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DEC-08-ORTMA-C-D

June 1977

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Document:	lilgliltlall RTS/8 User’s Manual
Order Number:	DEC-08-ORTMA-C-D
Revision:	000
Pages:	163
Original Filename:	https://svn.so-much-stuff.com/svn/trunk/pdp8/src/dec/dec-08-ortma/dec-08-ortma-c-d.pdf

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User ’5 Manual
Order No. DEC—OS-ORTMA-C-D

HTS/8
User’s Manual
Order No. DEC—OS-ORTMA-C-D

Version 28

digital equipment corporation mognord, mossochusetts
-

First

Printing, June
September

Revised:

1974
1975

February 1977

The information in this document is subject to
and should not be construed as a commitment by

change without notice
Digital Equipment
Digital Equipment Corporation assumes no responsibility

Corporation.
for

any

that may appear

errors

in this document.

software described in this document is furnished under a license
used or copied only in accordance with the terms of such
license.

The

and may be

Digital Equipment Corporation assumes no responsibility for the use
reliability of its software on equipment that is not supplied by

DIGITAL.

1974, 1975,

1977

by Digital Equipment Corporation

The postage prepaid READER'S COMMENTS
document requests the user's critical
paring future documentation.

The

following

are

trademarks

DIGITAL

form on the last page of this
evaluation to assist us in pre—

Digital Equipment Corporation:

MASSBUS

DEC

DECsystem—lo
DECtape

PDP

DIBOL

05/8

DECUS

EDUSYSTEM

PHA

OMNIBUS

UNIBUS

FLIP

COMPUTER LABS
COMTEX

FOCAL

RSX

INDAC
LAB-8

TYPESET-B

DDT

DECCOMM

DECSystem—20

RTS/8

CHIP

RSTS

TYPESET-lO
TYPESET-ll

CONTENTS

Page
Vii

PREFACE

CHAPTER

INTRODUCTION

1.1
1.2

RTS/8

USING

2.1
2.2
2.2.1

THE

CHAPTER

SYSTEM

TASKS

OPERATION

RTS/8

TASK

2-1

RTS/8

UNDER

STRUCTURE

CONCEPTS

2-1

TASKS

2-1

COMMUNICATION

Synchronization Through

Task

the

Use

of
2—2

Flags

2—3

Intertask Messages

2.2.2
2.3

EXECUTIVE

RTS/8

3.1
3.2
3.2.1
3.2.2
3.2.3
3.2.4
3.2.5
3.2.6
3.3
3.3.1
3.3.2
3.3.3
3.3.4
3.4
3.5

1-1
1-2

DESCRIPTION

REAL-TIME

Event

CHAPTER

1-1

INTERNAL

EXECUTIVE

USED

SEND

WAITE

SENDW

—

POST

Example of
ERS

USED

BLKARG

UNBARG
SUSPND
RUN

USING

3-1
3-1

EXECUTIVE

BETWEEN

TASKS

3-2
3—3

Flag

3—3
3-3

Receive Message

Post

RTS/8

COMMUNICATE

Send Message
Wait on Event
Send and Wait

RECEIVE

3-1

REQUESTS

COMMUNICATION WITH THE
ERS

2-5

TABLES

TASK

Event
ERS

3-4

Flag

for Message and Event

Flags

SET AND CLEAR TASK FLAGS
Block Task for Specified Reason

Unblock Task for Specified Reason
Suspend a Task's Execution
Run a Task
-

INTERRUPTS

EXECUTIVE

RTS/8

3—5
3-6
3-6
3-8

3-8
3-8
3-9

REQUEST WAIT STATES

3-12

RTS/8

SYSTEM TASKS

4-1

4.1
4.1.1
4.2
4.2.1

CLOCK

HANDLER

4—2

4.2.2
4.2.3
4.3
4.4
4.4.1
4.4.2
4.4.3
4.5
4.6
4.6.1

Examples of Clock Handler Calls

4—4
4-4

TERMINAL HANDLER

Additional Assembly Parameters Affecting
Terminal Handler Properties
Useful Equates in the Parameter File
Examples of Terminal Handler Messages

4—7
4-9
4-9

HANDLERS

4-10
4-11

Floppy Disk Handler

4-13

LINCtape Handler
Example of Mass Storage Handler Call

4-16

LINE

PRINTER HANDLER

MASS

STORAGE

OS/8

4-19

SUPPORT TASK

Mapping

4-18

POWER FAIL TASK

of Fields with
iii

08/8 Support Task

4-20

CONTENTS

(Cont.)

OS/8
RTS/8 COMMUNICATION
Using the OSBCOM Task
other Techniques
-

.1
‘.2

4.9.1
4.9.2
4.9.3
4.9.4
4.9.5
4.9.6
4.9.?
4.9.8
4.9.9
4.9.10
4.9.11
4.9.12
4.9.13
4.10
4.10.1
4.10.2
4.11
4.12
4.13
4.13.1
4.13.2
4.13.3
4.13.4
4.14
CHAPTER

(OSBCOM)

05/8 FILE SUPPORT TASK
UNIVERSAL DIGITAL CONTROLLER/INDUSTRIAL
CONTROLLER SUBSYSTEM (UDC/ICS) HANDLER
AO
Analog Output
AI
Analog Input
DO

Digital Output

DI
GC
EC
RC

Digital Input
Generic Code
Enable Counter
Read Counter

Disable Counter
Enable Contacts
ECT
DC

CS
DCT

Change

of State

Disable Contacts
UDC/ICS Assembly Parameters
UDC/ICS Error Conditions

CASSETTE HANDLER
Handler Function
Utility Function
CASSETTE

FILE SUPPORT
PDP-8A NULL TASK

HANDLER

KL8-A SUPPORT
Executive KL8—A Support
TTY Task KL8-A Support
KLB-A Support for the 08/8 Support Task
KL8-A Support for a User Task

EXIT TASK
MONITOR CONSOLE

ROUTINE

[.1

MCR COMMAND ARGUMENTS

MCR COMMANDS
.l
.2
.3
.4

DAte [mm/dd/yyyy [,Time-of—dayll
TIme [Time-of—day]
NAme Task-ID,Newname

REquest Task-ID

[,(@Time-of-day

Interval)

“T T NNH

[,Interval]]

STop Task-ID
DIsable Task-ID
ENable Task-ID
CAncel Task-ID

IU1U1U'IU1U1U'IU1U101U'IUIU'Icocon-00chWNNNNN -‘I—‘I—‘F—‘I—‘KOCDNQUIhWNI—‘O
o

SYstat

OPen Address

EXamine Address

CHAPTER

[Task-ID]
[,Count]

[,Count]
DEposit Address,Word [,Word]
POst
EXIT

MCR ERRORS
NONRESIDENT

MCR

ASSEMBLING AND LOADING TASKS
PARAMETER FILE

[,Word]

Address

STRUCTURE

Executive Specifications
iv

FOR

RTS/8

....

U'IU'IU1U1U'IU‘IU1U1U1U‘IU'IU1UIIIIIIImmmmpnpbw
0‘

|-'

mm NH

CONTENTS

(Cont.)

"U m LG ('0

6.1.2
6.1.3
6.1.4
6.1.5
6.2
6.3
6.4
6.5
6.6
6.6.1
6.6.2
6.6.3
6.6.4
6.6.5
6.6.6
6.6.7
6.6.8
6.6.9
CHAPTER

CHAPTER

Task

Definitions

System Task Specifications
System Wide Definitions
Task Setup

RTS/8 SYSTEM
OS/8 BITMAP PROGRAM
RTS/8 TASK PROGRAM
CONTROL FILES UNDER RTS/8

CREATING AN
USING THE
SAMPLE
USE

RTS/8

SYSTEM TASK PARAMETERS.
Clock Handler Parameters

Swapper

Parameters

Terminal Handler Parameters
Monitor Console Routine Parameters

08/8 Support

Task

ImmmmmmllllH+4u>q~du1ncuam

Parameters

KL8-A Support Parameters
Line Printer Handler Parameters
DECtape Handler Parameters
EXIT

Task

NONRESIDENT

7.1
7.1.1
7.1.2
7.1.3
7.2
7.2.1
7.3
7.3.1
7.3.2
7.3.3
7.4
7.4.1
7.5

OVERVIEW

TASKS

Writeable Tasks

Checkpointable

Tasks

Interaction Between Tasks
MEMORY
FREE

PARTITIONS

Command

NONRESIDENT

TASK

INITIALIZATION

for Nonresident Tasks

Parameters

Assembling Nonresident Tasks
Creating the SAVE Image File
INITIALIZATION FOR PARTITIONS

PARAMETER

Information

General

NONRESIDENT

TASK

DEMONSTRATION

8.1
8.2
8.2.1
8.2.2
8.3
8.4

MODIFIED

ADVANCED

IMPLEMENTATION

l—l

PROGRAM

PARAMETER FILE

NONRESIDENT

\l\l\l\l\l\l\l\l\l\l\l\l\l oqmmhwwI—J

(PARAM.PA)

TASK LISTINGS

Nonresident Task NR20
Nonresident Task NR22
ASSEMBLY AND
NONRESIDENT

LOAD

PROCEDURE

TASK ASSIGNMENT

RTS/8

PROGRAMMING

AND

TECHNIQUES

PERFORMING A RESCHEDULE
9.1
9.1.1
Writing Delicate Code
9.1.2
Inhibiting Task Switching
9.2
EXECUTIVE REQUESTS FOR ADVANCED APPLICATIONS
WAITM
9.2.1
Waiting for Multiple Event Flags
WAITX
Wait for Exactly This Event Flag
9.2.2
DERAIL
Derail a Task's Execution
9.2.3
9.2.3.1
Dangers of DERAIL
Restrictions Using DERAIL
9.2.3.2
STARTING PARTITIONS AT AN ARBITRARY BOUNDARY
9.3
9.4
DIRECT REFERENCES TO SYSTEM TABLES
-

i—‘O

EXECUTION

\OKDOLOKOKOKDLDOKOKD m\l\l\lU1U'lJ>-J>Ni-‘l—‘
I

CONTENTS

(Cont.)

Page
APPENDIX A

RTS/8

DISTRIBUTED

RTS/8

COMPONENT

APPENDIX C

RTS/8

FLOWCHARTS

C-l

APPENDIX

RTS/8

ASSEMBLY

D-l

APPENDIX

EXECUTIVE

APPENDIX

SOURCE

A-l

FILES

SIZES

B-l

ERROR MESSAGES

INTERNAL

TASK

E-l

TABLES

GLOSSARY

Glossary-l
Index-l

INDEX

FIGURES

FIGURE

2-l

Message Format and Linking of Messages

7-1
B-l

Nonresident Task

E-l

2-4
7-2

Implementation

RTS/8 System Memory Map
Allocation)

(Default Memory

Executive

Table

Internal

Task

B—4

E-5

Structure

TABLES

TABLE

l-l
2-1
3-1
3—2
3-3
4-1
9

B-l
B 2

RTS/8 System

Tasks

1—2

Summary of Event Flag States
Summary of Executive Requests
Names for Specifying WAITBITS
Summary of Wait States Incurred by Executive
Requests
Summary of Terminal Handler Assembly Parameter

Symbolic

Default Values
Summary of Task

3-12
4

Switching Flag

RTS/8 Component Sizes
MCR

2-3
3-2
3—7

Component Size

(TSWFLG)

States

B—l
B

9
4
5

PREFACE

This manual

describes the PDP—8 Real-Time
(RTS/8).
System
Operating
of
PDP-8 assembly language programming (PAL8) is essential
Knowledge
the
user
for a complete understanding of this manual.
In
addition,
should
be
with
familiar
real—time
systems in general and with the
The
operation and use of the development system for the PDP—8, 08/8.
in
information
Chapter 9, "Advanced RTS/8 Programming Techniques" is
has
It should be read after the user
for the experienced RTS/8 user.
with
RTS/8.
familiarity
gained
This

version

the

has

to
and
expanded
enlarged
The Major features include
new
two
KL8—A
EXIT
PDP-8/A
Support,
Task, and
Executive Requests.
Other features are the nonresident implementation
of the MCR, UDC/ICS support, an OS8COM facility that allows
the
08/8
system to talk to an RTS/8 task, and control files that allow the user
to efficiently make multiple task copies.
been
RTS/8 flowcharts have
added to show system operation.

incorporate

The

several

following

PDP—8

manual

new

been

RTS/8 features.
the
Null
Task,

handbooks

will

helpful

for

review

and

reference:
INTRODUCTION
SMALL

OS/8
UDC8

PROGRAMMING

(DEC-OB-XINPA-A—D)

COMPUTER HANDBOOK (90P45)
HANDBOOK (DEC-SB—OSHBA-A-D)
UNIVERSAL

DIGITAL

CONTROL

SUBSYSTEM

MAINTENANCE

MANUAL

(46H745)
PDP-8A MINICOMPUTER HANDBOOK (EB0621976)
ICS8 INDUSTRIAL CONTROL SUBSYSTEM MAINTENANCE

vii

MANUAL

(EKOICSSMM)

CHAPTER

INTRODUCTION

DESCRIPTION

RTS/8

1.1

of
family
compact real—time system designed for the PDP-8
This system allows up to 63 tasks to
(except the PDP—8/S).
basis.
concurrently and compete for resources on a fixed priority

RTS/8 is

processors
run

It
be used for a wide
can
processes must be monitored

range of applications in
As with
and controlled.

which

other

of
real-time

number

permit

the

and
The RTS/B Executive
controls
execution
interaction
among
tasks.
The
Executive
decides
which tasks should run (based on
priorities of the runnable tasks), and services the tasks by means

all

systems, RTS/8 responds to physical or conceptual events
timely execution and,scheduling of tasks.

Executive

the

(ERs).

Requests

tasks
basic program unit within
RTS/8.
RTS/8
system
The
in Table 1-1.
and
their
file
names
are listed
A resident
task
system supports both resident and nonresident tasks.
a nonresident
task is one in which the
resides permanently in memory;
is
and
device
storage
major portion of the task resides on a mass
loaded
into
that task becomes executable.
when
memory
only
Using
same
nonresident tasks permits portions of several tasks to share the
areas of memory,
providing economical use of memory.
A

task

the

(DEC-supplied)

most
standard
RTS/8 includes system tasks that control
A full complement of peripherals is supported,
devices.
and RK8—E moving—head disks, DF32
and
RF08
fixed-head

DIGITAL

I/O

including

RK8
TC08
LS8E

disks,

floppy disk,
LINCtape, DEC cassette, and LE8 and
line printers (RTS/8 does not
TD8E
The
Monitor
support
DECtape).
Console
Routine
(MCR) task provides an interface between the user at
the console terminal and the system.
The MCR provides the user with a
series of commands to control, inspect, and, to some extent, debug the
The MCR commands are straightforward and easy to
use.
They
system.
the
to schedule and execute tasks at specified intervals,
user
allow
suspend task execution, and print system status reports.
DECtape,

RX8

the
system task also is provided that allows a single copy of
08/8
in
the
to, run
system
background,
creating a real-time
With 08/8 in the
the
foreground—OS/8 background system.
background,

operating
user

The

only

has the facilities for program assembly, debugging, and editing.
minimum RTS/8 hardware configuration
for
a
required
foreground

system

PDP—8

family

processor,

4K words

of memory,

and

A
terminal capable of papertape
of
input.
capable
system
a
real-time foreground and 08/8 in the background requires a
running
PDP-8 family
with
KM8-E
or
TSS—8
Time
KM8—A,
processor
Sharing
a mass
options,
storage device (such as an RK8E cartridge disk or RX8
floppy disk), and two terminals (one must be dedicated to 08/8
system

console

execution).

’

l-l

INTRODUCTION

RTS/8 tasks are created by editing the RTS/8 master parameter file to
a parameter
file that describes the user's particular system.
produce
Task source files are then assembled with the
edited
file
parameter
The assembler can run either under 08/8, or
using the PAL8 assembler.
Then using
ABSLDR
under
the 08/8 support system under RTS/8.
OS/8,
all task binaries are joined into a complete RTS/8 system.
Table

l—l

RTS/8 System Tasks

Task

File

Name

Task

Name

System parameter file with
equates blank. Appropriate

PARAM.PA

inserted

values

should

create

specific parameter files.

RTS/8 Executive
Monitor Console Routine
Null task
08/8 Support Task
OS/8 File Support Task
Power Fail Task
Clock Handler Task
Terminal Driver Task
Line Printer Driver Task
TC08 DECtape Driver Task
RK8 Disk Driver Task
RK8E Disk Driver Task
RF08/DF32 Fixed—Head Disk Driver
Task
Cassette Driver Task
Cassette File Support Task
Universal Digital Controller/Industrial
Controller Subsystem Handler Task
Floppy Disk Handler (lst controller)
Floppy Disk Handler (2nd controller)
Floppy Disk Handler (3rd controller)
Floppy Disk Handler (4th controller)
LINCtape Driver Task
Nonresident Task swapper
Null Task for PDP-8A
Exit Task

RTS8.PA
MCR.PA

MCR

Function

‘

null
088

MCR.PA

task

OSBSUP.PA
OSBSUP.PA

OS8F
PWRF

PWRF.PA

CLOCK

CLOCK.PA

TTY

TTY.PA

LPT

LPT.PA

DTA

DTA.PA

RK8

RK8.PA

RK8

RF08/DF32

RK8E.PA
RF08.PA

CSA

CSA.PA

CSAF

CSAF.PA

UDC/ICS

UDCICS.PA

RX8A
RX8B

RXOlRT.PA

RX8C
RX8B

RXOlRT.PA
RXOlRT.PA

LTA

LTA.PA

RXOlRT.PA

SWAPPER

SWAP.PA

NULL8A

NULL8A.PA
EXIT.PA

EXIT

1.2

REAL-TIME

SYSTEM

OPERATION

software
that
allows
a
framework
memory, CPU time, and peripheral devices)
task
is
a
to be shared by several tasks.
of
Basically, a
portion
a
task is defined by
machine
code that performs a specific function;
definitions
of
and
convention since it overlaps with the
"program"
"subroutine."
A

multiprogramming

available

resources

system

(such

state
of
execution
Multiprogramming allows many tasks to be in some
If a task cannot use available central processor time
simultaneously.
is
because it is waiting for
I/O
(or
operation
completion of an
the
central
can be
other
some
blocked
condition),
processor
by
thus
switched to another task to use the available
time,
increasing
system efficiency.

INTRODUCTION

Most
at

real-time systems
times
or
varying

bound

1/0 bound.

tasks

these

cannot

required to
frequencies and

are

machine

run

resources

series

poorly utilized during the periods
most
tasks
real—time
are
addition,

should
to

wait

not

finish

priority

be efficiently
used,
central processor will

In
bound.
are
I/O
time-critical and
essentially
task
a
bound
slow, less important I/O or compute
and
a
Thus,
being executed.
multiprogramming
maximum
provide
scheduling the central processor

real-time

addition
internal

to
or

suspend the
deals

are

since the
the tasks

scheme for
utilization.

resource

Thus,

for

before

that run
serve a group of tasks
alternate between being compute

with

in
that
must,
system is a multiprogramming system
multiprogramming features, respond quickly to critical
external events.
The
is
to
real-time
system
required
operation of a less important task and start the task that
the

the

critical

event.

scheme establishes the relative importance of various tasks
This allows a less important task to be interrupted to
For
a
fixed
permit execution of a critical real-time task.
RTS/8,
scheme
was
chosen
such
a
because
is simple and
scheme
priority
A

priority
the

system.

reliable,

and

requires

low

scheduling

1-3

overhead.

CHAPTER

USING TASKS

2.1

THE

STRUCTURE

RTS/8

UNDER

TASKS

is the controlling program
in
an
RTS/8
System.
Executive decides which task should run based on the priorities of
the runnable tasks (those tasks not waiting for completion of any
1/0
It also provides services to the tasks by means of
or
other events).
Executive Requests.
Executive Requests are discussed in Chapter 3.
The
The

RTS/8 Executive

in an RTS/8
System.
and must account for
A
task
once
number,
system tasks within the total number of tasks.
cannot
the execution of the program, since
assigned,
change
during

The

user

can

RTS/8

assigns unique task numbers to each task
assign up to 63 (77 octal) task numbers,

uses

fixed

Task

priority system.

numbers

the

serve

following

purposes:
1.

The

task

number

various
task.

used

by the RTS/8 Executive

tables

system

which

The task number is used by
reference a particular task

Requests

(such

The
the

number

task
task

sending

number,

contain

other

tasks

the

index to
each

about

system

the
higher the

task's

priority

priority
of

the

the
task.
—

The Executive uses five internal tables to maintain information
A brief description of these tables is
the tasks in the system.
in Section 2.3.

2.2

CONCEPTS

RTS/8 is

TASK

performing certain Executive
message).
when

determines
the

information

lower

about

given

COMMUNICATION

the
task
i.e.,
driven,
highest priority runnable
continuously until it is completed or some event or condition
condition
Another change or
in the system causes it to be suspended.
event

executes
can

Tasks can be self-starting if assembled to
task.
started by another task, or started by the user
terminal console using the MCR task.
RTS/8 performs two main
task communication, as follows:

reactivate

run

the

system startup,

types of
1.

Task

Intertask

synchronization through
messages

the

use

Event

Flags

USING

2.2.1

Task

TASKS

UNDER

Synchronization Through

RTS/8

the Use of Event

Flags

Whenever two processes occur independently, one process
to
need
may
wait
until
the
of
execution
the
other
is finished.
This can be
illustrated by using the PDP—8 terminal interface as an example.
The
PDP—8, when ready to generate the first character, alerts the terminal

instruction.
PDP-8
The
wishes to do further I/O
It cannot
next
character
until
the
immediately.
terminal
raises its ready flag to signal that it is finished printing
When the flag is raised, the
the first character.
PDP—8
then
exits
from the wait loop and proceeds to load the next character.

by issuing

must

wait

now

Load

Teleprinter Sequence

(TLS)

JMP.-l loop if
the
proceed with

TSF;

a
to
Similarly, RTS/8 provides Event Flags as
signalling mechanism
tasks
with
each
other.
An Event Flag is a user-chosen
synchronize

location

that

contains

the

status

event.

The

events

are

either

1)
physical
processes such as a clock ticking or a valve closing, or
2) conceptual occurrences such as a certain string of characters typed
the
or
a
task for execution.
Like device
by
operator
scheduling
state,
completed
flags, an Event Flag can signify either a busy or a
defined as PENDING (>0) and FINISHED (=0), respectively.
Thus, a task
task via a message to perform a
can direct another
action,
specified
which time it sets a mutually—agreed upon Event Flag to the PENDING
When the second task has completed
it
the
action
value.
specified
the
this is known as Posting
sets
Event Flag to the FINISHED value;
As a simple example,
if
the
first
the Event Flag.
task
has
been
waiting for the Event Flag with the instructions:
at

then

from
has

TAD

Event

SZA

CLA

JMP

.-2

Flag

/LOAD EVENT FLAG IN
/IF EVENT FINISHED,
/KEEP TRYING

the Posting of the Event Flag will
its
loop, continuing on with the
completed its processing.

AC
SKIP

cause

the

knowledge

first
that

to
task
the second

exit
task

Since this loop ties up the PDP-8 processor, Event Flags
under
RTS/8
have an additional state, WAITING (<0).
Using the example just cited,
to
task
tell
the addition of the WAITING state now allows the first
WAIT
that
it
wants
to
until the Event Flag
the
Executive
RTS/8
is
FINISHED.
The
monitor
signifying the status of the second task
of the waiting task‘s PC and sets the Event Flag
the
contents
saves
The Event Flag is set
to
the
Wait bit in its Task Flags Table Word.
The WAITING state for an Event Flag is octal 4000 plus
WAITING state.
When the Event Flag is POSTed via
an
the waiting task's Task Number.
RTS/8 Executive Request call, the task WAITING for it is automatically
taken out of Event Flag Wait by RTS/8.
(If no other blocking bits are
is again runnable, and will resume execution
the
task
set,
waiting
when higher priority tasks are blocked.) WAITE is the mnemonic for the
RTS/8 Executive Request that Waits for an Event Flag.
This

code

would

look

follows:

CAL
WAITE
event

All

flag

Executive

Event

Flag

Requests

states

are

shown

described fully
in Table 2-1.

2-2

Chapter

summary

USING TASKS

UNDER

RTS/8

2—1

Table

Summary of Event Flag States

Event

Flag

FINISHED

2.2.2
Just

(posted)

PENDING

WAITING

Intertask
as

Value

State

Event

(4000

Task

No.)

Messages

Flags

under

RTS/8

analogous

are

hardware

device

hardware
are
to
I/O
data—sending
messages
analogous
start
a
instructions (for example, TLS).
That
task,
is,
messages
is
WAITING for a message, and at the same time,
the
task
providing
to
are
transmitted
the
task.
by
they pass information
Messages

flags,

Executive

Requests.

RTS/8 message consists

of a three—word Message Header
followed
by
of contiguous words of information to be exchanged between
two tasks.
The Message Header is
used
The
RTS/8.
exclusively by
first
word
of
the Message Header is the Event Flag for the message.
to
When the message is sent, the RTS/8 Executive sets the Event
Flag
PENDING state.
This signifies that the message has been sent but
the
No action occurs to the Event Flag upon receipt of
not yet completed.
the
however, RTS/8 requires that the
by the receiving task;
message
when
it
has
action
Event
the
receiver POSTS the
performed
Flag
This
the
(or
specified
implied)
by
message.
posting serves two
An

any

number

purposes:
1.

informs the task which
the requested action

allows

the

message

has
be

the

sent

that

been

sent

message

(the

completed,

and

again

(see

Item

"sender")

below).

uses
received by a task, RTS/8
the
Header to link these
Message
The second word is a CDF
messages together (see Figure 2—1).
(Change
Data
The third
instruction to the field of the next message.
Field)
A second word of 0 signifies
word is the address of the next message.
this is the last message.
that
If the receiving task is not actively
task's
waiting for a message, the message is placed on the
receiving
Input
Message Queue.
Messages are then queued in order of decreasing
from
sent
priority of the sender (increasing task number).
Messages
the same task are queued in the order in which they were issued.

the

multiple
second

messages are
and
third

waiting

words

2-3

USING TASKS

HTS/8 EXECUTIVE

UNDER

RTS/8

MSGTBL

MESSAGE 1

MESSAGE 2

MESSAGE 3

CDF

Event Flag

PTR

CDF

PTR

Message
Header

Message
Content

Figure
The
a

rest

receiving
It

should

into

data

word

noted

that

the

receiver's

Data

the

Event

The

same

Format

and

Linking

Messages

the message can contain any desired information.
Sending
does
not
physically move the message information to the
and
address
task, but provides the receiver with the field

first

the

Message

message

2-1

the message.

the

area.

information
This

has

the

message

message should not be modified by
Flag for the message is PENDING.
message

cannot

sent

not

copied

following implications:

second

the

time

sender

before

while

its

is FINISHED the first time.
Flag
RTS/8 enforces this
SEND
and
by checking the message Event Flag on a
operation
the
into
sender
Event Flag Wait if the message is
putting
Event

still
3.

the

PENDING.

in
store
information
legal for the receiving task to
of
the
In this way, an "answer“ to the
body
message.

be returned without the complications of
sending
to the sender.
back
For example, when a
message
task sends a message to the disk driver task requesting
1/0,
the driver places the error status of the completed operation
in a specific word in the
to
indicate
whether
an
message
error occurred.

message
a

can

return

2.3
The
the

EXECUTIVE

USING

TASKS

TASK

TABLES

INTERNAL

RTS/8

UNDER

information

Executive uses five internal tables to maintain
A brief description of
tasks
in
the system.

about

tables

these

follows:

Description

Table
Task

Table

State

information

Contains

(TSTABL)

contents
at

Task

Flags Table

Task

Input Message Queue
Table (MSGTBL)

time

the

task

such

PC,

the

Link

and

stopped running.

sent
Contains messages
that
have been
to this task.
This table is referred to

simply
Table

the

task's

task
Contains information about why the
is
not
running, i.e., it indicates for
what conditions (blocking or wait
bits)
the task is waiting.

(TFTABL)

Header

Residency

the

Used

(RESTBL)

for

the

Message Table.

this
table
nonresident tasks,
where the task is to reside in
and where it resides on the swap

specifies
memory,

device.

Partition

Table

Used

(PARTBL)

for

contains

nonresident tasks,
information
about

this

table

each memory
and
location

partition, such as length
of the partition.
Memory partitions
shared by nonresident tasks.

The

user

does

not

RTS/8.

However,

Appendix

need
a

know

detailed

the

format

explanation

of
of

tables
these
these tables is

are

use

given

CHAPTER

RTS/8 EXECUTIVE REQUESTS

COMMUNICATION WITH

3.1

RTS/8 EXECUTIVE

THE

Executive
via
Executive
the
RTS/8
in
locations
20—27
every field as a
across
communication region for ERs to facilitate Executive
Requests
The Executive can be called in any field via a JMS
boundaries.
field
The Data Field
20 instruction (designated symbolically as CAL).
(DF)
not
to be any specific value when the CAL is given, since
does
have
Field
the
the code in location 20 sets the DF to
Instruction
(IF),
sets the IF to 0 and jumps to the RTS/8 Executive.
with

communicate
(ERs).
RTS/8

tasks

RTS/8

Requests

uses

of
Most
the
summary of Executive Requests is given in Table 3—1.
The
in
in this chapter.
Executive
are
detail
Requests
explained
in
RESCHD, WAITX and DERAIL Executive Requests are described
Chapter

9.
The

RTS/8 Executive will

from
less

interrupt

than

(location
written

not

the

honor

request

any

task's

interrupted

switch

tasks

arising

Counter

(PC) was
This protects the RTS/8 Executive's entry point
100(octal).
20 in each field) from being destroyed.
User tasks must be

that

instructions

are

never

Program

below

executed

100

any

field.
All

ER's

except

higher-priority

3.2

ERS

USED

The

five

ERs

and

DERAIL

tasks

can

result

their

BETWEEN

TASKS

COMMUNICATE

associated

relinquish

SKPINS

with

the

Intertask

processor

control

action.

Messages

and

the

Event

An example of their
SEND, WAITE, SENDW, RECEIVE and POST.
WAITX
is shown in Section 3.2.6.
use
In addition, a sixth ER
called
is
described
in
Chapter 9, Advanced Programming Techniques (Section
9.2.2).

Flags

are

EXECUTIVE

RTS/8

Table

REQUESTS

3—1

Summary of Executive Requests

Code

Symbolic

Description

Section

Reference

Name

Send

SEND

RECEIVE

Look

for

message
2

Wait

WAITE

message

for

3.2.4

3.2.2

task

Event

3.2.1

receive

and/or

from

task

Flag

posted
3

RUN

Run

task

SUSPND

Suspend execution of

POST

Post

SKPINS

Insert

3.3.4

Event

Flag

code

into

task

3.3.3
3.2.5
3.4

interrupt

skip chain
DERAIL

BLKARG

or
Derail
execution to

Block

from

Send

SENDW

it
UNBARG

task

specific

Force

WAITX

Wait

for

Flag

Format:

Send

9.2.3

running

for

3.3.1

wait

for

3.2.3

from

task

3.3.2

that

running

RTS/8 Scheduler

the

RESCHD

SEND

task's

reason

blocked

3.2.1

address

new

and
message
be received

Remove

force

particular

Event

run

9.1.2
9.2.2

posted

Message

CAL
SEND

TSKNUM
MESSAG

of
field
the
the message located at MESSAG in the
If the receiving
the task whose number is TSKNUM.
is
for
a
sender
and
the
task has a higher priority than
waiting
is temporarily suspended and the receiver runs.
the
sender
message,
WAIT
In this case, the sender is not put
into
state
once
the
any
is
if the Event Flag in location MESSAG is
sent.
However,
message
PENDING (nonzero), meaning the message is still busy from
a
previous
the sender will be put into Event Flag Wait on location MESSAG,
SEND,
and only when the Event Flag becomes FINISHED (zero) will this SEND be
Care should be taken that a message is sent from only one
performed.
is
task as only the last request to send a busy
remembered;
message
the first task can go to sleep in Event Wait permanently.
The

CAL

SEND

sends

instruction

3.2.2

WAITE

Wait

RTS/8

EXECUTIVE

Event

Flag

REQUESTS

CAL

Format:

WAITE
EFLG

The

WAITE

checks

control

returns

changed

the status of location EFLG and if it
If
EFLG is PENDING,
the
caller.
and the calling task is put into Event

WAITING

is FINISHED,
its state is

Flag

Wait.

task or interrupt routine, the
be
task
must
becomes
runnable
The
Event
calling
Flag
again.
to 1) before use in most cases, particularly when a
initialized
(set
The
another
task.
task is initiating an event to be
completed
by
task
must reset the Event Flag before using it again in that
waiting
location

When

the

Event

EFLG

does

Flag

by another

POSTed

not

reset

itself.

NOTE
In

advanced

waiting

user
applications, the
may
for multiple Event Flags (see
Section 9.2.1 for description of WAITM).
In
this case the task will run whenever
is
any one of the Event
posted,
Flags
and not necessarily the one specified in
the WAITE.
To insure that a
particular

Event

Flag

described

3.2.3

SENDW

Send

—

and

is posted, use
Section 9.2.2.

the

WAITX

Wait

CAL

Format:

SENDW
TSKNUM

MESSAG

The

SENDW

exactly equivalent

the

sequence:

CAL
SEND

/SEND

THE

MESSAGE

/WAIT

FOR

RECEIVER TO

TSKNUM
MESSAG
CAL
WAITE

ACKNOWLEDGE

MESSAG

3.2.4

RECEIVE

Receive Message

Format:

TAD

TSKNUM

/ONLY TO
/SENDING

CAL

RESTRICT

ONE

TASK

RECEIVE
0

MADDR,

/MESSAGE ADDRESS STORED
CDF TO MESSAGE
/HERE;
/FIELD IN AC ON RETURN

the AC is zero when the RECEIVE ER is issued,
the
task's
calling
If there are messages in the calling
Input Message Queue is examined.
task's Input Message Queue, the first (i.e., highest—priority)
message
is dequeued and the address of its first data word is placed in MADDR.
If

CDF

the

field

the

message

3-3

stored

the

AC.

RTS/8
If

there

are

time

such

the

messages,
a

EXECUTIVE

task

message

sent

first examine its Input Message Queue
the state of the Input Message Queue.
If

the

Number matches
it
is
found,
message is not

This

allows

Wait

Message

this

task.
However,
Header in field 0
to

until

task may
determine

the RECEIVE ER is issued, the calling task's
searched
for a message whose sender's Task
If such a message
contents of bits 1-11 of the AC.
the queue as specified above;
removed
from
if a

Queue
the
is

placed

when

nonzero

Message

Input

REQUESTS

found,

the

issuing

message

from

only

task

one

given

placed
task

in
Message
received.

Wait.

NOTE

The

following information

useful

When a task is in
advanced
user.
MSGWT, after just having done a RECEIVE,
its
PC
as
stored in the TSTABL points

the

location

containing the CAL.
message comes in, the task
re-executes the RECEIVE ER
and
accepts
the message.
This mechanism is normally
to
the
user.
One
transparent
implication is that no harm is caused by
once
taking a task out of MSGWT because
the
task
starts
it
will
up
again,
re-execute the RECEIVE ER, and
back
go
into MSGWT.
back

Thus,

,when

when
a
Normally, if there are no messages in the Input Message Queue
task
However,
performs a RECEIVE, the task is put into Message Wait.
is
l in bit 0 of the AC (i.e., the AC is negative) when the RECEIVE
a

indicates that the task is not willing to wait.
Thus, with no
none
the
sent
task
Queue
Input
(or
messages in the
Message
by
in bits 1-11 of the AC), the task will then continue to run
specified
The zero AC provides the means
(at CAL +3) with the AC equal to zero.
for the RTS/8 Executive to inform the task that there were no messages
(of the desired type) pending.
issued

3.2.5

POST

—

Format:

Post

Event

Flag
TAD

EFPTR

/POINTER

EFFLD

/FIELD

EVENT

FLAG

CAL
POST
CDF

EVENT

FLAG

field
Event Flag pointed to by the AC, in the
the
specified
by
If its previous state was
is
set to the FINISHED (zero)
state.
CDF,
WAITING, the task that was waiting for it is cleared of its Event Flag
The

ER
If
sets the calling task in a WAIT state.
This
never
of
a
than
priority
higher
waiting for the Event Flag is
task
is temporarily suspended while
the
task,
calling
calling

Wait.

the

task

the

other

run.

the

RTS/8

3.2.6
The

Example of

ERs

for

EXECUTIVE

Message and

Event

Flags

RTS/8 ERs dealing with
Messages
interrupts under RTS/8 have not been
to
There is no
elementary.
advantage

illustrates
Since I/O and

following example

Event
and
Flags.
discussed yet, this

REQUESTS

the

example is
of
the
the
two
tasks
functions
separate, and the entire
keeping
elaborate
subroutine
send/receive structure is being used here as an
A description of the execution sequence follows the example.
call.
Task
A1

CAL

ALOOP,

SEND

/SEND

TASK

MESSAGE

/SEND

TASK

MESSAGE

/WAIT

FOR

MESl
A2

CAL
SEND
B

MESZ
A3

CAL
WAITE

MESSAGE

MESl

JMP

MESl,

ALOOP

ZBLOCK

/LQOP
/MESSAGE l
/RANDOM NUMBERS

15
37
23

MESZ,

ZBLOCK

/MESSAGE 2
/RANDOM NUMBERS

—l
4

Task
Bl

BLOOP,

CAL
RECEIVE
0

/GET

MADDR,

/SAVE

DCA

EFCDF

TAD

EFCDF

.+l

DCA

HLT

TAD

CLA

B8
B9

STA

CLL

TAD

MADDR

B10

CAL

MADDR

RTL

JMP

MESSAGE

/—3 IN AC
/AC POINTS TO
/EVENT FLAG

BLOOP

The

flow of execution in this example depends
on
which
tasks
has
higher
priority.
Assuming that at some time
become runnable and task
A
has
the
higher
priority,

execution

CDF

FOR

POST

MESSAGE

/DECLARE MESSAGE RECEIVED
/CDF TO MESSAGE FIELD HERE
/LOOP

HLT

Bll

MESSAGE

/PUT CDF INLINE
/CDF TO MESSAGE FIELD
/GET lST DATA WORD OF
/MESSAGE (DO NOTHING WITH IT)

POST

EFCDF,

of
both

the
A

two

and

sequence

follows:

Sequence

Reason

Task

has

Task

has

A3
B1

Task

Task
was

For

Execution

higher priority than task B.
higher priority than task B.
has higher priority than task B.
is now in Event Flag Wait
since

PENDING;

3-5

MESl

now

MESl

in WAITING state.

RTS/8 EXECUTIVE REQUESTS

Sequence

Reason

BZ—BlO

A is still
received MESl

waiting;

The

posted MESl and

Task

POST

810

Bll

Bl—BlO

now

This

resumed;
RECEIVes

brings

MESZ

and

POSTS

counter

A3
B

has

"woke

higher priority,

the

for

Task

has

Task

are

then
Task

A's

Bll

The

MESl

and

task

has

higher

of Message
priority, A is
out

runs.

810 sets
effect.

MESl

which

Task

processes MESZ and
returns for more,

and

the

A's

brings

B2-Bll

Wait;

Execution

For

FINISHED

Now

and

is:

task B tries to get another
There are no other messages, so
in Message Wait and A is run.

Wait

POSTed.

execution

Task

message
B
since

other

yet

higher priority than task A.
there
placed in Message Wait since
Task A
messages in its input queue.

sends

POST

not

program
re—execute
the

Reason

Wait;
stopped

MESZ.

will

MESl

sequence

Sequence

BZ—Blo

up"

SEND.

waits

now

WAITING.

now

of Event
Flag
has modified task

that

offending

RECEIVE

out

RTS/8 Executive

task

the

which has higher priority than B.
A continues executing.
A tries to send MESZ again;
B
has
MESZ is PENDING.
processed it;
Therefore, A is put into Event Flag

Execution

For

sends

MESZ

put

but

has

message.
task B is

put

"wakes

Message Wait.

MESl

up"

Since

FINISHED

3.3

ERS

Several

the

loops back

CLEAR TASK

FLAGS

SET

AND

allow

task

USED
ERS

WAITE

has

explicitly

and

set

effect

sends

and

clear

entry of another task, and to set flags
These ERS are BLKARG, UNBARG, SUSPND and RUN.

Table

Flags
entry.

BLKARG

3.3.1

Format:

Block

TAD

Task

for

TASKNUM

Specified
0

/OR

and

MESl

task

again.

in the Task
its own table

flags
in

Reason

SELF

task

CAL
BLKARG
WAITBITS

TASKNUM

contains

to
allowed
that task's
cause

zero,

the

run).

number

WAITBITS

the

blocked

specifies one or
Assuming WAITBITS

(that
bits

is,
be

set

not

is nonzero, this
will
Flags word.
If TASKNUM contains
the specified task to become non—runnable.
the issuing task will be blocked on
the
wait
bits.
specified
Task

3-6

EXECUTIVE

RTS/8

The

TASKNUM=O

form

task
task

the

issuing
issuing

this

of
task
number, the
as

the

action

this

to specify the
to
the
equal

only legal way

blocked;

REQUESTS

TASKNUM

undefined.

Example:
Task

into

placed

TAD

by executing the following code.

Wait

User

(14

CAL

BLKARG
USERWT

Symbolic
a

task

names

the

for

word

condition for blocking
in Table 3—2.

the

specifying

WAITBITS

Table

Symbolic

NONRWT

EFWT

Name

for

Names

3-2

Specifying

Value

4000

2000

unblocking

given

WAITBITS

Meaning
Nonresident
Wait
because it is not

This

task

cannot

run

in memory.

This task is waiting for
an
Flag Wait
a WAITING value
contains
(which
Flag
corresponding to this task) to be POSTed.
Event

Event

RUNWT

1000

Run

Wait

for the
Monitor
SWPWT

0400

EORMWT

0200

the

Event

for

ENABWT

0100

0040

0020

0001

task

cannot

run

This task
Message Wait
Flag to be posted or
whichever happens first.
is

reserved
does

RTS/8

waiting

message

for
not

Message Wait

task"
-

This

commands

task

the
task"

(see Chapter

waiting

this

—

use
use

This
Enable
Wait
task
is
waiting
Enabled.
Use of this bit is restricted
Monitor Console Routine for the "ENABLE
"DISABLE

memory.

—

because

being brought into

This bit
Wait
user—written
tasks.
bit.

DNEWT

This

Event

User

and

MSGWT

process

arrive,
USERWT

ER
RUN
task is waiting for a
with its number in the AC, or
operator to type "REQUEST task" to the
Console Routine (see Chapter 5).

Swap Wait
in

This

—

executed

5).
sent

message.

Task
set

does not exist.
This bit
cleared by a user task.

should

never

RTS/B EXECUTIVE REQUESTS

3.3.2

UNBARG

Unblock Task for Specified Reason

Format:

TAD

TASKNUM

CAL

UNBARG
WAITBITS

contains

TASKNUM

specifies

one

the
or

number

bits

the
be

task

unblock,
in

cleared

and

WAITBITS

task's Task Flags
word
zero
becomes
as
a
result
of
this
task becomes runnable;
if the specified task
the issuing task and
becomes
the
runnable,

If the Task Flags
operation, the specified
has higher priority than
task
is temporarily suspended while
issuing
word.

that

the

higher—priority

task

runs.

This

is a no-op (no
task's number.

issuing

operation)

issued

with

TASKNUM

equal

the

Example:
Task

taken

TAD

out

Wait

User

by executing the

following

code.

(14

CAL
UNBARG
USERWT

SUSPND

3.3.3

Suspend

—

TASKNUM

TAD

Format:

Task's

Execution
SELF

CAL
SUSPND

This

SUSPND

identical

TAD

TASKNUM

action

the

following instructions:

CAL
BLKARG
RUNWT

3.3.4

RUN

Run

Task

TASKNUM

TAD

Format:

CAL
RUN

This

RUN

identical

action

the

following

instructions:

TASKNUM

TAD
CAL

UNBARG
RUNWT

The
can

and

SUSPND

enough
be

RUN

exist because their
An
shorthand version.

ERs

warrant

task

used

function is performed often
example that shows how they

follows.

1000
data
data collection task is to print a report
every
points
When
the
data
without
collection/reduction
process.
interrupting
so
that
the
executed, the Report Generation Task comes up
running,
A

3-8

RTS/8

EXECUTIVE

REQUESTS

In this simplified example,
on
the first data.
occurs
first
report
been
have
already
the data operated on by the
may
report
program
A full example
before
the
next
for
reported.
being
cycle
updated
would require a scheme such as double buffering to protect the data.

Data

DLOOP,

TAD

(-1750

DCA

COUNT

Control

Task
DECIMAL

/1000

CAL

DATALP,

WAITE

/WAIT FOR DATA READY
/CODE TO STORE DATA
/POINT IN BUFFER

DATAEF
.

/GET A DATA POINT
/AND PROCESS IT
/COUNT OFF 1000 POINTS

ISZ

COUNT

JMP

DATALP

TAD

(REPORT
REPORT

/RUN

CAL

TASK

RUN
JMP

DLOOP

/KEEP

COLLECTING

COUNT,

Report Generation Task

/AC=0, SUSPEND
/UNTIL NEEDED
/HAS BEEN RUN

CAL

RLOOP,

SUSPND
JMS

TITLE

/PRINT REPORT
/WITH TITLE

JMP

eliminate

To
a

lower

3.4

interference

priority

USING

RLOOP

than

INTERRUPTS

with

/REPORT OVER-GO
/BACK AND WAIT
the

data

collection,

REPORT

should

have

DATA.

RTS/8

and
hardware
to
receive
dismiss
RTS/8 Executive contains code
and
to perform interrupt—initiated task switching, but it
interrupts
does not provide room for an interrupt skip chain.
Instead, the
skip
is
chain
a
and
is built up dynamically at system
chain
literally
A description of the SKPINS ER is
as
startup time via the SKPINS ER.

The

follows.
CAL

Format:

SKPINS
MODULE
MODULE

processing

the

address

(in

the

module.

3~9

current

field)

interrupt

RTS/8

interrupt processing
MODULE,

EXECUTIVE

module has

(SKP)
MODULE

JMP

CDF

CIF

—

CUR

—

CIF

/DISMISS THE INTERRUPT, MAYBE
/AN EVENT FLAG DEPENDING UPON
/CONTENTS OF AC

POSTDS

Whenever

following format:

—

SKDR

item

the

/THIS WORD GETS A POINTER
/TO THE NEXT MODULE
CONTAINS
/MODULE ENTERED HERE
/CDF CIF TO NEXT MODULE FIELD
/SKIP ON DEVICE READY
/(ONLY IF SKDR REALLY MEANS SKIP
/ON DEVICE NOT READY)
GO TO NEXT MODULE IN
/NOT READY
/CHAIN
SET DF AND IF
/THIS ONE IS MINE
/CORRECTLY
/INTERRUPT PROCESSING

See

REQUESTS

below

task

for

definition

the

instruction.

POSTDS

is broken at
is inserted.
This is
at
time
The
last
system
start—up
only.
module points to the interrupt dismiss routine as its "next
interrupt
In this way, RTS/8 tries to
avoid
module".
superfluous
interrupts.
SKPINS always inserts at the end of the skip chain.
This implies that
of
the Skips in the skip chain are ordered roughly
the
by
priority
which
inserted them, since any SKPINS ERS in a task are usually
task
executed as once-only code at system Start—up time.
executes

Once

user's

there

are

The

interrupt

The

Data

above
3.

before

any

must

clear

Instruction

and

the

module;

interrupt

user

indirect

module

interrupt chain

module

may

the

issue

any

those

are

correct

addressing

not

Skip

interrupt request.

Field
must

I/O

this

jumps

RTS/8

are

the

described

performed.

ERS.

Should
not
when
interrupt module
compute
excessively
are
off.
interrupts
Typical execution time should be under
If considerably more computing than this is needed,
a
75us.
should
be
scheduled to perform it by POSTing an Event
task
A POSTDS instruction is used to wake up the task
from
Flag.
Event

module

Field

interrupt

ER,

interrupt

control
its
receives
(i.e.,
restrictions on its execution:

module
several

interrupt

succeeds),

SKPINS

end
and
the
very
tasks
usually done
by

the

POST

Wait.

Interrupt modules
state

the

not

turn

interrupted

task

must

the
on
because
interrupts
be destroyed by a second

will

interrupt.
6.

of
the
contents
AC,
entry to the interrupt module, the
Data
Field
and
have already been saved, but not the
Link,
of
the
contents
Quotient
Therefore,
(MQ).
Multiplier
interrupt modules requiring the use of the MO should save it,
On

and
7.

then

restore

before

dismissing

the

interrupt.

the
setting
Interrupt modules must dismiss the interrupt by
to
0
and
Instruction
Field
issuing a POSTDS instruction.
An
Event
POSTDS is defined as a JMP I 24 instruction.
Flag
be POSTed when the interrupt is dismissed by setting the
may

3-10

RTS/8

Field

Data

the
the

location

POSTDS.

For

field

CDF

CUR

(EVFLG

CIF

Flag is

Event

the

FIELD

not

must

LOCATION

POST

AND

INTERRUPT

going
be

NOT

EVFLG

the
interrupt
posted by
prior to issuing the POSTDS

cleared

task

might contain

the

code:

initialization

code

(contained

task

that

runnable

time):

system start-up
START,

RTS/8 Paper Tape Punch handler

following sections
In

the
and
placing
Flag
prior to issuing the

Event

THIS
/DF
/EVFLG MAY

/DISMISS

the
instruction.

example,

the

Flag

routine,

For

REQUESTS

example:

TAD

Event

POSTDS
If

EXECUTIVE

CAL

SKPINS

/LINK
/INTO

THE

PUNCH

SKIP

THE

SKIP

CHAIN

/WAIT

FOR

MESSAGE

PTPINT

GETREQ,

CAL

RECEIVE

character

PUNCH,

punch subroutine used by the main body of the task:

O
DCA

/ENTER WITH
/SAVE CHAR
/WAIT UNTIL

TEMP

CAL

CHAR

PUNCH

READY

WAITE
PTPEF
ISZ

PTPEF

TAD

TEMP

/SET PUNCH EVENT FLAG
/TO THE PENDING STATE

PLS

/PUNCH

CHAR

CLA
JMP

PUNCH

/RETURN

Interrupt skip chain code:
PTPINT,

ZBLOCK

PSF
JMP

CDF

CIF

PTPINT

CUR

PCF
TAD

PTPEF,
TEMP,

RTS/8 does

/USED To CHAIN SKIPS
/CHECK PUNCH FLAG
/N0T READY
/SET CORRECT DF, IF
/CLEAR PUNCH FLAG

(PTPEF

POSTDS

/DISMISS INTERRUPT,
/POSTING PTPEF

/PUNCH

INITIALLY

READY

not provide
interrupt skip chain.

mechanism

for

removal

entries

from

the

RTS/8

3.5

EXECUTIVE

REQUESTS

EXECUTIVE REQUEST WAIT STATES

summary of
Table 3—3.

wait

states

generated by Executive Requests is

Table

Summary of Wait

Wait

States

3-3

by Executive Requests

Incurred

Condition

State

shown

Suspended
At

SEND

for

EFWT

none

busy

message

SEND

—

'CAL'
RECEIVE

If no messages
in Input Queue
and AC positive

MSGWT

(No wait
if AC=4000)

EFWT

WAITE

(No wait if
EF 'done')

not

RUN

none

SUSPND

RUNWT

POST

none

SKPINS

Event

'CAL'+3

Flag

FINISHED

'CAL'

task

—

self

'CAL'+2

—

none

—

DERAIL

none

—

BLKARG

any

(given by

task

self

'CAL'+3

argument)
If message

EFWT

SENDW

but
not

EFWT

Event

free

'CAL'+3

Flag

FINISHED

message

busy

'CAL'

UNBARG

none

—

RESCHD

none

—

WAITX

EORMWT

WAITM

any

If specified Event
Flag not FINISHED

(given by

'CAL'

'CAL'+3

argument)

NOTE:

(a)

(10)

'CAL'

denotes

the

Executive

Request.

message

been

POSTED

address

the

CAL

instruction

said to be busy if its Event Flag has
by its previous user.

the

not

yet

CHAPTER

RTS/8

The

SYSTEM

TASKS

tasks
that
control
RTS/8 system includes
system
PDP—8
Also included is
I/O devices.
Digital

standard

provides interactive system
a
of
allows
copy
single

the

from

control

console

the

task

that

terminal

and

most
one

to run in the
monitor
08/8
system
from
tasks;
protected
backgroun d.
Foreground tasks are
background
the
is not true.
reverse
The complete list of system tasks
however,
available in the RTS/8 system is as follows:

Clock

Handler

requests

accepts

—

actions

perform

messages

the

form

the

after

RTS/8
time

specified

has

elapsed.
Console

and

terminal

Line

Non-console
either line

Printer

Handler

Terminal
or

Handlers
character mode.

supports

L88,

—

handle

LS8E,

LP8

single

line

LV8

printer.
Mass

Storage Handlers

from

these

devices

the
of
information
passing
from memory for the RK08 and RK8-E
and RF08 fixed-head disks,
and
TC08
Control

and

moving-head disks, DF32
Data is read and written in
DECtape unit.
block format (400 octal contiguous words).
Floppy Disk Handler
floppy disk.
Handler
LINCtape
LINCtapes.

provides support

supports

both

for

08/8

the

standard

the

use

RTS/8

the

RX8

DIAL—format

and

allows the user to look up, create,
OS/8 Files Support Task
and
delete files in OS/8 directories from a foreground task.
This task, when used with the mass storage handlers, provides
the
to
read or write OS/8 files on mass storage
capability
—

devices.

08/8

Support

Task
in

operating system

—

user

Cassette

user

Handler

—

OS/8

background.

enables the
UDC/ICS Handler
types of UDC/ICS modules.

tape

execution

the

supports

the

allows

the

control

read

the

various

write

data

look

cassette.

Cassette

enter,

File Support Handler
delete files from a

and

—

allows

the

DECcassette

user

CAPS-8

up,

format.

SYSTEM

RTS/8

with
fail
it
Power Fail Task
when used
hardware,
power
for
an
shutdown
when
AC power is lost.
provides
orderly
Also, it allows a programmed restart when power returns.

Exit

Task

before

display

LED

sources

the

allows

making

PDP—8A Null

The

TASKS

exit

Task
of the

user

from

allows the
PDP—8A.

system tasks

message

CLOCK

4.1

issues

and

another

RECEIVE

Special

processing

user

supplied

are

to
as
"handlers"
referred
i.e., when idle they are in the Message
handlers
these
I/O request messages.
I/O operation, it POSTS the Event Flag

tasks

The

perform

RTS/8.

are

count

decimal

the

with
the
RTS/8
system.
completely message—driven,

Wait state.
Other tasks
send
When the handler completes the
associated
with
the
request

ER.

HANDLER

Handler Task can be assembled to
handle
one
of
four
any
The
user
clocks.
selects the clocks by setting the symbol
the parameter file to 0 for KD8-EA/DK8-EC, to l for KWlZ, to
to 3 for DK8—EP.
The Clock Handler accepts RTS/8
2
for
or
PDP-8A,
As the
messages and inserts the entries into an internal clock queue.
The

Clock

hardware
CLKTYP in

become
entries
due, they are removed from the queue, and the request
at
The user fixes the length of
the
is decoded and executed.
queue
time
assembly
by defining the symbol CLKQLN in the parameter file to
for
is
The default value
the minimum number of entry slots.
CLKQLN

20.
The

format

clock

ZBLOCK

CLKMSG,

is:

message

/3 WORDS RESERVED FOR RTS/8
/TASKNO=O MEANS TASKNO=SENDING

COMMAND+TASKNO

TASK

TIMEHI
TIMELo

EXTRAl
EXTRAZ

the
and TIMELO Specify a time interval from
present
of
The user specifies the number of
"system ticks".
a
the
second in the RTS/8 parameter file by
defining
SHERTZ.
The
hardware
tick rate (in ticks per second) is
parameter
HERTZ
CLKTYP
and
determined
are
specified by the parameter HERTZ.
SHERTZ equals the
the
user's hardware configuration.
completely
by
HERTZ must be
an
reciprocal of the software system clock resolution.
for
a
SHERTZ.
the
of
For
exact
parameters
example,
multiple

The

words

TIMEHI

in
terms
system ticks in

time

line—frequency clock might

be:

DECIMAL
HERTZ=

120

SHERTZ=

a
indicating that there will be 10 "system ticks" per second based on
clock.
Such
60-cycle
parameters
might be used if only 1/10 second

resolution is necessary in the Clock Handler.
interval
that can be expressed in TIMEHI and
This is approximately three days if
seconds.
Other
Clock

RTS/8 system tasks
The

Handler.

parameter

file

use

user

equal

the

symbol

CLOCK

Note
TIMELO

SHERTZ=60.

when

this
should
define
to the Clock
Handler's

4-2

the
that
maximum
is (2**24)/SHERTZ

referring
symbol
task

the

number.

the

RTS/8
It

RTS/8

should

system.
COMMAND

undefined

(See
is

if a
for

not

the

parameter

the

file.)

following meanings:
Description

Symbolic
the

POST

MARKTIME

interval
EXTRA2

after

CLKMSG

flag

event

and

EXTRAl,

elapses.
are

the

TASKNO,

ignored.

a
Execute
immediately.
task specified by TASKNO
after the specified interval
elapses.
EXTRAl and EXTRA2 are ignored.

CLKMSG

POST

SCHEDULE

RUN

2000

included

is
of

specified

1000

Handler

description

Clock

type of request and has the

the

Octal

0000

Chapter

TASKS

SYSTEM

the

DERAIL
the
immediately.
TASKNO
into
a
specified
by
subroutine whose address is
specified
in EXTRAl after the specified interval
EXTRA2 is ignored.
elapses.
POST

TIMOUT

CLKMSG

task

3000

SCHEDULE

PERIODICALLY

POST
RUN

a
Execute
immediately.
task specified by TASKNO
elapses,
specified interval

CLKMSG
ER

the

the
this
with the
command
re-queue
place
parameters EXTRAl and EXTRA2 in
This has the
TIMEHI
TIMELO.
of
and
task
effect of running the
specified

after
and

with

periodically

period specified

by EXTRAl and EXTRA2.
7000

CANCEL

Cancel

task

all

the

clock

requests

TASKNO.

specified

TIMELO,

EXTRAl,

ignored.

POST

and
CLKMSG

that

Note

time out.

\-——~k-—J
Command:

—_—|

0 MARKTIME
1 SCHEDULE
2 TIMOUT

3 SCHEDULE PERIODICALLY
7 CANCEL

Task number

Command Word

Format

Clock

Handler

the

TIMEHI,

EXTRA2

are

immediately.

are
the
requests
and that they
deleted
until
space in the queue

actually
occupy

for

not

still

they

RTS/8

SYSTEM

TASKS

The Clock Handler also maintains the current
ticks

until

time-Of—day

(in

system

in
symbolic locations TODH (high—order) and
TODL (low-order) in Page 0 of Field 0.
When this time—of-day
reaches
zero
(i.e., at midnight), it is reset to the quantity -(SHERTZ*86400)
date
word
in
(24 hours until midnight) and an OS/8-format
symbolic
location DATE in Page 0 of Field 0 is incremented by one day.
Note

bits,

midnight),

that in order
SHERTZ must

will

error

for the
be less

while

result

Examples of

4.1.1

quantity
than

192.

assembling

Clock

Handler

CAL

SHERTZ*86400 to be contained in 24
If SHERTZ is larger, an assembly

the

Clock

Handler.

Calls

/WITH A 60HZ SYSTEM TICK RATE,
/THIS CAUSES THE CURRENT TASK
/TO "GO TO SLEEP" FOR 2 SECONDS.

SENDW

CLOCK
SLEEPM

SLEEPM,

ZBLOCK

/MESSAGE HEADER
/SET EVENT FLAG AFTER INTERVAL
/INTERVAL IS 120 (DECIMAL) SYSTEM
/TICKS

0;17o

the

user

2“SHERTZ,

the

value
to
the
170
the
assembler
Changes
expression
preceding sequence becomes configuration—independent.

/RUN THE TASK REPORT ONCE
/EVERY HOUR, INDEFINITELY,
/ASSUMING A 60HZ SYSTEM TICK

CAL
SEND

CLOCK

RATE

RUNMSG

RUNMSG,

ZBLOCK

SCHEDULE

/MESSAGE
REPORT

0;l
64;5654

HEADER

PERIODICALLY

/RUN REPORT AFTER SPECIFIED
/INTERVAL AND PERIODICALLY
/THEREAFTER,
/FIRST RUN IS ALMOST IMMEDIATELY
/(l/60 SECOND)
/PERIOD BETWEEN RUNS IS 216000
3600
/(DECIMAL) SYSTEM TICKS
1 HOUR.
/SECONDS
=

TERMINAL

4.2
The

HANDLER

RTS/8 Terminal Handler handles a Single terminal in either line or
mode.
Input in line mode is terminated by a carriage return
“U
the
RUBOUT
and
and may be edited
an ALTMODE character
using

Character
or

characters.

typed

and

The

prints

line and returns
is terminated by

character
deletes the last valid character
entire
the "U
Character
deletes
the
Character mode input is not-echoed and
the carriage.
overflow of a specified character count.
RUBOUT

backslash;

of
this
If multiple terminals are to
be
handled,
multiple
copies
Handler
must be assembled.
Terminal
Assembly parameters in the body
to
the
handler
will
use
of the handler specify which device codes
its
These
also
access
terminal.
specify whether the
parameters
the
terminal
handler is to be a "console" Terminal Handler, that is,

4-4

RTS/8

SYSTEM

TASKS

The console Terminal
MCR
the
which
program is going to be run.
the
“C
on
is
a
invokes the MCR whenever
keyboard;
typed
For the
nonconsole terminal handlers treat “C as any other character.
console handler, "C wakes up MCR by POSTing an Event Flag.
on

Handler

of
the
Terminal
version
The parameters edited into the distributed
Handler assemble the handler to handle the PDP—8 console terminal as a
the
both
"console" device.
Thus, when the MCR function is required,
MCR
task and the Terminal Handler task must be assembled and included
to
Modification of the Terminal Handler
the RTS/8 system.
as part of
a
VT50
terminal and other features are described in Section
support
4.2.1.
The

format

of messages

Terminal

the

Handler

can

either

the

following:
ZBLOCK

ZBLOCK 3
ASSGN+tsknum

command+length
INBUF
OUTTXT

Description:
Types

text

OUTTXT

and

reads

text

Description:
ASSGN=200

specified by
command,
into

Assigns Terminal Handler to task specified
Deassigns Terminal Handler if tsknum=0

then

INBUF.

Legal Commands, which

can

combined,

are

follows:

Octal

Symbolic

Action

4000

NOPACK

Output text is in
unpacked ASCII, one

Output text is in
packed 6—bit, two

character

characters

per

terminated

2000

NOCRLF

IND

CR/LF

not

OUTTXT

output
NOLINE

word
a

first

0400

per

terminated by

after
1000

specified

type

0000.

the message.

points
of

word

the

Type

not

specified

word
a

00.

CR/LF after

typing

the message.

OUTTXT

is the first
the output text.

word

text.

Input is in character
mode;

Action

terminated

after 'length' input
characters read.

Input is in line mode;
terminated by a CR
ALTMODE (ESC). The
or
length is still tested.

Length

Is a
seven-bit
field
which
the
specifies
maximum
size of the input buffer if input is
in line mode, or the number of characters
to
if
is
in
If
character mode.
input
input
LENGTH—l
input is in line mode and there are
characters
in
the
input buffer, characters
other than carriage return,
RUBOUT
ALTMODE,
“U
and
will
not
be accepted or echoed the
message Event Flag is Posted.

INBUF

if
it
is
pointer to the input buffer;
no
The input buffer is
input is taken.
filled with input characters packed
one
per
word
with
the parity bit (bit 4) forced on.
If input is in line mode, the last
character
of
the line is followed by a zero word (if a
Is

zero,

4-5

RTS/8

OUTTXT

SYSTEM

carriage

return

-l(7777)

word

terminated

the

either

terminated
the
or
a
line)
ALTMODE
an
character
(if

line).

first word of the
text
output
IND=0) or a pointer to the first
word of the output string
ir
(if
IND=1000)
Is

string
the

ASSGN

TASKS

=200

the

(if

field

same

"Assigns"
specified
handler

the
task.

specified

only
task.

the

message.

Terminal
This will

Handler
to
the
the terminal
'from
the
accept
messages
If
another
task tries to
cause

a message
to the Terminal Handler
while
it is assigned, the message will be placed in
the Terminal Handler's
Queue
Message
Input
but will not be removed for processing by the
Terminal
Handler
until
the
is
assignment
released.
The
to
which the Terminal
task
Handler
is
can
the
release
assigned
assignment by sending a message assigning the
No
Terminal Handler to task number
0.
I/O
is
an
operation
performed
by
assignment

SEND

message.
Is

Command

specify

gbits 0-4}

_3 :

Packed ASCII
Unpacked ASCII

CR/LF at end of message
No CR/LF at end of message

7'39

OUTTXT is the first word

Input in line mode
I
Input in character modef

6—bit

field used with the ASSGN
command
task
the
number of the task to
to
be
If
which the terminal is
assigned.
the
is
this
field
is
terminal
zero,
the
terminal
task
to
deassigned
allowing
accept commands from any task.

tsknum

}

}_______J

OUTTXT points to first word

Bit 4 must be a 0

Length (bits 5-11)
If bit 3=1,

no.

of characters to input

If bit 3=0, maximum size of input

Command

and

buffer;

Length

Word

Format

Terminal

Handler

I/O

Mode

RTS/8

SYSTEM TASKS

Unused

Bit 4 must be a 1
Unused
Task Number

Command

4.2.1

Additional

Word

Format

Assembly

Terminal

—

ASSGN

Handler

Terminal

Affecting

Parameters

Mode

Handler

Properties
Several

an
aid
are
as
available to the user
This
section
describes these parameters.
values is shown in Table 3-4.

assembly parameters

the
summary of

using

VT50

TTY

their
=0

task.
default

CTRL/S

treat

not

and

CTRL/Q

in
A

special

characters.
If
this
feature
Support CTRL/S and CTRL/Q.
is enabled, typing CTRL/S while data is being

printed/displayed
data

This

can

the

terminal

will

cause

stop until the next CTRL/Q is typed.
CRT
to
on
fast
terminals
This
screen.
"freeze"
the
1
if
the
user's
must be set
to
is a model VTSO or VT52 since these
will
send
occasionally

used

temporarily
parameter
terminal
terminals

synchronization
computer of their
WIDTH

to
characters
own volition.

the

host

octal number that sets the page
TTY
is
width
characters.
For
currently set to 120(octal) characters.
example, setting the parameter

Where
width

WIDTH

changes

the

60
TTY

characters.

the

page
After
n

terminal,
automatically
type

width

the
out

80(decimal)
are

printed

handler

will

characters

carriage—return

to
is
line-feed.
it
desirable
Sometimes
this CR/LF (for example, when using
suppress
In
direct cursor
this
case,
addressing).
WIDTH should be set equal to 0.

SCOPE

This option is
the RUBOUT key
SCOPE=0

support

used to determine
as
follows:

treatment

RUBOUT
of
mode
provides the normal
(echo rubouts with a backslash).

4-7

RTS/8

SYSTEM

SCOPE=1

TASKS

RUBOUT to move

causes

position,

one

character from the screen.
in
column
1, RUBOUT still
visible effect.
TAB

This

the

physically
If

the

works,

cursor

but

has

is used to simulate tabs
by
of
This
number
spaces.
accomplished via the assembly parameter

option

proper
as

with

tabs.

TAB

not

tabs

spaces.

specifies
support tabs.

that

Fill

are

characters

hardware

the

FILL=0

provides

fill

characters.

FILL=n

sends

line

fill

feed.

range 1—5.
baud VTOSS.

FILL=4

CONSOL

means

CONSOL

wake

this

that

means

the

(nulls)

number n must
recommended

after
in the

for

2400

is
the
handler
being
console terminal(default).

the

for

characters

The

the

follows:

FILL

does

via

supported

assembly parameter

assembled

OLDTTY

the

The

TAB=1

CONSOL

hardware
does
software simulates

that

specifies

support

the
is

follows:

TAB=0

FILL

left

cursor

removing

MCR when

handler
is typed.

will

not

the
use
of
the
old
specifies
was
with
handler
which
supplied
1.
This
handler
has
fewer
RTS/8 version
than
handler but it is a
features
the
new

OLDTTY

two-page

LSBOT

The

shorter.

page

SCOPE,

TAB

effect

when
0

and

using

3-page

terminal

LSBOT

selected

listing of
three—page.

new

0(default)
the
by

use

the

specifies

two-page and

LSBOT

the
handler.

specifies

OLDTTY

old

WIDTH,
VT50,
described herein have no
this handler.

parameters

FILL

causes

OLDTTY

the

new

both

the

the
handler
only
to
be
parameter

listed.
TTFLD

Specifies
for

TTLOC

Specifies
Handler

the

example,

field of the TTY Handler
designates field 2.

the

task;

TTY
the
starting location of
for example, 3000 designates

starting location

4-8

task;

3000.

RTS/8

SYSTEM TASKS

Table

4-1

Summary of Terminal Handler Assembly
Default

Default

Parameter

Values

Meaning

Value

“Q

VTSO

Support “S,

WIDTH

120

Page width of

SCOPE

Rubouts

TAB

Simulate

FILL

CONSOL

"C wakes

OLDTTY

Use

3-page

LSBOT

List

only

TTFLD

Not

echo

fill

characters

80(decimal)

tabs

characters
up

MCR
TTY

TTY

task
task

selected

OLDTTY

as an
default
value, but
given
to
Show that the given
number
assignments for TTFLD and TTLOC load the
TTY
in
1
at
Handler
field
Starting
a

example
TTLOC

5000

location

4.2.2

Useful

Several

be
follows:

can

5000

Equates in the Parameter File

useful
used

equates
when

NOPACK

4000

NOCRLF

2000

(described

sending

messages

if
format.

Used

Section
to

TTY

4.2)
or

tasks.

They

not

6-bit

output message

which

available

are

LPT

output message should

not

are

ASCII

followed

by carriage return/line feed.
IND

1000

Used
the

NOLINE
ASSGN

Used

200

KL8ALINE

4.2.3

400

OUTTXT

points

Used

first

the

input is in character

Used to assign the
only by this task.

100

with

word

for

use

text.

output

KL8-A

device

support

(see

mode.

handler

Section

4.13.2).

Examples of Terminal Handler Messages
HIYA,

ZBLOCK
0
0
TEXT

Sending

the

/MESSAGE HEADER
/PACKED TEXT, END WITH CR/LF,
/NO INPUT
/TEXT TO BE OUTPUT

/HELLO/

above message

the

Terminal

terminal.
4—9

Handler

prints

HELLO

the

RTS/8
ZBLOCK

QUEST,

TASKS

/MESSAGE HEADER
/PACKED TEXT, NO CR/LF,
/48—CHARACTER INPUT LIMIT
/POINTER TO INPUT BUFFER

NOCRLF+60
ANSWER
TEXT

SYSTEM

/TYPE

THE

ANSWER:/

above message to the
Terminal
Handler
prints
the
terminal and inputs a reply without first
The answer obtained from the
above
carriage.
message

Sending

the

ANSWER:

the

printed

terminal

the

ZBLOCK

TYPANS,

/MESSAGE HEADER
/UNPACKED TEXT, INDIRECT,
/NO INPUT
/POINTER TO OUTPUT TEXT

0
ANSWER

LINE

PRINTER

THE

returning
could

by sending the following message:

NOPACK+IND

4.3

TYPE

WITH

CR/LF

HANDLER

or
LV8
LP8
LSBE,
RTS/8 Line Printer Handler outputs to an LE8,
The format of messages to the Line Printer Handler is
line
printer.
but
identical to the format of messages to the terminal handler,
the
INBUF word and the LINE bit are ignored (the INBUF word must, however,
be present in the message).

The

Command (bits 0-4}
0:
._| :

Packed ASCII
Unpacked ASCII

0:
1:

CR/LF at end of message
No CR/LF at end of message

OUTTXT is the first word
OUTTXT points to first word

0:
I:

}

‘

input in line mode
I
Input in character modef

Bit 4 must be a 0

Length (bits 5-11)
If bit
If bit

3:1, no. of characters to input
I
3:0, maximum size of input bufferj

Command

and

Length

Word

Format

—

Line

Printer

Handler

I/O Mode

RTS/8

SYSTEM

TASKS

Unused

Bit 4 must be a 1

Unused
Task Number

Command

4.4

MASS

Word

STORAGE

Format

Line

—

Printer

ASSGN

Handler

Mode

HANDLERS

fixed-head
RF08
DF32
and
for TC08
DECtape,
RK8E moving-head disks, RXOl floppy disks and LINCtape.
or
to
read
All mass storage handlers accept the same message format
write
blocks
on
various
mass storage devices.
However, the Floppy
Handlers

disks,

Disk

are

RK8

available

and

Handler

and

parameters other
in

described
The

format

the

LINCtape Handler

than

the

Sections

4.4.1

of messages

MSMESG,

ZBLOCK

the

herein.

use

These

additional

parameters

are

4.4.2.

and

mass

allow

described

ones

storage handlers is:

UNIT
RW

PAGES

FIELD
’

BUFADD

BLOKNO
STATUS

where:
UNIT

the number of the logical unit on which the operation
is to be performed.
DF32 and RF08 disks consist of only
one
unit.
units
TC08
has
0-7
DECtape
logical
to
its physical units 0-7.
LINCtape has
corresponding
units
its
physical
logical units 0—7 corresponding to
0—7.
RK8
disk
has logical units 0-3 corresponding to
units
its physical units 0—3.
has
RK8E
disk
logical
to the outer
0—7.
Units
0—3
(lower track
correspond
units
units
and
4-7
of
0-3,
number) half
physical
to
inner (higher track number) half of
_the
correspond
RXOl has units 0 or 1
physical units 0—3, respectively.
Is

which

corresponds

the

left

4000

for

and

right

drive,

respectively.
for

write

PAGES

to
transfer
Specifies the number of
(128—word)
pages
100
For example, PAGES=2000 specifies
(times
octal).
the transfer of
or
if
2048
words;
20(octal)
pages
PAGES=0, 40(octa1) pages or 4096 words are transferred.

read

operation,

operation.

SYSTEM TASKS

RTS/8

FIELD

The

the

PUP-8

field

in which

(times

transfer

takes place

RW+PAGES+FIELD word

octal).

For

sometimes

the

transfer
if

example,

field

called

the

takes

place

FIELD=30,

the

function

word

message.

Reserved for task use ——————J
Unit

Unit Word

Read operation

Write operation

Format

—

Storage Handlers

Mass

}

No. of pages to transfer

0-7:

Field of transfer

Reserved for task use

Function Word

the

Mass

address

Storage Handlers

the

buffer

transferred.

BLOKNO

on
the
Is the
number
the
device
from
which
block
transfer
will
All devices are assumed to have
begin.
of
On DECtape, the
first
128
words
256—word blocks.
each of an even/odd pair of 129-word DECtape records are
considered to be a block.

starting

that

storage
the

the

word

that

word

middle

three

are

operation

the

STATUS

handlers
same

on
the
handler sets
completion of
if
the operation is
a
zero
contains
successful, otherwise it will contain a nonzero quantity
of the device status register.
is
the
which
contents
handlers
should
test
Tasks which use the mass storage
the
after
this
word
I/O operation has been completed
to
has
been
Event
POSTed)
(that is, after the
Flag
if
the transfer.
errors occurred during
determine
any
three
All RTS/8 mass storage handlers retry
operations
if
are
encountered
before
times
errors
setting the

operation.

when

BUFADD

STATUS

Note

Format

nonzero.

of
words
to
identical
is performed.

4-12

the

message

the

arguments

RTS/8 mass
OS/8 handler

RTS/8

SYSTEM TASKS

Floppy Disk Handler

4.4.1

RXOl
dual
or
copy of the Floppy Handler can control one single
are
than
one RXOl, multiple copies of the handler
for
more
The format of messages to the Floppy Disk Handler is:
required.

Each

drive;

ZBLOCK

CODE+DEL+MODE+UNIT
RW+PAGES+FIELD
BUFADD

BLOKNO
STATUS

where:
as
an
BLOKNO is
interpreted
Regular condition.
PAGES
is
record
number.
Also,
OS/8
logical
the
number
interpreted in the 08/8 sense to mean

CODE

pages

data

transfer.

The

bit

DEL

ignored.
4000

PAGES
is
Condition.
Sector
Special
Physical
is
is
It
One
sector
transferred.
ignored.
as
specified by BLOKNO which is to be interpreted
TTTTTTTSSSSS.
That
is, the high order 7-bits of
This
BLOKNO represent the physical track number.
number
in the range 0—76 decimal (0-114
must
be

The low order 5 bits of BLOKNO
represent
This number must
number on that track.
the range 1—26 decimal (1—32 octal).

octal).
the

sector

Deleted

DEL

2000

100

marks

should

not

considered.

as
Handle
deleted
data
marks
(if
CODE=4000)
If writing a sector, write deleted data
follows:
Do not note this fact in STATUS word.
indication.
If reading a sector, set bit 5 of STATUS word to a
1 if read deleted
data
In
indication.
such
a
the
STATUS word may be nonzero even though
case,
no physical
error has occurred.
Other STATUS bits

are

MODE

data

relevant

and

STATUS

negative

means

Specifies

transfer

12—bit mode.

Specifies

transfer

8—bit mode.

OS/8 format

hard

error.

12-bit mode.
In 12—bit mode, the
that
an
comprise
OS/8 floppy
sector are packed into the first 96 bytes
of
the
sector, while the last 32 bytes contain random bit
In 8—bit mode, an
on
8-bit
the
patterns.
byte
floppy disk corresponds to the low order 8-bits of
a
12-bit word in memory.
Data in the high order 4
bits of a word in memory is not transferred to the
floppy disk.
64

12-bit

uses

words

12—bit mode, a
12-bit
words
of
contains 128 8-bit
In

UNIT

sector

contains

data.

bytes of

Specifies the drive unit
1.
a

The
dual

number

drive.

4—13

refers

(decimal)
a

sector

data.

number.
to

8-bit mode,

the

unit

may
on

the

0
left

RTS/8

0:
1:

Regular condition
Special physical sector condition

Do not handle deleted

Handle deleted marks

Transfer in 12-bit mode

Transfer in 8-bit mode

Left unit of dual drive

. .a

Right unit of dual drive

SYSTEM

TASKS

marks}

CODE

4000 (bit 0 set to 1) transfers one sector specified by

BLOCKNO as follows:

L
r

Physical track no.
(0-114 octal)

I
T

‘——_|

Sector no. on track

(132 octal)

Unit Word

Format

Floppy Disk

—

Handler

Hard error

Deleted data
INIT done

Parity error
CRC error

Status Word

The

Format

largest legal OS/8 block

block

756

If
is 755 octal.
a floppy disk
is generated.
Use of larger block
results.
Specifying an
illegal
with STATUS
error
4000.

number

Floppy Disk Handler

referenced, an error
numbers may produce
unpredictable
track

sector

may

produce

4-15

RTS/8
The standard

05/8 Interleave Scheme is

OS/8 Logical Block

Track

SYSTEM

(octal)

TASKS

follows:

Sectors

Floppy

(track/sector in decimal)

1/1,

1/3,

1/5,

1/7

1/9,

1/11,

1/13,

1/15

1/17,

1/19,

1/21,

1/23

1/25,

1/2,

1/4,

1/6

1/8,

1/10,

l/12,

1/14

1/16,

1/18,

1/20,

1/22

1/24,

1/26,

2/1,

2/3

2/5,

2/7,

2/9,

2/11

2/13,

2/15,

2/17,

2/19

2/21,

2/23,

2/25,

2/2

2/4,

2/6,

2/8,

2/10

2/12,

2/14,

2/16,

2/18

2/20,

2/22,

2/24,

2/26

3/1,

3/3,

3/5,

3/7

not

used

by 08/8,

and

cannot

accessed

the

12-bit

mode.

4.4.2
The

The

LINCtape Handler

DIAL
and
LINCtape Handler supports both 08/8
of messages to the LINCtape Handler is:

format

LINCtapes.

format

ZBLOCK

MODE+UNIT
RW+PAGES+FIELD
BUFADD

BLOKNO
STATUS
where:
UNIT:

Specifies the LINCtape

unit number

range

7.
MODE=0

Specifies OS/8
contain
block.

200

A LINCtape
is
Mode.
201
words
(octal)

to
presumed
per physical

DIAL

Specifies

=4000

contain

TASKS

SYSTEM

RTS/8

400

Mode.

(octal)

is
presumed
physical block.

LINCtape

words

per

if
LINCtape used is not checked to see
properly formatted for the specified mode.
format
Use
a
physical
improper
LINCtape with
will produce unpredictable results.
The

Note:

is
of

from

data

Read

=4000

Write data

Specifies the
100
(times

PAGES

transfers

20
40
transferred.

pages=0,

the

Specifies

FIELD

takes

LINCtape
of

number

128—word
For

octal).
octal
octal

PDP—8

pages
pages

field

pages

example,
2048
4096

or
or

which

10
octal).
transfer takes place

(times

place
the

FIELD=30,

LINCtape

BUFADD

Is the
starting
transferred.

BLOKNO

Is the block number on
transfer
will
begin.
blocks.
have 256—word

address

the
All
On

the

transfer
PAGES=2000
if
words;
to

BLOKNO
running in DIAL mode,
block
number.
physical
LINCtape

transfer

the

example,
in field 3).
buffer

which
the
assumed to
two

LINCtapes,

consecutive
blocks
comprise
physical
logical block.
Only the first 128 words
physical block contain meaningful data.
When

are

(For

device from
devices are

OS/8

words

one

OS/8

each

represents
this
number of
In

case,

must be even because an even
pages
If
is
PAGES is (incorrectly) odd,
transferred.
if
the
last
is
not
transferred,
except
page
PAGES=1
which
will result in one block (2 pages)
being transferred.
PAGES

STATUS

the

ones complement of tape
check
(checksum).
value 0 means no error.
STATUS is always 0 on
a Write operation.
are
Three
software
retries
Note that the
attempted on a checksum read error.
hardware performs infinite retries on most
errors
not
bad spot on
mounted,
(write—lock-out,
tape
until
tape) and does not return control to
RTS/8
successful.

The

CAUTION

the

the word following the
buffer
is
temporarily
is
destroyed while a LINCtape operation
The
is
location
then
progress.
restored
of
the
upon
completion
since
However,
operation.
RTS/8 is a
real-time system, code may be
executing
while the tape operation is in progress.
The user must make sure that
this
word
never
referenced while the LINCtape
is being used.
Under
no
circumstances
In

08/8 mode,

the

Should

the word

buffer

belong

following
another

4-17

the end of
task.

the

RTS/8

05/8 mode

DIAL mode

SYSTEM TASKS

Unit number

Unit Word

Example of

4.4.3

Mass

Format

—

LINCtape Handler

Storage Handler

Call

CAL
SENDW
DTA

/SEND A MESSAGE TO THE DECTAPE
/HANDLER
/AND WAIT FOR COMPLETION
/CHECK THE STATUS OF THE OPERATION

DTAMSG
STATUS
SZA CLA

TAD

JMP

/BAD
/OK

ERR

‘

DTAMSG,

ZBLOCK

ERROR

CONTINUE

ROUTINE

PROCESSING

/MESSAGE HEADER
/DECTAPE UNIT 4
/WRITE 256 WORDS FROM FIELD
/ADDRESS OF BUFFER
/INTO BLOCK 55 (RECORDS 132
/STATUS OF OPERATION STORED

4210
BUFFER

STATUS,

—

55
0

1
&

133)

HERE

POWER FAIL TASK

4.5

Task
which
the
mechanism
the
provides
by
system
If the power-fail/auto—restart hardware
from power failure.
a
option is present and if the system parameter PWRFAL was equated to
nonzero .value, the SPL (Skip on Power Low) instruction is included in
If
a
low
the
condition
the interrupt skip chain.
occurs,
power

The

Power

Fail

recovers

processor

state

saved

and

the

processor

halted.

When

power

is
restored
and
an
Event
back, the processor state is
Flag
Task.
Fail
The Power Fail Task
wakes
Power
POSTed
which
up
the
if
are
restores the clock, console terminal, and 05/8 terminal
they
present, and also performs an action for each task in the system based
Each task has a one—word
entry
on the contents of an internal table.
in this table, which contains:
comes

task

-1

If the EFWT (Event Flag Wait) bit should be
Task
Table
the
entry for this task
Flags
task should be taken out of Event Flag Wait)

should

done

this

nothing

for

4-18

(default value)
cleared

(i.e.,

in
this

RTS/8

DERAILed to location
is executing as well

task should be
it
in
which
EFWT bit cleared.
If

ADDR

the

field

Each task
table
by

message

the

alter

system may

sending

PWRMSG,

hav1ng

the

1ts

its

Fail
format

in the Power
The
Fail Task.

entry

Power

is:

ADDR

‘

the

message

TASKS

SYSTEM

Task's
of the

ZBLOCK

WORD

where:

is the new contents of
.for the sending task.

WORD

OS/8

4.6

the

Power

Fail

table

Task's

entry

SUPPORT TASK

of
the
08/8
operating
05/8 Support Task supports the execution
as
a
task
under
RTS/8.
OS/8 is run in the top two or more
system

The

and
extension
of
the
KM8-E
fields
under .control
memory
memory
timeshare
option (standard on PDP—8/E, 8/F, or 8/M with 8K or more of
or
core memory)
TSS—8 time sharing hardware option.

NOTE‘
to
module is used
The
timeshare
function.
is shipped with
in
this
jumper
function
(timeshare
disabled).
place
The PDP—8A utilizes the memory extension
and 'timeshare
by the
option provided
A
KM8—A extended option board.
switch
on
the
KM8—A
module is used to enable
the timeshare function.

jumper

select
module

the KM8-E

the

The 05/8
is
to
Task
at
Support
system
startup- time
configured
establish
a
between
devices and RTS/8 handler
correspondence
OS/8
are
tasks.
Terminal input and
from
by
OS/8
output
ring-buffered
several characters to minimize input loss due to the usurpation of the
CPU by tasks of higher priority.
of
of
Because
the
number
large
trapped CDF instructions in 08/8 and its Commonly Used System Programs
but
(CUSPs), response time is slower than a stand-alone
OS/8
system
still
The background OS/8 task must have the same
quite 'reasonable.
to
The
load
system device that was used by the.OS/8 system
RTS/8.
08/8 Support Task cannot run on a stand-alone PDP—8 without OS/8.
Several parameters in the system parameter file control
the
assembly
of
the
The parameters and their meanings are as
08/8
Support Task.
follows:
‘

OSFLDS

Defined

OSKBDV:

08/8.
Example:
memory
Set

for

the

number

fields

dedicated

’

OSFLDS=2

specifies

08/8.

equal to-the keyboard

two

fields

or'

IOT

code

'the

08/8

terminal.
OSKBDV=03
the
of
the
use
specifies
terminal keyboard of 08/8.
OS/8 requires its own dedicated terminal.

Example:
console
Note:

4-19

SYSTEM TASKS

RTS/8
OSTTDV

Set

equal

to the

teleprinter

IOT code of

the

08/8

terminal.
OSTTDV=04

Example:
console
OSFILL

teleprinter

Specifies how
line-feed
allows

specifies
for

null

many

character

high—speed

the

use

characters must
follow
a
the 08/8 terminal.
This
terminals
to
be
as
used

VT05

terminals.
For
standard
Teletypes1
DEeriter terminals, this parameter should be

OS/8
set

the

OS/8.

and

zero.

Example:

OSFILL=4

allows

the

use

2400

baud

VT05.
OSSYSD

Specifies
Example:

08/8 system device driver
as
specifies DTAO

the

OSSYSD=DTA

task.
the

08/8

all

OS/8

system device.

NOTE
user does
not
to
need
include
a
driver
for
the 08/8 terminal
terminal
device (it is built into OS8SUP).

The

OS/8 system

that

runs

under

the

05/8 Support Task

runs

INDUSTRIAL
BUILD,
BOOT,
BASIC, and BASIC and
PIPlO,
FORTRAN LAB runtime functions.
All references
to
the
and
keyboard
are
to
diverted
the
and
OS/8
teleprinter
specified
keyboard
References in 08/8 to the LE8, LSBE,
or
LV8
line
LP8
teleprinter.
are diverted
to the RTS/8 line printer handler if the system
printers
otherwise they are executed directly by the
parameter LPT is defined;
Task.
References to the following OS/8 device names will be
Support
diverted to the corresponding RTS/8 handler if one is defined:

CUSPS

except

DTAO—DTA7

LTAO-LTA7

RKAO-RKA3
RKBO-RKB3
RXAO-RXA7
If one is not
standard OS/8

defined,

OS/8 will perform the I/O

directly

using

the

handler.

addition, the 08/8 handlers SYS and DSK are diverted to the handler
Other references to I/O under the
by the parameter OSSYSD.
to
in
a
supported OS/8 system may cause the 08/8 support task
hang
References to a handler called RTS8 are diverted to OSSCOM (see
loop.
Section 4.7).
In

specified

4.6.1

Mapping

Fields with 08/8 Support Task

HGHFLD in the parameter file must
the
specify
highest
This is usually the
available to the entire RTS/8—OS/8 system.
The
highest field available in memory (e.g., 30 for a 16K machine).
task
OS8SUP
The field
maps OS/8 fields into real fields as follows.
which OS/8 uses as field 0 is actually HGHFLD.
3,
2,
OS/8 fields 1,
with
into
fields
field
are
consecutive
etc.
mapped
beginning

The

parameter

field

1Teletype

registered

trademark of

4-20

the

Teletype Corporation.

RTS/8

SYSTEM TASKS

a
references
If an OS/8 program
HGHFLD-OSFLDS+1, proceeding upward.
as these
will
results
occur,
than
field
HGHFLD,
unpredictable
greater
size
The software core
fields are mapped over the lower OS/8 fields.,
multi—field
should
be
used
OSFLDS
and
set
to
OS/8
is
by
correctly
'

programs.

OS/8

4.7

RTS/8 COMMUNICATION

(OSBCOM)

to
talk
08/8 Support Task contains a mechanism by which OS/8 can
To perform this communication, the 08/8 system must be
RTS/8 task.
a
This handler can be
dummy;
configured with a handler called RTS8.
In faCt, it can be some other handler to
it
need
not
do
anything.
Task
The 08/8
which the name RTSB has been assigned.
traps
Support
The arguments that are passed to the RTS8
all
calls to this handler.
to
task
an
RTSB
called
handler by an OS/8 program will be
passed
OSBCOM.
The user is responsible for writing this OS8COM task.

The
an

The

OSBCOM

task

performs

RECEIVE

RTS/8

ER.

The

task

can

then

receive a message any time an OS/8 program reads or writes to the RTS8
This message looks like any other message to a mass
handler.
storage
Bits 6 through
device.
OSBSUP does make one change to the arguments.
8 of the function word originally contain the
buffer.
field
of
the
This
is
When OS8COM
the
field where OS/8 expects the buffer to be.
the
contains
gets control, these bits identify the actual field that
buffer.
OS8COM
can
to
return
information
these
05/8
through

arguments.

4.7.1
An

Using

the

OSBCOM

Task

OS/8 program that runs an RTS/8
shown in the following example.

task

specified by

the

08/8

user

Example:
USR=7700
JMS

JMS

READ
'

DCA

TASKNUM

CIF

JMS

(USR

1
DEVICE

ENTRY,

RTSB

ADDR
HLT

/NOTE THAT THIS
/'ENTRY' IS SET

CODE
TO

THE

CIF

JMS

NOT

REUSABLE
POINT

ENTRY

0
ZBLOCK
JMP

(7605

AND

FOR

THAT

THIS

ALREADY

LOCATION

HANDLER

/CALL HANDLER
/DUMMY READ
/TASK NUMBER
/DUMMY
/RETURN TO OS/8

should be noted that TASKNUM is being passed as the second argument
of the first because OSBSUP automatically modifies bits 6—8 of

instead

the

/CALL USR
/TO DO A FETCH
/OF DEVICE 'RTS8'
/DUMMY ADDRESS (HANDLER WILL
/BE RESIDENT
/ERROR (HANDLER NOT FOUND)

ENTRY

TASKNUM,

/LOCATION OF OS/8 USER SERVICE ROUTINE
/PRINT MESSAGE "WHAT TASK WOULD YOU
/LIKE TO RUN?" ON THE OS/8 TERMINAL
/READS RESULT FROM OS/8 KEYBOARD
/RETURNS TASK NUMBER IN RANGE 1-77
/ IN AC
/STORE IT AWAY

first

argument, presuming that

4-21

mapped field

number

located

RTS/8

there.

OSBCOM expects three arguments after the handler
These must be
by the user.

return.

error

Where the
task that
OSBCOM is
what

SYSTEM TASKS

call plus

specified

08/8 portion

the

been
written,
program has
handles the RTS/8 side of the communication must
written like any other RTS/8 user task, and
an
it might look like is as follows:
TASK=OSBCOM

/088COM IS ASSIGNED
/PARAMETER FILE
/COMES UP RUNNING
/SPECIFY FIELD HERE

INIWT=O
CUR=4O
FIELD

the

OS8COM
written.
of
example
be

PRIORITY

THE

CUR%10

*200

/STARTING

START,

CAL

MADDR,

RECEIVE
0
DCA MSGFLD

ADDRESS

/IMMEDIATELY GO.INTO RECEIVE WAIT
/ADDRESS OF MESSAGE LEFT HERE
/CDF TO MESSAGE FIELD LEFT IN AC

HLT

MSGFLD,
“

ISZ

MADDR

ISZ

MADDR

TAD

/POINT TO FUNCTION WORD
/POINT TO BUFFER ADDRESS
/(SECOND OS/8 ARGUMENT)
/GET TASK NUMBER

‘

MADDR

CAL

/RUN THIS TASK
/OS8COM WANTS TO BE
/PRIORITY THAN TASK

RUN

TAD

MSGFLD

DCA

EFCDF

TAD

(—5

TAD

MADDR

/GET
/FOR

ADDRESS

HIGHER
IT

EVENT

RUNNING

FLAG

MESSAGE

CAL

POST

/POST

MESSAGE

HLT

EFCDF,

JMP

/GET

START

ANOTHER

MESSAGE

example, the task number was put in the second argument of the
it
call.
became the third word of the RTS/8 message
However,
call
because OSBSUP always adds a word to the mass
storage
argument
For a description of the 08/8 standard
list,
namely the unit number.
of
the
Software
handler call format, see Section 4.1
08/8
Support
of the standard message format for mass
For
a
Manual.
description
storage devices, see Section 4.4 of this manual.
In

this

08/8

Other

4.7.2

Other

Techniques

techniques which
1.

employed by the

user

are

follows:

of
the
5)
(word
RTS/8 handler STATUS word
message
by OSBCOM is nonzero, then return is taken to 08/8 at

the

posted
the

can

error

return

the

handler

Arguments may be passed back

call.

08/8

through

the

argument

list.
3.

from
where

than

three words of data need to be passed to
OSBCOM
the
user
can pass a CDF and address of
the area
If
CDF
first
data resides.
the
occurs
as
the
to
the
it
will be
handler
call,
automatically
before being passed to OSBCOM.

OS/8,
the

argument
relocated

RTS/8

4.8

FILE

OS/8

TASKS

SYSTEM

SUPPORT TASK

to
look
tasks
other
allows
up,
(OSBF)
This task is included
in OS/8 directories.
can
user
but
the
the 08/8 Support Task,
in the same
it
assemble
independently of that task (depending on which tasks are
The format of messages to OSBF
defined in the system parameter file).

The

OS/8 File Support Task

create,

and

delete files
source
file as

ls:

OSFMSG,

ZBLOCK

DEVHND"10+UNIT+FUNCT
FILPTR

STATUS

BLOKNO
LENGTH

where:
DEVHND

UNIT

Is the task
device.
Is

the

unit

number

the

handler

number

which

the

for

the

operation

desired

’

performed.
FUNCT

the

function

the

Represents
have

following

performed.

can

values:

returns
up the specified filename and
starting block number in BLOKNO, and its
LENGTH
two's
a
(as
complement
length in

Looks

its

number).
2000

specified filename into the first
(on the device) whose length is

Enters

the

empty

space

LENGTH.
or
the
in
exceeds
value
the starting block number of the new
file in BLOKNO.
If a file of the same
name
on
it
is
the
device
previously existed

equal

Returns

deleted.

Deletes

4000
FILPTR
,

Is
can

STATUS

pointer

field
be

Describes

the
to

the

used

The

value

LENGTH

in
4-word
filename
the
same
The PAL8 pseudo-op FILENAME
generate these filenames.
a

message.
to

the

final

status

the

operation

successful.
found on Lookup or
for file on Enter.

Operation
File
No

I/O

not

room

error

hardware
-1

unchanged.

specified filename.

follows:

0
1
2

Invalid

occurred.

error

status

directory

The
the

device.

Delete.
value

device.

the

RTS/S

SYSTEM TASKS

lljk

\__\,._J i

J
V

Function: —————_J
0 Lookup
1 Enter

2 Delete
3 Unused
Unused
Task number
Unit

OS8F

Function Word

Call

in
both OSSF and the 05/8 Support Task are present
a
an
system,
is
set
to
interlock
up
prevent simultaneous updating of directory
Because 08/8 tends to leave directory
blocks
blocks by both systems.
for
of
in
time, this interlock scheme causes
periods
memory
long
Before a Delete or Enter
operation
lengthy delays for the OS8F task.
is performed, OSBF waits until 08/8 is in a state in which:
If

There

active

temporary

corresponding
2.

USR

into

Look up operations
directory.

UNIVERSAL

(UDC/ICS)
The

file

the

08/8

device

UNIT.
Command

Decoder,

core.

are

not

DIGITAL

interlocked

since

they do

CONTROLLER/INDUSTRIAL

not

modify

CONTROLLER

the

SUBSYSTEM

HANDLER

handler
of

UDC/ICS

various

and

05/8 has just loaded the Keyboard Monitor,
or

4.9

DEVHND

types

the
user
the
to
control
the
capability
This handler performs
UDC/ICS functional devices.

gives

and
immediate
associated.
Immediate
actions
types of action:
include
reading and sending analog and digital values to appropriate
Associated
actions
can
be
linked
to
UDC/ICS functional devices.
within
events
the UDC/ICS (counters overflowing, switches
specified
The associated actions can do the following:
being thrown).
two

Run

2.
3.

Set

the'Event

specified task when the event occurs
Flag when the event occurs
DERAIL a specified task when the event occurs

The

number

determined

associated

assembly parameter

requests

the
size
RINGBUF.

that
the

can

pending

buffer, which

simultaneously
specified by the

RTS/8

The

UDC/ICS handler permits
Analog Output

Analog

Digital Output

Digital Input

Get

Enable

Read

Disable

Counter

Enable

Contacts

10.

Change

Input

from

12-bit value

read

digital

determine

—

analog channel

analog subchannel

State

value

send

—

Counter

10—bit

input

Counter

Code

TASKS

following operations:

send

Generic

the

SYSTEM

digital

channel

permit interrupts

disable
channel

value

the

current

from
COS

counter

channel

the

counter

from

interrupts

permit interrupts
find

from

for

code

the
generic
specified channel

current
read
channel

channel

contact

channel

for

contact

channel

value

channel

Disable

11.

Contacts

ignore interrupts from

Each
the

format
of
operation is discussed in detail below, including the
words
are
for
the
The
first
three
operation.
message
specifying
11
of
one
the
Word 4 specifies
required for use by the Executive.
which are as follows:
GC=3;
UDC/ICS
AO=O;
DO=1;
DI=2;
operations
5
AI=12.
Word
EC=4;
RC=5;
DCT=ll;
DC=6;
ECT=7;
CS=10;
Words
the channel being used for the indicated operation.
designates
6 through 8 may be required to completely specify the
and
operation,
the
number
used
is
The word that
the
dependent
operation.
upon
follows the last word specifying the desired operation is used for the
value
read
or
the
Word 10 of all UDC/ICS messages
value returned.

contains
The

the

general
ZBLOCK

error

format

state.

for

UDC/ICS message is:

OPERATION
CHANNEL

OPWORDl
OPWORD2
OPWORD3
VALUE
STATUS

4.9.1

Analog Output

Format:

channel

number
subchannel & value

Channel
word

value

is the analog output channel.
The subchannel and value
formed by the subchannel (0—3) in bits 0 and l and the 10—bit
in bits 2-11.
a
an
For example,
for
output
message
analog
number

operation:

RTS/8

AOEX,

ZBLOCK

SYSTEM TASKS

A0
.

/ANALOG OUTPUT
/CHANNEL 23
/SUBCHANNEL 2,

23
4614
ZBLOCK

/ERROR

Subchannel

614

AOER,

VALUE

INDICATOR

_—i

Value

Subchannel

4.9.2

and

Value

Word

Format

—

UDC/ICS

Handler

Analog Input

Format:

channel
subchannel

gain

answer

where channel is the analog input channel.
The
and
subchannel
gain
word need only specify the gain in bits 1—3 and the subchannel in bits
The handler automatically sets bit
9-11 for UDC, and 5-11 for ICS.
0
ICS bit 4);
(enable conversion) and read control register (UDC bit 8;
ICS analog converters must have addresses which are less
than
20
since
all
converter modules must be located in the first 16
(octal)
slots of the ICS unit.
After
is
value
conversion, 'the
digitized
placed in the answer word.

The

Enable conversion

Gain
ICS read control register;

(for UDC, bit 8)
ICS subchannel;

(for UDC, bits 9-11)

Subchannel

and

Gain Word

Format

UDC/ICS

Handler

SYSTEM TASKS

RTS/8
An

example of

ZBLOCK

AIEX,

for

message

analog input operation is
/ANALOG INPUT
/CHANNEL 17
/SUBCHANNEL 3,
/RESULT HERE

17
3
o
ZBLOCK

AIERR,

user

The

time

should

ensure

that

for

each subchannel conversion
indicated.
In general, it may
major channel are initiated from

INDICATOR

channel there is sufficient
5 milliseconds for ICS)
is
before
another
to
be
completed
be helpful if all A/D conversions for a
each

250 microseconds

for

4.9.3

GAIN

/ERROR

(approximately

follows:

AIANs,

the

major
for

UDC;

task.

same

Digital Output
DO

Format:

channel
value
Channel
be

output.

legal digital output channel
example:
ZBLOCK

DOEX,

value

the

number

DO'

'20

7777

»
.

ZBLOCK

DOER,

4.9.4

and

.For

/DIGITAL-OUTPUT
/CHANNEL~20
7777
/VALUE
=

/ERROR

INDICATOR

Digital Input

Format:

channel
result

Channel
contain

is
the

the appropriate
digital
input
value of the channel when read.

DIEX,

ZBLOCK
27

4.9.5

Format:
«

/ERROR

Generic

and

result

example:

/DIGITAL INPUT
/CHANNEL 27
/VALUE OF CHANNEL
/HERE

ZBLOCK

DIER,

For

DIANS,

channel

Code

channel
result

INDICATOR

WILL

PUT

will

RTS/8
The

code

generic

the

SYSTEM

TASKS

channel

specified

put

result.

For

example:
ZBLOCK

GCEX,

/DETERMINES GENERIC CODE
/CHANNEL 27
/GENERIC CODE PUT HERE

27
0

GCANS,

ZBLOCK

Generic

/ERROR

codes

2,3

error;

GCER,

follows:

are

Contact

INDICATOR

Interrupt Modules;

interrupt;

—

Counter

—

Controller

Module;

A/D

converter.

4.9.6

Enable

Counter

Format:

channel
initial

value

reload

value

event

action

address
Channel is the counter channel to be enabled,
first
to
be loaded into that channel,
value

is
value
the
reload value is the
If
the
after
event.
value with which to reload the channel
every
The event action and
reload
value is 0, the counter is not reloaded.
There
address words specify what happens when the counter interrupts.
are

mutually exclusive possibilities,

three

bit

appropriate
Bit

the

—

event

Set

action

word

Wait

Event

Address

Bit

Run

of
this
job
word not used.

task

specified
Address

Bit

—

that

word

by setting the

this
continue
job;
when
the event occurs.

run
the
message;
4-11
of
event action

task

sent

bits
not

indicated

follows:

Flag

execution

initial

and

word.

used.

DERAIL the
that
sent
the
task
the
message;
address word is only used by the DERAIL operation
DERAIL
the
address
of
the
and
specifies
The
subroutine must be in the same
subroutine.
field as the calling task.

If
bit
3
action just once.
0,
specified
Bit 3
is performed after each interrupt.
action
is
to
or
occur
once
indicates whether action
Do

repeatedly.
Several

enable

ECEXl,

counter
ZBLOCK
EC

7700
7710
4000
0

ECERl,

examples follow:

/ENABLE COUNTER
/CHANNEL 4
/INITIAL VALUE OF 7700
/RESET TO 7710 AFTER EACH
/POST EVENT FLAG ON EVENT
/IT OCCURS
/UNUSED
/ERROR INDICATOR

EVENT
EVERY

TIME

RTS/8

ZBLOCK

ECEXZ,

/ENABLE COUNTER
/CHANNEL 4
/INITIAL VALUE OF 1205
/DON'T RESET
/RUN TASK 16 ON EVENT EVERY
/OCCURS
/UNUSED
/ERROR INDICATOR

4
1205
0
2016
0
0
ZBLOCK

ECEX3,

/ENABLE COUNTER
/CHANNEL 5
/INITIAL VALUE OF 10
/RESET TO 7700
/DERAIL TO TASK 15 EVERY
/OCCURS
/AT LOCATION 5620
/ERROR INDICATOR

5
10

7700
1015

5620

4.9.7

Read

TIME

ECER3,

TASKS

ECERZ,

SYSTEM

TIME

Counter

Format:

channel
result
where

channel

read.

That

value

the
is

ZBLOCK

RCEX,

counter

RCANS,

4.9.8

value

current

example:

PUT

HERE

/ERROR

Disable

For

/READ COUNTER
/CHANNEL 6
/VALUE OF CHANNEL

RCER,

whose

RC
6
0
ZBLOCK

channel

placed in result.

INDICATOR

Counter

Format:

channel
where

channel

ignored.

For

DCEX,

the

counter

ZBLOCK

/ERROR

Enabi
Format:

interrupts

/DISABLE COUNTER
/CHANNEL 6

4.9.9

from which

DCER,

channel

example:

Contacts

ECT

bit

channel
action
address
&

event

INDICATOR

are

RTS/8
bit

where

the

from

which

and

the

channel
enable

bit

contact

action

Event

enable

is packed
are

function.
ZBLOCK

For

ZBLOCK

same

manner

/ENABLE CONTACT
/FROM BIT 2 OF CHANNEL 1
/ON lST OCCURRENCE OF EVENT,
/EVENT FLAG

the

/ERROR

required

are

messages

Change

POST

Format:

the

ZBLOCK

/ERROR INDICATOR

1001
4000

4.9.10

ECT'

Twelve

0-3

/ENABLE CONTACTS
/FROM BIT 13(OCTAL) OF CHANNEL 1
/RUN TASK 13 AFTER AN EVENT OCCURS

ZBLOCK

ECTE2R,

bits

the contact
channel
specified in bits 4—11
value from 0—l3(octal).

5401
2013

ECTEXZ,

Channel

specified in
example:

ECT

ECTEIR,

TASKS

specifies the bit

interrupts.

address

and

counter

ECTEXl,

word

SYSTEM

enable

INDICATOR

the

entire channel.

State

channel
result

channel is the contact channel whose
current
For example:
is to be placed in result.

where

value

COSEX,

ZBLOCK

0
ZBLOCK

4.9.11

DCT

/ERROR

Disable

INDICATOR

Contacts

DCT

Format:

bit

channel

where bit & channel is specified as in enable
13 octal) and bits
the bit (0
0-3
specify
For example:
to be disabled.
-

DCTEX,

ZBLOCK

4—11

/ERROR

INDICATOR

That is,
bits
the channel

specify

/DISABLE CONTACTS
/FROM CHANNEL 1, BIT
/l3(OCTAL)

5401
ZBLOCK

contact.

DCT

DCTANS,

state

/READ cos
/CHANNEL 1
/RESULT HERE

COSER,

COSANS,

change

RTS/8

UDC/ICS Assembly

4.9.12

SYSTEM TASKS

Parameters

UDC/ICS handler has several assembly parameters that the user must
The number and address
specify to indicate the UDC/ICS configuration.
are
is required only for those modules that perform interrupts.
They

The

follows:

‘
'

ring

counter

modules.

Number

contact

modules.

'Number

analog input converter modules.

FCTR

the

modules

The
module.
addresses.

Address

the

contiguous

Address

module.
the
contact
first
interrupt
be
at contiguous module
modules
must

must
FCT

first

stored

NAD

can

Number

NCNTR
NCNTC

that

of interrupts
buffer.

Number

RINGBF

Interrupt

counter

module

addresses.
of

Address

FAD

first

the

modules
addresses.

input

Number

NMPLX

A/D

must'

module.

Analog

contiguous

module

converter

multiplexer

modules

per

analog

converter

(ICS only).
used mainly
to
sizes ~of~
several
specify the
as
allocated
handler,
30(octal) words per
UDC/ICS
contact module, 3(octal) words/counter module, and 16(octal) words per
The UDC/ICS handler currently assumes that the handler
analog module.
and all its tables are entirely within the same data
field
(although
the user could easily reprogram this).

These parameters
tables
in
the

are

-4

The user must keep in mind when establishinngINGBF size that
buffer is full, UDC/ICS interrupts are disabled until there is
the buffer.
Also, each interrupt requires two entries in the
that is, the actual buffer size is 2 * RINGBF.

4.9.13

UDC/ICS

indicate

the

tenth

Error

error

word

task's

the

a
value
UDC/ICS handler places
The values and meanings are:

Meaning

Illegal generic code

for

Channel

value

Illegal

function code

operation

buffer;

message.

Value
1

the
in

Conditions

conditions,
the

if
room

specified

channel

and

‘

subchannel

UDC/ICS

control

hardware

error)

not

valid

responding

(power

off

RTS/8
The

initialize and check

should

user

condition puts

SYSTEM

this

TASKS

the

word.

error

encountered at noninterrupt
time
are
returned
thus
also
indicate
a
they may
faulty
UDC/ICS
functional device.
Generic codes of 0 or 1 encountered
at

Only

in
this
hardware

errors

manner,

time

CASSETTE

The

HANDLER

Handler

Cassette

variable-length

special functions
the

Cassette

two

are

DEC

various

(such

Handler

cassette

and

write

Handler

rewind, backspace file
Utility functions
gap, backspace block gap, and skip to file

—

read

4.10.1
The

operation:

gap,
gap

The user should call these functions in a
of
the
first
word
message defines the
handler or utility call.

call

operate eight
of

and
write
read
well
as to perform
write
One
end-file).
units.
to

user

cassettes,
rewind and

can

general categories
functions

the

allows

(CSA)

records

copy of

There

interrupt

ignored.

are

4.10

error

location.

Handler

Function

message

format
is:

the

Cassette

Handler

unit

when

sequence.
and either

using

file

The
the

handler

ZBLOCK

CALL

UNIT

FIELD

meaningful
cassette

write

NONSTORE

BUFADD
SIZE

STATUS
For

handler function,
follows:
as

the

after

words

the

RTS/8 message

header

defined

Word

bit
bit
bits

0
1

bit

0
0

bits
bit

call
Handler call
Cassette unit

0
0

Utility

Read
Write
Field

9—11

6-8
11

not

of buffer
store data

(applicable

only)

Word

3
4

Word

Buffer
Record
Status

address
size in
return

4-32

bits

4-11

read

are

RTS/8

Handier call

Utility call

SYSTEM

TASKS

Unit

Read

Write

Word

Format

—

Cassette

Handler

Field
0:

Read into memory

Check data

Function Word

Format

Handler

Call

user
conventions specify a record size of 200 bytes, but the
size
to
The buffer
377 (8 bits are transferred).
any
up
a
For
read
specified by the message cannot cross field boundaries.
is optional (although its word in the message
the
buffer
operation,
must be included), according to
2.
bit
11
of
word
TheL nonstore
be
for
Word 5
used
capability can
advancing through a long file.
contains the contents of status register B, which is
the
defined
by
bit setting as follows:

Cassette

can

use

Bit

Meaning
CRC

I—‘l—‘kOCDflONUIuh

/block

error

Timing
EOT/BOT
EOF

Drive empty
Read/write

l—‘O

Write

lockout

Ready

4-33

SYSTEM TASKS

RTS/B

CRC/block error

Timing
EOT/BOT
EOF
Drive empty

Read/write

‘

Write lookout

Ready

Status

Word

the

check

example of

starting

21200

4003
4020
1200:
0100

handler

cassette

ZBLOCK

MSGl,

read

and

not

.
_

.4
.

v
»

The
call

user

should

examine Word

message

write
is as

from

100
bytes
follows:

/HANDLER OPERATION QN UNIT 3
/WRITE FROM FIELD 2 THE
/BUFFER AT 1200 WHICH IS
/100 BYTES LONG
/STATUS RETURN

200 bytes from unit 2,

the

message

is:

/HANDLER OPERATION ON
/READ AND DON'T STORE
/UNUSED
/200 BYTES
/STATUS RETURN

0000
0200
0000

4.10.2

the

Handler

store

ZBLOCK
4002
0001

MSGZ,

Cassette

—

cassette unit

0000
To

Format

end of each cassette operation,
for errors encountered.

buffer

Return

UNIT

Utility Function

format
is:
ZBLOCK

message

the

Cassette

CALL+UNIT
FUNCTION
STATUS

4-34

Handler

when

using

utility

For

utility function,

defined

bit
bit

bits
Word

words

the

after

are

Handler

unit

Cassette

9—11

(function in bits

Status

call
call

Utility

0
1

Rewind

6—8):

30
40
50
70
Word

header

RTS/8 message

follows:

Word

the

TASKS

SYSTEM

RTS/8

Backspace file gap

Write

file

gap

Backspace block gap
Skip to file gap

return

\____\/____J

Function:
1 Rewind

3 Backspace file gap
4 Write file gap

5 Backspace block gap
7 Skip to file gap

Function

For

example,

request

ZBLOCK

MSG3,

Word

Format

rewind

the

is:

message

UNIT

is encountered, the operation is retried 3
times,
except
write
lock
is
out
placed on a write operation or an error
while reading CRC.

error
a

occurs

The

unit

Call

/UTILITY OPERATION
/REWIND
/STATUS RETURN

0010
0000
If

Utility

0001

when

—

CAPS—8 User's Manual (DEC—8E—OCASA-A—D) is
who are unsure of cassette conventions.

reading

suggested

for

users

4.11

The

CASSETTE

FILE

SUPPORT

HANDLER

Cassette File Support Handler (CSAF)
supports
format and allows the calling task to look

cassette
on

cassettes

handler

(CSA)

in
to

the
up

DEC

and

that

the
format.
This
handler
requires
perform the actual I/O operations involved.

The cassette operations ENTER,
Cassette
File Support Handler

LOOKUP

and

are

standard

enter

performed

files

cassette

the

which in turn calls the cassette
ENTER and LOOKUP require the user to
put‘ appropriate
a
record header area with which CSAF performs the file

(CSAF)

handler (CSA).
information
in
The header area must
operations.
cannot cross field boundaries.

least

40(octa1)

words

long and

SYSTEM TASKS

RTS/8

Word

definitions
Word

Word

bit
bit
bit
bits

for

0
1
2

1
1

ENTER

CSAF message

follows:

LOOKUP

9—11

unit

—

Address
status

Word

are

Field

for ENTER
CLOSE

header

for

return

for

header

ENTER

and

LOOKUP;

LOOKUP

(bits

6—8)
Word
In

all

the

cases,

status

Function:

Status

return

for

return

contents

the

ENTER

LOOKUP

and

Status

—_l

1 Close

2 Lookup
4 Enter

Unit

Unit Word

For

ENTER

cassette

format

and

the

LOOKUP,

standards
as

Format

(and

Cassette

File

format of the
therefore is

Support Handler

header

area

must

conform

compatible with CAPS-8).

with
This

follows:
Use

Byte

Filename
extension

Filename
File

type
1

ASCII

undefined

File

12-13

record length.
Currently word 12 must be
0

14—15

Unused

16-23

Date

24-35

Unused

(ASCII)
ddmmyy

Reference

8—bit

bytes,

file

with

the

specified

one

per

right

word,

justified
For

header

ENTER
area

operation,
is

found

the

specified unit,

4-36

name

specified
deleted.

the

RTS/8

For

The

TASKS

size
the record
header+l3 (byte 13).

operation,

LOOKUP

returned in
if an error

SYSTEM

location

this

occurs,

location contains

the
the

file

found

not

operation is automatically followed by

specified
file

REWIND.

Examples of messages follow.
ZBLOCK

MSG4,

/ENTER ON UNIT 0
/INFORMATION IN HEADER
/6400
/OF FIELD 1
/STATUS RETURN

4000
6400
0010
0000
ZBLOCK

MSGS,

/CLOSE ON UNIT 3
/STATUS RETURN

0000

The

PDP-8A NULL

PDP-8A

The

source

configure
parameter

also

counts
counts

which is called
the
null
task
file of its task

NULL8A

4.13

TASK

Task

Null

display.

KL8—A

1003

4.12

STARTING

AC
in
the
in
decimal
9999
7777 in octal in the MO display.
user
can
The
a
NULL8A, takes up
page.
into
an
RTS/8 system by inclusion in the

from
from

and

name

the

statement

NTASKS+1

SUPPORT

The KL8—A is a
that has three

4—serial line asynchronous multiplexer for the
PDP—8/A
lines with partial modem control and one line with full
modem control.
KL8-A support is available to the RTS/8 Executive, the
TTY
and the 08/8 Support Task.
To use KL8—A support, the user
task,
should perform the procedures that
in
are
the
described
following
sections.

Executive

4.13.1

The

KL8-A

Support

symbol KL8A in the parameter
of

number

being used,
If

the

KL8—A

KL8-A

KL8~A
then

symbol

KL8A=1

'KL8A'

support will

support

KL8ASR.PA must
.PAL

units

is
be

file

set

being employed by
is
set

the

value

user.

equal
If

one

KL8—A

the
is

spciified.
to

undefined

the

parameter

file,

provided by RTS/8.

is provided by the RTS/8
be assembled as follows:

KL8ASR<PARAM,KL8ASR

Executive.

The

source

file

RTS/8

The parameters

in the parameter

SYSTEM

TASKS

file that relate to KL8—A service

are

follows:

KL8A

undefined

that

means

service

KL8—A

desired.

lines
is
support for n
physical
desired.
Each
physical KL8—A provides
four lines.

means

KL8ADV

Device

code

Default

consecutive
If

41).
should
KL8ACT

for

Each

KL8—A

device

codes

(e.g.,

multiple

have

Specifies

first

the

40.

KL8-A's

consecutive
for

page

are

KL8—A.
uses

two

and

used,

they

device

codes.
of

start

KL8—A

routine.

Default
is 7400 (if
KL8A
The
KL8-A
connect
routine
l).
must
be
in
located
0.
It is
field
a
l-page long for one KL8—A and
grows
for every three additional KL8—A's
page
used (or
The
default
part
thereof).
connect
=

4.13.2

Task

TTY

KL8-A

value

KL8-A

support

this

parameter
routine

against

the

location

7577.

end

such

gets
field

that

jammed
0, ending

the
up
at

Support

KL8A
in
support in the TTY task is initiated by setting symbol
file
to
nonzero.
Then the KL8—A line to be used is
parameter
code
100.
For
specified in place of the terminal IOT device
plus
example, if the TTY task is to control line 3 of a KL8-A,
KL8—A

the

TTDEV

specified in

have
interface

KL8ALINE+3

is
the parameter file.
defined
(The symbol KL8ALINE
the value 100 in the parameter file.) If more than one KL8—A
is used, the lines are numbered consecutively beginning with

continuing

and

Physical lines

interfaces.
line number 1

are

numbered

from

KL8—A

Thus,

across

actually is physical

of
to

the

line number 5
KL8-A
interface.

logical

second

in
field
for
0
Executive
support requires additional memory
KL8-A support
Support but does not increase the size of the TTY task.
is included in both the old (2-page) and new (3-page) TTY task.

KL8-A

4.13.3
KL8-A

KL8-A

Support for the 08/8 Support Task

support for 08/8

similar

that

described

for

the

TTY

task.

symbol KL8A is
set to nonzero in the parameter file.
Then, the particular KL8—A line
is
specified
by
using a number of the form 100+line in place of the
device code, where "line" is the line number of the KL8-A that is 08/8
used.
The symbol KL8ALINE is conveniently defined as being 100
being
in the parameter file.
For 08/8 support, the parameter
However,

the

OSTTDV

following procedure

KL8ALINE+2

used.

First,

the

RTS/8

than

described

the

First,

task

TTY

Support for
in

support

similar

manner

the

KL8—A

KL8-A

The
in

for

should

task

user

and provide
chain
the line he wishes

the

Section

When more
of the KL8—A.
numbered successively as
4.13.2.

allows

user

program

KL8-A

the

KL8-J.

insert

must

2
be

Task

User

Executive

the
to

support

line

KL8-A

one

4.13.4

terminal output goes
is used, the lines

that

specifies

TASKS

SYSTEM

the

the
into
skip
interrupt
interrupt routine to service
the
via
following
accomplished
KL8-A

keyboard and printer

This

use.

code:
CDF

CUR

CIF

ICE
TAD

(LINE"4

JMS

(KL8ACT

KEYBD

PRINTER

where

ROUTINE

INTERRUPT

ROUTINE

line

number

LINE

the

KL8—A

specific

the
instruction

Second,

For

will

and

(0,1,2...)
(0—3).

KL8-A

user

must

define

that

will

used

may span across
4a+b where a is

the

when

line

physical

instruction

the

desired.

KL8—A

numbers
are consecutive,
begin at 0, and
KL8-A line number is actually of the form

outputting

line
KL8—A
The
KL8-As.
the
number
number of the

corresponding
to

example, if the device code for the KL8-A is
probably want an instruction such as

KL8—A

the

40,

TLS

the

line.

then

the

user

TLSX=6404

his

task.

Normally,

program

would

contain

the

code

the

KL8—A

character,

the

following

output

character:
TAD

char

TLS

When

using a KL8-A, the task
KL8ACT.
Then,
calling

would

used:

TAD

line
char

TAD

would
to

first

output

connect

support
code

"400

TLSX

The

4.14

The

not

EXIT
EXIT

included

cleared

by the

TLSX.

TASK

Task

not

system,

task performs the
command, that is,

required

If
for RTS/8 operation.
this
is
task
it is run by the MCR EXIT command.
The EXIT
same
functions as those performed by
MCR
the
EXIT
it waits for any pending operations to be completed,

4-39

RTS/8

SYSTEM TASKS

then turns off interrupts and returns to the
08/8
In
EXIT Task allows a user task to
the
addition,

operating

system.

request additional

This
is
special exit processing just prior to shutting down
RTS/8.
the user task send a message to the EXIT Task.
This
by
having
This word is the address of a routine
message contains a single word.
the same field as the message) that will be called (via a JMS) at
(in
done

MCR
When the
time of the exit.
will be called and executed
routines

the
to

the

EXIT

the

is
command
order that

Task.

NOTE

Task
will
Any message sent to the EXIT
not
Also, do not use the
posted.
get
EXIT
MCR REquest
run
command
to
the

Task.

these
typed,
they were sent

CHAPTER

MONITOR CONSOLE

5
ROUTINE

Monitor Console Routine (MCR) provides functions that the user
from
the console terminal to control, inspect, and debug
request
his system.
some extent)

The

can

(to

commands
indicates that it is active and ready to
by
accept
An
the prompting character > on the system console terminal.
and
word
MCR command consists of a
command
followed
by
arguments
terminated
Only the first
by either a carriage return or an ALTMODE.
The

MCR

printing

EXIT
for
the
characters of the command are
except
significant
If a
of 40 characters long.
be
a
Commands
can
maximum
to
the
MCR
the
returns
return
terminates
the
command
line,
carriage
for
another command when it finishes processing the current
terminal
MCR
If an ALTMODE terminates the
the
command.
command
line,
puts
The
in
a wait
state when it finishes processing the command.
itself
"C
MCR is brought out of this wait state by typing
on
the
(CTRL C)

two

command.

console

terminal.

for
no
other
the MCR prompts with its > and is waiting
input,
task
can use
the terminal.
Therefore, if the terminal is used
RTS/8
MCR
terminal
for something other than an
exclusive
instance,
(for
error
logging); type "C, type the MCR command and terminate it with an
ALTMODE character.
the
This procedure prevents the MCR from tying up

When

terminal.

5.1

MCR

Certain

COMMAND

ARGUMENTS

syntactic constructions

commands.

The

definitions

used

as arguments
arguments follow.

are

these

MCR

several

used
single comma or a single space may be
to separate arguments to MCR
interchangeably

commands.
Task-ID

Task-ID is either
If
it is a

octal

number

it represents the
internal RTS/8 Task Number.
This number also
If it is
the priority of a task.
designates
a name,
the first 4 characters
of
the
name
are
looked up in the MCR's Task Name table to
name.

produce

Time-of—day

Address

Task

number,

Number.

time-of-day is of the form hh:mm, where
hours
and
represents
past
midnight
represents minutes past hh:00.

Address

digits

that

5-1

octal

from

number

represents

PDP—8

hh
mm

memory

MONITOR CONSOLE

are

Word

If the address

address.

digits
digits
Word

ROUTINE

long

less
the

assumed

than

five

high

order

digits

0.
an

octal

number

from

long.

MCR COMMANDS

5.2
In

the MCR command descriptions that follow, the
significant
the
command word is capitalized.
Optional arguments are

portion
enclosed

in square brackets ([])
and
are
choices
embedded
in
parentheses,
exclamation points (1).
Commands preceded by asterisks
by
separated
(*) are not present if the user did not define the symbol CLOCK in the
file (indicating that a clock is not in the system),
RTS/8
parameter
if the symbol MCRCLK is set to 0 (in order to shorten the MCR
or
code
length).

5.2.1

The

[mm/dd/yyyy

DAte

date

[,Time-of—day]]

the system date.
For
the
the last digit is significant;
the
since
assumed.
The
date
is
197
RTS/B
system
at midnight, but all months are treated as
incremented
automatically
The second argument, if
is
set
specified,
being 31 days in length.
to
If no arguments are specified, the
the system time—of-day.
equal
in
terminal
the
form
current system date is printed on the console

mm/dd/yyyy,

year
portion of
others are ignored

the

specified,
only

becomes

date,

mm/dd/7y.
07/31/76

>DATE

07/31/76

5.2.2

[Time—of-day]

TIme

it
the
is
becomes
If
a
system
specified,
Time-of—day command
If
is
the
no
current
system
time—of—day.
specified
argument
time—of-day is printed out on the console terminal in the form hh:mm.
14:00

>TIME

14:00

5.2.3
The

NAme

Task-ID,Newname

character

specified

Newname

lost.

stored.
message

string

Newname

this

command.

can

Newname

becomes
The

Examples:

Task

number

REPORT

7
7

new
name

name

that

the

task

(if any)

if
is

are
be any length, but only the first 4 characters
should not be the name of any other task or an error

results.

>NAME

the
old

given

the

name

REPO.

5-2

MONITOR

REPORT,FOO

>NAME

Task

ROUTINE

CONSOLE

number

which

knOwn

REPO,

known

now

FOO.

NOTE

The

initializes

system

table

names

time

assembly

any

the

MCR

contain

the

that

are

tasks

DEC-supplied

name

listed
in
the parameter file (e.g., if
in
the
CLOCK
is
defined
the
symbol
parameter file as CLOCK=2, task number 2

gets
file
task

the

CLCK).

name

MCR.PA
names

after

can

REquest Task—ID

the

label

NMTBL, user
included
permanently

by modifying the MCR

5.2.4

editing

the

name

[,(@Time-of-day

table.

Interval)[,Interval]]

to
run
(if
immediately
REquest Task-ID command requests a task
Task—ID
is
a given
at
time—of—day, after a given
only
specified),
interval, or at a given interval.

The

Interval

form:

the

hours

minutes
seconds

system ticks

Table
task clears the RUNWT bit in the Task Flags
entry
task.
The interval, given in the third argument, specifies
the
If the parameter CLOCK in
period at which the task is rerun.
RTS/8 parameter file is not defined, the second and third arguments of
In
this command are ignored and the given task runs immediately.
the
examples given below, three different formats are used for the REquest
command, but only the first two characters are significant except when

Requesting
for
the

that

using

the

EXIT

command.

Examples:
>REQUEST
runs

task
>RE

runs

task

am).

runs

immediately.

FOO,@2:00
FOO

>RE

5,10M,5M

task

number

2:00

(if it

minutes

ten

after

from

now

am,

FOO

and

will

run

tomorrow

every

five

minutes

thereafter.

>REQ HIPR,1T,6T
On

machine

immediately
thereafter).

with

(that

is,

clock,

.016

this
command
runs
from now, and 10

seconds

HIPR
task
the
times per second

MONITOR

CONSOLE

ROUTINE

NOTE

If, at the
executed,

time

the REquest
command
is
be several hours
(which
may
after it is typed in) the task specified
Task—ID
does not have the RUNWT bit
by
set in its Task Flags Table entry,
then
the

REquest

command

operation), that is,
effect.
Similarly,

is
a
no—op
the command has

(no
no

the
task will not
run
execution
of
the
upon
REquest
if it had other bits set beside
command
the task will run only when
the
RUNWT;
other blocking bits are cleared.

5.2.5

STop Task—ID

The STop Task-ID command suspends execution of the task
specified
Task—ID
by turning the RUNWT bit on in the Task Flags Table entry
A task that has been stopped can be restarted by using
that task.
MCR

REguest
the

MCR

REsume

5.2.6

command

DIsable

task

that

task.

5.2.7

think

Task—ID

command disables
the ENABWT bit on

future
in the

execution of the
Task Flags Table

the
as

specified
entry for

Task—ID

in
the
The ENable Task-ID command clears the ENABWT bit
for the specified task, thus enabling it to
Table
entry
ENABWT bit was not set, the command is a no—op.

5.2.8

Task—ID

setting

ENable

command).

DIsable

The

(in this instance it is easier

by
for

CAncel

Task
run.

Flags
If

the

Task-ID

command cancels any clock queue
entries
involving
This includes l)any entries made by
specified
by Task—ID.
MCR (from previous timed Request
commands),
2)entries
involving
task
made
other tasks (e.g., a timed DERAIL) and
specified
by
a
timed
3)entries made by the specified task involving itself (e.g.,
In
the
timed POST, the event flag is not POSTed
case of the
POST).
and the task may hang up forever waiting for it.

The
the
the
the

CAncel
task

5.2.9

Task-ID

SYstat

[Task-ID]

an
is
command, depending on whether
specified,
argument
a
either
system status report or a status report in
general
If no
is
the
specified,
argument
greater detail on a single task.
Each line of the report
SYstat command prints a system status report.
For each
task
the
describes an existent task in the system.
report
the
task number/priority, task name (if it has one), and what
prints
Each blocking bit
blocking bits are on in its Task Flags Table entry.

The

SYstat

prints

5-4

printed
and

codes

ZGUJ'JUOZM

one-letter

their

meanings
for
for
for

Waiting
Waiting
Waiting
Waiting
Waiting

ROUTINE

CONSOLE

MONITOR

preceded by

code,

space.

The

one

letter

are:

flag

event
a

message
an
event flag

REquested or
swapped in

message

RUN

Disabled
USERWT bit set
Nonresident wait

addition,

has

messages

asterisk printed at the end
in its input queue.

line

the

means

task

waiting

is
obtained
a
task
detailed
status
on
by
report
single
as
of
that
task
an
the
Task—ID
argument to the SYstat
specifying
in
the
the
information
all
command.
The detailed report contains
general status report, followed by five octal words:
A

WORD

The

WORD

location

the

Task

Table

State

this
entry containing words 2-5;
word is followed by a colon
Task Link in sign bit, IF in bits 6-8,
DF in bits 9—11
(PDP-8/E and 8/A Flags

PC
AC

Examples:
A

general

SYstat

command

the

might produce

following

sample

output

line:
13

CARD

This line
has input

task

means

13,

the
E

1320:

0022

setting
Leaving

leave the SYstat
the system parameter
it out saves one page

5.2.10

OPen

The

user

OPen

starting

can

Address

Address
at

lllll/

CARD,

Event

Flag Wait

and

with

command:

single line:

This line indicates that CARD
and Link zero and 2525 in its
The

named

The

CARD

might produce
CARD

number

pending.

messages

>SYSTAT

Address

1741

0000

2525

stopped

location

21741

its

MO.

facility
MCRSYS

out

MCR
of
the
assembly
by
the RTS/8 parameter file.

code.

[,Count]

command
on

the

the
Count
locations
terminal in the form:

displays
console

octal

cccc

The range of locations displayed may cross
is not specified, it is assumed to be 1.

5-5

field

boundary.

Count

CHAPTER
ASSEMBLING

AND

LOADING TASKS

FOR

RTS/8

the
The user assembles RTS/8 tasks with parameter files,
08/8
using
PAL8
assembler.
RTS/8
parameter files are all edited versions of a
distributed
the
master parameter file
(PARAM.PA) that is included in
All definitions in
sources.
Appendix A lists the RTS/8 source files.
the master file which are to be supplied by the user are left blank in
the file.
For example, a sample line in the file is:
PDP8E=
If

this

PDP-8/A.

8/E

PDP

is set to
either machine

parameter
If

8/A,

PDP

the

not

Thus, a unique parameter file is
where
environment
environment,
hardware

the

and

set

tasks

ELSE

specified machine is a PDP—8/E
this parameter is set to

used,

for
the
created
is
a
combination

being

particular
of

the

RTS/8

available

run.

section.
The structure of the parameter file is discussed in the next
Other
sections
in
this
chapter describe 1) the 08/8 BITMAP program
locations
which allows the user to construct a map showing the memory
used
files, 2) a sample RTS/8 program 3) a general
by
binary
given
procedure for creating an RTS/8 system, and 4) a listing of parameters
and their functions that affect the individual RTS/8 system tasks.

6.1

PARAMETER

STRUCTURE

FILE

The

parameter

file

specify

particular RTS/8 system configuration.

contains

the

parameters that the

define
file
in
shown

user

must

parameter

is
demonstration
been modified for
the
program
for
user—defined
8.1.
This
file
also
contains
symbols
see
For further information on DECNET/8,
DECNET/8
RTS/8
DECNET/8.
that

has

Section

Programmer's Guide
The

parameter

sections

are

file

Reference

and

labeled

divided
as

Manual

into

follows:

Executive

Task

System Task Specifications

System Wide Definitions

Task

Specifications

Definitions

Setup

the

(DEC-08—LDPRA—A—D).

following five sections.

These

ASSEMBLING

AND

TASKS

RTS/8

FOR

Executive Specifications

6.1.1

the
Executive
section
control
parameters in the
Specification
of
the
Executive, and therefore are essential to the RTS/8
assembly
section
and
their
as
The parameters in this
are
system.
meaning
The

follows:

Meaning

Symbol

Set

PDP8E

PDP12

Set
or

Set

EAE

PDP—8/E,

machine

the

set

PDP12

MO during

KL8A

Set

be
Set

HGHFLD

power

into

this

is
PDP—8/A
symbol must

value

possible

the

machine being used;
is not being used.

KL8—A

the

switching.
in

fail/restart is enabled

contents

save

task

support

routines

the

should

system.

HGHFLD

with

octal
number

16K

highest field used;
specifies field 3 when

the

designating

machine

not,

system should

nonzero

PDP—lZ

interrupt

example,

using
Set

loaded

for

NTASKS

the

Set to 1 if
hardware.

PWRFAL

undefined,
to

PDP—8M

PDP-8F,

being used;

core

memory.

that
the
total
value
specifies
of tasks in the system.
It also

the highest number that can be assigned
task in the system.
Not all possible task
this
need be assigned to
actual
tasks;
merely sets the length of system tables.

represents
to

any
numbers

symbol
CHECKP

Set

nonresident

any

task

checkpointable.
PARTNS

Set

the

number

system.

Set

indicates

zero

partitions defined in the
PARTNS

partitions

memory
to

system.
that

partitions defined, that is,
and partition number 1.

6.1.2

Task

there

are

For
are

partition

allocated
no

memory

example,
two

memory
number
0

Definitions

section defines symbolic names
for
the
various
of all system tasks which are to be included
in the system are defined here.
included
should
Any system task not
have
the
line
which
defines it deleted from this section.
Perform
this deletion by inserting a slash (/) character at the
of
beginning
the line, which makes the entire line a comment.
Symbolic definitions
user
is
of the user's own tasks can be added to this
section.
The
that
reminded
the assignment of task numbers in octal indicates task
the
priority, that is, the lower the number, the higher
priority of
the task.
The

Task

system

tasks.

The

names

ASSEMBLING AND

The Task Definitions
shown below.

section,

TASKS

FOR

initially

RTS/8

appears

the

user,

EDITED BY USER
/COMMON TASK NUMBERS
NAMES GIVEN BELOW
/IT IS ADVISABLE TO DEFINE ALL TASKS HERE.
/ARE USED BY SOME SYSTEM TASKS AND SHOULD REMAIN COMMENTED OUT
/IF THE CORRESPONDING TASK IS NOT INCLUDED IN THE SYSTEM
-

/PWRF=
/CLOCK=
/SWAPPER=
/TTY=
/LPT=
/MCR=
/DTA=
/LTA=
/RK8=
/RF08=
/DF32=
/CSA=
/CSAF=
/UDC=
/RX8A=
/RXSB=
/RX8C=
/RX8D=
NTASKS
/OS8=
/088F=
/DDCMP=
/NSP=
/NIP=
/TLK=
/LSN=
/NULL8A=
/EXIT=
/DKC8A=

/POWER FAIL HANDLING TASK
SHOULD BE HIGH PRIORITY
/CLOCK HANDLER
/NONRESIDENT TASK SWAPPER TASK
/TELETYPE DRIVER TASK
/LINE PRINTER DRIVER TASK
/MONITOR CONSOLE ROUTINE
/DECTAPE DRIVER TASK
/LINCTAPE DRIVER TASK
/RK8 OR RK8E DISK DRIVER TASK
/RF08 DISK DRIVER TASK
/DF32 DISK DRIVER TASK
/CASSETTE DRIVER TASK
/CASSETTE FILE SUPPORT TASK
/UNIVERSAL DIGITAL CONTROLLER TASK
/FIRST FLOPPY CONTROLLER
/SECOND FLOPPY CONTROLLER
/THIRD FLOPPY CONTROLLER
/FOURTH FLOPPY CONTROLLER
NORMALLY LOWEST PRIORITY
/OS/8 SUPPORT
/OS/8 FILE SUPPORT
/DDCMP TASK FOR DECNET
/NETWORK SERVICES PROTOCOL TASK
/NETWORK INFORMATION PROGRAM
/NETw0RK TERMINAL COMMUNICATIONS TASK TRANSMITTER
/NETWORK TERMINAL COMMUNICATIONS TASK RECEIVER
/NULL JOB FOR PDP—8/A
/EXIT TASK
/AUXILIARY DKC8A HANDLER
-

—

This section of the parameter file is shown in Section
It
has
been
modified
for the demonstration program.
addition of the
two
used
in
the
tasks
nonresident

8.1
also

after
shows

it
the

demonstration

program.

6.1.3

System Task Specifications

The parameters
of
assemblies

in the System Task
the various RTS/8

controlling a specific task are
if
that
conditionally
only

Specifications section
system tasks.

all
task

Definitions

parameters

grouped
is
file.

6.1.4

System Wide Definitions

The

set

together

name

section
of
the
parameter
in
this
The parameters
section.
Section 6.4.

listed

The

control

the

parameters

and

assembled

the
Task
in
defined
the
user
edits
The
and their meanings are

of
the
definitions
System Wide Definitions section includes the
symbols that RTS/8 uses to describe Executive Requests and Task Status
It also contains useful definitions
instruction
such
as
Flag bits.
monitor
values and
call
functional
values,
equivalences,
UDC/ICS
The user should not alter this section.
system locations.

6—3

ASSEMBLING

Task

6.1.5
The

body
that

LOADING TASKS

AND

FOR

RTS/8

Setup

Setup section

uses
five symbols that the user defines in
the
this task to initialize the RTS/8 table entries needed to put
task in the system.
These five
and
their
definitions
symbols

Task
of

are:

Defines

TASK

the

the task
form:

number

the

task

the symbolic
defined in

name

statement

TASK=symbol
where
that

"symbol"
the

user

has

the

for

the

task

RTS/8 parameter

file.
Defines
in bits

CUR

the

field

6-8

(e.g.,

task's

the

starting

address

CUR=10).

NOTE

The
is

must

user

the

done

code

pseudo—op
For

Defines

START

Defines

INIWT

the

FIELD

code

task‘s

the

This
assembler

PAL8

lowest

the

CUR%lO
in field

places

starting

address
the task)

address

(not

initial wait bits in
the
Task
Flags
this task.
For example, INIWT
0
task is runnable when the system
starts

the

Table

entry for

means

the

INIWT

up;

the

starting
CUR.

FIELD.

starting

necessarily

task's

specified by

using

example,

task's

the

place
field

(1000

RUNWT

specifies

octal)

that

is not runnable initially and
is
in
a
This task becomes runnable
Run
condition.
Wait
ER
RUN
when another task issues a
or
when
the
If
a
types
Request command to the MCR.
operator
INIWT is
the
task
starts
undefined,
up
being
runnable.
this

task

Defines

VERS

version

task's

version

number,

parameter.

convention,

the

optional

number

becomes

task's

the

this

task's

the

initial

value.

The

user

can

corresponding
and

CUR3,

tables

etc.

define

symbols
The

up
for

the

three
other

adding

one

are

TASK2

assembly.
and

TASK3,

The
CURZ

task setup section places its data into the
RTS/8
is generated.
If
into them;
no executable code
in
three tasks can
be
created
one
assembly
by

origining

more than
for any additional
the
code
It should be noted
file.
that
only
demonstration program in Chapter 8.

desired,

tasks
tasks

tasks
one

the

task

end of the
is
defined

PARAM.PA

the

ASSEMBLING AND

6.2

RTS/8

CREATING AN

LOADING TASKS

FOR

RTS/8

SYSTEM

is
be created by using the general procedure that
It is assumed that the user has physically
section.
the
has
mounted a copy of the distribution medium, and
bootstrapped
nonresident tasks are treated in this
development
system.
Although
in
procedure, greater detail on employing nonresident tasks is
given
An

RTS/8 System
in

described

Chapter
The

can

this

general procedure
1.

RTS/8 System

follows:

the
for
required
system and user tasks
Utilize the
configuration to be employed.
tables and memory map given in Appendix B that show the RTS/8
to
their
and
their
default
sizes,
components,
origins

Layout

paper

determine

Assign

the

RTS/8

particular

creating

for

where

task

the

tasks

and

names

are

task

loaded
If

priorities.

into memory.
nonresident

tasks

used, assign the Swapper Task a higher priority than any
of the nonresident tasks.
Remember that the lower the" value
assigned to a task, the higher its priority.
are

When large programs are involved, a documentation file should
be
as
a
created
user
convenience to maintain a directory of
the system configuration.
This file can contain
information
as
such
the
tasks employed in the system, task names, task
priorities, and control files.

Obtain
Use

the

listing of the
08/8 command

.LIST
to

get

listing

(PARAM.PA).

from

line

terminal.

printer,

PARAM.PA

listing

from

Use an editor
under
to
establish
the
(EDIT or TECO
08/8)
values
of
the
parameters in the parameter file (PARAM.PA).
The structure of the parameter file is described
in
Section
6.1, and the parameters affecting the individual RTS/8 system
tasks are described in Section 6.6.
PARAM.PA

should

renamed

Create

integrity
6.

file

parameter

PARAM.PA

.TYPE
to

master

and

read

output

in as an
file.

DIGITAL—supplied

edit

any

control

input file, edited,

and

This procedure maintains

then

the

sources.

files

that

are

used

(See

Section

6.5).
7.

Assemble

the

tasks

with

the

parameter

file

after

all

the

This can be accomplished by
required parameters are defined.
as
individually assembling each task with the parameter file
follows:
.PAL

RTS8<PARAM,RTS8

.PAL

PARAM-NB,

RTS8

ASSEMBLING AND

The

CCL

option

—NB

LOADING TASKS

indicates that

FOR

RTS/8

binary file should

not be

is the assembly of the RTS/8 Executive.
This
has to be done for every task that is included in the system.
Each
control file used must also be assembled.
Assemble the
control file with the parameter
the
control
file,
placing
file
between
the
parameter file and the required module as
follows:
created.

Shown

.PAL
An

TTYl<PARAM,TTYCFl,TTY

alternate

use

and

efficient method

Batch

The

stream.

that

can

assembly,

employed
and

load

save

commands for the system are generated as a
Batch
The
job.
SUBMIT command is then used to run BATCH which will use
OS/8
the Batch job commands as
and
This
execute
them.
inputs
method can also be used for installing nonresident tasks into
the system.

assembly of each task, preceded by the parameter file, is
is
because
there
no
required
linking loader function with
The assembly process creates binary
files
from
the
RTS/8.
to
sources
that
are
be loaded and run.
Each RTS/8
ready

The

system task contains

that
assembles
it
for
code
of core memory.
The user can
of
assemble
to load into
areas
not
used
memory
by
or
the
tasks for loading into
edit
tasks,
system
system
and
locations
autoindex
specific areas.
Page 0
registers
tasks
can also
be redefined by editing the
used
by
system
assembler

into
tasks

affected

tasks.

Obtain

tasks

are

two
or
more
bitmap of RTS/8 tasks to determine if
erroneously loaded into the same memory area or use
page 0 locations (See section 6.3).

specific

area

the

same

Load

the

All

required system tasks,

system after

loaded

.LOAD

one

time

all

the

required

user

tasks

are

and

control

tasks,

assembled.

files

RT88,CLOCK,TTY,MCR,UT1,UT2

RTS/8 Executive Task always must be loaded first.
tasks are included in this step in order
nonresident
their resident portions and executive table entries.

Also,

The

10.

Save

the

can

follows:

system after

loaded

using

the

load

following

command:
.SAVE

filename

system is saved,
time it is needed.

the

each
ll.

SYS

the

user

does

not

have

rebuild

a
SAVE
create
file
tasks,
image
using nonresident
disk
(nonresident
image) for each nonresident task from its
binary file as follows:

When

.LOAD

Then

save

TASKX

nonresident

the

portion

the

task

the

swap

device:
.SAVE

where

DSK

partition,

DSK

TASKX

the

and

Nl-NZ

swap device, N1
is the highest
6-6

the

address

lowest

the

address

partition.

the

ASSEMBLING AND

12.

the

Start

The

system by using

the

TASKS

RTS/8

FOR

command:

following

filename
is

following

using

when

applicable

nonresident

tasks.

starts, it calls the 08/8 command decoder,
system
At
this
terminal.
console
types an asterisk on the
the block address of each nonresident task
initialize

the

When

which

time,
core

image

follows:

*DSK:TASKX=N

command line, DSK is the swap device and TASKX is the
image file containing the nonresident portion of task N.
Repeat this procedure for each nonresident task, one task per
This
and
the
last
line with an ALTMODE.
terminate
line,
time
procedure automatically initializes and starts the real

this

core

system.

RTS/8 system created with the procedure just described has
If an RTS/8 system was not
address
of
00200.
starting
it
halts
or
PDP—12,
specifically configured for a PDP—8/E
to
device
to
allow
the
clear
stray
any
initially
operator
or
nonstandard
hardware
switches
by
by
flags
operating
START.
Press START to resume operation on a PUP-8,
pressing
8/I or 8/L.
An
a

6.3

USING

THE

OS/8

BITMAP

PROGRAM

The

OS/8 BITMAP program can be extremely useful in determining that no
RTS/8 tasks are loading into the same area or using the same Page
0 locations.
and
OS/8 BITMAP accepts a list of binary files as input
as
its
Each location of core
produces
output a map of core memory.
has
the
which
memory is represented in this map by a
digit
single
following meaning:
two

Nothing

Information

has

been

loaded

into

this

location

Information

has

been

loaded

into

this

location

twice

Information

has

been

loaded

into

this

location

three

has

been

loaded

into

this

location

1mes

There

certain

are

places

core

memory

where

2's

are

allowed

bit
These areas are the RTS/8 Executive Tables
map.
(starting at location 01200), the MCR name table in the MCR, the power
fail
action table, and nonresident task partitions (which may contain
2's and 3's).
other
than
these
Appearance of a 3 or a 2 in an area
areas
three
just mentioned in the bit map indicates that two or more
tasks are being loading into the same location.

appear

6.4
The

its

SAMPLE

the

RTS/8

TASK

used

simplicity,

and

task

that

PROGRAM
as

example
show

the

The

in this section was
selected
for
basic concepts of RTS/8 operation.

The user requires
purpose of the task is simply to print "HELLO".
RTS/8 system configuration that includes a console Terminal Handler
It is assumed
that
the
(TTY) and the Monitor Console Routine (MCR).

6-7

ASSEMBLING

will

task

standard

running

AND

PUP-8

TASKS

FOR

RTS/8

E/F/M/A with 8K of

core

memory

and

terminal.

console

The program (SAMPLE.PA) listed below is complete, and
when
assembled
with
the
parameter file, will run as task 5 in a properly-configured
The task is initially in the Run Wait state.
When
system.
requested
the
user
the
Monitor
Console Routine, the task prints
by
through
"HELLO" on the console terminal, and then suspends itself.
If
again
requested by the user, the same sequence will occur.

/SAMPLE RTS/8

PROGRAM

TASK=5

/GIVEN A PRIORITY OF 5
/IN FIELD 0
/SET TO RUN WAIT STATE
/PLACED IN FIELD 0
/ANY AVAILABLE PAGE

CUR=0
INIWT=RUNWT
FIELD

*3000
CAL

START,

SENDW
TTY

MSGl
CAL
SUSPND
JMP

START

ZBLOCK

MSGl,

o;0

/HELLO/

TEXT

/MUST BE DEFINED AS "START"
/SEND AND WAIT
/THE TERMINAL
/THE MESSAGE BLOCK
/SUSPEND THE TASK
/RESUMES HERE IF REQUESTED
/RTS/8 LINKAGE
/TERMINAL OPTIONS
/TYPE HELLO

$
edited version of PARAM.PA now is required for this
configuration,
is
To produce PARAMS.PA from PARAM.PA, the
it
named PARAMS.PA.
following definitions are edited into the parameter file:

and

PDP8E=1
HGHFLD=10
NTASKS=10
TTY=4

MCR=3
NTASKS

the

assigned

largest task
number

any

It
used
with
this
number
system.
than
values for MCR, TTY and
the
The task values
smaller than 100 octal.

greater

sample task, and which is
MCR and TTY were arbitrarily chosen
SAMPLE,
zero

The

and

less
is

program
.R

than

the

range

is
the

greater

for
than

RTSB

plus

NTASKS.

then

assembled

follows:

PALS

*SAMPLE.BN<PARAMS.PA,SAMPLE.PA
The
the

system for the sample task requires the Executive Task
TTY

and

following Batch

MCR Task

run.

stream:

$JOB
.PAL
.PAL

PARAMS-NB,RT88
PARAMS-NB,MCR

.PAL

PARAMS-NB,TTY
PARAMS-NB,SAMPLE
.LOAD RTS8,MCR,TTY,SAMPLE

.PAL

.SAVE

SEND

SYS:SAMP

This

can

accomplished by using

the

ASSEMBLING AND

TASKS

FOR

RTS/8

is
the
program,
Assembly and loading of the tasks, including saving
to
be
is
not
PARAM
that
—NB
indicates
CCL
The
now
complete.
option
used
The

the

system

name

now

can

the
be

binary file being

run

5($)

HELLO

:9
>SYSTAT
MCR

03
04

TTY

>RE

(user

input is underlined):

/OS/8 RUN COMMAND
/REQUEST SAMPLE FROM MCR
/TASK EXECUTES AND SAYS 'HELLO'
/RETURNS CONTROL TO MCR
/SYSTEM STATUS COMMAND
/MCR TASK
/TERMINAL TASK
/TASK 5 WAITING TO BE RUN
/RUN TASK AGAIN
/TASK SAYS 'HELLO' AGAIN
/RETURN CONTROL TO MCR
/RETURN TO OS/8
/OS/8 MONITOR

SAMP

>RE

follows

created.

5($)

HELLO

:9
>EXIT
.

NOTE

($)

the

all

ALTMODE

input lines

are

character;
terminated by

other

Carriage

Return.

6.5

USE

CONTROL

FILES

UNDER

RTS/8

There are times when a user may want to assemble a given source module
in
than
more
one way and use the
results under RTS/8.
For example,
under
service
suppose there are three terminals that a user wants to
Each
terminal
has its own Characteristics, and each copy of
RTS/8.
the TTY task needs to have its own set of parameters.
user
must
The
load
three copies of the TTY task into memory at different locations,
and
in
This
cannot
be
different
fields.
possibly
accomplished
With
a
file.
efficiently when
single
using a
single parameter
each
parameter file, three copies of the file TTY.PA must be made and
one
edited
to
three
individual tailored copies of the TTY
produce
This procedure is not convenient or modular.
task.
A

better

equates
task.
between

way

the

.PAL
creates

called

this is to use a control file that contains all the
define the parameters needed by a particular TTY
file then is assembled
with
and
placed
together
For example,
parameter file and the TTY module.
to

necessary
The control

TTYl

<PARAM,TTYCF1,TTY

binary file

called

TTYl

from

TTY.PA

using

control

file

TTYCFl.

TTY
is
file
facilitate using this procedure, a skeleton
control
with
It
the
task
sources.
contains
all
the
RTS/8
supplied
parameters
that the user normally defines in the parameter file.
user
a
Thus,
who wants to use multiple terminals, instead of editing the parameters
in the parameter file, can create a control
for
terminal
file
each
is
that
used, and then edit the control file to make multiple copies

necessary.

example of

shown

TTY

Control

file

after

below.

6-9

has

been

edited

user

ASSEMBLING AND

TASKS

FOR

RTS/8

TASK=TTY1

/DEFAULT IS 'TTY'
/PRINTER DEVICE CODE
/KEYBOARD DEVICE CODE

TTDEV=

/
/

KBDEV=

DEFAULT

—

DEFAULT

—

TTDEV-l

CONSOL=l

VT50=

ENABLES

CTRL/S

AND

CTRL/Q

SCOPE=l

/
/

/NUMBER OF FILL CHARACTERS, I.E. 4
/TTY LINE WIDTH (0 MEANS INFINITE),
/120
/1 IF TTY HAS HARDWARE TABS

FILL:
WIDTH=
TAB:

DEFAULT

OLDTTY=O
LSBOT=

BOTH

LISTS

HANDLERS

(DEFAULT

TTFLD=20

TTLOC=3000

This

terminal.

position,
three-page
location
A

that has been
edited
for
task
will be assembled for the console
left
one
Setting SCOPE=l causes RUBOUT to move the cursor
The new
physically removing the character from the screen.
It is placed in field 2, starting at
handler is specified.

example shows

TTYl.

control

file

and

use

easily generate

6.6

handler

task

3000.

skeleton

can

file

control

TTY

terminal

RTS/8

SYSTEM

TASK

also supplied for the RXOl
floppy.
control files for other purposes.

Users

PARAMETERS

This section provides a convenient grouping of those parameters
which
the individual RTS/8 system tasks.
affect
Given for each system task
is the parameter, its function and where applicable, an example.
The
section or chapter where a detailed description of the task appears in
the text of this manual is noted after the task subhead.

6.6.1

Clock

Handler

Parameters

(Section 4.1)
MEANING

PARAMETER

CLKTYP

Specifies selection
0
l

CLKQLN

hardware

clocks

follows:

KW12

PDP—8/A
DK8-EP
number of
is 20).

Specifies minimum
queue

Specifies
HERTZ

number

and

Specifies
This

OCTAL,
octal

SHERTZ

the

which

the

hardware
are

decimal

ticks

second.
per
in that they
the
file
by

values

second.
number of system ticks
per
is followed by the pseudo-operator
its
radix
to
the
resets
original

parameter
base.

slots

entry

(default

in
the
are
parameter
preceded
pseudo-operator DECIMAL.
SHERTZ

DK8—EA/DK8—EC

clock
HERTZ

ASSEMBLING

6.6.2

Swapper

SUNIT

Terminal

Handler

the

set

KBDEV

following parameters

use

the

available

are

device

keyboard

proper
TTDEV-l.
the

user

code;

facilitate

the

task.

CTRL/Q
CTRL/S and
CTRL/S and CTRL/Q are
not treated as special characters.
CTRL/S
Typing
the
while
data
is
on
printed/displayed
being
next
screen
stops the data presentation until the
This parameter must be set to 1
is typed.
CTRL/Q
Is

set

the

(default)
When

CTRL/Q

enable

set

terminal

user's
and

CTRL/S

off

turn

or
VT52.
VTSO
the echo flag.

Both

being

l to specify that the handler
for the console TTY (default).
not
to specify that this handler should
the MCR when “C is typed.
Is

set

assembled

WIDTH

default

printer device code;

proper

value

functions.

CONSOL

unit;

set

default

The

the

value

VT50

drive

MEANING

TTDEV

TTY

physical

example,

(Section 4.2)

Parameters

PARAMETER

the

for
task.

task;
driver

RK8

device
the swap
selects RKAO.

driver

swap

specifies

RK8

Specifies

SUNIT

6.6.3

the

Specifies
SYS

RTS/8

(Section 7.4)

Parameters

SYS

FOR

TASKS

AND

octal

width.

TTY

set

that

number

specifies

Set

wake

the

TTY

is currently set to 120
width
of
80
decimal
a
(octal), that is,
page
WIDTH
characters.
60 sets the TTY page width to
48 decimal characters.

page

width

SCOPE

This option is
the RUBOUT key
SCOPE=0

support.

SCOPE=1

causes

the

provides

treatment

normal

mode

the cursor left
one
the character from
If the cursor is in column 1,
RUBOUT
but has no visible effect.
RUBOUT

physically

the screen.
still works,

This

determine

follows:

(default)

RUBOUT

position,

TAB

used
as

move

removing

option simulates tabs by the proper nUmber of
This
is
via the assembly
accomplished

spaces.

parameter
TAB=0
not

TAB

(default)
support

follows:

specifies

tabs.

The

that

hardware
does
simulates tabs by

the

software

spaces.
TAB=1

specifies

that

tabs.

6-ll

the

hardware

does

support

ASSEMBLING AND

Fill

FILL

characters
FILL

parameter
FILL=0

FOR

TASKS

RTS/8

via

supported

are

the

assembly

follows:

does

(default)

provide

not

fill

any

characters.
FILL=n

line

sends

feed;

recommended
OLDTTY

set

fill

n
n

must

characters
(nulls)
in the range 1—5.
baud VTS's.

for

2400

specify

handler.

TTY

Set

standard 3—page
fewer
features,

the

LSBOT

when

using

the

old

set

list

both

the

set

handler.
selected
to

Set

old

2—page

use

handler
shorter.

page
TAB

and

FILL

the
has

The
have

handler.

old
and
new
2-page
0(default) when only the

by OLDTTY is

listed.

of
field
specify the
specifies field 2.

TTY

for

Task;

example,
TTLOC

SCOPE,

effect

handler
TTFLD

The
is a

3-page

the

(default)

handler.
but
it

parameters VT50, WIDTH,

use

after
FILL=4

example,

for
Task;
specify the location of TTY
3000
a
specifies
starting location of

3000.
Several

equates

are

sending

messages

listed

TTY

LPT

the parameter file.
They are useful
Tasks.
These equates follow:

the

NOPACK=4000

Used

NOCRLF=2000

Used if the output message should
by carriage return/line feed.
Used

IND=1000

output message

OUTTXT

not

6—bit

first

points

the

character

ASCII.

not

for

followed

word

the

output text.
NOLINE=400

Used

the

ASSGN=200

Used
this

assign

Used

with

KL8ALINE=100

6.6.4

Monitor

Console

output
the

device

for

use

only

task.
KL8—A

Routine

support

Parameters

(see Section

(Chapter

4.13.2).

MEANING

PARAMETER

MCRSYS

handler

mode.

set

printing

the

system

facility

SYSTAT

status

desired

reports of existent

for

system

tasks.
MCRCLK

MCRFLD

set

by the

user.

set

locate
3.

the

MCR.

the

clock

field

MCRFLD

functions

which
=

are

places the

not

wanted

to
desired
in field

MCR

ASSEMBLING AND

MCRPRT

set

the

nUmber

nonresident
This
swapped.

which
into
will
be

partition

the

the
makes

portion

the

RTS/8

FOR

TASKS

MCR

the
parameter
the first page of the
however,
nonresident;
is always resident.
MCRORG

end

specify the
Default
causes
the field.

Set

task

set

MCR.

MCRCDV

08/8 Support Task

6.6.5

name

device.

console

load

which

set

the

number

the

the
the

MCR

TTY.

fields allocated for 08/8.
fields or 8K of memory

specifies

two

device

code

08/8.
set

the

OS/8 keyboard terminal.
of

use

the

console

terminal

Note:

OS/8 requires its

set

the

device

desired
selects
03 specifies the
for
08/8.
keyboard

that

OSKBDV

which

code

terminal.

dedicated

own

selects

OSTTDV
04 specifies
teleprinter.
the console teleprinter for 05/8.

set

OS/8

OSSYSD

against

MEANING

for

OSTTDV

MCR

(Section 4.6)

Parameters

OSFLDS

OSKBDV

MCR

the

of task
Default

PARAMETER

OSFLDS

location

starting

MCR

task.

select

OSSYSD

the
DTA

desired
the use

driver
device
08/8
system
DTAO
as
the 08/8
specifies

system device.
OSFILL

the number of null characters that
must
line feed character on the 08/8 terminal.
4 is specified
when
a
2400-baud
using
VT05
to
terminal.
Set
0
when
using standard
hard-copy terminals.
Is

set

follow
OSFILL

A terminal device
Note:
be included for the 08/8

6.6.6

KL8-A

Support Parameters

PARAMETER

KL8ADV

terminal

does

not

have

device.

(Section 4.13)
MEANING

for
the
Specifies the device code
Default is 40.
If multiple KL8-A's
should

KL8ACT

handler

have

consecutive

first
are

KL8-A.

used,

they

device codes.

routine.
Specifies the page for the KL8—A connect
Default
is
7400
The KL8-A connect
(if KL8A=1).
routine must be located in field 0.

LOADING TASKS

ASSEMBLING AND

6.6.7

Line Printer Handler Parameters

MEANING

Printer

6.6.8

the

Specifies

DECtape Handler

the

Parameters

Handler

6.6.9

EXIT

field

the

Line

Printer

Task.

(Section 4.4)

the

starting

location

the

DECtape

Task.

Specifies

Task

Line

the

MEANING

Specifies

DTAFLD

Task.

PARAMETER

DTALOC

location

starting

Handler

Specifies

LPTFLD

RTS/8

(Section 4.3)

PARAMETER

LPTLOC

FOR

the

field

the

DECtape Handler Task.

(Section 4.14)
MEANING

PARAMETER
EXITFLD

Specifies

the

field

EXITLOC

Specifies

the

starting

the

EXIT

location

Task.
of

the

EXIT

Task.

CHAPTER

NONRESIDENT

7.1
A

7
TASKS

OVERVIEW

nonresident

task

portion of

task

that

resides

The
the time the task is not runnable.
device
storage
during
mass
It
be
mass
can
any
storage device is called the swap device.
medium
an
RK8 cartridge disk or an RX8 floppy disk).
storage
(e.g.,
a
When a nonresident task becomes
the
Executive
executable,
posts
The Executive then runs a special task called the
residency
request.
task
of
the
nonresident
Swapper to load the nonresident or portion
mass

into
into

The memory area
The loading process is called a swap.
of which the nonresident task is swapped is called a
A
partition.
partition is a contiguous block of memory that is used
for task execution;
call.
it is readable in a
mass
storage
single
The
use
of nonresident tasks permits several tasks to share the same
areas of memory,
optimizing the use of available memory.
memory.

which

out

can be either
tasks
totally or partially nonresident.
Very few
in
the
nonresident
most
nonresident;
totally
applications,
Active
portion includes all, or nearly all, of the active locations.

Tasks
are

locations
are

never

includes
that may

are

those

accessed

messages,
be

needed

that

contain

by other
event

tasks.

buffers
tasks.

flags,

by other

executable instructions
The resident
portion
and

similar

data

that

task

passive registers

NONRESIDENT

TASKS

POP-8 MEMORY

SWAP DEVICE
OK

(Disk, DECcassette, etc.)
REAL TIME PROGRAM AREA
_

C ontains

nonresident

Contains:
1.

portion Of a
task

Resident tasks
Resident portions of
non

resident tasks

pK
PARTITION AREA

SWAPPER TASK

(SWAP-PA)

1. Contains non resident portion
of nonresident task when that

task is being executed.

3162122;
residenftask

2. Allows multiple tasks of same

out non-

relative size to run in the
same

memory area.

onto

Swap Device

:vvaglssai taejblerjnd

3. The characteristic of a partition
'5 as

Loads nonresident

portion of task into

follows:

checkpointable tasks.

Has a starting address

b) Resides completely within a

single memory field
c)

Length has to be an integral
number of pages

d) Cannot overlap another partition
nK

Figure

7-1

Nonresident

Task

Implementation

The

into
process that swaps the nonresident portion of a task
memory
is
similar
to
the
overlay
capability found in OS/8 FORTRAN IV and
related programs.
is
much
more
than
However,
swapping
powerful
Every nonresident task has two properties that establish
overlaying.
when and how
it
into
of
is
or
out
These
two
swapped
memory.

properties

are

is
the
another

made

"writeability"

and

"checkpointability".

"writeable" if its
device
whenever
A
writeable

nonresident portion must be
written
is swapped out to make room for
it
is
is
task
task
that
any
is
the
task's
code
i.e.,
during task
self—modifying
changeable
The
execution, and any task that must initialize before it can start.
writeability feature guarantees that the nonresident portion of a task
is always up to date by
the
of
the
device
swap
image
refreshing
nonresident portion whenever the task is swapped out of memory.

task

onto

swap
task.

—

task

is made

automatically,
task.

swapped

task
back

"checkpointable"
without
that was

its

consent,

out

memory

higher priority

is
of
memory
all higher priority tasks have
Execution then continues
at
necessary memory space.
it was interrupted, and the task is not aware that it

checkpointed
automatically as soon

relinquished the
the
point where
was
interrupted.

be
swapped
make room for a
and
out
swapped
may

NONRESIDENT TASKS

and
writeable
both
tasks
have
Some
nonresident
Checkpointable
Writeable tasks are utilized when a task must modify
characteristics.
or
instructions
JMS
it
includes
itself
temporary
(for
example,
those that are
are
for
Tasks
suitable
checkpointing
locations).

fairly long—running,

and

are

required only occasionally.

Writeable Tasks

7.1.1

or
writeable task is one that includes code that is self-modifying,
Before execution
initialized
before execution.
that
must
be
)n
the
begins, all nonresident tasks must reside as core image files
The core images are created by loading each nonresident
device.
swap
this can
task separately, and executing an OS/8 monitor SAVE command;
be done under BATCH.
When a task is executed, its nonresident portion
is
is read from this core image file
If
a
task
the
by
swapper.
its nonresident portion will be written into the same file
writeable,
when it is swapped from memory.
It is likely that a
writeable
task,
at
execution
start—up, would flag itself not writeable at some later
time when all initialization is completed.
The nonresident portion of
task is writeable if it must be saved on a mass storage device (swap
a
device) before overwriting it in memory with another task.

code

7.1.2

Checkpointable

Checkpointing
can

run

swap

the

7.1.3

short

Tasks

ideally suited

The

tasks

memory,

long running

for long—running
tasks.
the same area, swap them out of
back again.

in
task

Interaction Between

system
and

Tasks

Resident
tasks
can
interact
with
the
resident
any
portion of
nonresident
task.
Two
nonresident
tasks
that
occupy overlapping
their
resident
other
memory regions can interact with each
through
For example, if a nonresident task is executing, it sends
partitions.
a

resident.

7.2
The

and

message

acknowledge

the

then

sender's

However,

MEMORY

the

This
that is

locations
has the following
0

has

since
block
o

message
the sender

can
recipient
is not totally

resident.

PARTITIONS

swappable portion of

partition.

The

checkpointed.

message even though
message sent must be

partition
readable

nonresident
is
simply
one

mass

resides

contiguous

storage call.

in
block

Every

memory

partition

characteristics:

wholly contained in
a

task
a

starting

one

memory

field.

address.

a
(octal)
length (size) that must divide evenly by 200
OS/8 file structured devices read and write in one—half
(one page) increments.

normally begins

address

which

multiple

400.

NONRESIDENT

The

user

the

the parameters

set

can

for

file
or
the
parameter
procedure is described in Section

TASKS

the

establishing
Of

source

the

either

partition

Swapper Task.

This

7.4.

Partitions are
that
one
cannot
distinct,
is,
mutually
partition
another.
number
of
The n
overlap
Any
partitions can be defined.
with
n-l,
partitions are numbered in any order, from O tO
partition
number 0 being the first partition.
They need not be adjacent.

Only

one

task

can occupy a partition at
the
that
until
partition
in the next section), or (if

owns

(described
as
long
higher

tasks

priority

any given time.
task executes a

task is
share
the

the

that

The

occupying

"free"

command

checkpointable) as
remain
partition

nonexecutable.
It

even—numbered

400

location
every partition begins on the first
that is, the starting address is a multiple Of

Command

FREE

free

request can be appended to the function argument of
example, SEND, RECEIVE, etc.) as follows:

(for

CAL

free

the

some

ER's

/A CALL TO THE EXECUTIVE
/"COMMAND" IS ANY RTS/8 EXECUTIVE
THE
/REQUEST.
/ISSUING TASK IS TO BE SWAPPED OUT OF
/MEMORY IF SOME OTHER TASK
/BECOMES EXECUTABLE AND REQUIRES THE
/PARTITION BEFORE THE FREEING TASK
/CANCELS THE FREE REQUEST.

CCMMAND+FREE

pages,

octal.

7.2.1
A

convenient

most

request must be combined with

some

executive

other

request.

sequence:

CAL
FREE

will

issued,

interpreted

as:

CAL

SEND+FREE

other
free
Only nonresident tasks may issue free requests;
A
its
own
are
task
free
partition, but
may
ignored.

partition
A

task

any

other

either

case,

whenever

must

wait

for

pending request for the partition, it
If
is
there
no
partition
immediately.
partition, the freeing task continues to wait

task
free

has

is swapped into the
request for the
pending
in the free partition until
In

the

task.

another

normally frees its partition

event.

requests
never

some

other

occupant

requests

residency.

freeing task becomes executable again, it
with
other
executable
the
any
partition
along
task may become executable before any other
freeing
once

the

for
compete
The
Occupants.
In
this
the
free
task requests residency in the partition.
case,
is
command
cancelled, and the freeing task retains possession of the

must

partition.
swap

task

this

(which

programmer

may
is

read

case.

write

may not be
that
assured

Operation

necessary

effect

this

partition whenever the occupying
the
event,
writeable) must wait for an
the partition contains a running (i.e.,

By freeing

the

7-4

NONRESIDENT TASKS

If there are no
nonwaiting) task whenever possible.
writeable- tasks
is involved in freeing the
in
the
no
device
1/0
swap
partition,
partition.

7.3

NONRESIDENT

TASK

INITIALIZATION

The following procedure is recommended
containing nonresident tasks.

implement

any

RTS/8

system

task.
a
resident
task
as
debug each nonresident
the
debugging, load the task being debugged and only
the tasks required for execution of the task to be
debugged.
task
while resident, make it
Once
the
executes
correctly
in
the
nonresident.
Making a task nonresident is described
sections that follow.

Code

and

During

of
each
a
the
mark
nonresident
portion
listing,
of
task's
the
each
nonresident
task.
Determine
size
nonresident portion.
Then design the partitioning scheme and
allocate
nonresident tasks to memory partitions by modifying
the parameter file as described in Section 7.4.

so
its
nonresident
task
that
nonresident
Re-origin each
If necessary, ensure that
portion lies within its partition.
resident portions of nonresident tasks do
not
into
overlap
another
an
BITMAP,
partition.
OS/8
utility program, is

two
determine if
into the same
The use of BITMAP is
in
described
Section
memory section.
A detailed description of BITMAP is given in Chapter
6.3.
2
of the 08/8 Handbook.
task
Execute the task as
a
resident
once more
to make sure it does not contain location dependent

useful

for

this

since

tasks

are

allows

the

user

being

erroneously

loaded

if
on
an
odd
Also,
any
memory
partition
begins
numbered page, temporarily relocate each task that resides in
that partition.
An example of starting a nonresident task at
code.

arbitrary boundary

7.3.1

Parameters

Several

for

-assembly

given

Nonresident

Tasks

Section

must
be
when
initialized
employing
of
the
in
are
located
the
parameters
in
and
three
must
be
included
the

parameters

nonresident

tasks.
Five
file
parameter
(PARAM.PA)
nonresident task itself.
The

file
contains
parameter
(PARAM.PA)
SYS
and
which
CHECKP,
SWAPPER,
SUNIT)

employing

9.3.

nonresident

These

tasking.

five

parameters

must

parameters

(PARTNS,

initialized when
as
are
defined

follows:
PARTNS

set

the

PARTNS

set

that
CHECKP
SWAPPER

set

the

memory
to

number
to

zero

partitions
any

memory
partitions
the parameter file to
are

nonresident

defined
task

the

defined.
indicate

system.

checkpointable.

nonresident
task
it
must
be
task;
swapper
a
task number that is of higher priority than
the task it swaps, that is, a
number
lower
in
value
than that of any nonresident task in the system.

assigned

NONRESIDENT

SYS

set

example,

nonresident
Every
parameters:
PARTNO=

CPABLE=

0,
1,
0,
1,

WRITE:

task

RK8

the swap device driver
task;
specifies the disk driver task.

unit;
swap device physical drive
0
the disk cartridge
specifies

must

source

where n is the
if the task is
if the task is
if the task is
if the task is

for

include

the

three

following

task's

partition number
checkpointable
checkpointable

(starting

not

not writeable
writeable

these parameters correctly causes the program to
The presence of parameter PARTNO identifies a
task.
PARTNO
name
should
Hence, the variable
nonresident tasks.

unpredictably.

task

initialize

execute
not

is set to specify the
for
SUNIT
example,
drive.

SUNIT

Failure

designate
SYS

TASKS

nonresident
except in

used

nonresident task is not appreciably different from a resident
task.
However, buffers should not be in nonresident portions of a task since
the buffers will be
out
of
when
is
that
task
not
memory
being
executed.
There are no special coding restrictions.
The nonresident
in
while
a
is
nonresident
task
portion is always present
memory
It
is
to
safe
assume
that the nonresident
executing.
generally
is
There
a
portion is never present when the task is not executing.
structural
difference between resident and nonresident tasks;
slight
nonresident
tasks
defined
and
nonresident
have
resident
clearly
portions that cannot be intermixed.
A

Assembling Nonresident

7.3.2

Tasks

task
The
nonresident
nonresident task is assembled separately.
include
the
parameter TASK, but never the parameters TASK2 and
TASK3 (see Section 6.1.5, Task Setup).
Each

must

the
of
the
nonresident
swap device file that contains
portion
This file must contain
task
nonresident
requires special treatment.
first
of
the
location
the first word of the nonresident portion in
block
the second word of the nonresident portion in the
relative
1,
This file must be a core image;
second location, and so on.
however,
the
monitor
08/8
requires that the first location of any core image
section load into a memory address that divides evenly by
400(octal).
If
also
divides
the
address
in
the
lowest
evenly by
partition
There is no problem because
every
400(octal), this condition is met.
task can be assembled in the partition directly.

The

the

Modify~

parameter
Then

parameters.

to
establish
file
(PARAM.PA)
the nonresident task and the

assemble

the

desired
file

parameter

together.

7.3.3

Creating

Create

SAVE

image file

the

SAVE

image file

Image File
(nonresident

follows:

.R ABSLDR

*TASKX.BN$
.SAVE

DEV TASKX.SV

Nl-NZ

7—6

disk

image)

from

the

binary

NONRESIDENT

TASKS

address
each task, where DEV is the swap device, N1 is the lowest
The
the partition, and N2 is the highest address in the partition.
of
each
resulting core images contain only the nonresident portions
However, the
and meet all the requirements previously outlined.
task
control
core
first block of the core image (relative block 0) is the
As stated previously, it is
which is not used by the swapper.
block,
strongly recommended that the partitions begin at a location that is a
For

multiple
starting

since the 08/8 SAVE command only
400(octal)
400(octal) boundaries.

saves

areas

NOTE
SAVE

command
SAVE

7.4

files

image
08/8

under

LOAD may

constructed
08/8 CCL

the

Also,
used

create

the

image.

INITIALIZATION

PARAMETER

can

BATCH.

FOR

PARTITIONS

The user must initialize certain parameters to define the partitioning
The following
scheme.
They can be set in either PARAM.PA or SWAP.PA.
three variables are required for each of the partitions:

The

MFLDnn=

MEMORY

FIELD

ADDRnn=

MEMORY

ADDRESS

SIZEnn=

SIZE

PARTITION
OF

PARTITION

SPECIFIED

PAGES

sets
of
set up
file
to
the
accept
eight
parameter
When
more than eight partitions are defined,
parameters.
instructions
table
must
be
extended
to
parameter
according

user

can

partition
the

contained

source.

system overhead,
This

minimizes

it
the

Since

adding

is best to have
number of tasks

extra

partitions

does

not

partition

otherwise,

reason

partitioning

also

swapper

7.4.1

increase

as
possible.
many
partitions
Each
that must share a partition.

should have at least two occupants;
for
The
making the task nonresident.
defined by initializing the
required

parameters

scheme

can

there

within

the

source.

General

Information

entire partition
The
user
listing.
partition parameters
The

CREF
output
appears on the swapper PAL or
it
to ensure that all
should
check
carefully
for
each
(MFLDnn, ADDRnn and SIZEnn
partition)
were
defined
The parameter file generates the residency
correctly.
table entry for each nonresident task and it appears
PAL
on
the
or
CREF
The user should examine word 1 of
output listing for that task.
this entry to verify that
the
nonresident
task
PARTNO,
parameters
Word 2 of the residency
CPABLE, and WRITE were initialized correctly.
table entry will be zero because the task's block address on the
swap
is
device
unknown at assembly time.
This location is initialized by
the 08/8 command decoder shortly after program startup, and it can
be
examined
thereafter.
In the usual case, where the file is a
anytime
core
M
is
the
block
image, this location should contain M+l, where
address returned by the following command:
.DIR

table

DEV:TASKX.SV/B

NONRESIDENT

TASKX.SV

the

image

core

TASKS

the

device

swap

containing

the

nonresident portion of the task.

7.5

NONRESIDENT TASK

Perform
1.

the

IMPLEMENTATION

following procedure

Assemble

described

implement nonresident

every task that will be included in the
in Section 7.3.2.
Obtain PAL or CREF
Finally, obtain a bitmap of the entire

bitmaps.
verify that memory is allocated correctly.
are
legal only within partitions.
the

Create

tasks.

image file

SAVE

described

program

listings

and

system

and

the

Section

bitmap,

7.3.3.

binaries of
the
executive
and
each
RTS/8
task,
tasks.
nonresident
load
the
executive
Always
first.
Nonresident tasks are included in this
in
operation
to
order
load
their
resident portions and Executive table
entries.
Either save the loaded program as a core image file
or
start it from the keyboard.
the

Load

including

R
Start the real—time program
the
monitor
command.
using
This
calls the 08/8 command decoder, which types an asterisk
on
At this time, initialize the
the console terminal.
block
address of each nonresident task core image as follows:

*DEV:TASKX.SV=N
DEV is the swap device and TASKX.SV
is
'file* containing the nonresident portion of
task N.
Repeat this procedure for each nonresident task, one
task
line, and terminate the last line with an ALTMODE.
per
This
initializes
and
starts
the
procedure
automatically
real-time program.
In

this

line,

command

the

core

This

initialization procedure may be

under

image

OS/8

BATCH

executed

automatically

control.

Example:
$JOB SYSTEM
/RUN "SYSTEM" AND INSTALL
/NONRESIDENT TASKS.
.RUN

SYS

SYSTEM

*TASK1=35

/TASK 35

*TASK2=36$ /TASK 36
$END

Submitting
installing

SYSTEM.BI

its

two

runs

"TASKl"
"TASKZ"

RTS/8

nonresident

SAVE

IMAGE

SAVE

IMAGE

user

system

SYSTEM.SV,

tasks.

this
Accomplish
selectively
by
Debug the entire program.
HLT
if
instructions
ICE,
NOP,
(preceded
by
placing
been
appropriate) and examining the memory once the HLT has
Use the MCR and/or the console switch register to
executed.
HLT
instructions
and
remove
and
to
all
modify
place
resident
areas.
When using MCR, remember that
permanently
MCR
a
of
at
some
represents
snapshot
memory
output
undetermined
point in time that is long past by the time the
MCR has

output to the terminal.

CHAPTER
DEMONSTRATION

8
PROGRAM

tasks
chapter contains a demonstration of RTS/8 with nonresident
in
the
Included is a listing of the modified
foreground.
of
In
is
an
there
addition,
parameter file (PARAM.PA).
example
NR20
nonresident
tasks
and
(Tasks
NR22) and the assembly and load
instructions required for implementing the demonstration program.
This

executing

8.1

[2.8

MODIFIED

PARAMETERS

PARAMETER

FOR

\\\\\\\\\\

(C)

(PARAM.PA)

RTS/8

LSTFLGIO
XLIST LSTELG

TASKS
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FILE

V£8+DECNET
PREVENT LISTING

PARAM

1974,1975'1976 HY DIGITAL EQUIPMENT CORPORATION

ITHE
IAND

INFORMATION IN THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE
SHOULD NOT BE CONSTRUED AS A COMMITMENT BY DIGITAL EQUIPMENT
/CORPORATIDN.
DIGITAL EQUIPMENT CORPORATION ASSUMES NO RESPONSIBILITY
IFOR ANY ERRORS THAT MAY APPEAR IN THIS DOCUMENT.
/

/THE SOFTNARE DES§RIBED IN THIS DOCUMENT IS FURNISHED TO THE PURCHASER
IUNDER A LICENSE {OR USE ON A SINGLE COMPUTER SYSTEM AND CAN BE COPIED
IIWITH INCLUSION 0F DIGITAL'S COPYRIGHT NOTICE) ONLY FOR USE IN SUCH
ISYSTEM, EXCEPT AS MAY OTHERWISE BE PROVIDED IN WRITING BY DIGITAL.
/

IDIGITAL
/OR

EQUIPMENT
OE

RELIABILITY
IDIGITALo

\\\'\\\

CORPORATION ASSUMES NO RESPONSIBILITY FOR THE USE
ITS SOFTWARE ON EQUIPMENT THAT IS NOT SUPPLIED BY

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[PRINTER

DEVICE CODE
DEFAULT IS a
DEVICE CODE - DEFAULT IS TTDEV-I
I1 MEANS CONSOLE TTY (DEFAULT)
II ENABLES CTRL/S AND CTRL/O
l1 MEANS TTY CAN DO A BACKSPACE
/NUMBER OF FILL CHARACTERS, 1.5. A
ITTY LINE WIDTH (D MEANS INFINITE). DEFAuLT
I1 IF TTY HAS HARDWARE TABS
(I TO USE OLD E'PAGE TTY HANDLER
/1 LISTS BOTH HANDLERS (DEFAULT a)
IFIELD OF TTY TASK (TIMES 10)
ILOCATION OF TTY TASK

FILLNIDTHI
TAB.

DLDTTYI
LSBOTI
TTFLDI
TTLUCI

XLIST

IFNZRO

KLBA

XLIST

LSTFLG

IKLUA
/KL8A
IFDEF

1D
EXIT

XLIST

LSTFLG

DEVICE CODE
DEFAULT IS AD
CONNECT ROUTINE PAGE - DEFAULT
-

IEIELD
1)

LSTFLG

EXIT

TASK (TIMES
TASK

IFNDEF

PDPBE

<PoPaE-1>

IFNDEF

P9912

IFNDEF
IFNDEF
IFNDEF

EAE
PWRFAL

<EAEIO>

KLBA

(ALBA-u»

XLIST
IFDEF

1
NSF

XLIST

LSTFLG

10)

<PHRFALIO’

or LOGICAL CHANNELS ccca'sa
FOR 3 CHANNELS
/THESE ARE NUMBERED 1.2.3
INUMBER or NUDE NAMES IN NODE TABLE
IFIELD or NSF TASK AND MOST NETWORK

[NUMBER
/E.C. 3

NSPFLDI

IETABLES
2600

7466

ILOCATION OF EXIT

XLIST

MAXNODI

XLIST

MAXCCB'

NDDNUMI

IKEYBDARD

IKLSADV'
IKLBACTI

NSPLOCI

TABLE

CONSOL'

[EXITFLD'
IEXITLOC'

PARTITION

LSTFLG

VTSG'
SCOPE!

XLIST

TTY

KBDEVI

\\\\\\

END

BEING

TABLES

USED

(5.5.

an)

INCLUDE CCBTAB, LNKTAB, NODTAB AND NETTAB)
must aE .LE. 322a
IURIGIN or NSP TASK.
ITHE DEFAULT IS CURRENTLY 329a
INODE NUMBER or THIS NDDE

136

DEMONSTRATION

[IMPORTANT RELATIVE

ORIGINS

[DOCMP3
[NSP3

PAGE
PAGE

[NETWORK

USE PAGE

TASKS

[ADDRESS

[ADDRESS
USE

CORE

TABLE

PAGE

NODE

POOL)

FOLLOWS:

AST DE~OUEUER
GOD TABLE
NODE TABLE
NETWORK 'INFORMATION'

FOLLOWS:

LINE:

NETWORKS TASKS

36-77
77-177

IO-Ia,
15-17,

TABLE ENTRIES

[EACH ENTRY
[WORDS 1-3

HAS

TUE FORM
NODE

NAME

(b-OIT:

O-PADDED)

LINE NUMBER

[WORD 4
[WORD

[ADDRESS

0200-3577
32DO-7577

0;
O;

[ODCFLDT
[NSPFLOB
[NODE

TASKS

NETNURKS

DEFAULT

OF
OF
OF
OF

[ADDRESS

DRLXITI NSPLOCPABOO
CCBTABI DRLXIT*ZDO
NODTABI CCSTABOIOD
NETTABI NDDTASfibO
[THE

WITHIN

PROGRAM

BIT 031 IF ADJACENT NODE
BITS 4'11 CONTAIN NODE NUMBER

[

IFDEF TASK ‘
FIELD NSPFLDXIO

IFZERO

TASK-NSF

*NODTAB

NODTAB,

[NAMEI

TEXT

[LINE
[NODE

O
0

tNETTABoa
NODNUM

[NAME/

[OUR
[OUR

IPDEP

1
DDCMP

XLIST

LSTFLG

TEXT

FIELD

NUMBER
NUMBER
NODE
NODE

NUMBER
NAME

XLIST

HAXLIN-

PHYSICAL LINEs BEING USED
FOR 3 LINES
/THESE ARE NUMBERED 0,1,2
/SET TO NUHuER 0F NODE PDOL PACKETS To ALLOw
[THE NODE POOL EXISTS AT THE END OF DOOMP
[JUST BEFORE THE LCB TABLE (SIMILAR TO THE CLOCK
/EAcH PACKET REQUIRES 1a HORDS OCTAL. (ABOUT 10.
ILTHE DEFAULT REOUIRES a PAGES CORE)
[NUMBER

[9.6.

MAXPKTI

[KGBEI
DDCFLDI

DEFINITION OF LGB SIZE (00 NOT ALTER)
[GLOBAL DEFINITION OF PACKET SIZE (DO NOT ALTER)

DDCFNCI
HEAOPKI
LCBTABI

[ADDRESS OF ODGMP 'FUNCTION CALL' ROUTINE
ODCLOC
DOCLOCtSOZO
[ADDRESS OF START OF PACKET FREELIST
HAXPKT'PKSIZEOHEADPK
[ADDRESS OF LINE CONTROL BLOCK TABLE

[ELOBAL

NETWORKS

PAGE

GLOBALS

DDCEFI
FREHD'

[DDCMP

[LOCATION OF

DDCTL'

DDCHD'
ATNINP'

OHDRI
OCRCL'

ODCRCLI
OUTCOFl
DDCUSRI
XLIST

52
55
65
65

67
NSP

I[O

EVENT

FLAG
I[O PACKET FREELIST HEAD
[POINTS TO TAIL OF DDCMP INPUT OUEUE
[POINTS TO HEAD OF DDCHP INPUT QUEUE
[POINTS TO TRANSMIT COMPLETE RING BUFFER
[LOCATION OF HEADER BUFFER FOR TRANSMITS
[HEADER CRC FOR TRANSMITS
[DATA CRC FOR TRANSMITS
[DATA OESCRIPTOR FOR TRANSMITS
[DEFAULT USER OF DOOM? TASK

1’

XLIST

IFDEF

NIP

XLIST

LSTFLG

[NIPFLDt

[FIELD OF NIP

[NIPLDCI

[LOCATION

[SKIMPI

PAGE)

TO IOT SKELETON IF KGBE IS PRESENT (E.G. 6110)
[FIELD OF DOCMP TASKILCBTAB AND 'NODE POOL' tE.G. 20)
[THIS FIELD MUST BE DIFFERENT FROM NSPFLD
[ORIGIN OP OOCHP TASK
[THE ABOVE MUST BE BELOW SODD-SIZE 0F NODE POOL AND LCBTAB
[THE DEFAULT Is CURRENTLY EOO

[IMPORTANT

[NIPART'

OUEUE)
PER

[SET

DDCLOCI OaOO

LOBSIZI
PKSIZEl

(TIMES

10)

NIP
[PARTITION FOR NIP
1
TO
TO
GET SHORT
[SET

NIP

8-5

DEMONSTRATION

PROGRAM

/NIPLOG-

IDEVICE

INIPRESI

IDEFAULT IS LPT IF IT EXISTS (OTHERWISE
ILDCATION FOR RESIDENT PORTION OF NIP

NIP

IREOUIRED

IDEFAULT
XLIST

IFDEF

TLK

XLIST

LSTFLG

ITLKFLDI
/TLKLOCI
TLKCHNI

IECB
XLIST
IFDEF
XLIST

/FIELD
[START
CHANNL TO

LSN

OUTPUTS

ONLY IF NIPART
Is NIPLoc-aaa

OF TLK
OF TLK
ASSIGN

TASK
TASK
TO TLK

or LSN
OF TLK
ASSIGN

TASK (TIMES
TASK
T0 LSN TASK

TTY)

DEFINED

TASK

LSTFLG

ILSNFLDI
/Ls~Loc=

IFIELD

LSNCHN:

IECB
xLIST
XLIST

[START
CHANNL TD

1w)

LSTFLG

IEOUIVALENCESS
AC7776I
ACTTTSI
ACADODI
ACSTTTI
ACZDDDI
ACDDOZI

CLL STA

RAL

STA
STL
STA

RIL

/MDNITOR

CALL

CALI
POSTDSI
wAITMI

SENDI
RECEIVI
wAITERUNSUSPNDI
POSTl

cLL
CLA
CLL
CLA
CLA

RAR
RAR
STL RTR
STL RTL

JMS
JMP
JHS

VALQES:
2U

I
I

"it" MEANS CRITICAL VALUE MAY NOT
INOTE:
IHE CHANGED WITHOUT MODIFYING SYSTEM CODE11
lsEND MESSAGE
[RECEIVE MESSAGE
[WAIT FOR EVENT FLAG
IEDNTINUE TASK EXECUTION
I§USPEND TASK EXECUTION
IPOST AN EVENT FLAG
IINSERT CODE INTO INTERRUPT SKIP CHAIN
IINITIATE END-ACTION
[BLOCK TASK FOR REASON SPECIFIED IN ARG
ISEND MESSAGE AND WAIT
IPNBLOCK TASK FOR REASON SPECIFIED IN ARG
IEDRCE A RESCHEDULE
IWAIT FDR EXACTLY THIS EVENT FLAG

1
2
3
4

SKPINSI 6
DERAIL' T
BLKARGI 1D
SENDWI
11
UNBARGI 12
RESCHD‘
wAITX:
FREE-

ICALL THE EXECUTIVE
IDISMISS AN INTERRUPT
IWAIT FOR MULTIPLE EVENTS

13
10
400D

lftFREE

XLIST

I
UDC

IFDEF

PARTITION

XLIST
LSTFLG
AO'OTDO'IIDIIEIGCISIECIAIRCIS
DClblECTITICSIIOIOCTIIIIAIIIZ
1’
XLIST
LSTFLG
XLIST
ITASK

stwus

NDNRNT'
EFNT'
RUNNTI
SHPNTI
EDRMWTI

FLAGS:

neat

TASK WAIT
FLAG WAIT
[SCHEDULE wAIT
xywswAPPER WAIT
/§va~r FLAG on MESSAGE WAIT
xusen SPECIFIED WAIT
IENABLE WAIT
IMESSAGE NAIT
(RESERVED FOR
INETWDRK WAIT
1y.ooes NOT EXIST WAIT

IFNZRO

KLaA

none
2000
1aa0
maze

maze

USERNTI 01oz
ENABHTI
MSGNTI
NETWTI
,DNEWTI

mean
0020
eaxz

IiaNDNRESIDENT

IEVENT

«IFNDEF

KLaACT

POSSIBLE

KLaA-1/3‘200
KLUDI
KLaACTI 1Qaz-KLUD>>
TSNFLG'

TODL'
TDOHI
DATE'
MCREFI

35
36
37
4%
41

SH INHIBIT FLAG
[LOW ORDER TIME OF DAV

ITASK

IHIGH ORDER TIME OF
[DATE IN 086 FORMAT
IMCR

START

EVENT

DAY

FLAG

IN
IN
IN
IN

FIELD D

FIELD
FIELD
FIELD
IN FIELD

8-6

D
0

O
D

FUTURE

use:

DEMONSTRATION

ISOME

USEFUL

EOUAIES

TTY

FOR

AND

LPT

PROGRAM

MESSAGES:

[TEXT IS NOT PACKED IN b-BIT
IOUTPUT SHOULD NOT BE FOLLOWED BY CR/LF
IOUTTXT FTS T0 FIRST WORD OF TEXT
IINPUT IS IN CHARACTER MODE
IASSIGNS DEVICE
/USED TO SPECIFY A LINE OF A KLBA

NDPACK'ODUD

NoanF-aeua
IND-100D

NOLINEuaoU
AssGN-aon

KLSALINEIIUU
xLIST

1
¢
IFDEF
CLOCK
XLIST
LSTFLG
SOME USEFUL EOUATES

MARKTIMEI
SCHEDULETIMOUTI

XLIST
IFDEF

STANDARD

CLOCK

MESSAGES!

IPOST EVENT FLAG AFTER SPECIFIED INTERVAL
IRUN TASK AFTER SPECIFIED INTERVAL
/DERAIL TASK AFTER SPECIFIED INTERVAL
[USED AS MODIFIER TO ‘SCHEDULE'
IRE'OUEUES RUN REQUEST AFTER SPECIFIED INTERVAL
'SCHEDULE FOO PERIODICALLY'
IE.G.
/DELETE ALL REQUESTS FROM SPECIFIED TASK FROM DUEUE

PERIODICALLY:

CANCELI
XLIST

FOR

1660
2600
200D

TUBE
1’

IFORCE

1
TASK

LISTING

OFF

XLIST
ITASK
IHUST

TABLE SETUP
BE

IPNDEF
IFNDEF
IFNDEF

DEFINED

"TASK",

"CUR","ININT"9

AND

"START"

TASK!

I~1wr
ININTE
ININTS

<ININTID?
¢ININTZIO>
<1NIHT3ID>

iTASK'a+MSGTBL
2
ZBLDCK
tTASK‘AwTSTABL

IMESSAGE

CURX16+CUR

IINITIAL FLAGS

BUFFER

INITIALLY CLEAR

START
B

XLISTI

[INITIAL

IEDEF

VERS

XLIST
VERS

IINITIAL MD

>
XLIST
XLIST
*TASKfiTFTABL

INIWT

XLIST
>

IFDEF
TASK?
XLIST
iTASK2‘2+HSGTBL
2
ZBLDCK

IMESSAGE

BUFFER

IINITIAL

FLAGS?

INITIALLY CLEAR

iTASK2‘4+TSTABL

cuRax1o+cpaa
STARTE
O

XLISTI
XLIST
VERSE
XLIST

IINITIAL

IfOEF

VERSE

IINITIAL MD
>

XLIST

tTASKa+TFTABL
INIuTa

XLIST
>

IFDEF
TASK}
XL151
iTASKS‘EtMSGTBL
2
ZBLOCK

*TASK3‘4+TSTABL
CURIX10+CUR5

IMESSAGE

BUFFER

IINITIAL FLAGS}

START}
0

XLISTI
XLIST

IINITIAL AC 0

ItDEF

VERSS

XLIST

*TASKStTFIABL
ININTS
>

IINITIAL MO
>

XLIST

VERS3

INITIALLY CLEAR

DEMONSTRATION

IFDEF
IFOEF

TASK
PARTNO

PROGRAM

XLIST
IRESIDENCY

(RESTBLJ

TABLE

ENTRY!

NONRESIDENT

IINITIALIZED FOR

TAsns

ONLY

*TASK-SNAPPER-l‘éfiRESTBL

PARTNO‘QOPARTBLtCPABLE‘CPABLE+HRITE
xLIST
IFNDEF
IFNZRO

SNAPPER tNOSWAPp‘ERROR‘>
ISNAPPER MISSING
TASK-SNAPPERI4666
(SWPRIO,‘ERROR‘thON'RESIDENT TASK
IHAS PRIORITY HIGHER THAN SNAPPER

IFDEF

P‘RTNO

IFNDEF

TASK

IFNDEF
IFNDEF
IFZERO

IPARTITION BUT NO TASK
£NOTASK,‘ERROR*’
SWAPPER <N05WAP9.ERR0R‘>
IPARTITION BUT NO SKIPPER
PARTNS
IMISSING PARTITIONS
<NOPARTp‘ERROR‘>
PARTNO'PARTN8&4666
[PARTNO.GE.PARTNS
<PRTERR,‘ERROR‘>

)

XLIST

NONRESIDENT

8.2

The

following

8.2.1

are

TASK

LISTINGS

listings

nonresident

tasks

Nonresident Task NRZO

TASKI26

16466
16461
16462
16463
1646a
16465
16466
16467
16416
16666
16663
16664
16665
16666
16611
16612
16613
16614
16615
16616
16617
16626
166e1
16622

6626
6626
6466
6661
6661
6616
5666
6666
6661
6666
4626
4611
6661
6666
4626
4611
6663
6666
5266
6666
6666
6666
6666
6661
6666
6666
6666
2461

2313
4662
6646
2225
1616

1116
6766

TASK'26
TASKte6
STARTI466
WRITEll
CPABLE=1
CUR‘16

INIWTtRUNWT+NONRwT
PARTN0I6
FIELD CURX16

*466
CAL
SENDwoFREE
CLOCK
SLPMSG
CAL
SENDW+FREE
LPT

LPTMSG
JMP START
*666

SLPMSG:

ZBLOCK

638HERTZ

LPTMSGo

ZBLOCK

6
6

TEXT

/TASK

RUNNING/

(NR20 and NR22):

DEMONSTRATION

8.2.2

PROGRAM

Nonresident Task NR22

TASKIZ2

10400
10401
10402
10403
10404
10405
10406
10407
10410

10630
10633
10634
10635
10636
10641
10642
10643
10644
10645
10646
10647
10650
10651
10652

0022
0022
0400
0001
0001
0010
5000
0000
0001
0400
4020
4011
0001
0630
4020

TASK'22

TASK:22
START-400
wRITEI1
CPABLEII
CURIIE
INIWTIRUNWT+N0NRNT
PARTN0I0
FIELD CURXlE
t400

CAL
SENDW+FREE
CLOCK
SLPMSG

CAL
SENDw+PREE

4011
0003
0636
5200
0630
0000
0000
0000
0001
0000
0000
0000
2401

2313
4062
6240
2225
1616
1116
0700

LPT
LPTMSG
JMP

START

*630

SLPMSG'

ZBLOCK

GISHERTZ
LPTMSG;

ZBLDCK

0
0

TEXT

ITASK

RUNNING/

DEMONSTRATION

8.3

ASSEMBLY AND

The assembly
follows:

and

LOAD
load

PROGRAM

PROCEDURE

procedure for

the

demonstration

program

RTEEBEF‘ARAMT'RTSB~

+PAL

ERRORS

DETECTED:

LINKS

GENERQTED:

.RfiL

CLDCKiRfiRfiMyCLOCK

ERRORS

DETECTED:

LINKS

GENERATED:

.RNL

HflRiRfiRfiMyMCR

ERRORS

DETECTED:

LINKS

GENERQTED:

.RfiL

USRSURiRflRfiMyUSSSUR

ERRORS

DETECTED:

LINKS

BENERATED:

.PAL

TTYfiPARflMaTTY

ERRUR$

DETECTED:

LINKS

GENERnTfin:

.RQL

LRTfiRQRfiMyLRT

ERRORS DETECTED:
LINKS GENERATEDE

0
Q

RESEiRfiRfiMyRKBE

.RfiL

ERRORS

DETECTED:

LINKS

GENERATEDX

NREOiRfiRfiNvNREO

.RAL

ERRORS

DETECTEDE

LINKS

GENERQTED:

NRRRfiRflRfiMvNRBR
DETECTED:
0

.RAL

ERRORS

GENERfiTEDZ

LINKS

swnprhnmnmyswnw

.RNL

ERRORS

DETECTED:

LINKS

GENERRTED:

ABSLDR

*NR20$
NRBO

.Sfi

SYS

fiDSLDR

10400W10fi?7

*NRQR$
NR2?

.SA

SYS

RBSLDR

10400W105??

*RTSBvMCRyCLOCKyRKBEyTTYyLRTyOSSSUR
*SNARyNRROrNRRQ$
.SA

8Y8

RTSSUB

This example shows the assembly of the parameter file and
the
source
task
itself.
The
binaries of each nonresident task are then loaded
device.
into memory, and their nonresident portions saved on the swap
All
tasks
then loaded using the ABSLDR with the RTS/8 Executive
are
tasks
in
the
being loaded first.
Finally, the core
image of all
memory is saved using the 08/8 SAVE command.

8—10

PROGRAM

DEMONSTRATION

NONRESIDENT

8.4

following

The

NR20

tasks

and

AND

TASK

ASSIGNMENT

the

execution of
the system.

NR22

EXECUTION

RTS/8

showing

the

assignment

.R RTSBUQ
*NRROWQO

*NRERmRE
*$}SY
01
CLCK

TTY

LPT

MON

HRS

USSF

SNAP

038

}RE

PER

PEXIT
O

of
In
the
above
the
installation
the
user
terminates
example,
A SYstat
tasks
with an ALTMODE, and returns to the MCR.
nonresident
Section
command is executed which prints a system status report
(see
The REquest command is then used to run tasks NR20 and NR22.
6.2.9).
Shown below is output from tasks NR20 and NR22 on the line printer.

TASK
TASK
TASK
TASK
TASK
TASK

20
20
20

20
22

TASK

RUNNING
RUNNING
RUNNING
RUNNING

RUNNING

RUNNING
RUNNING
20 RUNNING

2%
22

The

EXIT

the

08/8 monitor.

command

typed

terminate

RTS/8 execution

and

return

CHAPTER

ADVANCED

9.1

PERFORMING A

Frequently,
common

task
tasks

two

Code

needs to manipulate
tasks are running

Since

area.

want

delicate
accessing data in

access

code

Consequently,
while

PROGRAMMING TECHNIQUES

RESCHEDULE

Writing Delicate

9.1.1

arise

RTS/8

the

wants

another

data

another

task

will
at
same
time.
same
data
the
to
run
with interrupts disabled

'simultaneously', problems

task.

NOTE

disabled
temporarily
on
either
a
or,
IOF/ION pair
CIF
machines with memory
a
extension,
inhibits
instruction
which
interrupts
until the execution of the next
or
JMP
JMS instruction.

Interrupts may be

using

For example, suppose
B
Task
decrements

execution.

/TASK

The

code

A increments location COUNT occasionally and
location
COUNT
from time to time during program
might look like the following:

Task

LOOPA,

ISZ

COUNT

JMP

LOOPA

COUNT,

/TASK
LOOPB,

B
.

STA

Y,
z,

TAD

COUNT

DCA

COUNT

ADVANCED

RTS/8

JMP

LOOPB

PROGRAMMING TECHNIQUES

If Task A increments COUNT the
same
decrements COUNT, it would be assumed
of the program.
However, this is not

condition

can

for

has

higher priority

event

with
COUNT.

store

that

noting

the

suspends Task

and

resumes

then

and

into COUNT.
event Task A was
back

back
goes
containing a 5 and stores
program execution.
This

to
a

situation is prevented
the
delicate code.

around
be

Task

the
a

end
race

and

Task

interrupt
a

The

service

interrupt

and

Task

for

has

bumps COUNT from 6

COUNT

just occurred,

then

resumes

with

incorrect

for

which

routine,

now

Task

occurs

Task

waiting

into

Task

currently containing

an
However,
The AC contains

sleep.

than

COUNT

occur

Task B is ready to decrement
after location Y has been executed.

ready

Task

occur.

Suppose that Task

waiting

of
number
that
times
that COUNT would be 0 at
so
since
necessarily

the

now

proper

from
by
happening
disabling
interrupts
Either of the following two solutions can

employed:
Solution

/TASK
LOOPB,

Y,
Z,

Solution

/TASK

LOOPB,

STA

CIF

IOF

STA

TAD

COUNT

DCA

COUNT

Y,
Z,

COUNT

DCA

COUNT
,

LOOPB

JMP

Solution 2 (only
instruction

9.1.2

JMP

JMS

CUR

TAD

ION

CIF

usable

JMP

Task

with memory
uses
the
extension)
temporarily inhibits interrupts until the

machines

it
since
instruction

Inhibiting

LOOPB

executed.

Switching

Although the procedure in

the

previous section

very inefficient.
on
data which could

can

is desired to
accessed by other
it

used,

lot

perform
be
tasks, it may be
manipulation
to turn off interrupts.
Inhibiting interrupts for long
inappropriate
timed
periods of time could affect other portions of the system where
an
can be
lost (for
events
are
Also,
interrupt
very
important.
turned
off
for
a
if
are
clock
example,
interrupts)
interrupts
significant amount of time.
times

can

A task
the
can
inform
this case, another solution is possible.
RTS/8 Executive that it wants to continue to run, and that while it is
a
executing a certain piece of code, no other task should run even if
This process is known as
task
of
higher
priority becomes runnable.
inhibiting task switching.

For

ADVANCED

RTS/8

PROGRAMMING

TECHNIQUES

circumstances
unusual
under
should be inhibited only
is
While
task
with
care.
inhibited,
switching
performed
get
interrupts may still occur and the interrupt service routine will
is
control.
if
task
inhibited, the interrupt
However,
switching
task
service routine will always return control
to
the
interrupted
after
the
has been serviced even if higher priority tasks
interrupt
Task
and

are

switching

runnable.

now

NOTE

If the
which

wishes
accessed

user

data
manipulate
interrupt—level

inhibited
be
must
interrupts
task
since
switching alone
inhibiting
will not be sufficient in this case.

routine,

There are
follows:
Method
PC

bottom

Task

inhibiting
is

switching

than
page 0 of

less
of

methods

two

100.

task

automatically inhibited
delicate

Thus,

which

switching

whenever
be

could

code

are

task's
the

placed in

field.

any

inhibit task switching by zeroing location 35 in
location is symbolically referred to as TSWFLG (task
In
in
file.
the
parameter
switching flag) and is defined as such
either
case, after the task is through with its delicate code, it may
not be sufficient for
to
TSWFLG
to
its
the
task
reset
original
This
is
that there may be some other
due
to
the
fact
value(l).
run
because
higher—priority task that is entitled to run but did not
task
was
this
out
The
user
find
inhibited.
can
by
switching
If another task became runnable
while
interrogating location TSWFLG.
task
was
the
executive
sets the task
inhibited,
RTS/8
switching
Method

field

task

may

This

task
When a task is ready to
allow
switching flag to -1.
it must examine this flag before resetting it to 1.
again,
task
returns
to
the
control
scheduler.
-1, the
RTS/8
performed by using the RESCHD ER as follows:

switching
If

it
This

was

CAL
RESCHD

This

causes

RTS/8

task

perform

of highest priority
RESCHD after re—enabling

which

occurs.

late
The

for

reschedule

be executed.
task switching,
to

preferred code for

previously

/TASK
LOOPB,

inhibiting
shown

task

allows
does

user

switching

does,

for

below:

B
.

CDF

DCA

(TSWFLG

/INHIBIT

TASK

SWITCHING

STA

y,
z,

TAD

COUNT

DCA

COUNT

ISZ

(TSWFLG

/ALLOW
9—3

TASK

the

runnable

perform a
task
then a higher
priority
run
until the next interrupt

entitled
to
run
not
might
The interrupt may never occur, or
proper program execution.

described

that
a

SWITCHING

Task

not

too

which

was

may

ADVANCED

.+3

JMP

PROGRAMMING TECHNIQUES

RTS/B

/SHOULD WE RESCHEDULE?

CAL

/YES

RESCHD
CDF

CUR

/NO

dMP LOOPB
NOTE

routines

Interrupt level
at

summary

set

TSWFLG

the

states

should

shown

Table

9-1

Value

switching

Task

switching inhibited

Task switching inhibited;
reschedule as soon as possible

—1

EXECUTIVE

9.2.1

WAITM

Sometimes

OR)

State

allowed

Waiting

for

desirable
The

Multiple
wait

Event

for
the

for

Waiting

Flags.

quite simple.

REQUESTS FOR ADVANCED APPLICATIONS

Event

States

(TSWFLG)

Task

9.2

look

9-1.

Table

Summary of Task Switching Flag

TSWFLG

not

TSWFLG.

Flags

a
combination
(AND
logical
logical AND of two Event Flags

sequence:

CAL
WAITE
A

/WAIT

FOR

EVENT

/AND

THEN

WAIT

been

POSTed.

FLAG

CAL
WAITE
B

waits

until

both

and

have

FOR

EVENT

FLAG

is
more
difficult
the logical OR of several event flags
is a possible race condition between the various tests and
POST
the
Event
which
task
executions)
Flags
(or
interrupts
for
there

Waiting
since
the

involved.

The

successfully is

testing
state

key
not

to
to

an
OR
of several Event Flags
between
the
to
occur
interrupts
Flag and the placing of the task in a Wait

waiting

allow

the first Event
of the flags were

none

for

any

POSTed.

ADVANCED

special
be

must

TECHNIQUES

accomplished by using a special sequence of instructions and a
It
WAITM.
WAITM is defined as JMS I 25.
call
named
RTS/8
0
to
executed with interrupts off, the Instruction Field set

This

PROGRAMMING

RTS/8

to the current field, and it must be followed
Task
the
Flags
containing
blocking bit(s) to be set in the
The
Table.
action of WAITM is equivalent to the action of the RTS/8
BLKARG ER except that a fast path through the RTS/8 Executive is taken
and
remain off until the blocking bits are on in the Task
interrupts

the

and

Field

Data

set

word

Table.

Flags

that a task "TASK" wants to
is
control should go to
POSTed,
Flags
BDONE.
location
if B is POSTed control should go to
location ADONE;
If
neither is POSTed, the task must wait until one of them is POSTed.
The code to perform this function is:
For

example of the

test

TESTAB,

use

WAITM,

and

Event

two

assume

IOF

OFF

/INTERRUPTS

TAD

DELICATE

CODE

SNA

CLA

JMP

ADONE

TAD

(4000+TASK

DCA

TAD

SNA

CLA

JMP

BDONE

TAD

(4000+TASK

DCA

CIF

GDP

CUR

/ADONE MUST TURN INTERRUPTS ON
/SET A TO "WAITING" STATE
/INDICATING
/THAT THIS TASK IS WAITING ON IT

/BDONE MUST TURN INTERRUPTS ON
/SET B To "WAITING" STATE
/INDICATING
/THAT THIS TASK IS WAITING ON IT

WAITM

/BLOCK TASK ON EVENT FLAG WAIT
ONE OF THE TWO
/WE'RE BACK
/EVENT FLAGS HAS BEEN POSTED.
/GO BACK TO FIND OUT WHICH ONE

EFWT

TESTAB

JMP

9.2.2
The

WAITX

Event

Flag

EFWT),

and

containing
it

will

is
is

Exactly This

similar

the

Event

WAITE

FINISHED,

the

task's
CAL

PC in the
this ER.

TSTBL

the

Thus,

the WAITX.
If the
the Posting of the
go back into EORMWT.

re-execute

than

immediately

Consequently,

control

specified

Flag

for

not

other

reason

will

Wait

—

will

never

Flag

ER.

The

task

goes

exception
into

EORMWT

that

the

(instead of

to
the
location
back
points
when the task resumes execution,
EORMWT bit was cleared for
some
Event Flag in question, the task

unless
the
Event
past this ER
(see discussion of DERAIL, Section

flow

actually posted

If a WAITE had been used and
if
was
on
the
task
9.2.3).
waiting
Event
can
multiple
(which
happen using WAITM), then control
Flags
conceivably could start up after the WAITE ER because some other Event
and
one
that
is
no
cared
This
about, was posted.
Flag,
longer

situation

9.2.3
The

can

DERAIL

control

not

Derail

ER modifies

with

occur

Task's

WAITX.

Execution

execution of a
subroutine
of
It does not cause

the

special

exceptional condition.

cleared.
9-5

specified
the
any

task

wait

task
to

bits

and

transfers

process
to

get

set

some
or

ADVANCED

TAD

Format:

RTS/8

PROGRAMMING TECHNIQUES

TASKNUM

CAL
DERAIL

ADDR

This ER simulates a "JMS ADDR" for the task whose number is
contained
TASKNUM
ADDR is assumed to be in the same
in
(the "derailed" task).
The derailed task‘s PC
field in which the derailed task is executing.
its Task State Table entry) is stored in ADDR;
the PC entry in
(from
its Task State Table entry is
then
set
to
ADDR+1.
Two
important

points concerning

operation of

the

DERAIL

are

follows:

derailed task's AC, Link, and Data Field settings are not
DERAIL
the
therefore they must be saved and
saved
ER;
by
In this sense,
a
restored by the derail subroutine.
derail
subroutine is very much like an interrupt at the task level.

The

The contents of the derailed task's Task
DERAIL
ER.
If
affected
the
the
by
runnable, the derail subroutine will not
the task becomes runnable.

Flags word

are

task
executed

not

is not
until

derailed

ER is generally used by a high priority task to
an
signal
condition
to
An example would be a
lower priority tasks.
to
abort
process—control environment where it is sometimes necessary
all
if
the room temperature exceeds some critical value.
operations
This can be checked by a task which measures room temperature every 10
It is inefficient and unmodular to include shutdown code in
seconds.
A
this "watchdog task" for all machinery
controlled.
better
being
is to provide a location to which each equipment-controlling
solution
task can be DERAILED in order to shut down its own piece Of equipment.
the DERAIL ER to provide a similar
Power—Fail
task
uses
The
RTS/8
be
used
facility on power—fail recovery (see Section 4.5), which can
to reinitialize a task.

The

DERAIL

emergency

Example:
An

example of
DENTRY,

DERAIL

routine

follows:

SAVAC

/DERAIL ROUTINE
/SAVE AC

SAVLNK

/SAVE

LINK

/SAVE

DATA

0
DCA

POINT

ENTRY

RAR

DCA
RDF
TAD

(CDF

DCA

DFRESET

CDF

CUR

/HANDLE

RESUME,

DFRESET,
NORESUME,

SAVAC,
SAVLNK,

TAD

SAVLNK

CLL

RAL

TAD

SAVAC

HLT
DENTRY

JMP

CLA

CLL

CDF

CUR

JMP

RESTART

EMERGENCY

/BRANCH TO
/TO RESUME
/BRANCH TO

/RESTORE

FIELD

CONDITION

'RESUME'
WHERE

'NORESUME'

LINK

/RESTORE AC
/RESTORE DF
/RESUME (SAME FIELD)

/RESTART

YOU

TASK

YOU

LEFT
IF

WANT
OFF

NOT

ADVANCED

PROGRAMMING TECHNIQUES

RTS/8

if
trouble
A task can get into serious
If this happens,
already in a derail routine.
is
no
There
the original PC, AC, link, etc., will be lost.
simple
be too
routine
in
the
derail
off
solution.
may
interrupts
Turning
occurred
late to prevent this
the second derail could have
already

Dangers of

9.2.3.1
is
it

derailed

DERAIL

while

before

Consequently,
than

routine

derail

the

even

entered

time.

first

the

not
more
DERAIL should make
sure
that
a
done
at
a
time.
Alternatively, before doing a
check an interlock flag (which it must maintain) to
The test and
target task has been derailed or not.
should be performed with interrupts inhibited.

user

doing

DERAL

one

was

DERAIL, a task can
see
whether
the
set of such a flag

is
not
If
a
task
Restrictions Using DERAIL
runnable,
If the task is in Event Flag
it will not make it runnable.
derailing
When
Wait, it will remain in Event Flag Wait until the event occurs.
the
is POSTed, the task will wake up and begin to run in
Event
Flag
its derail
in
routine.
routine
rather
than
the
mainline
Thus,
9.2.3.2

—

it to perform
task might be
not
be able to run for some time.
may
in Receive Wait at the time, the derail
message came in for that task.

derailing

task

always work.

not

may

get

some

The

important job immediately
of

one

For

the

example,

routine

would

and
Wait states
if the task were
a
not run until

to
be
around this restriction is to code the task
it
that
waits on events using WAITX instead of
always
WAITE.
Then, if the user wants to derail this task, the task is first
taken out of MSGWT or EORMWT and then derailed.
A

partial solution

derailed

example of the code for this situation is

follows:

TASKNUM

TAD

CAL
UNBARG

/UNBLOCK THE TASK
/FROM MESSAGE-RELATED

MSGWTlEORMWT
TAD TASKNUM

WAITS

CAL
DERAIL
DENTRY

This

will

work

because

both

the

RECEIVE

and

the

WAITX

Executive

the PC back to the CAL before going into a Wait state.
Requests
bump
for
Thus, no harm is done if the task is taken out of that wait state
an
incorrect reason.
When the task resumes running at that point, it

will
due

the CAL (RECEIVE or WAITX) and go back into
the
Wait
This method will not work if the task was in EFWT
necessary.
a WAITE ER because
the task would resume running
the
thinking
had
been
A way to
when
in
fact
it
had not.
Flag
posted

re-execute

state

Event

circumvent
of

and

STARTING

9.3
The

this

WAITE,

(other than WAITX) is for the task to do
poll the Event Flag upon waking up.

PARTITIONS

ARBITRARY

advanced user can start a partition at an
arbitrary
the following assembly and loading proCedure.
The

assumes

PAL8

that
of

the
the

partition
task

in
run

which the
is three

pseudo-operators FIELD and
detail in the 05/8 handbook.

RELOC

instead

BOUNDARY

using

portion

WAITM

user

writes

pages

long

are

used,

the

boundary
by
example given
nonresident

(11200-11777).
and

described

The

ADVANCED

RTS/8 PROGRAMMING TECHNIQUES

/TASKX
FIELD
*1000

/SET

RELOC

1200

/LOAD THIS CODE AT 11000—11577
/BUT ASSEMBLE IT TO RUN AT 11200—11777

FIELD

<CODE>

PAGE

<CODE>

RELOC

The

load

assembly,
.R

and

save

procedures for the code

PAL8

*TASKX<PARAM.PA,TASKX.PA
.R

(ASSEMBLY OF TASK)

ABSLDR

*TASKX$
.SAVE

The

9.4

which

DIRECT

task
tables
as
the

(LOADING

DEV

swapper,

11200,

are:

TASKX

11000-11577

may

directly

obtain

following

SYSTEM

two

11000)

into

the

partition

TABLES

locations
itself

interrogate
information

INTO

TASK

(SAVING OF TASK-THREE PAGES OF
CODE)

upon loading this task, places it
is where it was assembled to run.

REFERENCES

about

restrictions

are

the
any

Executive

RTS/8

other

task,

long

observed:

Due to the interrupt-driven nature of the system, these table
entries may change at any time;
therefore, interrupts should
are
tested
and
be inhibited between the time these entries
the
that
time
processing which depends on the testing is
For example, testing the Message Queue Header for
completed.

show no messages, but an I/O interrupt occurring
after the test might allow a higher priority task
This
to
run.
task
might send a message, invalidating the
be
result of the test.
To prevent this,
should
interrupts
turned off during and after the test.

task

may

immediately

entries
System table
Executive Requests.

may

changed

only

RTS/8

through

that
table
permit
Symbols have been defined in the system parameter
The
to
references
be made into these tables symbolically.
symbolic
the
address
of
the
table
system
symbolic expressions which yield

entries

for

task

N+TFTABL

are:

Task

N;
N“2+MSGTBL

Flags Table entry for
if

zero,

task

Input Message Queue
task

messages

task
runnable.

Header

if zero, task
in its queue.

has

for
no

ADVANCED

RTS/8

PROGRAMMING TECHNIQUES

N“4+TSTABL

First

N“2+RESTBL

Entry

word of Task
for task N.

First

word

example,

input

queue
CDF

o
I

SNA

CLA

JMP

NONE

code

/EXEC
/TURN

TABLES

/ANY
/NO
/YES

MESSAGES?

INTERRUPTS

FIELD

OFF

(TASK"2+MSGTBL

TAD

ION

The

task

for a task to determine whether it had
messages
without issuing a RECEIVE request, the code would

ICE

NONE

must

eventually

turn

interrupts

Table

Residency

entry for nonresident
For

Table

State

back

on.

in
be:

its

APPENDIX

RTS/8

The

RTS/8

source

File

Name

Task

files

SOURCE

DISTRIBUTED

included

distributed

the

Task

Name

file

System parameter

RTS8.PA

Appropriate values
specific parameter
RTS/8 Executive
MCR

MCR.PA

null

OS8SUP.PA
OSBSUP.PA

088

task

OSBF

PWRF.PA

PWRF

CLOCK.PA

CLOCK

TTY.PA

TTY

LPT.PA

LPT

DTA.PA

DTA

RK8.PA
RK8E.PA

RK8
RK8

RF08.PA

RFO8/DF32

CSA.PA

CSA

CSAF.PA

CSAF

UDCICS.PA

UDC/ICS

RXOlRT.PA

RX8A

RXOlRT.PA

RXBB

RXOlRT.PA
RXOlRT.PA

RX8C
RX8D

LTA.PA

LTA

SWAPPER

NULL8A.PA

NULL8A

EXIT.PA

EXIT

are:

with

should

all

equates

inserted

files.

Monitor Console Routine
task
08/8 Support Task
OS/8 File Support Task
Power Fail Task
Clock Handler Task
Terminal Driver Task
Line Printer Driver Task
TC08 DECtape Driver Task
RK8 Disk Driver Task
RK8E Disk Driver Task
RF08/DF32 Fixed-Head Disk Driver
Task
Cassette Driver Task
Cassette File Support Task

Null

Universal Digital Controller/
Industrial Controller Subsystem
Handler

SWAP.PA

tape

Function

PARAM.PA

MCR.PA

FILES

Task

Floppy Disk Handler (lst
Floppy Disk Handler (2nd
Floppy Disk Handler (3rd
Floppy Disk Handler (4th
LINCtape Driver Task
Nonresident Task Swapper
Null
Exit

Task
Task

for

PDP-8A

controller)
controller)
controller)
controller)

blank.
create

APPENDIX

RTS/8

SIZES

COMPONENT

of
following table gives the approximate size and default origins
An
of
the
each
map
showing
memory
RTS/8
RTS/8
system.
component
be
The modules may
default memory allocation is shown in Figure B—l.
in
memory at the user's discretion except for RTSS,
placed
anywhere
CLOCK and SWAP.
Also, certain modules must be placed in field 0 where
indicated in the tables.
The

The following
follows:
NTASKS

parameters,

Number

which

tasks

are

used

Table

MCRSYS

MCRCLK

KLINES

Number

MCR

CLOCK

functions

physical

are

defined

system

Number of entries in clock queue
1 if MCR SYSTAT function desired,

CLKQLN

B—1,

KL8—A

desired,

else

lines

Any fractions from divides should be dropped.

Table

B—1

RTS/8 Component Sizes

Number

Software

Default

Component

Origin

Pages
(1 page
=128 words)

RTS/8

00200

5+NTASKS/18

Required

Comments

Must

00200-

locations

Executive

Uses
01200.
locations
0
20-47
and

page
0-3
and

auto-index

Module

lst page
after end of
RTS/8 Executive

(or
New

3+CLKQLN/22

Must

17.

field

Uses

auto-index

SWAPPER)

03400

10.

Terminal

Module,

Old

Terminal

Module,

(Continued

page)

RTS/8

COMPONENT

Table B-1

SIZES

(Cont.)

RTS/8 Component Sizes

Number

Pages

Software

Default

Component

Origin

Required (1 page
=128 words)

14400

14600

04200

04400

LINCtape

15000

RK8 Disk
Module

04200

Fail

10200

1+NTASKS/32

Module

10600

Printer

Line

Comments

Module
TC08

DECtape

Module

Disk

RK8E

Module

DF32/RF08
Module

Power

Module
UDC

7—11 depending
table space

page
locations

0
130—144

Requires

cassette

Uses

desired.
Cassette

13600

13000

Module
Cassette

Support

Label
Module

handler.

OS/8 File

04600

Support Module

support present,

08/8

otherwise

Requires

mass

storage handler.

062001

Must

run

field

run

field

08/8 Support

Must

06200*

Task

—

for

requires
08/8 plus

8K
a

mass

storage

handler.
0
page

locations

Uses

164—177.

Monitor
Routine

Console
Task

17600 minus

length
with

KL8A

"console"
handler
and page 0
locations 100-117.
See Table B-2 for

5+3xMCRCLK+

Requires

MCRSYS

terminal

(NTASKS+40)/64.

all

options
no

(15200
and

support)

1Moves

down

by length

of KL8A support

code if KL8A

details.

support present.

(Continued

page)

RTS/8

COMPONENT

Table

B-1

SIZES

(Cont.)

RTS/8 Component Sizes

Number

Software

Default

Component

Origin

Pages
(1 page
=128 words)

RXOl

13200

SWAPPER

page after
end of RTS/8
executive

15000

1/2

EXIT

lst

Required

Comments

Must

field

May relocate
within

NULL8A

13600

KL8A

17600 minus

1+KLINES+1

Support

length

Must

page

field

RTS/8

COMPONENT

SIZES

HTS/8 SYSTEM MEMORY MAP (Default Memory Allocation)

PAGES

HELDO

HELDl

0
200

—

600

400L

‘

PWRF

RTSB

"’

—

(20 tasks)

T-

uomcs

i
2000
SWAP

—

l—-

CLOCK

3000

—

RK8E

TTY,V1

INULL8A

IRKB

l—
_

J—CSA

ILPT

RF08

5000

RXOlRT

TTY,V2

4000

CSAF

l—

ImA

IEXIT

—

GA
..

—

OSBF

6000
Lar g e

MCR

OSBSUP

3mm
MCR

7000
__

iKL8ASR

-L

KEY:

RTS/8 modules may vary in size and placement in memory depending upon the chosen system configuration.
The following symbology has been chosen to show component default allocation in memory.

Fixed

Expandable

Relocatable

Relocatable
and Expandable

Figure

B—l

RTS/8 System Memory Map

(Default Memory Allocation)

RTS/8

COMPONENT

Table
MCR

less

than

SYSTAT

LENGTH:

CLOCK

DEF

ORIG:

NONRS:

SIZES

B—2

Component Size

34(octal)

tasks

34(octal)

LENGTH:

tasks

6 pages
6200

5 pages
6400

ORIG:

PART:

6200
6400-7377

PART:

6200
6400-7577

LENGTH:

ORIG:

6200

ORIG:

6200
6400—7577

PART:
CLOCK

LENGTH:

ORIG:

SYSTAT

CLOCK

SYSTAT

NONRS:

pages

pages
5600

NONRS:

pages
6000
5600

PART:

6000-7377

LENGTH:

ORIG:

pages
5400
5200

5600

PART:

6000-7577

PART:

5400—7377

SYSTAT

LENGTH:

CLOCK

ORIG:

12 pages
5200
5200
5400-7577

NONRS:

PART:

pages
5400
5200
5400-7377

NONRS:

DEF

ORIG:

NONRS:

PART:

APPENDIX

RTS/8

This

FLOWCHARTS

appendix contains RTS/8 flowcharts

system operation.

that

graphically

show

RTS/8

RTS/8 FLOWCHARTS

Calling Sequence:

SAVE AC IN
ACA R G

TAD VAL

CAL

p+1

FUNCTION CODE

p+2
p+3
”+4

ARG1

CAL

AGR2 (or return)
RETURN
=

JMS 2O

Thru Current Field:

TASKSWITCHING

TSWF4‘:
’

ALLOWED
?

CDF CUR

CIF 0

CMP CALIOF (field 0)

DSPOST

XWAITM

Rescan

ASAP

II
INHIBIT TASK-

SWITCHING.
EXECUTE

CLEAR RESCAN

DISPATCH JUMP

FLAG

THRU COMMAND

TABLE.

ION

IGNORE

FREE BIT

Function
Code

’
JMP I .+FUNC+I

‘
0

XSEND

Pg. 04

XRECEIV

Pg. 011

XWAITE

Pg. 07

XRUN

Pg' (3‘20

XSUSPND

Pg. 020

XPOST

Pg. 014

XSKPINS

Pg. 0-15

XDERAL

Pg. 016

XBLKARG

Pg. 013

XSENDW

Pg. 04

XUNBARG

Pg.C-12

XTSTOP

Pg. o8

XWAITX

Pg. 07

SAVE CALLING

FIELD

‘

SAVE RETURN

ADDRESS

‘
GET FUNCTION

CODE

‘

SAVE
COMMAND

SW
SW designates an operation that is performed

only when usmg nonresrdent operations.
EAE designates an operation that is performed

only when the Extended Arithmetic Element
is used.

RTS/ 8

FLOWC HARTS

SET UP

RETURN FIELD

Yes

TSWFLG=1

TSWFLG

Cannot

TASKSWITCHING

Happen

NEEDS RESCAN

—1

KEEP TASKSWITCHING
INHIBITED

TSWFLG=0
No

ALLOW TASKSWITCHING
JMP I 20
RETURN TO
CALLING TASK

Pg. C-8

RTS/8

FLOWCHARTS

SEND
SENDW

Calling Sequence:
SET

CLEAR

WAIT FLAG

CAL

p+1
p+2

SEND (W)

p+3

MSGADR

P+4

RETURN

TASK It (Sending to)

‘
GET TASK
NUMBER TO
SEND MSG TO
Initial Values
p

MSGADR, 0000
0000

p+1

Becqmes
Sending Task =2
CDF to next
msg, if any

GET MESSAGE

AENDRESS

p+2

0000

Addrofnext
msg

p+3

Start of Message

MESSAGE
ALREADY IN QUEUE

(FIRST WORD OF MESSAGE
=0)
.7

BACKUP RETURN
TO CAL
ADDRESS
BUMP RETURN

TO
CAL+4

I
AC:

FIND RECEIV-

MESSAGE

ING TASK 2's

ADDR ESS

ENTRY IN

MSGTBL

I
Pg. C-7

GET DATA
FIELD OF

MESSAGE

(0 if none)

ADDTOQ

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RTS/ 8 FLOWCHARTS

from page 05

I
FREE MSG WAIT

AND/OR EVENT
WAIT BITS IN

Via call to FREEJ

STATUS TABLE

I
L21 IF RECEIV-

ING TASK IS

This will be tested if

RUNNABLE &OF

this CAL was a SEND and

HIGHER PRIORITY

not a SENDW.

THAN SENDER;

L=0 IF NOT

—IOZ

STORE SENDING
TASK NUMBER

IOCO—I
KZ‘I—

IN MSG HEADER

Link indicates whether
a new

task should be

run or

not.

The link status will be
checked later on in

STORE CDF TO
NEXT MSG IN
MSGHDR

=0 if none

POSTEX.

Z—

STORE PC OF

CD—I—I
I'T'IUO

NEXT MSG IN

MSGHDR

=0 if none

Message is now
linked into the
message queue.

CAL WAS

SENDW

Pg. C-12

FLOWCHARTS

RTS/8

WAITE
WAITX

Calling Sequence:
CLEAR

SET ACARG

ACARG

TO —1

I
Enter Here From

GET ADDRESS

SEND or SENDW

OF EVENT

CAL

p+1
p+2

WAITE

p+3

RETURN

EVENT FLAG ADDR

FLAG

WAlTS

7"
SAVE ADDRESS

ACARG ¢ —1

OF EVENT FLAG

lOF

Restart caller if

Yes

TASKSW allows

Pgt C-3

EVTFLG

4000 + TASK

Give it waiting status

PUSH PC BACK
TO POINT

TO CAL

AC=EFWT
‘

Store Event Flag Wait
in

Flag Table

AC=EORMWT

Jump with link clear
(tested at TSTOP)

ll
TSWAIT

Pg. 08

Pg. C-8

FLOWCHARTS

RTS/ 8

Wait for message.

Enter here from RECEIVE.

BACKUP
CALLING PC
TO DO CALX

AGAIN

SET LINK
AC

MSGWT

Message Wait Status

SAVE AC
IN MASK

TSWATX

I
STORE IN
TASK #’s
FLAG TABLE
ENTRY

'ON

CLEAR TASK AC

SAVE AC IN
ACARG

I
GET TASK
NUMBER’S
ENTRY IN

STATUS TABLE

to page 0-9

Interrupts were off here
if we came from XWAITE.

RTS/8 FLOWCHARTS

from page 08

II
SAVE RESTART

FLAGS, PC, AC

SAVE MO

EAE

II
FREE PARTITION
IN FREE BIT

WAS SET IN
COMMAND
SW

RTS/8 Scheduler

FINDJ

Schedule next
runnable task

TASK #=1

(start scan
from top)

ENABLE

TASKSWITCHING

I
SET ’MACHINE

STATUS UNIMPORTANT'
FLAG

FINDJL

GET TASK #‘s
ENTRY IN
FLAG TABLE

Interrupts temporarily
inhibited here.

FLAGS=0

Pg. 010

(RUNNABLE)
.7

Note no end of table
check
a

BUMP TASK
NUMBER

there must be

runnable task.

(Null

task is always runnable.)

RTS/8

FLOWCHARTS

Here from FINDJ (Scheduler)
Found a runnable task

ION

I
GET TASK #'s
ENTRY IN
STATUS TABLE

IOF

Ir
SAVE OLD
STATUS IN TEMP

LOCS OF INTER»
RUPT ROUTINE

Interrupt
Dismiss
Code
This is tested on an

8/E or 8/A only

PENDING
INTERRUPTS
7

SWEEP OLD
STATUS INTO

DF, IF, AC, PC,
ETC.

RESTORE MO

EAE

ION

JMP I 0
RETURN FROM

INTERRUPT

Pg. C-I7

RTS/ 8

FLOWCHARTS

RECEIV

Calling Sequence:
p-1

TAD ARG

CAL

p+1
p+2
p+3

MADDR, 0

RECEIV
RETURN

GET ENTRY
IN MESSAGE

QUEUE

II
GET FIRST

WORD OF
QUEUE ENTRY

Pg. 08

UNLINK THIS

MESSAGE FROM
THE QUEUE

II
STORE ADDR OF
MESSAGE |N

ADVANCE TO
NEXT MESSAGE
ON THE QUEUE

SENDING

CAL + 2

TASK OF MSG
=ARG
2

I
AC

CDF

TO MESSAGE

Pg. C-3

C-ll

RTS/8 FLOWCHARTS

UNBARG

XUNBARG

GET BIT MASK

FROM ARG.
LIST

IOF

CLEAR MASK
BITS IN FLAG

Call FREEJ

TABLE
LII if clearing mask
bits makes task

runnable and it is

higher priority; L=0
ION

otherwise.

Pg. C-3

RTS/8

FLOWCHARTS

BLKARG

XBLKARG

GET WAIT BITS
FROM ARG.
LIST

BLOK

CALLING

TASK TO BE BLOCKED

(TASK #

SET MASK BITS
IN FLAG TABLE

ENTRY OF SPECIFIED TASK

Pg. C-3

p—1

TAD TASK#

CAL

p+1
p+2

WAITBITS

p+3

RETURN

BLKARG

RTS/8 FLOWCHARTS

POST

Calling Sequence:
p—1

TAD EFPTR

SAVE ORIGINAL

CAL

EVENT FLAG

p+1

POST

p+2

ECDF,CDF EFFLD

p+3

RETURN

I
CLEAR EVENT
FLAG

WAS

SOMEONE
WAITING FOR THIS TO
HAPPEN (OLD FLAG

NEGATIVE)

GET WAITING
TASK’S 3 FROM
LOW ORDER BITS

OF THE OLD
FLAG

CLEAR BOTH
EVENT FLAG
WAIT AND

EVENT OR MSG
WAIT

Pg. 012

Pg. C-3

RTS/8

FLOWCHARTS

SKPINS

Calling Sequence:
p

CAL

p+1
p+2
p+3

SKPINS
MODULE ADDR
RETURN

GET FIRST
MODULE WORD

ALREADY IN
THE SKIP

CHAIN!!!

PUT mswns

Pg- 03

ROUTINE ADDR
IN 1st

WORD

II
PUT CDF, CIF
OF DISMIS IN

2nd WORD

I
PUT MODULE

ADDRESS AND

CDF, CIF IN
LAST MODULE

OF INTERRUPT
SKIP CHAIN

Pg. 03

RTS/8

FLOWCHARTS

DERAH.

Calling Sequence:
GETTASK#%
STATUSTABLE

p—1

TAD TASK#

POINTER

CAL

n+1
n+2

SUBROUTINE

9+3

RETURN

‘
STORE
RESTARTPC
INSUBR

STORE SUBR+1
IN RESTART

Pg. C-3

DERAIL

RTS/8

FLOWCHARTS

INTERRUPT
ROUTINE

TIME~

GO TO

SHARING

OS/8

INTERRUPT

SUPPORT

If present

SAVE THE
MACHINE

STATUS

USERSK
I
USER-INSERTED

SKWSFORANY
CRUCIAL DEVICES

GO TO

APPROPRIATE
INTERRUPT
MODULE

ig;%g;ggo
FAIL RESTART

”ALT

.NTEEgUPT

7
~

/
POWER-UP
RESTART

POWER
FAILURE
AC

POWER-UP

EVENT FLAG

ADDRESS

GO TO
CLOCK
HANDLER

Pg. 018
If present

GO TO FIRST
USER INTERRUPT MODULE

RTS/8 FLOWCHARTS

POSTDS

Come here from user

issuing POSTDS
YES

p—
p—

p—
[1

Pg. 01 0

HMO.)

CDF EFFLD
TAD EFPTR

CIF O

POSTDS

SAVE THE OLD
EVENT FLAG
VALUE

II
ZERO EVENT
FLAG

WAS A
TASK WAITING
ON THIS FLAG? (OLD
VALUE NEGATIVE?)

Pg. 010

CLEAR EVENT
FLAG AND EVENT

OR MESSAGE
WAIT BITS IN

Call FREEJ

TABLE ENTRY

OF WAIT TASK

Run the waiting task if
its flag word is now zero

Pg. 010

and it is higher priority
than the current user.

to page 0-19

RTS/8 FLOWCHARTS

from page 0-18

TASK

SET RESCAN

SWITCHING

FLAG

INHIBITED

CTSWF LG

—1

Pg‘ 010

SAVE STATE
FLAG—1
7

SAVE CURRENT
TASK'S PC, AC
IN ITS STATUS
TABLE ENTRY

SAVE
TASK'S MO

EAE

ION

V
PREPARE TO
START NEW
TASK

Start Swapper

Pg. C-9

STA RTJ

RTS/8 FLOWCHARTS

RUN

Q
AC

Calling Sequence:

RUNWT
Run Wait

p-1

TAD TASK:

CAL

p+1
p+2

RETURN

RUN

Pg. 012
Go and set
the flag bits

SUSPND

Calling Sequence:

RUNWT

‘

Pg. 013

p—1

TAD TASK:

CAL

m1
m2

SUSPND
RETU RN

RTS/8

FLOWCHARTS

WAITM

XWAITM

SAVE AC
IN 'COMMAND'

CLEAR AC, L

FAKE A CAL

DISABLE
TASK
SWITCHING

PUT WAIT
BITS IN AC

TSWAIT

Pg. C-8

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RTS/ 8

FLOWCHARTS

FROM
PREVIOUS PAGE

IS
TASK

RESIDENT

STARTS

Start task

PUT TASK
INTO SWPWT

TAKE SWAPPER
OUT OF RUNWT

FINDJ

APPENDIX

RTS/8

Certain

user

standard

PAL8

errors
error

ERROR MESSAGES

ASSEMBLY

are
caught
diagnostics on

assembly

the

terminal

time.
of

They

produce

form

the

IC
US

tag

where the
below.

tag specified

Tag

Module

MCRBLK

MCR.PA

indicates

the

Error

was
declared
nonresident
(MCRPRT
and MCR origin was incorrectly
defined)
a
Nonresident
multiple of 400.
portion

Redefine

System
user

See

should

RTS/8

not

comments

Executive
See

incorrectly.
CURBIG

RATERR

PARAM.PA

CLOCK.PA

tables

were

was

Fix:

Redefine

CUR.

HERTZ

multiple Of

specified
larger than

Redefine

too

than

192

SHERTZ

less

Fix:

Redefine

generated

value

for

CUR

HGHFLD.

HERTZ

SHERTZ.

SHERTZ

must

file.

SHERTZ
large.
(decimal).
SHERTZ

parameter

D-l

line

error.

source.

task

parameter
CLOCK.PA

the

User

Fix:

TODERR

source

which

not

unless

occur

sources.

which generated
Internal

start

MCRORG.

error;

modified

Fix:

RTS8.PA

which must

is second page
block boundary.

MCR
a

Fix:

TBLERR

described

MCR

several

error

Possible

SYSERR

type

file.

RTS/8

Tag

NOKL8A

ASSEMBLY

ERROR

Possible

Module

KL8ASR.PA

The symbol KL8A
parameter file.
Fix:

KLOERR.

MESSAGES

KL8ASR.PA

Error

not

was

defined

Set symbol KL8A in parameter
equal to number of physical
KL8-A's present.

The

symbol

the

file

Fix:

KL8A was set equal to
KL8ASR.PA was assembled.

the

file

yet

assemble KL8ASR.PA if KL8—A
is not desired or redefine
in the parameter file.

not

support
KL8A
HITMON.

KL8ASR.PA

The KL8-A service overlaid location 7600
in field 0.
Ignore this error if you do
not

want

Fix:
NOSWAP

PARAM.PA

Redefine

nonresident

system with

OS/8 resident

preserve

KL8ACT
task

code.

file.

parameter

assembled

was

swapper.

Define SWAPPER in
file
parameter
undefine PARTNO in user task.

Fix:

SWPRIO

PARAM.PA

nonresident

priority

than

was
task
the swapper.

higher

given

Change priority of swapper

Fix:

user

task.
FLDERR

PARAM.PA

form

(e.g.

Fix:

HGHFLD,

Correct

parameter
CURERR

PARAM.PA

field

a
Some
parameter
representing
10 was not in the
number
times

One

the

was

not

Fix:

value
file.

symbols CUR,
the proper

Correct

times

MCRFLD,

etc.)

parameter

CUR2,

CUR3

form.

value in user
of task.

field

correct

task

APPENDIX

EXECUTIVE

INTERNAL

TABLES

TASK

about
Executive uses five internal tables to maintain information
tasks in the system.
Each task's task number is used as an index
into the first four tables to retrieve and update information for that
task.
The internal tables are as follows:

The
the

The

Task

holding
task

Table

State

the
most
follows:

Word

(TSTABL)

recent

contains

contents

CPU

entries

4—word

for

registers

the link (bit 0)
the Greater Than Flag (bit 1) —if
exists on machine being used
the User Mode Flag (bit
-if
5)

each

flag
flag

exists on machine being used
the Instruction Field (bits 6-8)
the Data Field (bits 9-11)
Word

—

contains

the

contents

the

Program Counter

contains

the

Contents

the

Accumulator

contains

the

contents

Quotient

(MQ)

assembled

(PC)
Word

Word

—

Whenever the
the
task's

the

(AC)

the Multiplier
if the system
has

been

MQ.
it

the contents of
the corresponding
CPU registers.
its
Whenever a task
Task
stops
executing,
State
Table
entries
are
to the new contents of these
set
The Task State Table is located after the Message
registers.
Table, that is, at location NTASKS+2"2+MSGTBL—4 in field 0.

system executes

Task

State

task,

entries

Table

loads

into

Example:
Consider

the

following

entries

TSTABL

for

task.

4012
3376
1234
0211

The

task

interrupted just

instruction
of

entry

registers

location

1).

for

this

task

about

execute

3376

(entry 2) of field 1
the
contents
of
point,

are

entered

the

TSTABL.

1234

(entry 3), and the M0 is 0211 (entry 4).
set
(bit 0 of entry 1), and the data field is
entry 1).

The
2

the

(bits

6—8
the
CPU
The AC is
link
is

(bits

9-11

EXECUTIVE

The

Task

holding

INTERNAL

TASK

Flags

Table

(TFTABL)

various
the task

flags

(bits)

whether
Task
Flags
is set in a

runnable.

TABLES

contains

—

for

each

task

entries

l—word
task

determine
only if its

runnable

Each flag (bit) which
entry contains zero.
nonzero word
indicates
a
reason
the
task
why
run.
cannot
The currently defined flags, if set, and their
meanings are as follows:
Table

Octa 1

Symbolic

4000

NONRWT

2000

Meaning
Wait
Nonresident
because it is not

This

task

cannot

run

memory.

This task is waiting for an
Flag Wait
contains a WAITING value
(which
Flag
corresponding to this task) to be POSTed.

EFWT

Event

1000

RUNWT

0400

Run

Wait

for

the

Monitor

task
with
to

operator

Swap Wait

SWPWT

This

executed

This

—

waiting

for

its

number

the

RUN

AC,

to
task"
"REquest
(see Chapter 6).

type

Routine

Console

the

task

cannot

process

because

run

brought into

being

memory.

This task is
Message Wait
waiting
an
for
Event Flag to be set or a message to
arrive, whichever happens first.

0200

EORMWT

Event

0100

USERWT

This bit
Wait
tasks.
user-written
bit.

0040

User

sent

0001

DNEWT

Does

Task

that

is,

Flags

Table

location

This

task

future

use.

Not

for

the

TFTABL

task

waiting

runnable.

located

after

the

NTASKS+2A4+TSTABL—l

entry for

waiting

task

—

task

1000
the

This
Exist Wait
it is nonexistent.

Examples:
1.

use
use

by
this

message.

Reserved

—

The

not

6).

because
0000

for

does

—

Message Wait

MSGWT

NETWT

reserved

RTS/8

to
This
is
be
task
Wait
waiting
of
this bit is restricted to
Use
Enabled.
"ENable
the
the Monitor Console Routine for
task"
commands.
and
"DIsable
task"
(See

Chapter

0010

Enable

ENABWT

0020

run.

Task
in

cannot

State

field

run

Table,

EXECUTIVE

the

TFTABL

INTERNAL

TASK

TABLES

for

task

entry

0440
the

task

waiting

was

disabled from running by
while
the nonresident
to be swapped in.

terminal

MCR

the

for

TFTABL

operator
of

the

the
task

task

the

portion

0000

task is runnable.
However, this task
of higher priority has precedence.

the

The

may

not

run

task

contains
Input Message Queue Header Table (MSGTBL)
that represent the "head"
(start) of the input

Task

2-word

entries

message

queue

for

each

task:

zero,

there

Word

—

non—zero,

the

first

word

the

are

the

message

was

not

word

messages
is a CDF

the

the
the

queue;
of

field

queue.

this word is a
pointer
the
first message in the

zero,

address

in
to

queue.
The

Table

Message

Executive

field

located

the

end

the

RTS/8

Example:
Consider

the

following

entries

MSGTBL

for

task.

6211

2044
Since

input
entry

the first entry is a nonzero, there are messages in the
The first
queue waiting for this task to receive them.
is a CDF instruction to field 1.
The second entry is a

pointer
2044

The
each

indicating
field

that

the

Residency

Table (RESTBL)
nonresident task.

Word

first message

begins

location

1.
—

contains

2-word

entries

for

contains a
to
the
task's
Partition
pointer
Table entry in bits 0 through 9.
Bit 10 is set
if a task is checkpointable, and bit 11 is
set
if
a
task
is
writeable.
Checkpointable and
writeable tasks are defined in Section 5.1.

contains

the absolute block address (plus 1
to
the core control block) of the task's

allow

for

core

image

the

swap

The Residency Table is located after
that is, at location TFTABL+NTASKS+2

device.
the
Task
Flags
in field 0.

Table,

EXECUTIVE

INTERNAL TASK

TABLES

Example:
Consider

the

following

entries

RESTBL

for

task.

1611
0124

This

task has a nonresident portion.
The
4-word
table
used by this task begins at location
entry
task is not checkpointable (bit 10 of entry 1 is a
is writeable (bit 11 of entry 1 is a l).

The
the

disk—resident portion of this
swap device.
(The save image

The Partition Table
each partition.
It

Word

—

(PARTBL)
is

contains

field
device

the

4—word

partition
in

(size)

6—8)

argument of

for

entry

number.

bits

l-5

and

mass

driver call that reads an
the partition with the "WRITE" bit
of this word is the partition busy

set.

partition.

contains

the

Word

contains

RESTBL
-

contains
into via

the

task begins at block 124
begins at block 123.)

length

(bits

Word

—

indexed

partition
1610.
The
0), but it

address

memory

pointer

word

of
1

storage
into
occupant

the

Bit

flag.

the

occupant's

entry.

unused

Partition

The

multiple
i.e.,

Table must
at
an
address
that
is
a
begin
of
four.
It is located after the Residency Table,
location NTASKS—SWAPPER“2+RESTBL+3&7774 in field 0.

Example:
Consider

the

following

PARTBL

entries

for

particular

partition.
5421
1400
1553
0000
This partition is currently in use (bit 11 of entry 1 is a l)
task whose 2-word RESTBL entry begins at location 1553
a
by
The partition begins at location 1400
(entry 3).
2)
(entry
of
field
2
6-8
of
The partition is 14
(bits
1).
entry
(octal) pages long (bits 1-5 of entry 1).

Figure

E—l

Executive.
that
exact

they

summarizes
the
The
Residency

internal

task

of
table
structure
the
Table are optional in
The
are
employed.

Partition
tasks
nonresident

Table

and

used only when
in memory depends on the
of
these
tables
other parameters in the parameter file.
They can

are

location

tasks and
for a particular assembly
end of the parameter file

number

the "System Locationsz" heading
assembly listing.

under

found
at

the

TASK STATE
TABLE

Word 1

TASK FLAGS

(TSTABL)

TABLE

(TFTABL)

RESIDENCY

PARTITION

TABLE (RESTBLI

TABLE (PARTBL)

messages in queue, if

Instruction

Data

Bits determine if task is

If zero,

Field

runnable

nonzero, word is CDF to the field

Link

(IF)

(DF)

6-8

9—11

of first message

bit 10 check-

writeable

Contains the

Length (size) and

Field argument (bits 1-8) of the
mass

storage device driver call

with 'write' bit set
If nonzero, this word is

Counter (PC)

Contains pointer to task PARTBL
entry in bits 0-9;
pointable; bit 11

that reads occupant into partition

Contents of Program

Word 2

TASK INPUT MESSAGE
OUEUE HEADER (MSGTBL)

Task runnable if entry

pointer

the first message in the queue

Block address plus 1 of the task’s
core

image on swap device

(bit 0).

Contains starting address of
the

partition

contains zero

Contains pointer to word 1 of

Contents of Accumulator

Word 3

Represents the "head" of the
input message queue for each

(AC)

Bit 10 of word 1 is set if task

the

checkpointable

occupant’s RESTBL entry

task
0

Bit 11 of word 1 is set if task

writable
Word 4

Unused

Contents of Multiplier
Quotient (MO)

HAILDHXB
TVNXELNI
XSVL

Upon task execution, TSTABL

Bit 0 is always set (write)

Bit 11 of word 1 is the

loaded into corresponding CPU

registers

partition memory flag
-

Upon task interruption, TSTABL

entry set to new contents of

CPU

registers

Figure

E—l

Executive

Internal

Task

Table

Structure

SETHVL

GLOSSARY

in
which
the
arithmetic
The
register
operations are performed (abbreviated AC).

Accumulator

information

Representation

Analog

continuous

variables.

Analog Channel

Argument

UDC/ICS functional device.

variable
of

call

variable
function

depends;

necessary to find
the index).
(i.e.

Assembler

which

program

into
machine
locations for

Auto—index

op-codes
symbolic
memory
assigns

translates

and

language
variables

and

constants.

from
absolute
locations
in
is
field
memory
any
through
that
addressed indirectly, the
contents
of

Whenever

one

0010

location
the

The

the
0017

incremented by one, rewritten in
and used as the
effective
the current instruction.

location,

same

address
Auto-restart

the
which is given in
a
information to it;
of
a
the
value
value
the known reference factor
item in a table or array
an

constant

subroutine
upon whose

ability

start

the

CPU

automatically

power—up.
Baud

unit

measure

data

flow

(one

bit

per

second).
Bit

Bit

binary digit
12 bits).

composed

method of keeping track of used and
unused
entities
by
assigning one bit in a table to
each entity.
A

Map

Block

consecutive
machine
words,
as
a
handled
unit,
digits
to
and
reference
particularly with
input
an
is
400
octal
block
OS/8
output;
also to inhibit a
process
contiguous words;
from continuing.
A

set

characters

Block

(each PDP—8 word

The

Gap

blank

space

between

blocks

recording

medium.

Blocking

Bits

Byte

RTS/8 Monitor Table which

given

group

upon
Cassette

Bits

why

of
a

task

binary

digits

usually

operated

unit.

magnetic tape device

data

specify

blocked.

storage.

Glossary—l

used

for

program

and

Central

Processing

Unit

unit

The

computing system

the

circuits

and

execution

includes

that

the interpretation
instructions
(abbreviated

controlling
of

CPU).
Task

Checkpointable

task

out

checkpointable if it may be swapped
without
its
automatically,
to make
room
for
higher
priority

memory

consent,
tasks.
Clear

the

erase

contents

the

replacing

location
storage
with
normally

contents,

zeros.

Clock

time

keeping

measuring device
provides

within

the

periodic

system;

computer

interrupts.
Communication

Region

Locations

20—27

simplify

passing

field

Compute Bound

field,

every

executive

used

request

across

boundaries.

Requiring extensive
relative

other

(or

total)

hardware

use

the

CPU

(such

elements

I/O devices).

Configuration

The

number

types of hardware

and

present

system.
Contact

Channel

UDC/ICS functional device.

adjacent
The

Controller
Core

Image

File

Storage

that

circuitry

'picture'
Core

other

file

in
resides
memory
immediately
sections of code.

which

Code

Contiguous

in
of

controls

The main high—speed
which
binary data

CPU

Channel

Registers

(e.g.,

general

facts,

PC,

IF,

in
the

cores.

term

used

3—bit
field

store

the

DF).
to

denote

letters
elements of
or

and

any

all

symbols.

information

which

produced by computer.

which determines the
memory
in
taken
are
which
operands

addressed
indirectly
(abbreviated DF).

Debug

file.

SAVE

used
to
the
operation

numbers,

connotes basic
can be processed

Field

magnetic

circuitry
affecting

High—speed
CPU

Data

(i.e.,
as

UDC/ICS functional device.

information

Data

known

storage of a computer
is
by
represented
of

switching polarity
Counter

also

core);

device.

format

image

core

detect,

locate

program.

Glossary-2

and

correct

instructions

mistakes

Actions

Deferred

Actions which
actions

Deferred

Requests

are

considered

serviced

after

Requests which
and

low-priority and
higher—priority

considered
until
serviced.
are

performed

not

are

low-priority
high-priority

requests.
Derail

transfer
control
or
execution
task to a subroutine.

specified
Device

Codes

Numbers

assigned

device

each

the

system.
Device

Status

Digital

the

status

current

device.

information

Representation

discrete

units.

Digital

Channel

UDC/ICS functional device.

Driver

See

Dynamic

Pertaining

Handler.
to

quantity

condition
therefore relative

refers

Entry Point

Event

Flag

features

location
be

The

location which
or

The program which
other programs or

Requests

Means

affected
by
is
and
time)
also
condition;

the

system run-time.

routine

which

control

execution begun.

and

contains

the

status

either a result
being
a physical
occurrence).

(event

operation,

Executive

transferred

event

Executive

The
can

that

(such

some

controls

execution

the

some

routines.

communication

tasks

between

and

the

RTS/8 Executive.
Field

division

referring
File

Gap

fixed

times
Functional

Devices

of
to

PDP—8

memory.

computer

length of blank tape separating files
recording medium;
generally several

the

size

devices

The

on
memory
4K section

block

available

gap.
for

under

use

the

UDC/ICS handler.
Gain

Generic

Codes

Handler

increase

Bound

signal

power.

used to identify which type of
UDC/ICS
functional
device caused an interrupt and to
direct program control to service routines.

Codes

routine

operation
I/O

which
of

is designed
device.

A condition in which a process
much I/O but using very little

Glossary-3

control

the

performing

CPU

time.

Indirect

Address

Initialization

address

a
instruction
which
computer
location where the address of the
referenced operand is to be found.

indicates

Code

which
sets
and
counters,
switches,
addresses to zero or other starting values at
the beginning of or at prescribed points in a
Code

routine.

computer

Input Buffer

section

for

used

memory

storage of input

data.

Instruction

Field

which
holds
the
contents
register
determining from which field the operand of a
addressed
instruction
should
be
directly
taken (abbreviated IF).
A

Interactive

Highly responsive

Interface

The

Interlock

Scheme

their
A

control

that

Module

routine which
which caused an
list

Queue

acts

actions

the

upon

current

Clock

event

each
which is
to
the

perform,
time
action

one.

clock

the

external

interrupt.

accompanied
by the interval
to elapse from the
previous

Line-frequency

in execution caused by some
external
is
execution
resumed at a
usually
time.

Interval

devices

break

later

Processing

boundary

operation is interdependent.

event;

Interrupt

the

inputs.

and/or software
systems.

devices

two

Arranging

Interrupt

hardware

common

between

real—world

whose ticking occurs
line frequency.

multiple

power

an
address
register in the PUP-8;
automatically by the PAL8
generated
an
assembler to indirectly address
off-page
symbol.

Link

one—bit

pointer

Logical

Loop

function
of
whenever

logical
is

which

two

either

true

sequence

repeatedly

inputs

input is

is
instructions that
until
a
terminal

true.

executed

condition

prevails.
Mass

Storage Device

device

large
the
Master

Parameter

File

such

central

file

disk
of

amounts

data

unit.

processing

included in
the

which
RTS/8
parameters

the
user

specific

DECtape which stores
readily accessible to

distributed sources of
can edit to
indicate
his
to
system

configuration.
Memory Address

memory

holds

reference

Glossary-4

the address
instruction.

specified

Message

contiguous

information

area

memory

execution

about

which
contains
tasks.

it
RTS/8 task is called message—driven if
to
in
executes
messages
response
only

Message—driven

received
Mnemonic

from

other

tasks.

Alphabetic representation

Module

routine

function

instruction.

machine

octal

which

handles

particular

function.
Monitor

Console

Routine

user
the
The Monitor routine which provides
which
allow him to control,
with
functions

Multiplier Quotient

12—bit

the

used

accumulator

Two

same

Nonresident

Task

A
a

programs (tasks) in memory at the
which execute alternately depending
current state of the system.

time

the

Characters

Overflow

control

the

operation

Null

task is a task or a portion
is swapped into memory when
executable.

nonresident
task
that

becomes

No-op

with

condition

operation
of

storing.

Pack

conserve

Page

the

file

a
mathematical
when
result whose magnitude is
data presentation is capable

number

POSt

PDP—8

core

which

arguments which may

indicates

binary

values.

one

whether
the
total
in a word is even

digits

odd.

Pointer

address

record

which
of

section

200(octal).

used

bit

information.

by combining

assigned different
Parity Bit

000.

code

memory

occurs

beginning

multiple
A

ASCII

that

proceeds

sequence.

128fword (decimal)

memory

file

yields

than

greater

Parameter

occurs;

instruction

Characters
A

with
in
conjunction
mathematical
perform

(abbreviated MQ).

operations
Multi-programming

debug his system.

and

inspect,

word

containing

memory.

post

FINISHED

Event

state

the

address

Flag

means

via

another

set

RTS/8

word

Executive

Request.
Posted

One

the

states

that
"FINISHED".

indicating
as

Glossary-5

the

event

flag,

event

complete;

same

Power—fail

Priority

Scheme

the

power

computer.

scheme by which certain operations
of
execution
a
set of instructions

preference
Program Counter

interruption

other

over

the

given

operations.

which contains the address of
the
instruction to be executed (abbreviated

PC).

Promptinq

Character

character
terminal
and
action.

which

prints
the

cues

the

a
queue
waiting list (e.g.,
waiting for processing time).

Queue

Ready Flag

Real—time

System

bit

which

ready

system

while

that

device

controller

accept commands

which

programs

sets

when

the

CPU.

from

computation

some

performed

related physical process is occurring
the results of the computation can be

used

console

perform

user

guiding

the

measuring

physical

process.

Receiver

The task which has received
another task (sender).

Record

A
as

Record

Header

Ring—buffer

Area

collection
a
unit.

items

message

data

from

treated

which

of at least 40(octal) words in length
contains
information
to
necessary

perform

cassette

area

operations.

area
for
data
on
a
accessed
storage
Similar to Queue,
first—in, first-out basis.
of
character
but usually
involves
storage

codes.

Scheduling

of
The
operation
computing tasks.

Sender

The task which has
task (receiver).

Sign

Bit

Simulate

bit

The
To

which

program
program.

Skip Chain

sent

contains

represent the

sharing

with

resources

message

the

sign

function
another

among

another

number.

a device,
system
device, system or

the
instruction sequence which determines
~of
an
interrupt request on a PDP-8;
contains one or more tests for each
possible
(hardware) interrupt condition.

source

State

Status

complete description of
piece of hardware or of a

That
or

the

condition of

task.

portion of the state which other devices
might be interested in.

tasks

Glossary-6

Subchannel

One

of the
functional

Suspend

Symbols

Names

task

which

can

used

can

Synchronization

halt

temporarily

another

program.

means

flags)

UDC/ICS

execution

higher priority

analog

while

task

runs.

or
which
assigned values
specific locations in

indicate

tasks

coordinating
that

4 channels
device.

task

one

(through

executes

while

event
others

wait.

System Ticks

obviate

the

from

knowing

the

RTS/8 convention designed

tasks

the

system

frequency of the clock.
Task

task is a routine which performs a specific
A
or
function.
task
be
"resident"
may
A
is
"nonresident".
task
resident
A nonresident
permanently located in memory.
is
task is loaded into memory as
it
needed
A

and
Task

Flags

Table

overlaid

can

its

after

completion.

of
l—word
entries
in
whose contents determine
task is runnable.

table

Executive
not

Task

the

RTS/8

whether

Input Message Queue

Header

Table

table of 2-word entries which represent the
head
of
the
input message
queue for each
A

task.
Task

Task

Number

State

unique
assigned

Table

-ach

Switching

The

entries

which

contents

63
(decimal)
RTS/8 system.

and
an

CPU

contains

registers

the
for

task.

act

execution of one task
execution
of
another
from
it was last stopped.

stopping

peripheral device

data

Utilities

task

4—word

recent

ontinuing
point that
Terminal

between

each

table

ost

Task

number

can

enter

Routines

leave

perform

and

the

system through which
computer.

the

non—Monitor

functions.
Word

the

stored

PDP—8,
in

one

Glossary—7

12-bit unit of data which may
addressable location.

INDEX

Digital output UDC/ICS operation,

4-4, 5-1
Analog input UDC/ICS operation,
ALTMODE,

4—27
DIsable command,

5—4
Disable contacts UDC/ICS

4-26

Analog output UDC/ICS operation,

Disable counter UDC/ICS

Arbitrary boundaries, 9—7
Assembling nonresident tasks,

Distributed

Editing parameter file,
7-8

ENable

4—31

Buffers,

6—5,

6-8

5—4

conditions,
UDC/ICS, 4-31
Event flag states
Event flags, 2-2

Error

control,

nonresident tasks, 7—8
Batch stream, 6-6, 6-8

ER,

command,

Enable contacts UDC/ICS operation,
4—29
Enable counter UDC/ICS operation,
4-28

Assembly error messages, D-l
Assembly parameters, UDC/ICS,

BLKARG

files, A-l

source

8-11

6-5,

nonresident tasks,

operation,

4—29

7-6

Assembling tasks,
Assembly,

Batch

operation,

4-30

4-25

3-6

summary,

EXamine command, 5-6
Executive internal task

7-6

instruction, 3—1
CAncel command, 5—4
Cassette file support handler,
CAL

E-l
Executive KL8—A

2—3

tables,

2—5,

4—35
file support system
tasks, 4—35
Cassette handler, 4—32
Change of state UDC/ICS opera—
tion, 4—30
Character mode, 4—4
Checkpointable tasks, 7-3
Clock handler, 4-2
Clock handler system parameters,
Cassette

support, 4-37
states,

Executive request wait
3-12
Executive requests,

BLKARG, 3-6
DERAIL, 9-5
POST, 3—4
RECEIVE, 3-3
RUN, 3-8
SEND, 3-2
SENDW, 3-3
SKPINS, 3-9
SUSPND, 3-8
UNBARG, 3 8
WAITE, 3-3
WAITX, 9-5

6-10

CTRL/C,

4—5,

5—1

Communication

region,

3-1

Component sizes, B—l
Control files,
use of,
6-9
Core image, 7-6, 7—7
Creating an RTS/8 system,
Creating SAVE image file,

EXIT
EXIT
EXIT

command,

Field mapping, 4—20
FINISHED state, 2-2
Floppy disk control file,
Floppy disk handler, 4-13
Flowcharts, C-l
FREE command, 7—4

6-6 I

5-2

Debugging,
nonresident

task,

Generic code UDC/ICS

6-14

operation,

4-27

Demonstration program,
DEposit command, 5—6

ER,

6-10

7—8

DECtape handler system parameters,

DERAIL

6-14

6-5

7-6

DAte

command, 5-6
task, 4-39
task system parameters,

8—1

9-5

Inhibiting task switching,
Instructions,

_Digital input UDC/ICS operation,

CAL, 3—1
POSTDS, 3-10

4-27

Index-l

9~2

INDEX

Instructions

(cont.),

(CONT.)

Nonresident

WAITM, 9-4
Interrupt module restrictions,

task

3-10
3-9
2-3

batch control,
loading, 7-8

7—8

image file,
starting, 7-8

SAVE

KL8—A

support

system parameters,

7—5

7-1

7—8

assembly,

Interrupt skip chain,
Intertask messages,

parameters,

Nonresident tasks,
Nonresident tasks,

7-8

6-13

08/8 support task,

4-38

Obtaining listings,

task, 4-38
User task, 4—39

TTY

OPen

OS/8
OS/8
08/8
08/8

LINCtape handler, 4—16
Line mode, 4-4
Line printer handler, 4—10
Line printer system parameters,
\

6—5

command, 5-5
file support task, 4—23
operating system, 4-19
support task, 4-19
support task system param—
6—13

eters,

OS/8-RTS/8 communication,

4u21

6-14

Loading,
7—8

task

file,
definitions,

8-11

task

setup,

task

specifications,

Parameter

nonresident tasks,

Loading tasks,

6-6,

storage handlers,
MCR command arguments,
address, 5-1

Mass

4-11

structure, 6-1
Partition parameter initializa-

tion,

space,
task-ID, 5-1

5-1

PDP—8A null
PENDING

5-1

time-of-day,
word, 5-1

commands,
CAncel, 5—4
DAte, 5-2
DEposit address,
DIsable, 5-4
ENable, 5—4
EXamine address,

POST

5—5

address,
REquest, 5-3
STop, 5—4

5-6

Power

Read

5-6

UDC/ICS operation,

operation,

RTS/8 description, l-l
RTS/8 task structure, 2—1
RUBOUT,
RUN ER,

component size, B-5

MCR

error

4-4
3-8

Sample task program,
SAVE image file,
creating, 6-6, 7-6

5-6

system parameters, 6—12
Memory partitions, 7-3
Message header, 2—3
Message table, E-3
MCR

command,

counter

4-29
Real-time system
RECEIVE ER, 3-3

REquest command, 5-3
Residency table, E-3

MCR

NAme

instruction, 3-10
fail task, 4—18

5—6

SYStat, 5—4
TIme, 5—2
messages,

2-2

3-4

ER,

POSTDS

5-2

address,

OPen

E—4
4-37

reschedule, 9—l
POst address command, 5-6

5-6

POst

task,

state,

Performing

MCR

EXIT,
NAme,

7-7

Partition table,

single

6-3

file

Parameter

5-1

comma,

6—2

6-4

6-7

nonresident tasks, 7-8
the system, 6-6, 8-11
SEND ER, 3-2
SENDW ER, 3-3

Saving

5-2

Nonresident MCR, 5-6
Nonresident task debugging, 7—8
Nonresident task implementation,
7—8

Nonresident task initialization,
7-5

Index—2

SKPINS

ER,

3-9

Starting,
nonresident tasks, 7—8
STop command, 5-4
SUSPND ER, 3-8
Swap device, 7—1, 7-6

1—2

INDEX

Swapper system parameters,

Syntactic constructions,

(CONT.)

6-11

5-1

command, 5-4
System parameters,
clock handler, 6—10
DECtape handler, 6-14
EXIT task, 6-14
KL8-A support, 6—13
SYstat

line

printer,

MCR,

6—12

TTY

6-14

08/8 support task,
swapper,

Terminal handler, 4—4
Terminal handler system parameters, 6—11
Terminal parameter default values,
4—9
TIme command, 5—2
Timeshare function disabled, 4-19
TTY

6—13

6-11

terminal handler, 6-11
System status report code, 5-5
System tables direct references,
9-8

System task summary, 4-1
System tasks,
cassette file support, 4—35
cassette handler, 4—32
clock handler, 4—2
EXIT, 4-39
floppy disk handler, 4-13
LINCtape handler, 4—16
Line printer handler, 4-10
mass
storage handler, 4-11
OS/8 file support, 4-23
08/8 support, 4—18
PDP-8A null, 4—37
power fail, 4-18
terminal handler, 4—2
UDC/ICS handler, 4—24

control file, 6—9
task KL8-A support,

UDC/ICS assembly parameters, 4-31
UDC/ICS error conditions, 4-31
UDC/ICS handler, 4-24
UDC/ICS handler system tasks, 4-24
UDC/ICS operation,
analog input, 4-26
analog output, 4-25
change of state, 4—30
digital input, 4-27
digital output, 4-27
disable contacts, 4-30
disable counter, 4~29
enable contacts, 4—29
enable counter, 4—28

generic code,

Task
Task
Task
Task
Task

Using BITMAP program, 6-7,
Using interrupts, 3—9

communication, 2-1
flags table, E—Z
number, 2-1
state table, E-l
status report, 5-5

synchronization,

4—27

counter, 4—29
UNBARG ER, 3-8
Use of control files, 6-9
User task KL8-A support, 4-39
read

WAITBITS

Task

4—38

symbolic

names,

3—7

WAITE

ER, 3-3
WAITING state,
WAITM

2-2

instruction,

WAITX ER,

9-4

9-5

Writeable tasks, 7—3
Writing delicate code,

2-2

Index-3

7—5

9-1

RTS/8 User's Manual
DEC-08-ORTMA-C-D

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RTS/8

Read data

.4000 Write

SYSTEM

floppy disk.

from

data

TASKS

floppy disk.

transfer
Specifies the number of pages to
(times
100
0 transfers 40 pages (a full
octal).
Pages
This value takes the range 0-37
in
bits
field).
this
is ignored if CODE
of
word.
PAGES
1—5
In that case,
4000.
either
100
12—bit
(Octal)
or
words
200
8-bit
(from 200 words) are
bytes
transferred depending on MODE.

PAGES

FIELD

the field of buffer
this word have the

Specifies
Bits

Specifies the address of the
buffer
containing data.
determined by FIELD.
Length
0 or on MODE
PAGES if CODE

BUFADD

(times

6-8

first

of
buffer

the

depends

word

of
Field
of buffer
if CODE

octal).

0-7.

range

4000.

Represents first logical OS/8 block to transfer if
CODE
0.
Each OS/8 block consists of 4 sectors.

BLOKNO

Track

ignored

If
‘employed.
physical track and

and

interleave

2—to—1

CODE'==

4000,

sector

numbers

scheme
contains
the
format

word

this
in

TTTTTTTSSSSS.

STATUS

Receives‘

the

status

the

operation

hard
error
If 0, no error has occurred.
This
occurred.
2000.
may be positive nonzero only if DEL
If

completion.

negative,

The

meaning

the

STATUS

Bit

'Meaning

0
1—3

Not

used

Not

used

5
6-7

Not

Hard

bits

error

Deleted

by controller
by RTS/8
data

indication

by controller
Reserved for future use by

controller
INIT done
(can

used

temporary power
controller)

Parity

10
11

CRC

after
failure to

occur

error

NOTE

follows:

power

fail

INIT
the
error
this error occurs,
send
the
should
I/O

restart,

might
the calling task
message again.
occur.

When

upon
has
word