4 through ll of the AC is typed out and routed through
the switchboard to all buffers connected to the user's program character output.

4—17

Load Teleprinter Sequence (T LS)

Octal Code: 6046

Event Time: 2, 3

Operation:
4.5

Same as TPC.

HIGH-SPEED PAPER TAPE READER

Octal Code: 6011

Skip On Reader Flag (RSF)
Event Time:

Operation:

The reader flag is sensed, and if it contains a binary 1, the contents of the PC

is incremented by one so that the next sequential instruction is skipped.

The reader Flag is

bit 8 of status register 1, and has a value of 1 if the reader buffer is not empty. If the reader
wait flag in the wait mask is

1, the program is dismissed until the reader flag is 1, otherwise,

control returns to the user program immediately.
Octal Code: 6012 or 6016

Read Reader Butter (RRB)
Event Time:

Operation:

The contents of the reader buffer is transferred into bits 4 through 11 of the AC

and the reader flag is cleared it the reader buffer is empty.
the AC.

This instruction does not clear

If the reader buffer is empty and the reader wait flag is 1, the user program is dis-

missed until the reader flag is 1.

If the reader buffer is empty and the reader wait flag is 0,

this IOT is a NOP.

Reader Fetch Character (RFC)

Octal Code: 6014

Event Time:

Operation:

The reader flag and the Monitor reader buffer are both cleared, the reader is

started to fill the Monitor reader buffer and the reader flag is set after the first character is

read.

Read Reader String (RRS)

Operation:
reader.

Octal Code: 6010

RRS allows a user program to read a string of characters from the paper tape

Before executing RRS, load the AC with the beginning address of a 2-word bIOck,

where
Word 1:

contains the negative of the number of characters to read.

Word 2:

contains the address —1 of the first word of a buffer.

4-18

If the reader wait flag in the wait mask is

l, the program is dismissed until the transfer is

completed, otherwise, control returns to the user program immediately. The reader flag is
set to l

4.6

when the transfer is complete.

The AC is cleared by RRS.

HIGH-SPEED PAPER TAPE PUNCH

Octal Code: 602]

Skip On Punch Flag (PSF)
Event Time:

Operation:

The punch flag is sensed, and if it contains a binary l, the contents of the PC

is incremented by one so that the next sequential instruction is skipped.

The punch flag is

bit 9 of status register 1, and has a value of i if the punch buffer is not full.

If the punch

flag is l and the punch wait flag is l, the program is dismissed until the punch flag is i.
If the punch flag is 0 and the punch wait flag is 0,
returns to the user program

operation is performed and control

immediately.

Clear Punch Flag (PCF)

Octal Code: 6022

Event Time:

Operation:

If the punch buffer is not full, the punch flag is cleared in preparation for

punching the next character from the computer.
wait

If the punch buffer is full and the punch

flag is l, the program is dismissed until the punch flag is i.

and the punch wait flag is 0,

If the punch buffer is full

operation is performed and control returns to the user pro-

gram immediately.

Load Punch Buffer and Punch Character (PPC)

Octal Code: 6024

Event Time:

Operation:

An 8-bit character is transferred from bits 4 through ll of the AC into the punch

buffer and then this character is punched.

PPC does not clear the punch flag.

If the punch

buffer is full and the punch wait flag is l, the program is dismissed until the punch flag is
i.

If the punch buffer is full and the punch wait flag is 0,

control returns to the user program immediately.

operation is performed and

Load Punch Buffer Sequence (PLS)

Octal Code: 6026

Event Time:

2, 3

Operation:

Identical to PCF Followed by PPC.

Punch String (PST)

Octal Code: 6020

PST allows a user program to punch a string of characters.

Operation:

Before executing PST,

load the AC with the beginning address of a 2—word block, where
Word 1:
Word 2:

contains the negative of the number of characters to be punched.
contains the beginning address --1 of the string to be punched;

the characters should be right iustified one per word.

Upon execution of PST, the system takes only as many characters as will fit in the punch
buffer; it then makes the appropriate adjustment to word 2 to indicate a new starting address
and to word 1 to indicate the reduced character count.

It returns to the instruction follow—

ing the PST. If the character count is reduced to zero, the instruction Following PST is

skipped.
4.7

The AC is cleared by PST.

DECTAPE

Octal Code: 6764

Load Status Register A (DTXA)

Operation:

DTXA allows a user program to read and write records (l28—word blocks) on

DECtape.

Load the AC with the beginning address of a 4-word block, where

Word l:

contains

Bit=l
contain the transport unit select number

0-2

6-8
9

lO-ll

for read data function

for write data function

to enable

disable DECtape control flag (DTCF) and error

flag from causing a program interrupt.
DECtape control flag (DTCF) and error
to
cause
flag
program interrupt

unused

Word 2:

contains the beginning DECtape block number

Word 3:

contains the negative of the number of records to transfer

Word 4:

contains the beginning core address —1 of record buffer

After DTXA is given, the DECtape request is placed in the DECtape request queue and the

DECtape and error flags are cleared in status register 2. Execution of the user program con—
tinues immediately without waiting for the

4-20

DECtape request to be completed.

If the wait

mask contains a 1 bit corresponding to the DECtape flag of the selected unit, the program

will be dismissed until the DECtape request has been completed.

The DECtape queue is one

deep for each unit, therefore, four different DECtape requests may be overlapped if they
refer to different units.

An attempt to overlap a DECtape request on the same Unit will

result in the user program being dismissed until the first request has been completed.

After

the completion of any DECtape request, the corresponding DECtape flag in status register 2
The AC is cleared by DTXA.

is turned on.

Octal Code: 6771

Skip On Flags (DTSF)
Event Time:

Operation: The contents of both the error flag and the DECtape flag is sampled, and if
either flag contains a binary l, the contents of the PC is incremented by one to skip the
next sequential instruction.

If both flags are zero and if either of the corresponding wait

flags are l, the user program is dismissed until the skip condition is satisfied.

Octal Code: 6772

Read Status Register B (DTRB)
Event Time:

Operation:

The contents of DECtape status register B is loaded into the AC by an OR trans-

fer.

The AC bit assignments are:
error

O~U1->QJN—'O
4.8

flag

mark track error

..,. 3' .1O C (O 3'

_.| —I

end of tape
select error

parity error
timing error
unused

DECtape flag

AUTOMATIC LINE PRINTER

The Automatic Line Printer and Control

(Type 645) IOT instructions are simulated precisely as

they appear in the Small Computer Handbook.

The line printer error flag is bit l0 of status register 2,

and the done flag is bit ll of the some register.

The wait mask and priority interrupt mask have the

same

significance as with other devices.

4-21

Octal Code: 6651

Skip On Line Printer Error (LSE)
Event Time:

Operation:

The contents of line printer error Flag is sensed, and if it contains a binary 1,

indicating that an error has been detected, the contents of the PC is incremented by one so
that the next sequential instruction is skipped.
If Line Printer Error Flag

Symbol:

1, then PC+l "PC

Octal Code: 6652

Clear Printer Buffer (LCB)
Event Time:

Operation:

Both sections of the line printer buffer are cleared in preparation for receiving

new

character information
0

Symbol:

LPB

Octal Code: 6654

Load Printer Butter (LLB)
Event Time:

Operation:

A section of the printer buffer is loaded from the contents of bits 6 through ll of

the AC, then the AC is cleared.

AC 6 through ll

Symbol:

LPB, then 0 "AC

Skip On Line Printer Done Flag (LSD)
Event Time:

Octal Code: 6661

Operation: The contents of the line printer done flag is sensed, and if it contains a binary
l, the contents of the PC is incremented by one so that the next sequential instruction is

skipped.
If Line Printer Done Flag

Symbol:

Clear Line Printer Flags (LCF)

1, then PC + l *PC

Octal Code: 6662

Event Time: 2

Operation:

Symbol:

The line printer done and error flags are cleared.
0

Line Printer Done Flag

‘*

Line Printer Error Flag

4-22

Clear Format Register (LPR)

Octal Code: 6664

Event Time:

Operation:

The line printer format register (FR) is cleared and then loaded From the contents

of bits 9 through 11 of the AC, and the AC is cleared.

the printer buffer (LPB) loaded last is printed.

The line contained in the section of

Paper is advanced in accordance with the

selected channel of the Format tape it the contents of AC8 is a T.

If AC8 is a 0, paper

advance is inhibited.

4.9

INCREMENTAL PLOTTER

The Incremental Plotter and Control (Type 3503) IOT instructions are simulated precisely as

they appear in the Small Computer Handbook.

The plotter flag is bit 0 of status register 2.

The wait

mask and priority interrupt mask have the same significance as with other devices.

Skip On Plotter Flag (PLSF)
Event Time:

Octal Code: 6501

Operation: The plotter flag is sensed, and if it contains a

l the contents of the PC is

incremented by one so that the next sequential instruction is skipped.
If Plotter Flag

Symbol:

Clear Plotter Flag (PLCF)
Event Time:

i, then PC + 1 "PC

Octal Code: 6502

Operation: The plotter flag is cleared in preparation for issuing a plotter operation command.

Symbol:

Pen Up (PLPU)
Event Time:

Plotter Flag

Octal Code:

6504

Operation: The plotter pen is raised from the surface of the paper.

Pen Right (PLPR)

Event Ti me:

Octal Code: 6511

Operation: The plotter pen is moved to the right in either the raised or lowered position.

4-23

Drum Up (PLDU)

Event Time:

Octal Code: 6512

Operation: The plotter paper drum is moved upward. This instruction can be combined with
the PLPR and PLDD instructions.

Drum Down

Octal Code: 6514

(PLDD)

Event Time:

Operation:

The plotter paper drum is moved downward.

Pen Left (PLPL)

Octal Code: 6521

Event Time:

Operation:

The plotter pen is moved to the leFt in either the raised or lowered position.

Drum

Octal Code: 6522

Up (PLUD)

Event Time:

Operation: The plotter paper drum is moved upward. This instruction is similar to PLDU
except that it can be combined with PLPL or PLPD instructions.

Octal Code: 6524

Pen Down (PLPD)
Event Time:

Operation: The plotter pen is lowered to the surface of the paper.

4.10

CARD READ ER

Skip on Card Reader Flag (CRSF)

Octal Code: 6632

Event Time:

Operation:

The contents of the card reader flag is sensed, and if it contains a 1

(indicating

that the card column is present for reading), the contents of the PC is incremented by one so
that the next sequential instruction is skipped.

The card reader flag is bit 6 of status register

2 and it has the value 1 if a card is in the card buffer.
card reader wait flag is

If the card reader flag is 0 and the

1, the program is dismissed until the card reader flag is 1; otherwise,

control returns to the user program immediately.

4-24

Octal Code: 6634

Read Card Equipment Status (CERS)
Event Time:

Operation: The contents of the card reader flag and status flags are transferred into the
contents of bits 7 through 9 of the AC.

card reader flag

not

(1 if card in T58 card reader buffer)

ready (covers not in place, power is off, start pushbutton has not been
pressed, hopper is empty, stacker is full, a card is jammed, a validity check
error

has been detected,

the read circuit is defective)

end of file (EOF) (hopper is empty and operator has pushed EOF button)

Read Card Reader Buffer (CRRB)
Event Time:

The AC bit assignments are:

Octal Code:

667]

Operation: The contents of the card column buffer is transferred into the AC and the card
reader flag is cleared if the card reader buffer is empty.
or

binary information.

One CRRB reads either alphanumeric

If the card reader buffer is empty and the card reader wait flag is

l, the program is dismissed until the card reader flag is T.
and the card reader wait flag is 0,

If the card reader buffer is empty

operation is performed and control returns to the user

program immediately.

Select Alphanumeric (CRSA)
Event Time:

Octal Code: 6672

Operation: The card reader alphanumeric mode is selected and a card is read into the card
reader buffer.

Information read into the card reader buffer is in 6—bit alphanumeric form

(the Hollerith code representing the decoded lZ-row character in one column). If the card
reader wait flag is

l, the user program is dismissed until the card reader flag is 1; otherwise,

control returns to the user program immediately.

Select Binary (CRSB)

Octal Code: 6674

Event Time:

Operation:

The card reader binary mode is selected and a card is read into the card reader

buffer in l2-bit binary form.

If the card reader wait flag

l, the user program is dismissed

until the card reader flag is 1; otherwise, control returns to the user program immediately.

4—25

Upon instruction to read the card reader buffer, the contents of the l2-bit column
is transfen'ed into the AC.

In the alphanumeric mode a 6—bit Hollerith code is transferred

into bits 6 through ll of the AC, and bits 0 through 5 of the AC are cleared.

In the binary

mode, the binary contents of the 12 bits (or rows) in a card column are transferred into the
AC so that row X is read into AC bit 0,
row

9 into AC bit ii.

Read Card String (RCS)

Operation:

row

Y into AC bit

1, row 0 into AC bit 2,

and

The mode is specified by either the CRSA or CRSB instruction.

Octal Code: 6630

RCS allows the user program to read a string of characters from the card reader.

Before exeCUting RCS, load the AC with the beginning address of a 2—word block, where
Word 1:

contains the negative of the number of columns to be read.

Word 2:

contains the address -l of the first word of a buffer.

If the transfer is terminated before the column count has been reduced to zero, the card
reader flag is turned on the words 2 and l contain the address —l of the next buffer location
and the negative of the number of columns remaining to be read,

packed right justified, one per word independent of mode.

4—26

respectively.

Columns are

CHAPTER 5
ERRO R DIAGNOSTICS

5.I

USER PROGRAM

The following error messages are typed on the user's printer by the Error Phantom when error
conditions occur in a running user program.

If the user program is not era bled for system error interrupts,

the error messages are typed in the following format.
Sl FOR USER CI

AC=C2,

L:C3,

PC=C4

INSTR=C5
Si is a string,

describing the nature of the illegal instruction C5 which user program CI has executed at

location C4.

At the time the illegal instruction was executed the value of the accumulator was C2 and

the value of the link was C3.

For example,

ILLEGAL IOT

The user program has executed an IOT which the system regards
illegal. The illegality may be for one of two reasons:

5.2

The IOT itself may be illegal.

The parameters to a legal IOT may invalidate it.

SYSTEM INTERPRETER

The following error messages result from illegal requests to the System Interpreter.

They are

printed by the System Interpreter on the printer.
SI

The System Interpreter does not understand the command.
SI

ILLEGAL REQUEST

command

The user has requested an illegal service.

This error usually

results when some parameter has been given an incorrect value
or the request refers to a
facility not owned by the user.
SWITCHBOARD ERROR

The user has attempted to set a Permission Table bit not owned

by him; or the user has attempted to make a connection in the
Switchboard Table for which permission has not been granted.

SAVE LIMIT ERROR

The user has given invalid bounds in the command to save binary
core image.
The first bound must be lower than the second.

CONSOLE IN USE

The user has tried to log in on a console which is already in
use; or he has attempted to add a console to those he already

LOGOUT TO
RELEASE

owns.

The user has attempted to use a console which is not logged in.

UNAUTHORIZED
ACCOUNT
FULL

Cl HAS S]

The user has attempted to log into the system with an invalid
account number or name.
This message may appear on an attempt to log into TSS/8 From
It means that all disk swapping tracks are in use.
a console.
Job Cl had device Sl; the request For its acquisition cannot be

granted.
Cl

iob number
device name

APPENDIX A

TSS/8 CHARACTER SET
TSS/8 accepts 8-bit ASCII character only.
Information Interchange.

listed below

The acceptable characters and their 6- and 8-bit octal equivalence are

_______Character

6-Bir*

8-Bit

Octal

—Charact_e_[

6-Bir*

O ctal

Octal

Space

240

300

241

30]

242

302

243
244

43
44

304

245

305

46
47

306

246
247

(
)

lO
lI

250
25]

3] 0
3] l

252

3] 2

253

3] 3

254

3] 4

255

315

256

3] 6

257

3l7

260

320

26]

32]

262
263
264

322
323
324

,
-

303

307

265
266
267

325
326
327
330

270

27]

33]

272

332

;

273

[

333

34
35

274
275

\
]

74
75

334
335

336

276
277

“

337

ASCII is an abbreviation For USA Code For

Used to store passwords and Filenames only

APPENDIX B
SUMMARY OF COMMANDS

A Monitor command is a string of characters terminated by a semicolon (;) or a carriage return
or

(RETURN key). Parameters to commands may be octal numbers, decimal numbers, character strings,

single letters.

In the Following summary, parameters are coded as Follows:

C1, C2,

...

represent octal numbers

D1, D2,

represent decimal numbers

$1, $2,

represent character strings

Ll, L2,

represent single letters

Logging In and Out
LOGIN Cl 5];

Request to login;
Cl

user's account number
user's password

LOGOUT;

Request to logout; processing and console time is typed out

TIME c1;

Request typeout of processing time;
Cl
iob number
Without Cl, current iob is assumed;
Before logging in and without Cl, time-oF-day is typed out;
If Cl=iob 0, time-oF-day is typed out.
=

Console Manipulation
ASSIGN K C];

SLAVE c1;

Request console;
K

console
console number

Slave an owner console;
Cl
console number
=

UNSLAVE c1;

Unslave an owned console;
Cl
console number
=

RELEASE K C];

Release console;
K
console
Cl
console number
=

Device Allocation

ASSIGN Ll;

Access device;
Ll

R For paper tape reader
P for paper tape punch

C For card reader
L For line printer

I For incremental plotter

B-l

Device Allocation

(Cont)

ASSIGN D C];

Access DECtape unit;
=

DECtape
device number

Release device;

RELEASE Li;
RELEASE K C];

RELEASE D c1,-

K
D

R, P, C, L, orI, (see ASSIGN Li;)

console

DECtape unit

console or DECtape number

File
OPEN c1 ST

c2;

Establish association between internal file number and file;
CT
internal file number
5]
file name
C2
account number
=

Close files;
Si
list of internal file numbers

CLOSE $1;

CREATE SI;

Create new file;
5]
name of new file
=

RENAME C1 ST;

Rename a file;
Ci
internal file number
=

REDUCE C1

EXTEND C]

D1;

Di;

new name

of file

Reduce length of file;

internal file number
number of segments to be removed from end of file

Extend length of file;
C1
internal file number
=

PROTECT CT C2,-

number of segments to be added to end of file

Protect a file;
CT
internal file number
=

new

file protection mask

read protect against users with different project

write protect against users with different project

number
number
4 read protect against users with same project
number
10 write protect against users with same proiect
number
Or the sum of any combination

FCI;

Print out association between internal file numbers and files
CT
internal file number
=

Control Of User Programs
START Ci;

Execute user program;
CT
starting location
=

8-2

Control of User Programs (Cont)

START;

Restart user program;

DEPOSIT Cl C2.. .Cn;

Store in core memory;
CT
location
=

contents to be stored

location Cl+n-l
510 decimal

EXAMINE c1

D];

List specified contents;

first location

number of location to be listed

D1510 decimal

Saving and Restoring Binary User Programs
Save core image;

SAVESh
SAVE Si c1,SAVE $1 c1

c2;

SAVE $1 c1 c2 c3;

of file
tile address of first word to be

name

saved; if not specified, entire 4K is saved
core address of first word to be saved; if not specified,
entire core is saved
core

address of last word to be saved; if not specified,

entire core is saved

LOAD C]

S];

LOAD C] S1

C2;

LOAD C] Si C2 C3;
LOAD C] Si C2 C3 C4;

Load core image;
CT
owner's account number
=

file address of first word to be loaded; if not specified,
entire 4K is loaded
core

address of first word to be loaded, if not

specified, entire core is loaded
core address of last word to be loaded; if not
specified, entire core is loaded

Run System file;

RS];

name

of file

Run user file;

RUN S];

S]
RUN C]

of file

name

S];

WHERE;

name

of file

Run user file;

owner's account number

name

of file

Stop execution
Type out contents of location counter, accumulator, link,
and switch register

USER;

Type out number of the [ob and devices owned

USER c1,-

Type out device numbers;
CT

user's account number

B-3

Saving and Restoring Binary User Programs (Cont)
SWITCH Cl;

Set switch register;
Cl

word to be set

Switchboard
SET Ll L2 Cl L3 C2;

Set bit in Permission or Switchboard Table;
L1

for Permission Table

for Switchboard Table

K for keyboard

for user program

keyboard or program number
for input buffer

0 for output buffer

RESET Ll L2 Cl L3 C2;

receiving buffer number

Clear bit in Permission or Switchboard Table;

parameters are as in SET, above
READ LT L2 Cl L3 C2;

Read bit in Permission or Switchboard Table;
parameters are as in SET, above

DUPLEX;

Echo typed characters on printer;

ALLOW c1,-

Permit console Cl to output on this console;
Cl

UNKCL

console number

Output to console CT;
Cl

console number

B-4

APPENDIX C

SUMMARY OF IOT INSTRUCTIONS

PROGRAM CONTROL
6000

SIM

6001

ION

6002

Set Interrupt Mask
Interrupt Turn On
Interrupt Turn OFF
Read Interrupt Mask

6005

IOF
RIM
SWM

6006

CWM

6007

RWM

Set Wait Mask
Clear Wait Mask
Read Wait Mask

6200

CKS

Check Status

6402
6403
6404

SLV

Slave A Console
Unslave A Console

6003

UNS
SSP

Set Switchboard and Permission Tables

641 0
641 1

WAIT

Wait

URT

User Run Time

641 2

TOD

Time Of Day

641 3

RCR

Return Clock Rate

641 4
641 5
641 6

DATE
SYN
STM

Date

Quantum Synchronization
Set Timer

6420
6421
6422
6430
6440
6442

TSS

Skip On TS8

USE

CON
SSW

User
Console
Set Switch Register

ASD

Assign Device

REL

Release Device

7402

HLT

Halt

7404

OSR

OR With Switch Register

FILE CONTROL
6600

REN

Rename File

6601

OPEN

Open File

6602

CLOS

6603

RFILE

Close File
Read File
Protect File
Write File
Create File
Extend File
Reduce File
File Information

6604

PROT

6605

WFILE

6610

CRF

6611

EXT

6612
6613
6614
6617

ACT

Segment Size
Account Number

6616

WHO

Who

RED

FINF
SIZE

INPUT BUFFER CONTROL
6030
603 1

KSR

Read Keyboard String

KSF

6032

KCC

6034

KRS

6036

KRB

Skip On Keyboard Flag
Clear Keyboard Flag
Read Keyboard Buffer Static
Read Keyboard Buffer Dynamic

6400

KSB

Set Keyboard Break

6401

SBC

Set Buffer Control

Flags

OUTPUT BUFFER CONTROL
6040

SAS

6041

TSF

Send A String
Skip On Teleprinter Flag

6042
6044

TCF

Clear Teleprinter Flag

TPC

Load Teleprinter and Print

6046

TLS

Load Teleprinter Sequence

HIGH-SPEED PAPER TAPE READER AND CONTROL (TYPE PC02)
6010
601 1

6012
6014

RRS

Read Reader String

RSF

Skip On Reader Flag

RRB

Read Reader Buffer

RFC

Reader Fetch Character

HIGH-SPEED PAPER TAPE PUNCH AND CONTROL (TYPE PC03)
6020

PST

Punch String

602 1

PSF

6022

PCF

Skip On Punch Flag
Clear Punch Flag

6024
6026

PPC

Load Punch Butter and Punch Character

PLS

Load Punch Buffer Sequence

DECTAPE CONTROL (TYPE TC01)

6764
6771
6772

DTX A

Load Status Register A

DTSF

Skip On Flags

DTRB

Read Status Register B

AUTOMATIC LINE PRINTER AND CONTROL (TYPE 645)

6651
6652
6654

LSE
LCB

666 1

LSD

Skip On Line Printer Error
Clear Printer Buffer
Load Printer Buffer
Skip On Line Printer Done Flag
Clear Line Printer Flags
Clear Format Register

LLB

6662

LCF

6664

LPR

INCREMENTAL PLOTTER AND CONTROL (TYPE 3508)
6501

PLSF

6502

PLCF

Skip On Plotter Flag
Clear Plotter Flag

6504

PLPU

Pen Up

6511

PLPR

Pen Right

6512

PLDU

Drum Up

C-2

INCREMENTAL PLOTTER AND CONTROL (TYPE 3508) (Cont)
6514

PLDD

Drum Down

6521

PLPL

Pen Left

6522
6524

PLUD

Drum Up

PLPD

Pen Down

CARD READER AND CONTROL (TYPE 45])
6630

RCS

Read Card String

6632

CRSF

Skip On Card Reader Flag

6634

CERS

Read Card Equipment Status

667T
6672

CRRB

Read Card Reader Buffer

CRSA

6674

CRSB

Select Alphanumeric
Select Binary

APPENDIX D

REQUIRED MODIFICATIONS

The PDP-S/I or POP-8 computer must have the following KT08/I time-sharing modifications
to be used in a

TSS/8 system.

UF is a l-bit register that specified Monitor (UF:O) or
(Ule) mode. In Monitor mode all instructions are legal; in user mode HALT, OSR, and IOT
instructions are trapped via the program interrupt system. UF is cleared by the LOAD ADDress switch.
a.

USER FLAG REGISTER (UF)

SAVE FIELD REGISTER EXTENSION

user

(SF6)

When a program interrupt occurs, this bit

is cleared and then loaded from the UF.

The U8 serves as a l-bit input buffer for the UF. All
transfers into the UF are made through the UB, except transfers from the computer console switches.
The Change User Flag (CUF) instruction loads the UB with the value contained in the Memory Buffer
(MB). The Restore Memory Field (RMF) instruction transfers the contents of SF6 into the UB to restore
the UF to the condition that existed prior to a program interrupt. The UF is cleared by the LOAD
c.

USER BUFFER REGISTER (UB)

ADDress switch.
The following machine instructions have been changed to operate as indicated.
a.

Name and Mnemonic:

CHANGE USER FLAG (CUF)

Octal Codes: 6264 and 6274
Execution Time:

l.5 ps

Operation: 6264 sets the UF to 0; 6274 sets the UF to l. The next JMP or JMS
instruction causes the appropriate mode to be entered.

Symbol:
b.

MB8

Name and Mnemonic:

SKIP ON USER IOT (SKIOT)

Octal Code: 6245
Execution Time:

1.5 ps

Operation: HALT, OSR, and IOTs when executed with UF=l, sets the user IOT
(UIOT) flag and, if the program interrupt is enabled, causes an interrupt.
c.

Name and Mnemonic:

CLEAR USER IOT (CIOT)

Octal Code: 6204
Execution Time:

1.5 ps

Operation: Clears the user IOT (UIOT) flag.

Symbol:
d.

UIOT

Name and Mnemonic:

READ INTERRUPT BUFFER (RIB)

Octal Code: 6234
Execution Time:

1.5 ps

D-l

Operation:

The contents of the Instruction Field, Data Field, and User Flag held in
the Save Field Register during a program interrupt are transferred into bits
6 through 8, 9 through II, and 5,

Symbols:

SFO-2 *AC6-8,

Name and Mnemonic:

respectively.

SF3-5 *AC9-ll,

SF6 "AC5

RESTORE MEMORY FIELD (RMF)

Octal Code: 6244
Execution Time:

l.5 us

Operation: This instruction is used upon exit from the program interrupt subroutine in
another field. The Instruction Field, Data Field, and User Flag that were
interrupted by the subroutine are restored by transferring the contents of
the Save Field Register into the Instruction Buffer and Data Field Registers
and the User Buffer.

Symbols:

SFO-2 *IB,

SF3-5 "DF,

D-2

SF6 "UB

APPENDIX E
STORAGE ALLOCATION

STORAGE MAP

E.I

A mental picture of the system's storage allocation is illustrated below.

PDP

B/I

CORE MEMORY

FIELD

FIELD 1

’
/

//’
/

/
/

//
/
1

_A:

/l/

///

RESIDENT
MONITOR

USER
PROGRAMS

$//

4K
/

\
\

\
\
\

SYSTEM

INTESSSETER
ERROR

ISJISTTIE‘:

FILE
PHANToM

IZATION

USER

FILE

PROGRAMS

STORAGE

000

PHANTOM

.0.

km“ SYSTEM MONITOR m’l
IG-—~*———~—~SWAPPING

Figure E-I

E.2

AREA

——————-—Dl

TSS/ 8 Storage Map

FILE DIRECTORIES

There are two directories on the disk: the Master File Directory, referenced mainly by the

system, and the User File Directory, referenced by the TSS/8 user.
is to serve as a directory for the UFD.

One of the Functions of the MFD

A UFD is a particular user's own file directory and will contain

the names of programs he has created on the disk.
The UFD itself is a file like any other file except that its filename is a binary number in
combination with a four-letter password.

The leftmost seven bits of the binary combination are used

for the project number, and the remaining five bits are used for the programmer number.
is logged in under a specific

When a user

project-programmer number and references the disk, he is actually re—

ferencing his own area through the UFD having his proiect-programmer number as its name. He may of
course,

specifically code his routine to reference UFD's of other users or the MFD; whether he is success-

ful or not will depend upon the type of protection that has been

specified for the area he is trying to

reference.
An illustration of He file directories is shown below.

MASTER

WORD 1

PROJECT

FILE