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DEC-8E-OCASA-B-D

December 1974

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users manual

digital equipment corporotfon

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DEC- 8E-0CASA-B-D

CASSETTE

PROGRAMMING SYSTEM
USER'S MANUAL

from Software
For additional copies, order No. DEC-8E-0CASA-B-D
Distribution Center, Digital Equipment Corporation, Maynard,
Massachusetts 01754

First Printing, March, 1973
Revised September, 1973
Printed July, 1974

The information in this document is subject to change without notice
and should not be construed as a commitment by Digital Equipment
Corporation. Digital Equipment Corporation assumes no responsibility
for any errors that may appear in this manual.
The software described in this document is furnished to the purchaser
under a license for use on a single computer system and can be copied
(with inclusion of DIGITAL'S copyright notice) only for use in such
system, except as may otherwise be provided in writing by DIGITAL.

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

The HOW TO OBTAIN SOFTWARE INFORMATION page, located at the back of
this document, explains the various services available to DIGITAL
software users.
The postage prepaid READER'S COMMENTS form on the last page of this
document requests the user's critical evaluation to assist us in
preparing future documentation.

The following are trademarks of Digital Equipment Corporation:
CDP
COMPUTER LAB
COMSYST
COMTEK
DDT
DEC
DECCOMM
DECTAPE
DIBOL

DIGITAL
DNC
EDGRIN
EDUSYSTEM
FLIP CHIP
FOCAL
GLC-8
ID AC
IDACS

INDAC
KAIO
LABLAB-8/e
LAB-K
OMNIBUS
OS/8
PDP
PHA

PS/8
QUICKPOINT
RADRSTS
RSX
RTM
RT-11
SABR
TYPESET 8
UNIBUS

CONTENTS
PAGE

CHAPTER 1 THE CASSETTE PROGRAMMING SYSTEM
1.1
1.1.1
1.1.2

INTRODUCTION TO A CASSETTE STORAGE SYSTIM
Hardware Components
Software Components

1.2

VfflAT

1-2
1-4
1-4

1.3

THE SYSTEM CASSETTE

1-4

1.4

MOUNTING AND DISMOUNTING CASSETTES

1-5

1.5

CONCERNING EXAMPLES

1-6

1.2.1
1.2.2

IS A CAPS-8 CASSETTE?
The Format of a Cassette
The Sentinel File

1-1
1-2
1-2

CHAPTER 2 GETTING ON-LINE WITH THE CAPS-8 SYSTEM
2.1

SYSTEM PROGRAMS

2-1

2.2

2.2.1
2.2.2
2.2.3

SYSTEM CONVENTIONS
File Formats
Filenames and Extensions
Input/Output Devices

2-1
2-1
2-2
2-2

2.3

LOADING THE KEYBOARD MONITOR

2-3

2.4
2.4.1
2.4.2
2.4.3

USING THE KEYBOARD MONITOR
Making Corrections
Special Characters
I/O Designations and Specification Options

2-3
2-3
2-4
2-5

KEYBOARD MONITOR COMMANDS
Run Command
Load Command
DAte Command
Directory Command
DElete Command
Zero Command
REwind Command
Version Command

2-5
2-6
2-7
2-7
2-7
2-8
2-9
2-10
2-10

2.6

NOTES ON DEVICE HANDLERS

2-11

2.7

MONITOR ERROR MESSAGES

2-12

5.1
5.2
5.3
5.4
5.5
5.6
5.7
5.8

CHAPTER 3 SYMBOLIC EDITOR
3 .

INTRODUCTION

3-1

3.2
3.2.1
3.2.2
3.2.3

CALLING AND USING THE EDITOR
EDITOR Options
Input and Output Specifications
Version Numbers

3-1
3-1
3-2
3-3

111

)

3.3
3.3.1

MODES OF OPERATION
Transition Between Modes

3-4
3-4

3.4
3.4.1
3.4.2
3.4.3
3.4.4
3.4.5
3.4.6
3.4.7
3.4.8
3.4.9
3,4.10
3.4.11
3.4.12
3.4.13

SPECIAL CHARACTERS AND FUNCTIONS
RETURN Key
Erase (CTRL/U)
RUBOUT Key
Form Feed CCTRL/FORM)
The Current Line Counter C.
Slash (/)
LINE FEED Key
ALT MODE Key
Right Angle Bracket (>)
Left Angle Bracket C<)
Equal Sign (=)
Colon (:)
Tabulation (CTRL/TAB)

3-4
3-5
3-5
3-5
3-5
3-6
3-6
3-6
3-7
3-7
3-7
3-7
3-7
3-7

3.5

COMMAND STRUCTURE

3-8

3.6
3.6.1
3.6.2
3.6.3

COMMAND REPERTOIRE
Input Commands
Output Coimuands
Editing Commands

3-8
3-9
3-10
3-12

3.7

TEXT COT.LF.CTION

3-15

3.8

3.8.1
3.8.2

CHARACTER SEARCHES
Single Character Search
Character String Search

3-16
3-16
3-17

3.9

EDITOR ERROR MESSAGES

3-21

3.10

EDITOR DEMONSTRATION RUN

3-23

CHAPTER 4 SYSTEM COPY
4 .

INTRODUCTION

4-1

4.2

4.2.1
4.2.2
4.2.3

CALLING AND USING SYSTEM COPY
System Copy Options
Input and Output Specifications
System Copy Example

4-1
4-1
4-2
4-3

4.3

SYSTEM COPY ERROR MESSAGES

4-4

CHAPTER 5 PALC ASSEMBLER
5 . 1

INTRODUCTION

5-1

5.2

5.2.1

CALLING AND USING PALC
PALC Options

5-1
5-5

5.3

CHARACTER SET

5-5

5.4

STATEMENTS
Labels
Instructions
Operands
Comments

5-6
5-6
5-6
5-7
5-7

5.4.1
5.4.2
5.4.3
5.4.4

5.5.1
5.5.2
5.5.3

FORMAT EFFECTORS
Form Feed
Tabulations
Statement Terminators

5-7
5-7
5-7
5-8

5.6

NUMBERS

5-9

5.7
5.7.1
5.7.2
5.7.3
5.7.4
5.7.5
5.7.6
5.7.7
5.7.8

SYMBOLS
Permanent Symbols
User-Defined Symbols
Current Location Counter
Symbol Table
Direct Assignment Statements
Symbolic Instructions
Symbolic Operands
Internal Symbol Representation for PALC

5-9
5-9
5-9
5-10
5-11
5-12
5-13
5-13
5-13

5.8
5.8.1
5.8.2

EXPRESSIONS
Operators
Special Characters

5-14
5-14
5-17

INSTRUCTIONS
Memory Reference Instructions
Indirect Addressing
Microinstructions
Autoindexing

5-20
5-20
5-20
5-21
5-23

PSEUDO-OPERATORS
Indirect and Page Zero Addressing
Radix Control
Extended Memory
5,,1)3.3
End-of-File
5.,1)3.4
5,,1^.5
Resetting the Location Counter
Entering Text Strings
5,,1)3.6
Suppressing the Listing
5,,1)3.7
Reserving Memory
5,.1)3.8
5,.1^.9
Conditional Assembly Pseudo-Operators
Controlling Binary Output
5,.1)3.1)3
Controlling Page Format
5,.1)3.11
Altering the Permanent Symbol Table
5,.1)3.12

5-24
5-24
5-24
5-25
5-26
5-26
5-27
5-27
5-27
5-28
5-28
5-29
5-29

5.5

5.,9.1
5.,9.2
5.,9.3
5.,9.4
5..Ij?
5,,1)3.1
5,,1)3.2

5.11

LINK GENERATION AND STOl^AGE

5-30

5.12

CODING PRACTICES

5-31

5.13
5.13.1

PROGRAM PREPARATION AND ASSEMBLER OUTPUT
Terminating Assembly

5-32
5-33

5.14

PALC ERROR CONDITIONS

5-33

CHAPTER 6 CASSETTE BASIC
6.1

INTRODUCTION

6-1

6.2

CALLING BASIC

6-1

6.3

NUMBERS

6-2

6.4

VARIABLES

6-3

ARITHMETIC OPERATIONS
Priority of Operations
Prentheses and Spaces
Relational Operators

6-4
6-4
6-5
6-5

6.6.1
6.6.2
6.6.3

IMMEDIATE MODE
PRINT Command
LET Command
Looping PRINT and LET Commands

6-6
6-6
6-7
6-7

6.7

EXAMPLE RUN

6-8

6.8

BASIC STATEMENTS
Statement Numbers
Commenting the Program
Terminating the Program.
The Arithmetic Statement
Input/Output Statements
Creating Run-Time Input Files
Loops
Subscripted Variables
Transfer of Control Statements
Program Chaining
Subroutines
Functions

6-10
6-10
6-10
6-11
6-11
6-12
6-25
6-27
6-29
6-31
6-34
6-35
6-37

6.9.1
6.9.2
6.9.3
6.9.4
6.9.5

IMPLEMENTING A USER-CODED FUNCTION
Coding Formats
Floating-Point Format
Incorporating Subroutines with UUF
Writing the Program
Examples of User-Coded Functions

6-44
6-44
6-46
6-46
6-47
6-47

6.10
6.10.1
6.10.2

FLOATING-POINT PACKAGE
Instruction Set
Addressing

6-50
6-50
6-51

6.11
6.11.1
6.11.2
6.11.3
6.11.4
6.11.5
6.11.6
6.11.7
6.11.8

EDITING AND CONTROL COMMANDS
Erasing Characters and Lines
Listing a Program
Running a Program
Stopping a Run
Loading a User-Coded Function
Erasing a Program In Memory
Renaming a Program
Saving a Program

6-52
6-52
6-53
6-54
6-54
6-55
6-55
6-55
6-56

6.12

CASSETTE BASIC ERROR MES55AGES

6-57

6.13

CASSETTE BASIC SYMBOL TABLE

6-59

6.5

6.5.1
6.5.2
6.5.3
6.6

6.8.1
6.8.2
6.8.3
6.8.4
6.8.5
6.8.6
6.8.7
6.8.8
6.8.9
6.8.10
6.8.11
6.8.12
6.9

CHAPTER

USING CAPS-8 CODT

7.1

FEATURES

7-1

7.2
7.2.1

USING CODT
Commands

7-2
7-2

7.3

ILLEGAL CHARACTERS
ADDITIONAL TECHNIQUES
TTY I/O-FLAG
Interrupt Program Debugging

7-8

7.4

7.4.1
7.4.2

7-9
7-9

Octal Dump
Indirect References

7-9
7-9

7.5

ERRORS

7-9

7.6

OPERATION AND STORAGE
Storage Requirements - CAPS-8 System
Programming Notes Summary
COMMAND SUMMARY

7-9
7-10
7-10

7.6.
7.6.

7.7

CHAPTER 8

7-11

CAPS-8 UTILITY PROGRAM

8.1

INTRODUCTION

8-1

8.2

8.2.1
8.2.2

CALLING AND USING THE UTILITY PROGRAM
Utility Program Options
Input and Output Specifications

8-1
8-1
8-2

8.3

UTILITY PROGRAM ERROR MESSAGES

8-2

CHAPTER 9

BOOT

9.1

OPERATING PROCEDURES

9-1

APPENDICES

ASCII Character Codes

A-1

Error Message and Command Summaries

B-1

PALC Permanent Symbol Table

C-1

CAPS-8 Demonstration Run

D-1

Monitor Services

E-1

Assembly Instructions

F-1

TABLES
Table 2-1 CAPS-8 Extension Names
Table 2-2 Directory Options
Table 2-3 Keyboard Monitor Error Messages
Table 3-1 EDITOR Options
Table 3-2 Command Format
Table 3-3 Input Commands
Table 3-4 List Commands
Table 3-5 Text Transfer Commands
Table 3-6 Editing Commands
Table 3-7 Search Character Options
Table 3-8 Terminating a String Search
Table 3-9 EDITOR Error Codes
Table 4-1 System Copy Options
Table 4-2 System Copy Error Messages
Table 5-1 PALC Options
Table 5-2 Use of Operators
Table 5-3 PALC Error Codes

2-2
2-8
2-12
3-1
3-8
3-9
3-10

3-11
3-12
3-16
3-20
3-21
4-1
4-4
5-5
5-15
5-34

Table 6-1 Cassette BASIC Functions
Table 6-2 Function Addresses
Table 6-3 Floating-Point Accumulator
Table 6-4 Floating-Point Instructions
Table 6-5 Relative Addresses
Table 6-6 Cassette BASIC Error Messages
Table 6-7 Cassette BASIC Symbol Table
Table E-1 Monitor Memory Map
Table E-2 Utility Subroutines and Locations
Table E-3 Header Record Structure

6-38
6-45
6-46
6-50
6-51
6-57
6-60
E-1
E-1
E-11

ILLUSTRATIONS
Figure
Figure
Figure
Figure
Figure

1-1
1-2
1-3

E-1
E-2

Cassette Programming System
CAPS-8 Cassette
Mounting a Cassette
Switch Option Characters
Ring Buffers

Vlll

1-1
1-3
1-6
E-10
E-10

CHAPTER 1
THE CASSETTE PROGRAMMING SYSTEM

1.1 INTRODUCTION TO A CASSETTE STORAGE SYSTEM

The PDP-8 Cassette Programming System (CAPS-8) is a small programming
system for the PDP-8/E (8/M or 8/F) computer and is de signed around
the use of cassettes for program storage, rather than DE Ctape, paper
tape
or
disk storage.
CAPS-8 replaces paper tap a procedures
completely. The MI8-E Hardware Bootstrap initially loads the Cassette
Keyboard Monitor into memory; with the use of the Mon itor all file
transfers and program loading and storage is done v la cassette,
Cassettes are more convenient and reliable and much easie r to use than
paper tape, and in addition, cut the time involved in loading and
storing programs using paper tape by almost one half.

CAPS-8 provides the user with a Keyboard Monitor,
I/O facilities at
the Monitor level,
and a library of System Programs, including a
machine language assembler, an editor, and a higher-level programming
language.

Figure 1-1 Cassette Programming System

1-1

1.1.1 Hardware Components
The Cassette Programming System is built around a PDP-8/E, 8/M, or 8/F
computer with a minimum of one TU60 dual cassette unit, a console
terminal (LA30 DECwriter, LT33 or LT35 Teletype, or VT05 DECterminal)
and BK of memory. A line printer is optional.

1.1.2 Software Components

A brief description of the software
Cassette Programming System follows.
greater detail later in the manual.

package available with the
Each program is discussed in

MONITOR - The Keyboard Monitor provides communication
between the user and the Cassette System Executive
Routines by accepting commands from the console terminal
keyboard.
The commands allow the user to run system and
user programs, save programs on cassette, and obtain
directories of cassettes.

Symbolic EDITOR - The EDITOR allows the user to modify or
create
source files for use as input to language
processing programs such as BASIC and PALC.
The EDITOR
contains powerful text manipulation commands for quick
and easy editing.

PALC Assembler (Program Assembly Language Cassette)
PALC accepts source files in the PAL machine language and
generates absolute binary files as output.
These files
can then be loaded cind executed using Monitor commands.

BASIC - BASIC provides a
higher- level
programming
language which is easy to learn and use.
It includes
such language features as user-coded functions, data
files on cassette, and program chaining.

System Copy (SYSCOP) - SYSCOP allows the user to transfer
files from one cassette to another,
giving him the
ability to make multiple copies of a cassette and "clean
up" full cassettes so that they may become available for
future use.

—

1.2 WHAT IS A CAPS- 8 CASSETTE?

A CAPS-8 cassette is a magnetic tape device much like that used in a
cassette tape recorder. The tape itself and the reels it is wound on
(see Figure
are enclosed inside a rectangular plastic case
1-2)
making handling, storage, and care of the cassette convenient for the
user.

1-2

On either end of one side of the cassette are two flex ible plastic
tabs called write protect tabs (see A in Figure 1-2)
There is one
tab for each end of the tape; since data should only be w ritten in one
direction on the tape, the user will need to be concerne d with only
the tab which is specifically marked on the cassette labe 1.
Depending
upon the position of this tab, the user is able to pro tect his tape
against accidental writing and destruction of data.
Wh. en the tab is
pulled in toward the middle of the cassette so that the hole is
uncovered,
the tape is write-locked; data cannot be writ ten on it and
any attempt to do so will result in an error message.
Wh. en the tab is
pushed toward the outside of the cassette so that the hoi e is covered,
the tape is write-enabled and data can be written onto i t.
Data can
be read from the cassette with the tab in either positior.
The bottom of the cassette (B in Figure 1-2) provides an opening where
the magnetic tape is exposed.
The cassette is locked into position on
a TU60 cassette unit drive so that the tape comes in cont.act with
the
read/write head through this opening.

Both ends of the magnetic tape in a cassette consist of clear plastic
leader/trailer tape;
this section of the tape is not used for
information storage purposes, but as a safeguard in handling and
storing the cassette itself.
Since cassette tape is susceptible to
dust and fingerprints, the leader/trailer tape should be the only part
of the tape exposed whenever the cassette is not on a drive.

Figure 1-2

CAPS-8 Cassette

1-3

1.2.1 The Format of a Cassette

A cassette is formatted so that it consists of a sequence of one or
more files. Each file is preceded and followed by a file gap.
(A gap
in this sense is a set length of specially coded tape.) All cassettes
must start with a file gap; any information preceding the initial file
gap is unreliable. A file consists of a sequence of one or more
records separated from each other by a record gap. The first record
information
of a file is called the file header record and contains
concerning the name of the file, its type, length, and so on.
A
(Chapter 2 provides more information concerning header records.)
12 8
(decimal) characters of information;
record generally contains
there are approximately 600 records per cassette tape.
Records consist of a sequence of one or more cassette bytes; a byte in
turn consists of eight bits each representing a binary zero or one.
Characters and numbers are stored in bytes using the standard ASCII
character codes (see Appendix A) and binary notation.
The number of records of information on a cassette tape may be
On the outside of the cassette case is a clear
estimated by the user.
plastic window (C in Figure 1-2) . Along the bottom, of this window is
series of marks; each mark represents abovit 50 inches of magnetic
a
Knowing that approximately 2 records fit on an inch of tape,
tape.
the user is able to make a reasonable guess as to the length of tape
By simply glancing at the
and number of records available for use.
width of the tape reel showing in the window, the user can tell
Since he is given no advance
quickly if he is very close to the end.
warning of a full tape condition, the user must visually keep track of
Should the tape become full
the length of tape he has available.
before his file transfer has completed, einother cassette must be
substituted, cuid the transfer or output operation must be restarted.
.

1.2.2 The Sentinel File

This
The last file on a cassette tape is called the sentinel file.
file consists of only a file header record and represents the logical
end-of-tape. A zeroed or blcink cassette tape is one consisting of
only the sentinel file.

1.3 THE SYSTEM CASSETTE

The software discussed in Section 1.1 is provided to the user on a
single cassette called the System Cassette. This is the cassette on
which the entire CAPS-8 System resides, and it is utilized for all
system functions. The System Cassette must always be mounted on drive
serves as the default device when the user fails to specify
0; drive
another.

1-4

NOTE
Each TU60 dual cassette unit has two
drives . The drive on the left is always
odd-numbered and the drive on the right
even-numbered; thus, drive
will be the
If the user has more
left drive.
than
one TU60 dual cassette unit, he should
pirobably label the drives in consecutive
order so that there will be no confusion
when he is using the system.
The write protect tab on the System Cassette should usucilly be in the
write-locked position so that data will not accidently be written on
it; it is suggested that the user make a copy of thisi
cassette as
protection against loss or accidental destruction.

1.4 MOUNTING AND DISMOUNTING A CASSETTE

To mount a tape on a drive, hold the tape so that the open part of the
cassette is to the left and the full reel is at the top. Set the top
write protect tahi to the desired position depending upon whether data
is to be written on the tape.
Open the locking bar on the cassette drive by pushing it to the right
away from the drive (see A in Figure 1-3) . Next hold the tape up to
the cassette drive at approximately a 45-degree single and insert the
tape
into
the
drive
by applying a leftward pressure while
simultaneously rotating the cassette over the drive spirockets.
This
Push the
brings the tape into position against the read/write head.
tape into the unit so that when the cassette is properly mounted, the
(Figure
locking bar automatically closes over the cassette back edge.
1-3 illustrates this procedure.)
Press the rewind button on the cassette unit (see B in Figure 1-3;
there is a rewind button for each drive) . This causes the cassette to
(Pressing the
rewind to the beginning of its leader/trailer tape.
rewind button ci second time causes the cassette to revrind to the end
The
of the leader/trciiler tape and to the physical end--of-tape.
cassette unit will click; this sound is almost inaudibJ.e and the user
Normal usage
may not hear it unless he is listening carefully.
requires that the user press the rewind button only once whenever he
wishes to manually rewind a cassette) . Even though tapes which are
not actively being used on a drive should already be positioned at the
beginning, the user should develop the habit of
automatically
When the tape has finished winding, the
rewinding a cassette.
The cassette is now in place; and ready for
cassette will stop moving.
transfer operations.

1-5

Figure 1-3 Mountincr a Cassette
Before removing a cassette f rom a drivei, the tape should always be
rewound to its beginning,
This can be done by pressing the rewind
button on the cassette unit or by issuing the REwind Monitor Command
as
explained in Chapter 2
Rewinding a tape ensures that the clear
leader/trailer tape will be the only tcipe exposed at the open part of
the cassette.
To remove a cassette from the cassette drive, open the
locking bar and the cassette will pop out.
When cassettes are not
being actively used on a cassette drive, they can be stored in the
small plastic boxes provided for this purpose by the manufacturer.

NOTE
Before using a new cassette, or prior to
using a cassette that has just been
shipped or accidently dropped, mount the
cassette on a drive so that the Digital
label faces the inside of the unit and
perform a rewind operation. Remove the
cassette,
turn it ovcir,
and perform
another rewind operation.
This packs
neatly in the cassette and
the tape
places the full tape reel at the proper
tension.

1.5 CONCERNING EXAMPLES
In the chapters that follow, care has been
taken to include acutal
machine printout whenever possible.
In cases in which there may be
some discrepancy as to whether a character was typed by the user or by
the system, that typed by the system will be underlined.

1-6

CHAPTER 2
GETTING ON-LINE WITH THE CAPS-8 SYSTEM

2.1 SYSTEM PROGRAMS

The Cassette Programming System is distributed on a single cassette,
called the System Cassette, which contains all the programs necessary
for loading the Monitor into memory and creating and lunning system
The directory of the System Cassette is as
user programs.
cind
follows

C2B00T .BIN
MONFOrt • BIN
sybcop • BIN
EDIT
.BIN
PALC
.BIN
BASIC .BIN

01/22/73
01/22/73
01/25/73
01/02/73
01/02/73
01/02/73

Ul
Ul

V2
VI
VI
VI

System files are in binary format (see Section 2.2.1). The first two
files on any System Cassette must be C2B0OT.BIN and MONTOR.BIN; these
C2B00T.BIN
two files comprise a bootstrap cind the Keyboard Monitor.
loads the Monitor into memory from the System Cassettes; the Keyboard
Monitor links the user and the CAPS-8 System by providing a means of
communication between the two. By accepting commands from the console
terminal keyboard, the Cassette Keyboard Monitor allows the user to
run system and user programs, save eind recall files utilizing cassette
storage, and create, assemble, and load programs.

2.2 SYSTEM CONVENTIONS

The following
procedures and
other systems.

conventions concern file formats and file naming
standard for the CAPS-8 System, as well as for many

aire

2.2.1 File Formats

The Cassette Programming System makes use of two types of file formats
ASCII and Binary.

—

Files in ASCII format conform to the American National Standard Code
Interchange in which alphanumeric characters are
for Information
represented by a 3-digit code. A table containing ASCII character
codes in 7- and 8-bit octal is provided in Appendix A.

Binary format files consist of 12-bit binary words representing PDP-8
The standard DEC binary format is used with
machine language code.
Binary files contain
the exception that no checksum is necessary.
field addresses and memory instructions and are read directly into

2-1

memory for immediate execution. CAPS- 8 System Programs are in binary
format, and programs which the user assembles with PALC are translated
into files in binary format.

2.2.2 Filenames and Extensions

System and user files are referenced symbolically by a name of as many
(A-Z)
followed
alphabetic characters
or digits
(0-9)
as
six
optionally by an extension of from 1 to 3 alphabetic characters or
(the
first character in a filename must be alphabetic) . The
digits;
extension to a filename is generally used as an aid in remembering the
CAPS-8 format of a file. Table 2-1 lists commonly accepted extensions
it is
the user may or may not conform to this list as he chooses;
included here only as a guide:
,

—

Table 2-1 CAPS-8 Extension Names

Meaning

Extension
PAL
BIN
BAS
TXT
DOC
DAT

PALC source file (ASCII)
System or user binary format file
BASIC source file (ASCII)
Text file (ASCII)
Documentation file (ASCII)
Data file (ASCII or other)

Generally the user may call his files by any mnemonic filename and
some cases, if he omits specifying an
In
extension he chooses.
extension, the System Program he is running may assume an extension.
For example, PALC assumes an extension of .PAL unless the user
.BIN unless
another
indicates another, and the Run command assumes
extension is specified.

2.2.3 Input/Output Devices

There are three available categories of input/output devices in the
Cassette Programming System: console terminal keyboard (including
paper tape reader and punch if an LT33 Teletype containing these units
the console terminal) , cassette drives 0-7, and a line
is used as
There are no permanent device names in the CAPS-8 System.
printer.
Command strings cind I/O designations are entered in such a way that
the user specifies the device by a drive nximber and the file by a
option characters allow the user to direct listings to the
filename;
line printer or to otherwise change the normal operating procedure of
is the default device if
drive
The System Cassette
a program.
For example:
no drive number is specified.

—

.DI/L

2-2

—

(DI is a Monitor command instructing the computer to print a directory
Since no drive number is specified, drive
listing of a cassette.
The option character L sends
is
assiomed.
the System Cassette
output to the line printer instead of the console teriiinal, which is
the normal output device.)

—

2.3 LOADING THE KEYBOARD MONITOR

The CAPS-8 hardware bootstrap and C2B00T.BIN on the System Cassette
(Both
are used to load the Cassette Keyboard Monitor into memory.
Loading the Monitor is
bootstraps are described in Appendix E.)
accomplished as follows:
1.

Ensure that the computer and terminal are on-line.

Press and raise the HALT key. Make sure that the SINGLE
STEP key is in a raised position.

Place the System Cassette (write- locked to protect data)
onto cassette unit drive 0;

Press and raise the

SVJ

key.

At this point the RUN lamp should be on and the System Cassette should
begin to move. The hardware bootstrap calls the first program on the
System Cassette (C2B00T.BIN) which in turn loads the Keyboard Monitor
If
an error occurs during the loading
into memory.
(MONTOR.BIN)
process (for example, an error may be caused by the cassette being
improperly mounted, by a missing file on the tape, or by the
occurrence of an I/O error) no error message will inform the user
Instead, the System
since the Monitor is not completely in memory.
If
this
Cassette may stop moving and the computer may loop or halt.
is the case, steps 2-4 above should be repeated.
Once the Monitor has been loaded, the System Cassette stops moving and
This
dot is typed at the left margin of the console terminal page.
a
instructs the user that the Monitor is now in memory and ready to
accept input commands.

2.4 USING THE KEYBOARD MONITOR

Each command to the Keyboard Monitor is typed at the console terminal
keyboard in response to the dot at the left margin. A command is
entered by pressing the RETURN key.

2.4.1 Making Corrections

Corrections may be made to the command line providing they are made
before the line is entered (that is, before a carriage return has been
typed). The RUBCUT key is used to correct typing errors. Pressing the

2-3

RUBOUT key once causes an open bracket
to be typed followed by the
[)
last character entered into memory. After this character is echoed on
Successive RUBOUTs
the console terminal it is deleted from memory.
each cause one more character to be printed and deleted. The first
non-RUBOUT character typed (after the last RUBOUT in a sequence)
causes a closing bracket (]
to be printed, thus enclosing only the
deleted portion of text within brackets. For example:
(

)

The user types: ,R BACIC (RUBOUT) (RUBOUT) (RUBOUT) SIC
The console terminal shows: ^H BACIC CCIC 3SIC
The string is entered to the Keyboard Monitor as: .R BASIC

2.4.2 Special Characters (CTRL/C, CTRL/0, and CTRL/U)

Control can be returned to the Keyboard Monitor while under any of the
System Programs by typing a CTRL/C (produced by holding down the CTRL
If the Monitor
is not
key and simultaneously pressing the C key) .
still in memory, a CTRL/C causes a complete rebootstrap by reading the
When it is
appropriate files from the System Cassette on drive 0.
ready to accept input, the Keyboard Monitor types a dot at the left
margin of the teleprinter (i.e. console; terminal) page.

Teleprinter output can be suppressed by typing a CTRL/0 (produced by
holding down the CTRL key and simultaneously pressing the O key)
This allows execution of the program to continue, but stops all
Typing a second CTRL/0 will resume output again.
console printout.
Unless output is extremely lengthy, or unless the program is waiting
for input from the user, processing of a program after an initial
CTRL/0 will usually be completed before the user is able to type a
Printout will automeitically resume when control is
second CTRL/0.
returned to the Keyboard Monitor (indicated by a dot at the left
margin)

NOTE
certain
prevent
CTRL/0
does
not
important error messagess from printing
on the console terminal.

A command line may be deleted completely, before it is entered, by
typing a CTRL/U (produced by holding down the CTRL key and pressing
This causes the current command line to be ignored and
the U key) .
returns control to the Keyboard Monitor. The Monitor prints a dot at
the left margin to indicate that it is ready to accept another
command.

2-4

2.4.3 I/O Designations and Specification Options

Whenever the user runs a System Program or performs any I/O operation,
he must indicate the file(s) to be accessed, the cassette drive (s)
on
which they are located, and any desired options associated with the
operation. Procedures used in entering this information are explained
below.

Monitor commands generally require only a single command line which
specifies the unit drive number (in the range 0-7), fiLename{s), and
option (s) in the following format;
.COMMAND DRIVE

#: FILENAME:. EXT/OPTION (S)

COMMAND represents one of the eight Monitor commands discussed in
Section 2.5.
The filename should be separated from the drive number
by a colon.
Options are alphabetic characters and are separated from
the rest of the command line by the slash character (/)
Successive
options follow one another without any separating character.
The
command line is executed by typing a carriage return.
.

I/O specifications to System Programs follow a different format.
First the System Program is called from the System Cassette using the
Monitor Run command. The System Program then asks for the input
filename, drive number,
and options, jind then the output filename,
drive number, and options. This information is usually requested in
two separate command lines, but the actual format varies between
System Programs. Generally, the command strings appear as follows:
.R SYSTEM PROGRAM/OPTIONS

INPUT-DRIVE #:FILENAME
OUTPUT-DRIVE #:FILENAME
The appropriate chapter should be referenced for the accurate format.

Options are available in most System Programs and Monitor commands
allowing the user to change the order or format of input and output
operations from that which would normally be carried out by the
program.
Again,
interpretation of options varies; the user should
refer to the appropriate section or chapter to learn which options are
available and what actions will result from their use.

2.5 KEYBOARD MONITOR COMMANDS

There are eight Keyboard Monitor commands available to the user.
Commands are typed in response to the dot printed by the Monitor and
are entered when the RETURN key is pressed.
Each command consists of
one or more alphabetic characters,
followed by a space (or any
non-alphcibetic character) .
Any error made while utilizing these
commands will result in a message informing the user (see Section
2.8). After occurrence of an error, control returns to the
Keyboard
Monitor and the command must be retyped.
(Since several of the
commands begin with the same letter, the user must be sure to note how
much of the command must be entered in order to distinguish it from
other commands. While it does not matter if too many characters are
entered, too few will cause errors.)

2-5

;

2.5.1 Run Command
The Run command is of the form:
.R Drive #: Filename/Option (s)

The Run command instructs the Monitor to load and execute the file
specified in the command line. The file should be in self-starting
binary format (tihat is, the last location in the source file must be
an
origin setting which indicates the starting address of the file)
as the file is not in self-starting binary format, the program will be
loaded but execution will not begin; the user will have to proceed as
though he were using the Load command (see Section 2.5.2).
The user
may omit specifying an extension as the Monitor assumes .BIN.
For
example:

CART.BIW

CART

Regardless of which command string the user types , the Monitor assumes
.BIN, searches drive
for the file CART. BIN, and executes it.

Options allowed in the command line depend upon the program the user
is
running.
Availability of options and results of their use are
discussed in Chapters 3, 4, 5 and 6. No error occurs if the user
specifies an option not allowed by a program; the option is simply
ignored.
Patches to
Multiple files may be executed using the Run command.
programs, BASIC user-coded functions, and programs the user may have
created using PALC can be executed as follows:
.R Drive #:PR0G1, Drive #:PR0G2 ,. . .PROGn/Option (s)

where n represents any number of programs as long as the total number
The
of characters on the input specification line does not exceed 64.
user must enter programs in the command line in the order in which he
wants them executed cind must be careful to include appropriate
starting, chaining, and return addresses (see Appendix E)
For example , assume the user has written a routine which will be used
for debugging purposes; each time a certain condition is met during
execution, this routine will be accessed, print a message and cause
The routine has been created using the CAPS-8
execution to halt.
EDITOR, assembled with PALC, and is stored on cassette drive 1 as
DBG. BIN;
it is loaded into memory with the user's program (TABLE.BIN
stored on cassette drive 0) . The programs are loaded as follows:

TABLE.BIN* :DBU.B I iV
1

2-6

Chapter 6, BASIC, contains an example of running multiple
conjunction with the BASIC user-coded function feature.

files

2.5.2 Load Command

The Load command is used to load a binary file into memory
the form:

and

takes

.L Drive #:Filename.ext/Option(s)

This command is similar to the Run command except that the computer
halts after loading the file. To start execution, the user sets the
correct starting address in the Switch R€>gister, presses ADDR LOAD,
the file is in self-starting binary format, the
CLEAR and CONT
(if
user need only press CONT) ; appropriate addresses included in the
program (see Appendix E) will return control to the Keyboard Monitor
after execution.

Multiple files may be loaded in the same manner as in the Run command
by simply specifying them in correct execution order on the command
line:
.L Drive #:PR0G1, Drive

# :PR0G2. . . .PROGn/Option(s)

Again, n may represent any number of programs as long as the
number of characters on the command line does not exceed 64.

total

2.5.3 DAte Command
The DAte command is of the form;
.DA mm/dd/yy

where mm, dd, and yy represent the current month, day and year as
(One or two-digit numbers in the range 0-99 are
entered by the user.
allowed in the DAte command. The Keyboard Monitor does not check for
errors other than the entry of a number which is outside this range.)
This date will then appear in directory listings (see Section 2.5.4),
If the
the date of creation of all new files will be included.
cind
DAte command is not used, directory listings will contain only
filenames, as illustrated in Section 2.1.

2.5.4 Directory Command
The Directory comiuand is of the form:
.Dl Drive #/Option(s)

and causes a directory listing of the cassette on the drive specified
No colon is necessary after the
to be output on the console terminal.

2-7

drive number. There are
Directory command:

two

options

availcible

for

use

with

the

Table 2-2 Directory Options

Meaning

Option
/L

Causes the listing to be output
on the line printer rather than
the console terminal.

Causes a "fast" listing to be
creation
produced
(omitting
dates and version numbers)

requested
In the following example a directory of cassette drive 2 is
output
(the version number in the directory listing reflects the

and

number of times the file has been accessed and
CAPS-8 EDITOR; see Chapter 3, Section 3.2.3):

changed

using

the

li^/f>9/7!3

FILE

.BIN

(^3/17/78

ABCDEF.PAL
A
R

.ASC

y.T

^22

This same directory using the F option will be reduced to:

lH/29/7f>

.RIM
FILE
ABCnEF.PAL
A
B

.ASC

2.5.5 DElete Command

The DElete command is of the form:
.DE Drive #: Filename. ext

and causes the filename on the specified drive number to be deleted
The filename is replaced by the name *EMPTY in
from the directory.
Only
the directory listing and the file can no longer be referenced.
one file may be specified in the DElete command string at a time.

2-8

For example, assume the user wishes to delete the
from the directory of cassette drive 3. He types:
.DE

filename

MATH. DAT

3:MATH.DAT

and then obtains a directory listing of drive
appear as follows:

11/17/78
TAPE
.BAS
*EMPTr.
.ASC
TOR

The

directory

will

11/02/72
11/07/72

where *EMPTY represents the deleted filename MATH. DAT.

2.5.6 Zero Command

The Zero command is of the form:
.Z

Drive

#: Filename

and specifies that the sentinel file of the indicated cassette is to
be moved so that it immediately follows the file indicated in the
command line.
(See Chapter 1 for a description of the sentinel file.)
All files following the sentinel file are deleted from the cassette
and that portion of the tape is completely reusable.

For example, assume cassette drive

LOOK
BASE
FOfJR

.ASC
.RAS
'BIM

l'^/23/7a

contains the following directory:

11/17/72

EMPTY.
RAC E

and the user wishes to save only the first three files.
Zero command as follows

uses

the

^Z 3:F0';R.Bir\J

and the sentinel file is placed immediately after the
The directory now reads:

LOOK. ASC
BASE. BAS
FO'JH.BIM

3/23/72

11/17/72

2-9

file

FOUR. BIN.

;vhen

no filename is specif ed in the command line, for example;

the cassette is said to be zeroed, or completely deleted of files; the
sentinel file is moved to the beginning of the cassette so that the
entire tape is available for use. This method is useful in "cleaning
cassettes which may contain several Ef-IPTY files in the directory
up"
listing but have become full and therefore unavailable for further
use.
First, any needed files are transfered to another cassette using
SYSCOP (see Chapter 4) , then the directory of the old cassette is
zeroed.
The sentinel file is written at the beginning of the tape
making the cassette completely reusable.

All new tapes must be zeroed before they are first used.
This ensures
that a sentinel file is present on the tape and moved to the beginning
of the tape.

2.5.7 REwind Command

The REwind command is of the form:
.RE Drive

and causes the cassette on the drive numiber specified to be rewound to
its beginning.
(The user can also cause
the tape to rewind by
pressing the rewind button on the cassette unit.) System Programs and
Monitor commands always rewind a cassette before accessing a file, but
if the user delevopes the habit of rewinding the cassette himself he
performs a timesaving action.
A cassette should always be rewound
before it is removed from a drive.

2.5.8 Version Command
The Version command is used to find out
Monitor currently in use. Typing:

the

version

number

the

instructs the Monitor to respond with
example:

the

appropriate

indicates that version 1.2 is currently in use.

2-10

number.

For

2.6 NOTES ON DEVICE HANDLERS

Device handlers for the CAPS-8 System are described in Appendix E.
few notes of interest concerning their use are included here.

The line printer perforins a form feed operation before beginning an
output task.
Characters are unpacked from the output buffer and
printed. A form feed is also produced following the completion of an
output task. The line printer handler is capable of handling only an
80 column printer.,
If the console terminal is an LT33 Teletype
containing reader and
punch units, these may be used as input/output devices in conjunction
with the Teletype keyboard. To punch a tape, simply place the punch
unit to ON; to read a tape, place the reader unit to START.
Characters will be printed on the Teletype keyboard as they are read
or punched.
Binary tapes may not be punched.

NOTE
The purpose of the Cassette Programming System is
the
elimination
of
paper
tape procedures
Cassettes provide a more convenient, reliable and
faster means of program storage than paper tape.
Therefore, although paper tapes may be read and
punched using the LT33 paper tape units, there is
no support for this type of I/O' and its use is not
encouraged.
If the user's program does not over-write certain areas of memory, the
parts of the Monitor which are in these locations are available for
use.
This allows the user who takes advantage of writing his own
programs in the PAL machine language to access system hcindlers and to
restart or rebootstrap the Cassette Keyboard Monitor after program
execution.
Infojrmation concerning Monitor Service Routines,
I/O
routines, device handlers, and internal descriptions of the Keyboard
Monitor are provided in Appendix E.

2-11

2.7 KEYBOARD MONITOR ERROR MESSAGES

The following error messages may occur when the
used incorrectly:

Table 2-3

Keyboard

Monitor

Keyboard Monitor Error Messages

Message

Meaning

BAD COMMAND

The user has
failed to follow the
correct syntax for Monitor commands.
This may be the result of mispelled
commands
or
too many or improper
arguments in a command string.

FILE NOT FOUND

The Monitor could not locate the file
(or
files) specified.
The user should
check to be sure that filenames are
spelled correctly and that the unit
drive number specified is correct.

INPUT ERROR ON UNIT n
OUTPUT ERROR ON UNIT n

An I/O error has occurred on the cassette drive specified.
This may be
caused
by an incorrectly formatted
cassette or may be due to a timing
The user should try the I/O
error.
transfer using another cassette.

UNIT n NOT READY

There is no cassette on the drive
specified, or no such drive exists.

Ul-ILOCK

UNIT n

The user tried to write data when the
write protect tab of the cassette on
the drive specified was write-locked.
To
write
data
this tab must be
write-enabled.

2-12

CHAPTER 3
SYMBOLIC EDITOR

3.1

INTRODUCTION

The CAPS- 8 Symbolic EDITOR is used to create and modify ASCII source
files so that these files may be used as input to other System
Programs such as BASIC and PALC.
The EDITOR considers a file to be divided into logical units called
pages.
A page of text is generally 50-60 lines long, and corresponds
approximately to a physical page of a pi'ogram listing.
(Note that
is not the same as a memory page) .
The EDITOR reads one page of
this
text at a time from the input file into its internal buffer where the
The Editor contains commands for
page becomes available for editing.
creating, modifying, or deleting characters, lines, or complete
logical pages of text. All commands consist of a single letter or a
letter with arguments, and are executed by typing the RETURN key.

3.2

CALLING AND USING THE EDITOR

To call the EDITOR from the System Cassette, type:
.R EDIT/Options
in response to the dot

3.2.1

(.)

printed by the Keyboard Monitor.

EDITOR Options

There are two options available for use with the EDITOiR; these are
(Option usage has been previously discussed
described in Table 3-1.
in Chapter 2, Section 2.4.3).

Table 3-1 EDITOR Options

Meaning

Option

TAB

when

Convert two or more spaces
reading from input device.

More than one file will be used for input.
(When one of these commands E, F, J, N, R,
end-of-file
is
or Y is issued and an
the EDITOR pauses and requests
encountered,
that the user specify another input file,
thus allowing continuation of the command.
has not been previously
If the /M option
specified in the input line, the end-of-file
See Section 3.9
condition remains in effect.
for an example.)

—

3-1

3.2.2

Input and Output Specifications

After the EDITOR has been called from the System Cassette it asks
the input specification as follows

for

*IN-^JT FILE-

The user responds with the input cassette drive number and
filename and extension, if any. For example:

the

input

*INP'JT FILE- 1 : ABA . PAL

specified, the
drive)
is
If only a filename (and no input cassette
assumed; the EDITOR prints the user's
is
default device drive
input specification line, only first it includes the assumed default
device before echoing the filename, as illustrated below:

—

The user has typed the filename AB, but before this is printed, the
If the input file is
EDITOR inserts 0: and then goes on to echo AB.
not found or if a syntax error occurs, the EDITOR prints a question
(*) at the left margin, and waits for
types cin asterisk
mark
(?) ,
another input designation. Any number of input files is permitted.

return only
If no input specification is made, (that is, a carriage
has been typed in response to the INPUT request) , a new file will be
The
created using the console terminal keyboard as the input device.
EDITOR allows input from the keyboard via the Append command (see
Example Using the EDITOR for an illustration of this method of
creating a program)
If more than one input file is to be entered, the /M option must be
specified when the EDITOR is called from the System Cassette. The
user responds to the INPUT FILE line with the drive number and
filename of the first input file. He enters output information as
When the end-of-file is
described next, and then edits his file.
reached during the editing procedure, the EDITOR again prints the
INPUT FILE request cind the user responds with the drive number and
filename of the second file. When the user finishes editing his final
file and no more input files are available, he responds to the
editor's INPUT request by typing a carriage return; the EDITOR
continues and closes the output file. All input files are combined
under the one filename specified in the output line.

The EDITOR initially requests output info:nnation by printing:
•O'JTP'JT

FILE-

3-2

The user responds with the output
example

drive

number

and

filename.

For

Again, if no device is designated, drive

is assumed and echoed.

If the output file is to have the same name as
the input file,
the
user need only type the correct output drive number followed by a
carriage return; the EDITOR will echo the assumed name. For example:
»IM?'?r FILF.- l sFILJ^.BAS
*0 1Ton FILE- ff; FILE.BAS

The EDITOR allows only one output file and creates the header for this
file on the specified cassette,
deleting any file already on that
cassette under the same name (and replacing it with "EMPTY in the
directory listing)
and leaving the cassette correctly postioned for
further output.

NOTE
If no output designation
is
specified
(that is,
a carriage
return only has
besen typed in
response to the OUTPUT

FILE
request) ,
the
only
output
operations which may be performed are L
(list buffer on the console terminal) or
V (list buffer on the line printer)
Only cassette files in ASCII mode are acceptable for use by the
EDITOR.
No error message is given if non-ASCII files are input, but
the results of editing operations are garbled.
Once I/O file designations are entered, the Symbolic EDITOR is ready
to accept commands from the keyboard.
It signifies this by printing a
number sign (#) at the left margin; this symbol occurs whenever the
EDITOR is waiting for a command.

3.2.3 Version Numbers

Each time a filename is indicated in response to the output file
is
assigned to it. This number
specification line, the number
(called the version number) signifies that a new file has been created
and that it hcis not been previously edited or referenced under this
filename.
The user may call a file from a specified cassette, make corrections
to it and change it any number of times before he is finally satisfied
with it or ready to use it for some other operation. In this case, he
may reference the file in the output specification line; by specifying
only the output cassette drive number followed by a carriage return,
since the filename itself will not be chcinged. Each time he does

3-3

this, the version number of the file is increased by 1.
When the
version number of a file has been incremented in this manner so that
it is greater than 0, it appears in directory listings on the same
line as the filename (see Chapter 2).

NOTE

Version numbers associated with edited
files should not be confused with the V
Monitor command,
which
prints
the
version of the Monitor currently in use.

3.3

MODES OF OPERATION

The EDITOR operates in one of two different
text mode.
command mode all input
In
interpreted as commands instructing the
operation.
In
text mode, all typed input
replace, be inserted into, or be appended to
buffer.

3.3.1

modes:
command mode or
typed on the keyboard is
EDITOR to perform some
is interpreted as text to
the contents of the text

Transition Between Modes

Immediately after being loaded into memory and started, the EDITOR is
command mode.
The special character # is printed at the left
margin of the teleprinter page indicating that the EDITOR is waiting
for a command.
All commands are terminated by pressing the RETURN
in

key.
In text mode, the EDITOR performs I/O operations on text stored within
the text buffer.
Text is input to the EDITOR buffer until a form feed
is encountered.
A line of text is terminated by a carriage return.
If no carriage return is present, the text entered on the current line
is ignored.
The buffer has room for approximately 5200
(decimal)
When text has been input to the extent that there are
characters.
only 256 decimal locations available in the buffer, the console
terminal rings a warning bell.
From this point on, whenever a
carriage return is detected during text input, control returns to the
EDITOR command mode and the bell is rung. This line-at-a-time input
may continue until the absolute end-of-buf fer is encountered. At this
point,
no more text will be accomodated in the buffer; a "?" is
printed and control returns to command mode every time the
user
attempts to input more text.

3.4

SPECIAL CHARACTERS AND FUNCTIONS

A number of the
functions,
These

console terminal keys have special
operating
keys and their associated functions are described

be low

3-4

3.4.1

RETURN Key

typing the RETURN key causes a
In both command and text modes ,
carriage return cind line feed operation and signals the EDITOR to
process the infoimiation just typed.
In command mode,
:Lt
allows the
EDITOR to execute the command just typed, A command will not be
executed until it is terminated by the RETURN key (with the exception
In text mode, RETURN causes the line of text
of =, explained later).
which it follows to be entered in the text buffer. A typed line is
not actually part of the buffer until terminated by the RETURN key.

3.4.2

Erase (CTRL/U)

The erase character (CTRL/U combination) is used for error recoveries
It is generated by holding the CTRL
in both command and text modes.
When used in text mode,
key while simultaneously typing the U key.
CTRL/U cancels everything to its left back to the beginning of the
line; the EDITOR echoes i V and performs a carriage
return/line feed
(CR/LF) ;
the user then continues typing on the next l;.ne.
When used
in command mode,
CTRL/U cancels the entire command; the EDITOR
performs a CR/LF and prints a #. The erase character cannot cancel
past a CR/LF in either command or text mode.

3.4.3

RUBOUT Key

In
Rubout is used in error recovery in both command and text modes .
text mode typing the RUBOUT key echoes a backslash (\) and deletes the
Repeated rubouts delete from right to left up
last typed character.
to, but not including, the CR/LF which separates the current line from
For example:
the previous one.,

THE O'J'JICKWWICK

RROW'NJ

FOX

will be entered in the buffer as:
THE O'JICK

3H0\*»:M

FOX

When used in command mode, RUBOUT is equivalent to the <;TRL/U feature
the EDITOR prints a #, performs a
and cancels the entire command;
CR/LF, and waits for another command to be entered.

3.4.4

Form Feed (CTRL/FORM)

A form feed signals the EDITOR to return to command mode. A form feed
the
CTRL and FORM keys
typing
generated
by
character
is
simultaneously. This combination is typed while in text mode to
indicate that the desired text has been entered and that the EDITOR
The EDITOR performs a CR/LF and
should now return to command mode.

3-5

prints a # in response to a CTRL/FORM to indicate that it is back in
command mode. CTRL/G is usually equivalent to CTRL/FORM except in the
case of a SEARCH command, as explained in Section 3.8.1.

The Current Line Counter

3.4.5

(.)

The EDITOR keeps track of the implicit decimal number of the line on
The dot (produced by typing the
which it is currently operating.
period key) stands for this number and may be used as an argument to a
command.
For example, .L means list the current line; .-1,.+1L means
list the line preceding the current line, the current line,
and the
line following it, then update the dot (current line counter) to the
decimal number of the last line printed.
The following commands affect the current line counter as indicated:
1.

After a Read or Append command, the current line counter
is equal to the number of the last line in the buffer.

After an Insert or Change command, the current line
counter is equal to the number of the last line entered.

After a List or Search command, the current line counter
is equal to the number of the last line listed.

After a Delete commeind, the current line counter is
equal to the number of the line immediately after the
deletion.

After a Kill command, the current line counter is

equal

to 0.

3.4.6

After a Get command, the current line counter
to the number of the line printed by the GET.

After a Move command, the current line counter is not
updated and remains whatever it was before the command
was issued.

Slash

equal

(/)

The slash symbol (/) has a value equal to the decimal number of the
It may also be used as an
highest numbered line in the buffer.
argument to a command. For example: 10, /L means list from line 10 to
the end of the buffer.

3.4.7

LINE FEED Key

Typing the LINE FEED v*iile in command mode is equivalent to typing .+1
and will cause the EDITOR to print the line following the current one
and to increment the value of the current line counter by one.

3-6

3.4.8

ALT MODE Key

Typing the ALT MODE key while in command mode will cause the line
following the current line to be printed and the current line counter
to be incremented by one.
If the current line is also the
last line
in the buffer,
typing either ALT MODE or LINE FEED will gain a
response of ? from the EDITOR indicating that there is no next line.
Some console terminals provide an escape key (ESC) in place of the ALT
MODE.
Their functions are identical.

3.4.9

Right Angle Bracket

{>)

Typing the right angle bracket (>) while in command mode is equivalent
to typing .+1L and will cause the EDITOR to echo > and then print the
The value of the current line
line following the current line.
counter is increased by one so that it refers to the last line
printed.

3.4.10

Left Angle Bracket

(<)

Typing the left angle bracket (<) while in command mode is equivalent
to typing .-IL and will cause the EDITOR to echo < and then print the
The value of the current line
line preceding the current line.
counter is decreased by one so that it refers to the last line
printed.

3.4.11

Equal Sign

(=)

or
The equal sign is used in conjunction with the pointer's dot
(.)
IVhen
typed in command mode the equal sign causes the
slash
(/) ,
In
EDITOR to print the decimal value of the argument preceding it.
this way the user may determine the number of the current line (.= )
or the number of
,
or the total number of lines in the buffer (/=
some particular line (/-8= ) without counting lines from the beginning
No carriage return need be typed following the equal
of the buffer.
)

sign.

3.4.12

Colon

(:)

Typing a colon produces the same result as the equal sign

3.4.13

(=)

Tabulation (CTRLAAB)

The EDITOR is written in such a way as to simulate tab stops at
8-space intervals across the teleprinter page. When the CTRL key is
held down cind the TAB key is typed, the EDITOR produces a tabulation.
A tabulation consists of from one to eight spaces, depending on the
Thus, the
number needed to bring the carriage to the next tab stop'.

3-7

: :

EDITOR may be used to produce neat colutnns on the teleprinter or line
printer page. The tab function is used in conjuction with the /B
option (for input and output) to allow the user to produce cind control
tabulations in the text buffer during input operations.
On
input
(under a Read command) , the EDITOR will replace a group of two or more
spaces with a tabulation if the user has specified the /B option.

3.5

COMMAND STRUCTURE

A command directs the EDITOR to perform

a desired
operation.
Each
command consists of a single letter, preceded by zero, one, two or
three arguments. The commemd letter tells the EDITOR what operation
to perform; the arguments usually specify which numbered line or lines
of text are affected.
Command format is illustrated in Table 3-2,
where E represents any command letter.

Table 3-2 Command Format
Type of Command

Command
Format

No Argument:

Perform operation E

One argument

Perform
operation
referenced line.

Two Arguments

m,nE

Perform operation E
through n, inclusive.

Three Arguments: m,n$jE

3.6

Meaning

on
on

the

lines

This combination is used by the
MOVE command only and is explained
in Section 3.6.3.

COMMAND REPERTOIRE

Commands to the EDITOR are grouped under three general headings:
Input Commands
Output Commands
Editing Commands

Explanation of the three types of commands is detailed in the
following sections. Each command description will state if the EDITOR
returns to command mode after completing the operation specified by
the command.
All commands are entered when the RETURI^ key is typed.
The EDITOR prints an error message consisting of a question mark
whenever the user has requested nonexistent information or used
inconsistent or incorrect format in typing a command. For example, if
command requires two arguments, and only one (or none) is provided,
a
and
the EDITOR will print ?, perform a carriage return/line feed,
Similarly, if a nonexistent command
ignore the command as typed.
character is typed, the2 error message ? will be printed, follov/ed by a
However, if
carriage return/line feed; the command will be ignored.

3-8

an argument is provided for a commmand that does not require one,
the
argument will be ignored and the normal function of the commmand

For example:

performed.

Result:

User Types:

The buffer is empty.
The user is asking for
nonexistent information.

L
?

The arguments are in the wrong order.
EDITOR cannot list backwards.

7,5L
?

This command requires two arguments before
the $; only one was provided.

The user types a nonexistent command letter.

17$10M

3.6.1

The

Input Commands

Two commands are available for inputting text, and
Table 3-3.

are

described

Table 3-3 Input Commands

Command

Format
#A

Action and Explanation
Append the incoming text from the console
terminal
keyboard
to the information
(if there
is no
already in the buffer
input
file the buffer will be empty
initially) . The EDITOR will enter text
mode upon receiving this command and the
user may then type in any number of lines
The new text will be appended to
of text.
if
the information already in the buffer,
(CTRL/FORM key
until a form feed
any,
typed;
control
then
combination)
is
returns to comniand mode.
By using the Append command with an empty
buffer, a symbolic program may effectively
the
be generated on-line by entering
program via the keyboard.

Any rubout encountered during execution of
delete the last
an Append command will
Repeated rubouts will
typed character.
delete from right to left up to but not
beyond the beginning of the current line.

Table 3-3 Input Commands (Cont'd)

Command

Format

Action and Explanation
Read a page of text from the input file on
the specified unit drive.
The EDITOR will
read information from the input file until
form feed character
a
(CTRL/FORM key
combination)
is
detected or until the
EDITOR
senses
a
text
buffer
full
condition. All incoming text except the
form feed is appended to the contents of
the text buffer.
Information already in
the buffer remains there.

NOTE
In both these
commands,
the
EDITOR ignores ASCII codes 340
through
376.
These
codes
include the codes for the lower
case alphabet
(ASCII
341-372)
The EDITOR returns to command
mode only after the detection of
a form feed or when a buffer
full condition is reached.

3.6.2

Output Commands

Output commands are subdivided into list and text transfer commands.
List commands will cause the printout of all or any part of the
contents of the text buffer to permit examination of the text.
Text
transfer commands provide for the output of form feeds, corrected
text, or for the duplication of pages of an input file.
List or text
transfer commands do not affect the contents of the buffer.

List Commands
The commands in Table 3-4 cause part or all of the contents of
text buffer to be listed on the console terminal or line printer.

Table 3-4 List Commands

Command

Action and Explanation

Format

LIST the entire page.
This causes the
EDITOR to list the entire contents of the
text buffer on the console terminal.

#nL

LIST line n.
followed by
feed.

3-10

This line will be printed
a carriage return and a line

the

Table 3-4 List Commands (Cont'd)

Command

Action and Explanation

Format

#m,nL

LIST lines m through n
console terminal.

V
V

inclusive

the

List the entire text buffer on
printer (if one is available)

the

line

#nV

List line n of
printer.

the

line

#ra,nV

List line m through
line printer.

the

buffer
n

inclusive

The EDITOR remains in command mode after a list command, and the value
of the current line counter is updated so as to equal the number of
the last line printed.

Text Transfer Commands
The following commands control the output of text and form feeds. The
EDITOR
is
designed to minimize the possibility of illegal or
meaningless characters being written into a source file; therefore the
illegal
(nonexistent)
codes 340-376 and 140-177, and most illegal
control characters will not be output.
Tcible 3-5

Command

Text Transfer Commands

Action and Explanation

Format

Output the current buffer to the output
file and transfer all input to the output
file; close the output file.

Transfer the entire contents of
buffer to the output buffer.

#nP

Transfer line n only to the output buffer.

#m,nP

Transfer

the

text

lines m through n
inclusive
m must be less than n) to the
output buffer.
When the output buffer
becomes full, the text is output to the
indicated output file.
The P command
automatically outputs a FORM character
(214) after the last line of output.
(where

Transfer the contents of the text buffer
to the output buffer,
delete the text
buffer and read in the next logical page
of text from the input file.

3-11

Table 3-5

Command

Format

Text Transfer Commands (Cont'd)

Action and Explanation
Execute the above sequence n times
If
n
is greater
than the number of pages of
input text, the command will proceed in
the specified sequence until it reads the
end of the input file, then it will return
to command mode.

#nN

The N command cannot be used with an empty
text buffer.
A ? is printed if this is
attempted.

Immediate end-of-file.
The Q
command
causes
the entire text buffer to be
output.
All text written into the output
buffer is then written into the output
file and the
file closed, with control
returning
to
the
Cassette
Keyboard
Monitor.

3.6.3

Editing Commands

The following commands permit deletion, alteration,
text in the buffer.

expansion

Table 3-6 Editing Commands

Command

Format

Action and Explanation

List the numlber of
available
memory
locations in the text buffer. The EDITOR
returns the number of locations on the
next line.
To estimate the number of
characters that can be accomodated in this
area,
multiply
the
number
of free
locations by 1.7.

#nC

Change line n. Line n is deleted, and the
EDITOR enters text mode to accept input.
The user may n aw type in as many lines of
text as he des ires in place of the deleted
line.
If more than one line is
inserted,
all subsequent lines will be automatically
renumbered and the line count will be
updated
app ropriately.
A
CTRL/FORM
terminates the command

#m,nC

Change lines m through n inclusive (m must
be numbered less the n) .
Lines m through
n are deleted and the EDITOR enters text
mode allowing the user to type in any
All
number of lines in their place.
subsequent lines will be automatically

3-12

Teible 3-6

Command

Format

Editing Commands (Cont'd)

Action and Explanation
renumbered to account for the; change
the line count will be updateid.

and

After any Change operation, a return to
command mode is accomplishesd by typing a
CTRL/FORM. After a Change, the value of
the current line counter
is equal to
The C
the number of the last line input.
command utilizes the Text Collector in
altering text (see Section 3.7).
(

)

#nD

Line n is removed from the
Delete line n.
text buffer. The current line counter and
the numbers of all succeeding lines are
reduced by one.

#m,nD

Delete lines m through n inc:lusive.
The
space used by the line to be deleted is
reclaimed as part of the Delete function
(refer to Section 3.7, Text Collection).

Find the
Used during a string search.
next occurrence of the string currently
being searched for
(see Section
3.8.2,
Inter-Buffer Character String Search)

Get and list the next line which has a
label associated with it.
(A label in
this context is any line OJ: text which
does not begin with a space, slash, TAB,
The EDITOR begins with the
or RETURN) .
line following the current l:.ne (line .+1)
and tests for a line with a label.
This
will most often be a line beginning with a
tag; it might also be a line containing an
origin.
For example:
TAD
nCA

(This is
line)

the

current

/THIS IS A COMMENT
(This line would be
printed by the command
G)

TAD
(This line would also
be printed if another
G were typed)

*5P10'1

#nG

Get and list the next line which begins
with a label; the EDITOR begins at line n
and tests it and each succeeding line as
described in the preceding example.

3-13

Table 3-6 Editing Cominaiids (Cont'd)
Conunand

Format

Action and Explanation

Both G and nG update the current line
counter after liinding the specified line.
However, if either version of the GET
command reaches the end of the buffer
before finding a line beginning with an
ASCII character other than a tab, slash,
or space, the current line counter retains
the value it vras assigned before the GET
was issued, and a ? is typed to indicate
that no tagged line was found.
The EDITOR
remains in conunand mode after a
GET
command
I

#nl

Insert the typed text before line n until
a form
feed
(CTRL/FORM) is encountered.
The EDITOR enters text mode to accept
input.
The first line typed becomes the
new line n.
Rubouts are recognized.
Both
the
line count and the numbers of all
lines
following
the
insertion
are
increased by the number of lines inserted.
The value of the current line counter is
equal to the number of the last line
inserted.
To re-enter command mode,
the
CTRL/FORM key combination must be typed
(terminating text mode) .
If this
is
not
all subsequent commands will be
done,
interpreted erroneonusly as
text
and
entered in the program immediately after
the insertion.

Insert text before
without an argument)

Initiate an inter-buffer string search
(See Section 3.8.2, Inter-buffer Character
String Search)

Kill
(delete)
the entire page in the
buffer.
The
values
of the special
characters (/) cind (.) are set to zero.
The EDITOR remains in command mode.

line

(when

NOTE
The EDITOR ignores the commands
nK or m,nK. This prevents the
buffer from accident ly
being
destroyed if the user intended
to type a List command (m,nL)

3-14

used

)

Table 3-6 Editing Commands (Cont'd)

Command

Format

#m,n$jM

Action and Explcination
Move lines m through n inclusive to before
line j (m must be numerically less than n
and j may not be in the range between m
and n) .
Lines m through n are deleted
from their current position
and
are
inserted before line j .
The lines are
renumbered after the move is completed
although the value of the current line
counter (,) is uinchanged, as moving lines
does not use any additional buffer space.
(The $ character is produced by typing
a
SHIFT/4.)

A line or group of lines may be moved to
the end of the buffer by specifying j as
For example, 1,10$/+1M.
/+1.
Since the
MOVE command requires three arcjuments , it
must have three arguments in orcier to move
even one line. This is done by specifying
the same line number twice.
For example,
5,5$23M.
This will move line
to before
line 23.
The EDITOR remains in command
mode after a Move command.
:>

#nS

Search line n for the character specified
after typing the S and a carriage return.
Allow modification of the line when the
character is found.
(See Section 3.8.1,
Single Character String Search.

#nY

Skip to a logical page in the input file,
without writing any output. For example,
This command reads through 4
#5y.
logical pages of input,
deleting them
without producing output. The fifth page
read into the text buffer and control
is
automatically returns to command mode.
If
there are no more pages of input, the
EDITOR issues a ? and returns to command
,

mode.

#$TEXT"
#$TEXT'
#"

Perform a character string search for the
string TEXT
(see Section 3. 8.. 2,
IntraBuffer
Character
String
Search)
Following a string search, #" causes a
search for the next occurrence of the
string.

3.7

TEXT COLLECTION

The CAPS-8 EDITOR contains an automatic text collector which reclaims
buffer space following the use of a D, S, or C command.
If a full

3-15

(using
buffer condition is reached, the user may output lines of text
and then delete these lines from the
for example)
the P command,
buffer— text collection is automatic and always occurs on the three
commands mentioned above.
,

NOTE
If extremely large amounts of text are deleted,
the text collection process could take several
amounts
text,
For
small
of
no
seconds.
appreciable time is lost.

3.8

CHARACTER SEARCHES

—

Two types of searches were mentioned in Table 3-6 the standard
character search and the character string search. Each is explained
in turn.

3.8.1

Single Character Search

The single character search may take one of the following forms:
#S

or
#nS

or
#m,nS

where m and n represent line numbers (m<n) , and S initiates the search
This command searches the entire text buffer (or the line(s)
command.
The search character is typed by
indicated) for the search character.
the user after he types the RETURN key which enters the command, aind
The EDITOR prints the contents of
does not echo on the teleprinter.
the entire buffer or the indicated line(s) until the search character
When the search character is found, printing stops and the
is found.
user types a response chosen from the following table:
Table 3-7 Search Character Options

Result

Option

Enter text at that point at which
the search character was found and
printing Sitopped.

text

CTRL/G

(bell rings)

Change the; search character to the
search
typed;
character
next
continues.
If the character is not
line ,
the
in
the
contained
remainder of the line will be typed
and control will be returned to
(For example, CTRL/G
command mode.
CTRL/G would cause the remainder of
the line to be listed.)

3-16

)

Table 3-7

Search Character Options (Cont'd)

Result

Option

3.8.2

CTRL/FORM

Continue searching for the
occurrence of the character.

RETURN key

End
line
here,
deleting
subsequent text on that l;.ne.

all

LINE FEED key

Make two lines out of the current
line.
Typing a line feed actually
inserts a carriage return without
returning control to command mode.

RUB OUT key

Delete characters from th«: line. A
rubout echoes a backslassh (\) for
When all
each character deleted.
characters
have
been
deleted,
echoing of "V stops.

Character String Search

The character string search can identify a given line in the buffer by
the contents of that line or any unique combination of characters.
This search returns the line number as a parameter that can be used to
There are two types of string search
further edit the text.
available: intra-buffer search and inter-buffer search.

Intra-Buffer Character String Search
The intra-buffer search scans all text in the current buffer for a
If the
string is not found, a ? is
specified character string.
If the str ing is
found,
printed and control returns to command mode.
the number of the line which contains the string i s put into the
current line counter and control waits for the user to issue a
searching for a character string in this manner
command.
Thus,
furnishes a line number which can then be used in con junction with
other EDITOR commcinds. This provides a useful framework for editing,
as it eliminates the need to count lines or search for 1 ine numbers by
listing lines.
(which
An intra-buffer search is signalled by typing the ALT MODE key
The user
in response to the # printed by the EDITOR.
echoes as $)
then types the string to be found (as many as 20 characters may be
specified any additional characters typed are echoed but not included
The search string cannot be broken across line
in the search) .
(')
terminates the character
Typing a single quote
boundaries.
string; when the RETURN key is typed the search is performed beginning
Use of the double quote (") causes the
line 1 of the text buffer.
at
and " as command
(Use of
search to begin at the current line +1.
elements prohibits their use in the search string. An incorrect
response resets the current line counter to the becfinning of the
buffer.

—

3-17

For example, assume the text buffer contciins the following text:
ABC DEF bJO

lAaB3C4D5E6
.STRINtaABCD

The user wants to list the line that contains ABC; this could be
by typing:

done

#$ARC'L

The search begins with line 1 and continues until the string is found.
The current line counter is set equal to the line in which the string
ABC occurred, and the L command causes the line to be printed as
follows
ABC DEF

CJJO

Control returns to command mode, awaiting further commands.
user wanted to find the next reference to ABC, he could type:

the

r-L
In this case, " is a command which causes the last string searched for
to be used again, with the search beginning at the current line +1.
It is not necessary to enter the search string again.
The command may
be used several times in succession.
For example, if the user wanted
to find the fourth occurrence of a string containing the characters
FEWMET he could type:
#$ FEWKET"""'L

This command lists the line which contains the fourth occurrence of
that string.
The L (List) command (or amy other command code) can be
given following either
or ". The L command causes the line to be
listed when and if it is found.
'

In order to clear the text string buffer, the user can type:

The system responds with a question mark and the text string buffer is
cleared.
and " allow for easy and useful
The properties of the commands
example
illustrates.
In order to change CIF
editing, as the following
20 to CIF 10, the user can issue the following commands:
'

3-18

#$D'JM, '$CIF 30"C
1'3
/'MEW FIi;LD (CTRL/FORM)

GIF

The above set of instructions first causes the EDITOR to start at line
and search for a line beginning wi1ji DUM,. A search is then made
1
for GIF 20, starting from the line after the line containing the
string DUM, . When this string is found, the line number of the line
containing the string GIF 20 becomes the current line number.
The G
command is given, and the user then changes the line to the correct
instruction, GIF 10 /NEW FIELD .

Since this search feature produces a line number as a result, any
operations which can be done by explicitly specifying a line number
can be done by specifying a string instead.
For example:

will list the fourth line after
STRING in the text buffer.

the

first

occurrence

the

text

£$LABEL1, '^LABELa^-L

will list all lines between the two labels, inclusive.

will do a character search on the line which contains PFLUG.
(The
user types the search character after typing the :return key that
enters the line.)
In cases where both strings and explicit numbers
are used,
"should be used first.
For example, the following commands:

strings

#l+SnAD! 'L

will not list the next line after the string BAD! occurs.
syntax is

The correct

#?V3AD! • +1L

Inter-Buffer Gharacter String Search
The inter-buffer search scans the current text buffer for a character
string.
If the string is not found, the current buffer is written to
the output file, the buffer is cleared, and the next buffer is read
from the input device. The search then resumes at line 1 of the new
buffer. This process continues until either the string is found or no
If input is exhausted, control returns to command
more input is left.
mode with all the text having been written to the output file.
If the
string is found, control returns to command mode with the current line
equal to the numlDer of the line containing the first occurrence of the
string.
For example, a command to find the character string GONZO may

3-19

appear as follows:

SliOIVZO'

#.=002^
the $ is printed
The J conunand initiates an inter-buffer search;
automatically by the EDITOR, and the user types in the character
string he wishes to search for. The search proceeds, and when the
string is found, control returns to cormiand mode. The user types the
.= construction to discover the number of
the line in the current
buffer on which the string is contained. To find further occurrences
The F command
of the string GONZO, the user can use the F command.
uses
the last character string entered to search the buffer starting
from the current line count +1.

#.= 3106

The above example causes a search for the string GONZO starting at the
If
no output file is specified in the J or F
current line +1.
commands , the EDITOR reads the next input buffer without attempting to
produce any output. This provides an easy way of paging through text
for a particular string.

After the J or P commands have processed the entire input file,
or Q command must be executed to close the output file.
The following two commands may be used
command, once given:

abort

the

string

Table 3-8 Terminating a String Search

Explanation

Command
CTRL/U

A CTRL/U will return control to the
EDITOR command mode if executed while
string
search
entering text in
a
command; the string search command is
ignored, as in the following example:
#J
SWORDtfJ

the
search
for
inter-buffer
The
characters W0:RD was aborted by the user
typing fU before terminating the string
or ".
with
'

RUB OUT

Executing the RUBOUT key while entering
text for use in a string search causes
the text so far entered to be ignored
and allows a new string to be inserted.
The EDITOR answers the command by typing

3-20

Table 3-8

Terminating a String Search (Cont'd)

Command

Explanation
$,

as seen in the following example:
jfSCHAR

(RUBOUT)

An example of the use of the character string search is contained
the EDITOR Demonstration Run found at the end of this chapter.

3.9

EDITOR ERROR MESSAGES

Errors made by the user while running the EDITOR may be of two types.
Minor errors
(such as an EDITOR command string error, an attempt to
execute a read or write command without assigning a device, or
a
search for a nonexistent string) will cause a question mark to be
typed at the left margin of the teleprinter paper.
The command may be
retyped.

Major errors force control to return to the Keyboard Monitor and may
be due to one of the causes listed in Table 3-9 . These errors cause a
message to be typed in the form:
?n+C

where n is one of the error codes in Table 3-9 and '^C indicates that
control will pass to the Keyboard Monitor when a character is typed.

Table 3-9 EDITOR Error Codes

Error Code

Meaning
The EDITOR failed in reading from a
An error occurred in the device
device.
handler;
likely
most
hardware
a
malfunction.

The EDITOR failed in
generally
device;
malfunction.

writing
a

onto a
hardware

A file close error occurred. The output
file could not be closed; either the
cassette
reached
an
end-of-tape
condition, or a sentinel file needs to
be written before any new output files
can be created on the cassette.

3-21

time the EDITOR encounters a syntax error.
In
euiy
addition, the following error message may be printed by the EDITOR:

A ? occurs

Meaning

Message
UNIT HAS OPENED FILE

Two files cannot be open on the same
device at the same time.

During the editing of a file, the output cassette specified in the
is
command string may become full before the editing process
completed.
If this is the case and further writing is attempted on
that cassette, cin error occurs. The output file is closed and the
message:
FULLi-OUTPUT FILE-

The user must now indicate a new output cassette and file
is printed.
which will contain the text that would not fit on the first cassette
Since the contents of
and any further editing the user wishes to do.
the text buffer are retained through this procedure, no text will be
lost if this error occurs.

NOTE
If no output file is specified when this
occurs,
the EDITOR again
condition
requests an output file; this continues
output
designation
is
until
the
correctly specified.

Assuming the new output device is valid, the EDITOR will continue the
operation which filled the old file, putting all output into the new
output file. After editing is completed, the output files should be
The entire process may then appear as
combined using the EDITOR.
follows:

^R EDIT
flNPUT FILE- 0;IN
^OUTPUT FILE- 1; OUT
#Y

SSTRING'
FULL OUTPUT FILE-2 t OUTEWP
#.L

Device 1: is full.
2: is specified as the
new output device
and editing continues.

TAD STRING

#.D
#E

3-22

—

When
At this point the output "file" is 2 files 1:0UT, 2:0UTEMP.
output is split like this, the split may have occurred in the middle
Therefore, the output files should never be edited
of a line.
In a case such as
separately as the split lines will then be lost.
this, the files should be combined with the EDITOR as follows:
^R EDIT/M
»INPUT FILE- : OUT
OUTPUT FILE- 5;0UT
l

INPUT FILE- 2;0UTEMP
INPUT FILEThe new file, OUT, may then be edited.

3-23

3.10

EDITOR DEMONSTRATION RUN

The following example illustrates both the use of the EDITOR to create
a new
file an(a a few of the commands available for editing.
Sections
of the printout are coded by letters which correspond
with the
explanations following the example.

EDIT

INPUT FILEOUTPUT FILE-0:PROO.PAL
#A

CHRPUT ,0
SNA
J MP

CDF
OCA
TAD
SPC
JMP
SNA
JMP

CHRPUT

/ACCEPTS CHAR IN AC AND
/PACKS IT INTO OUTPUT BUFFER
/IGNORES NULL

SHELF
WI\HATl
PUT#1
CLO

PUT#2

CM A

OCA WHATl

#.-5S
SNA CLO\A

#.L

SNA CLA

#P
#K

TAD SHELF
AND (360
CLL RTL

^R EDIT
INPUT FILE- 0;PRQG.PAL
OUTPUT FILE-1 : PROG. PAL

#R
ISSPC'L
SPC

#•5

SPC\A
#E

3-24

The user calls the EDITOR; the output
file will be called PROG, PAL and will be
stored on the default dcjvice—cassette
drive 0.
There is no input file since
one will be created from the console
The Append command
terminal keyboard.
is used to insert text into the empty
buffer.

Text is inserted.

The user makes a mistake
RUBOUT key to correct it

More text is added.

The user notices a typing mistake he has
made several lines back in the text. He
types a CTRL/FORM to finish the Append
illegal
for
the
searchs
command,
character, corrects it, and then lists
the line.

The P command writes the current buffer
into the output file placing a form feed
The K command
after the last line.
deletes all text in the current buffer
in preparation for a new page of text.

The user inserts new text using the
Append command. When he is finished he
types a CTRL/FORM to end the command.

file;
The user closes the
Cassette
the
returns
to
Monitor.

the user
In looking over the listing,
notices einother mistake; he opens the
in
file, calling it by the same name
both the input and output specification
lines.

The Intra-Buffer Character String Search
illegal
the
locate
to
used
is
instruction and list it.

The Single Character Search is used to
find the letter to be corrected, and the
RUBOUT key deletes it.

The file is closed and control
returns to the Keyboard Monitor.

3-25

and

uses

the

control
Keyboard

again

CHAPTER 4
SYSTEM COPY

4.1

INTRODUCTION

The CAPS-8 System Copy
(SYSCOP)
program allows the user to copy
individual files or all files from one cassette to another, giving him
the ability to make multiple copies of a cassette,
add files to a
cassette, emd "clean up" full cassettes so that they may become
available for future use.
System Copy transfers all non-empty files
on the specified input cassette to the specified output cassette;
space taken up by previously deleted files (*EMPTY files) is regained.
(Single file
transfers of ASCII files can be performed using the
CAPS-8 EDITOR; see Chapter 3.)

4.2

CALLING AND USING SYSTEM COPY

To call SYSCOP from the System Cassette, the user types:
.R SYSCOP/Options
in response to the dot

4.2.1

(.)

printed by the Keyboard Monitor.

System Copy Options

There are three options available for use with System Copy; these
options are discussed in Table 4-1..
(Option usage is explained in
Chapter 2, Section 2.4.3.)
Table 4-1 System Copy Options

Option

Meaning

This option allows the user to transfer
individual
cassette
files from one
cassette to another.
To use the /F
option, the user responds to the request
specification
with
the
for
input
cassette drive number and the name of
the file to be copied.
If the user
mcikes
a typing error while entering the
input specification, he can type CTRL/U
to redo the entry.

drive 1
If the /U option is specified,
is copied to
zeroed and then drive
is
is especially
(The /U option
drive 1.
useful for making copies of the System
Cassette.) When the /U option is used,
specifications are
further
I/O
no
necessary.

This option causes the output drive
(indicated in thes output specification
line) to be zeroed before any copying
begins.

4-1

4.2.2

Input and Output Specifications

Before indicating the input and output drives to be used for the copy
operation, the user must ensure that the proper cassettes are mounted.
The input cassette (the one to be copied) should be write-locked to
protect the data. The output cassette (the one that will be the new
copy) should be write-enabled to receive the data.
When the input and
output cassettes are mounted on the correct drives, the user is ready
to begin the copy operation.

After SYSCOP has been called from the System Cassette, it asks for the
input specification as follows:
IN-

The user responds with a single digit (0 through 7)
specifying the
input cassette drive number.
A carriage return is not necessary.
If
the /F option was used, the user responds to the IN- query with the
drive number and the name of the file to be copied; in this case, the
user must also type a carriage return.
In the
following example, a
file named ECHO is to be copied from drive 1.

IN-:ECHO

After the input specification has been entered. System
the output specification as follows:

Copy

requests

OUT-

The user responds with a single digit (0 through 7)
specifying the
output drive number.
The output drive number cannot be the same as
the input drive number.
If the user wishes to change the input/output
specifications at this point, he may type a carriage return instead of
the drive number eifter OUT- to return to the IN- message.

After both input and output drives have been indicated, the copy
operation starts.
All non-empty files on the input cassette are
copied, in order, onto the output cassette.
(If
a
file is to be
copied onto a cassette under the same filename and extension as one
already present on the cassette, it will still be copied; however,
future reference to the file will cause the first file under that name
to be accessed.
To circumvent this condition, the user should first
delete any old files or 2ero the output cassette.) IVhen all files have
been copied, control returns to the Keyboard Monitor.

4-2

through 7 are accepted in
Only two responses other than the digits
reply to the input/output specification messages: carriage return and
CTRL/C.
Carriage return returns the user to the input specification
message; CTRL/C returns the user to the Keyboard Monitor. Any other
response is considered illegal.
Illegal responses are
neither
accepted nor echoed by System Copy; System Copy simply waits for the
user to type a legal response.

System Copy Example

4.2.3

In this example, the user wishes to make a copy of the System Cassette
which is mounted on drive 0. One purpose of the copy operation is to
A
regain wasted space being taken up by previously deleted files.
directory listing shows that the System Cassette currently contains
the following files
:

C2B00T.BIN
M0NTOR.BIN
SYSCOP.BIN
*EMPTY.

01/22/73
01/22/73
01/25/73

EDIT
PALC
BASIC

01/02/73
01/02/73

.BIN
.BIN
.BIN

01/l()2/73

EMPTY.
EMPTY.
EMPTY.
EMPTY.
ABC

01/22/73

The user mounts a write-enabled cassette on drive
He than calls System Copy as follows
tape.

and

rewinds

the

_j_R

SYSCOP/Z

The /Z option will zero the cassette mounted on the cassette drive
specified in the OUT- message (drive 2) , leaving only the sentinel
System Copy then requests the input and output
file on the cassette.
drive numbers and the user responds as follows:
INQ UT- 2

If System Copy detects any problems during
The copy operation starts.
the copy operation, it prints one of the error messages explained in
Section 4.3. A successful copy operation returns control to the
The user can then issue a Directory command to
Keyboard Monitor.
example,
a
In this
ensure that all files were copied correctly.
successful copy operation should produce the following directory
listing:

C2B00T.BIN
MONTOR.BIN
SYSCOP.BIN
EDIT
PALC

BASIC

.BIN
.BIN
.BIN

ABC

01/22/73
01/22/73
01/25/73
01/02/73
01/02/73
01/02/73
01/22/73

4-3

4.3

SYSTEM COPY ERROR MESSAGES

Errors which occur during a System Copy operation may be of two types :
user errors and cassette errors. User errors may be corrected with
Cassette errors
the appropriate action as detailed in Table 4-2.
normally require the user to use cinother cassette (for either input or
Control does not return to
output) to complete the copy operation.
The user may
the Keyboard Monitor when a System Copy error occurs.
use CTRL/C to return to the Monitor if he cannot correct the indicated
error.

Table 4-2 System Copy Error Messages

Meaning

Message
INPUT ERROR ON UNIT n

An input error has occurred on the
cassette drive specified. The user
should try the copy operation using
another cassette.

UNIT n NOT READY

There is either no cassette on the
cassette drive specified or no such
drive exists.

UNIT n WRITE LOCKED

The user tried to write data when
protect tab of the
the
write
cassette on the drive specified was
write-locked.

OUTPUT ERROR ON UNIT n

An output error has occurred on the
The user
cassette drive specified.
should try the copy operation using
another cassette.

4-4

CHAPTER 5
PALC

5.1

INTRODUCTION

PALC (an acronym for Program Assembly Language for Casse:tte) is an 8K
2-pass assembler (with em optional third pass) designed for the CAPS-8
System. A program written in PALC source language is translated by
the assembler into a binary file in two passes.
Pass 1 reads the
input file and sets up the symbol table; pass 2 reads the input file
and uses the symbol table created in pass 1 to generate the binary
(object) file.
The binary file may then be loaded into memory using
the Cassette Keyboard Monitor.
PALC allows I/O using any CAPS-8 device which handles ASCII text.
It
from the System Cassette using the Keyboard Monitor Rian
is called
command, accepts input generated by the CAPS-8 EDITOR,
eind
will
generate output acceptable for use with both the Monitor Load and Run
commands

5.2

CALLING AND USING PALC

The user calls PALC from the System Cassette by typing;

^R PALC/Options
PALC responds by printing:
-INPUT FILES

The user enters his input cassette drive number cind filename in answer
to the asterisk printed by PALC; a total of three input specifications
are allowed, so that the input interaction may appear as follows:
-INPUT FILES
*1 :TaA.PAL

*0»THB.PAL
jtllTKC.PAL

Usually input files will contain the extension .PAL (see Chapter 2,
Section 2.2.2), and PALC will assume this extension unless the user
explicitly designates another. Thus in the above example the user may
have responded by typing only 1:TRA, 0:TRB, and 1:TRC, in which case
PALC would automatically assume and echo the .PAL extension.
If the filename contains an extension other than .PAL, the user
specify this extension when entering the input. For example:

-INPUT FILES
tFAIL.I
jtS t TABLE .ASC
.tf ISHOR.
jfel

5-1

must

In the case of the third input file (SHOR.) an extension is not to be
indicated.
If the user wants to prevent PALC from assuming .PKL, he
must be sure to include a period in the input line; otherwise PALC
will append .PAL and look for the filename with that extension.

input line, the
If the user does not specify a drive numtier in his
device drive
is assumed.
PALC will automatically insert
filename as the user has
the
0: in the input line before echoing
entered it. For example:

default

—

0 8FLOA.HAL
PALC assumed both
The user actually typed only the characters FLOA;
and the .PAL extension and correctly inserted these
the drive number
in the I/O line before echoing the complete line.

A carriage return typed in response to any of the asterisks
that there are no more input files.
After the input specifications have been entered,
binary output as follows:

PALC

indicates

requests

the

-BINAHY FILE

The user responds similarly here by indicating an output drive number
Only one binary file is allowed and it should have the
and filename.
extension .BIN (since the Monitor Run and Load commands assume this
If
the user wants his binary file to be called by the
extension) .
same name as the first input file he need only type the drive number,
PI<LC will echo this, adding the
and a carriage return.
a colon,
For example:
filename with a .BIN extension.
-INPUT FILES
*l : OPEN. HAL

-BINARY FILE
*e tOFEN.BIN

and the extension (.BIN) are assumed if
As in the input line, drive
the user fails to specify them, and a response of only a carriage
return indicates that no binary file is to be produced.

Once the binary output line has been ansv/ered, PALC prints;
-LIST TO

The user has a choice of sending his output listing to either the
console terminal or the line printer. To send output to the console
terminal the user types the characters TTY in response to the asterisk
as follows:
-LIST TO
*TTY

5-2

To send output to the line printer, the user responds by typing LPT:

-LIST TO
JtLPT

A response of a carriage return indicates that no

listing

produced.

During a PALC assembly only one listing is produced and it may be sent
to only one device, either the line printer or console terminal.
A
second listing must be produced by another assembly.
If more cassettes are to be involved in the assembly than the user has
TU60 unit drives,
a certain
procedure must be followed during the
assembly process. For example, assume the user has only one TU60 dual
cassette unit, and 3 input files are stored on individual cassettes.
His I/O specification is as follows :

-INPUT FILES
*1 !F1 .PAL

j!l0:F2.PAL

*0:F3.PAL
-BINARY FILE
±\ :RESLT.BIM
- UIST TO
*LPT
PALC is a 3-pass assembler, therefore all three input files will be
referenced 3 times. Assume the user has mounted IrFl.PiVL on drive 1,
and 0:F2.PAL on drive 0;
assembly begins.
First the file Fl is
processed, then F2 . After assembly of F2 PALC looks for F3, but since
the file is on a third cassette which is not mounted,
the assembly
pauses and PALC prints:
MOUNT FS.PAL'f
This pause in the assembly allows the user to dismount a cassette and
replace it with the cassette containing the file F3.PAL. The user
then responds to the above I/O line with the drive niimber on which he
has mounted the new cassette (assume 0), as follows:
MOUNT F3.PAL70
is
valid, PALC responds by typing a CR/LF and
If the response
continues pass 1 of the assembly.
(An invalid response causes PALC to
print a ?; the user may then type the correct response.)

When pass 1 is completed PALC automatically begins the second pass,
which creates the binary file. The binary output file specification
must now be made.
Regardless of the output specification indicated in
the initial dialogue, PALC pauses and asks:
MOUNT iiESLT.BIN?

5-3

The user must mount the output cassette which is to contain the binary
file and respond with the drive numhier on which he has mounted it.
Assume he decides to mount the cassette on drive 0. He replaces the
cassette currently on that drive
(containing F3.PAL) with the new
cassette amd responds to the command line as follows:
KOJNT HESLT.BIN7

PALC then opens the binary file on this cassette and prints:

BINAHY FILE OPENED ON
NOTE
The cassette used for binary output may
not contain any of the input files.
Under no
circumstances
should
the
cassette containing th€! binary file be
removed from the drive until pass 2 is
completely finished. PAIiC will indicate
completion of the pass by printing the
message, "BINARY FILE CLOSED".

After specification of the binary output file, PALC continues pass 2
of the assembly by processing the first input file, Fl.PAL, currently
on drive 1. After this file is processed, PALC pauses smd asks:
MOUNT F2.PAL?
is only partially
Since the binary file being created on drive
complete at this point, the user musst not remove the cassette from
that drive.
He must instead remove the cassette
from drive 1 and
replace it with the cassette containing F2.PAL, He then types 1 in
response to the I/O line and assembly continues until F3.PAL is
needed.
PALC again pauses and asks

MOUNT F3»PAL?

Again the user replaces the cassette on drive 1 with the appropriate
one, correctly answers the I/O line, and assembly continues.

—

Once pass 2 is done, pass 3 the listing pass must be processed.
may again be used for input, cind assembly of input files
Drive
continues in the same manner as during passes 1 and 2
The procedure of mounting and dismovinting cassettes may be repeated as
many times as necessary until all input files are processed and the
during any of the
If an I/O error occurs
desired output produced.
three passes or if an output cassette becomes full, the user must
restart the assembly beginning with pass 1.

5-4

NOTE

When the assembly is complete, PALC
tC
prints
(CTRL/C) .
The user then
mounts the system cassette and types
CTRL/C to return to the Monitor.

5.2.1 PALC Options

Table 5-1 lists the options available in PALC which may
in the Monitor Run or Load specification line.

Option

5.3

Table 5-1 PALC Options
Meaning

Generate a DDT- compatible symbol table
(applicable only if a listing file is
specified)

Generate non-paginated output.
Header,
numbers
page
and
page format are
suppressed (applicable only if a listing
file is specified)

Used in assembling very large programs;
causes system containing 12K or more of
memory to use fields 2 and up as symbol
table storage.

Generate the symbol table, but not the
listing
(applicable only if a listing
file is specified;
the /H option is
assumed)

Omit the symbol table normally generated
with the listing (applicable only if a
listing file is specified)

Output a carriage return/line feed in
place of the form feed character (s) in
the program
(applicable only
if
a
listing file is specified)

CHARACTER SET

The following characters are acceptable as input to PALC:
1.

The alphabetic characters: A through

The numeric characters:

The characters described in following sections as
special characters and operators

through

5-5

indicated

Characters which are ignored during assembly such
as LINE FEED, FORM FEED, and RUBOUT

All Other characters are illegal (except when used in a
cause the error message:

comment)

and

IC AT nnnn

to be printed during pass 1; nnnn represents the location at which the
illegal character occurred.
(As assembly proceeds, each instruction
is assigned a location determined by the current location counter (see
When an illegal character or any other error is
Section 5.7.3).
encountered during assembly, the value of the current location counter
is returned in the error message.) Illegal characters do not generally
If an illegal character occurs in the middle
cause assembly to halt.
of a symbol, the symbol is terminated at that point.

5.4 STATEMENTS

PALC source programs are usually prepared on the console terminal
Each statement
(using the CAPS-8 EDITOR) as a sequence of statements.
typing the RETURN
is written on a single line and is terminated by
key.

There are four types of elements in a PALC statement which are
identified by the order of their appearance in the statement and by
the separating (or delimiting) character which follows or precedes the
These are:
element.
label,

instruction

operand

/comment

A statement must contain at least one of these elements and may
contain all four types. The assembler interprets and processes the
statements, generating one or more binary instructions or data words,
or performing an assembly process.

5.4.1

Labels

A label is the symbolic name created by the programmer to identify the
If present, the Icdjel is
location of a statement in the program.
It must begin with cm alphabetic
written first in a statement.
character, contain only alphanumeric characters, and be terminated by
no intervening spaces between any of the
a comma; there must be
characters and the comma.

5.4.2

Instructions

An instruction may be one or more of the mnemonic machine instructions
(Assembly
or a pseudo-operation which directs assembly processing.
pseudo-ops are described later in this chapter; Appendix C summarizes
both the mnemonic machine instructions and pseudo-ops used by PALC.)
Instructions are terminated with one or more spaces (or tabs if an

5-6

operand follows) or with a semicolon, slash, or
described in Section 5.5.3.

5.4.3

carriage

return,

Operands

Operands are the octal or symbolic addresses of an ass£>mbly language
instruction or the argument of a pseudo- operator, and can be any
expression.
In each case, interpretation of an operand depends
upon
the instruction or the pseudo-op.
Operands are terminated by a
semicolon, slash, or carriage return.

5.4.4

Comments

The programmer may add notes or comments to a statement by separating
these from the remainder of the line with a slash.
Svich comments do
not affect assembly processing or program execution but are useful in
the program listing
for later analysis or debugging.
The assembler
ignores everything from the slash to the next carriage return.
(For
an example see Section 5.5.3, Statement Terminators.)
It is possible to have only a carriage return on a line, resulting
a blank line in the final listing.
No error message is given.

5.5

FORMAT EFFECTORS

The following characters are useful in controlling the format of an
assembly listing.
They allow a neat readable listing to be produced
by providing a means of spacing through the program.

5.5.1

Form Feed

The form feed code causes the assembler to output blank lines in order
to skip to a new page in the output listing during pass 3; this is
useful in creating a page-by-page listing.
The form feed is generated
by typing a CTRL/L on the console terminal.

5.5.2

Tabulations

Tabulations are used in the body of a source prograrr; to separate
fields into columns (for details refer to Chapter 3).
For example, a
line written:
GO, TAD TOTAL/MAIN LOOP

is much easier to read if tabs are inserted to form:

5-7

5.5.3

/MAIN LOOP

TAD TOTAL

GO,

Statement Terminators

The RETURN key is used to terminate a statement and causes a line
feed/carriage return combination to occur in the listing.
The
semicolon (;) may also be used as a statement terminator and is
considered identical to a carriage return except that it will not
terminate a comment. For example:
TAD

/THIS IS

COMMENT; TAD B

The entire expression between the slash (/) and the carriage return is
considered a comment. Thus in this case the assembler ignores the TAD
B.

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

HTrt

HTH
However, the programmer can alternatively place all three instructions
on a single line by separating them with the special character
semicolon (;) eind terminating the entires line with a carriage return.
The above sequence of instructions can then be written:

HTH;HTH;HrR
These multi-statement lines are particularly useful when setting aside
For example, a
a section of data storage for use during processing.
4-word cleared block could be reserved by specifying either of the
following:
LIST,

or
LIST*

Either format may be used to input data words (data words may be in
the form of numbers, symbols, or expressions, explained next.) Each of
the following lines generates one storage word in the object progrcun:

5-8

DATA> 7777
A+C-B
S

123+82

5.6

NUMBERS

Any sequence of digits delimited by either a SPACE, TAB, semicolon, or
carriage return forms a number.
PALC initally interprets numbers in
octal (base 8) . This base can be changed to decimal using a special
pseudo-operator (discussed in Section 5.10.2). Numbers are used in
conjunction with symbols to form expressions.

5.7

SYMBOLS

A symbol is a string of alphanumeric characters beginning with a
letter and delimited by a non-alphanumeric character. Although a
symbol may be any length only the first six characters are recognized;
since additional characters are ignored, symbols which are identical
in their first six characters are considered identical.

5.7.1 Permanent Symbols

The assembler contains a table (called its permanent symbol table)
which lists the symbols for all PDP-8 pseudo-op codes, memory
Transfer)
reference instructions, operate and lOT (Input/Output
These instructions are symbols which are permanently
instructions.
defined by PALC and need no further definition by the user; they are
summarized in Appendix C. For example:
HLT

5.7.2

instruction
This
is
a
symbolic
7402 by the
assigned
the
value
assembler and stored in its permanent
symbol table.

User-Defined Symbols

(and represented in its
All symbols not defined by the assembler
permanent symbol table) must be defined within the source program.

A symbol may be used as a statement label, in which case it is
assigned a value equal to the current location counter; it is called a
symbolic address and Ccin be used as an operand or as a reference to an
Permanent symbols (instructions, special characters, and
instruction.
pseudo-ops) may not be used as symbolic addresses.
The following are examples of legal symbolic addresses:

ADDH*
TOTAL*
SUM*
Al«

5-9

The following are illegal symbolic addresses:

AD>Kj
7ABC*
LA BEL#

D+TAG*
LABEL t

(contains an illegal character)
(first character must be alphabetic)
(must not contain imbedded spaces)
(contains a legal but non-alphanumeric character)
(must be terminated by a comma with no
intervening spaces)

5.7.3 Current Location Counter
As source statements are processed, PAIjC assigns consecutive memory
addresses to the instructions and data words of the object program.
The current location counter contains the address in which the next
word of object code will be assembled <ind is automatically incremented
each time a memory location is assigned. A statement which generates
a
single object program storage word increments the location counter
by one.
Another statement might generate six
storage
words,
incrementing the location counter by six.
The user sets or resets the location counter by typing an asterisk
followed by the octal absolute address value in which the next program
word is to be stored.
If the origin is not
set by the user,
PALC
begins assigning addresses at location 200.
*300
/SET LOCATION COUNTER TO 300
TAG,
CLA
J MP

B,
A,

DCA B

The symbol TAG (in the preceding example) is assigned a value of 0300,
the symbol B a value of 0302, and the symbol A a value of 0303.
If a
symbol is defined more than 'once in this manner,
the assembler will
print the illegal definition diagnostic:
ID address

where address is the value of the location counter at the second
occurrence of the symbol definition. The symbol is not redefined.
(For cin explanation of diagnostic messages refer to Section 5.14
PALC
Error Conditions.) For example:

*300
CONTIN,

TAD A
DCA COUNTER
JMS LEAVE

JMP START
-74

COUNTER,
START,

CLA CLL

START,

5-10

The symbol START would have a value of 0300, the symbol CONTIN would
have a value of 0302, the symbol A would have a value of 0304, the
symbol COUNTER (considered COUNTE by the assembler) would have a value
When the assembler processed the next line it would print
of 0305.
(during pass 1)
IR COUNTE+0001

Since the first pass of PALC is used to define all symbols, the
assembler will print a diagnostic during pass 2 if reference is made
For example:
to an undefined symbol.
*7170
A,

TAD C
CLA CMA
HLT
JMP A

The dollar sign must terminate
all PDP-8 assembly programs.

C,
$

This would produce the undefined symbol diagnostic:
US A+0003

5.7.4

Symbol Table

Initially, the assembler's symbol table contains the mnemonic op-codes
the machine instructions and the assembler pseudo-op codes as
As the
listed in Appendix C; this is its permanent symbol table.
source program is processed, user-defined symbols along with their
The symbol table is
binary values are added to the symbol table.
listed in alphabetical order at the end of pass 3.
of

During pass 1, if PALC detects that the symbol table is full (in other
words, there is no more memory space in which to store symbols and
their associated values) , the symbol table exceeded diagnostic is
printed:
SE address

The assembler then prints +C and waits for a response from the user.
If the
By typing + C the user can return control to the Monitor.
system contains more than 8K of memory, the user may choose the /K
(see Section 5.2,1) , or more address
option with the Run command
also
It is
arithmetic may be used to reduce the number of symbols.
possible to segment a program and assemble the segments separately,
(See
taking care to generate proper links between the segments.
PALC's symbol capacity is 768 symbols. The permanent
Section 5.11.)
leaving space for 699 possible
symbol table contains 69 symbols,
user-defined symbols. Each additional 4K allows 768 new symbols.

Section 5.10.12 provides instructions concerning altering PALC's
permanent symbol table should the user wish to add instructions more
suited to his programming needs.

5-11

5.7.5

Direct Assignment Statements

The programmer may insert new symbols with their assigned values
directly into the symbol table by using a direct assignment statement
of the form:

SYMBOL=VALUE
VALUK may be a number or expression. No spaces or tabs may appear
between the symbol to the left of the equal sign and the equal sign
itself.
The following are examples of direct assignment statements:
A=6

EXITrJMP

C:A+B

All symbols to the right of the equal sign must be already defined.
The symbol to the left of the equal sign is subject to the same
restrictions as a symbolic address , and its associated value is stored
The use of the equal sign does not
in
the user's symbol table.
increment the location counter; it is, rather, an instruction to the
assembler itself.

A direct assignment statement may also equate a new symbol to the
In this case, the two
value assigned to a previously defined symbol.
symbols share the same memory location.
BETAZ17
GAMMA^BETA
The new symbol, GAMMA, is entered into the user's
the value 17.

symbol

table

with

The value assigned to a symbol may be changed as follows:
ALPHAr5
ALPHA=7
The second line of code shown changes the value assigned to ALPHA from
legal but will generate an RD error message,
(This
is
7.
5
to
explained below.)

Symbols defined by use of the equal sign may
expression. For example:

used

cUiy

valid

*?.00

A:100
B:400
A+B
TAD A

/DOES NOT UPDATE CLC
/DOES NOT UPDATE CLC
/THE VALUE 500 IS ASSEMBLED AT LOG. 200
/THE VALUE 1200 IS ASSEMBLED AT LOG. 201

If the symbol to the left of the equal sign has already been
the redefinition diagnostic:

defined,

RD address

will be printed as a warning, where address is the value of the
The new value will be
location counter at the point of redefinition.

5-12

stored in the symbol table; for example:

CLA=7600

will cause the diagnostic:
RD '^0200

Whenever CLA is used after this point, it will have the value 7600,

5.7.6

Symbolic Instructions

Symbols used as instructions must be predefined by the assembler or
If
a
statement has no label, the instructions may
the programmer.
appear first in the statement and must be terminated by a space, tab,
semicolon, slash, or carriage return. The following are examples of
legal instructions:

TAD
PAGE
ZIP

5.7.7

mnemonic machine instruction)

(an assembler pseudo-op)
(an instruction defined by the user)

Symbolic Operands

Symbols used as operands normally have a value defined by the user.
The assembler allows symbolic references to instructions or data
Operands may be numbers or
defined elsewhere in the program.
expressions. For example:
TOTAL* TAD AC I

TAG

(already defined by the
The values of the two symbols ACl and TAG
add (see Section 5,8.1,
2's complement
are combined by a
user)
Operators) . This value is then used as the address of the operand.

5.7.8

Internal Symbol Representation For PALC

Each permanent and user-defined symbol occupies four words in the
symbol table storage area. A PDP-8 instruction has an operation code
and seven
a page bit,
of three bits as well as an indirect bit,
The PALC assembler distinguishes between pseudo-ops,
address bits.
permanent
symbols,
and
instructions,
other
memory reference
user-defined symbols in the symbol table.

5-13

5.8 EXPRESSIONS

Expressions are formed by the combination of symbols, numbers, and
certain characters called operators, which cause specific arithmetic
operations to be performed. An expression is terminated by either a
comma, carriage return, or semicolon.

5.8.1 Operators

There are seven characters in PALC which act as operators;
+
1-

%
!

SPACE

Two's complement addition
Two's complement subtraction
Multiplication (unsigned, 12-bit)
Division (unsigned, 12--bit)
Boolean inclusive OR
Boolean AND
Treated as a Boolean inclusive OR
except in a memory refctrence
instruction

Two's complement addition and subtraction are explained in detail in
Chapter 1 of INTRODUCTION TO PROGRAMMING? the user should refer to
that handbook if he wishes more information.
No checks
for overflow
are made during assembly, and any overflow bits are lost from the high
order end. For example:

7755+24 will give a result of

The operators + and - may be used freely as prefix operators.

Multiplication is accomplished by repeated addition.
No checks for
sign or overflow are made.
All 12 bits of each factor are considered
as magnitude.
For example:
3000+2 wall give a result of 6000

Division is accomplished by repeated subtraction.
The number of
subtractions which are performed is the quotient. The remainder is
not saved and no checks are made for sign.
Division by
will
arbitrarily yield a result of 0. For example:
7000%1000 will yield a result of

This could be written as:

-1000%1000
in this case the answer might be expected to be -1 (7777) , but all
bits are considered as magnitude and the; result is still 7.

Use of the multiplication and division operators requires ein attention
to sign on the part of the programmer beyond that which is required
for simple addition and subtraction.
The following table of examples
is given for reference.

5-14

Table 5-2 Use of Operators

Expression

Also written as:

Result

-1+2
-2-3

7777+2
7776-3

+1
7773 or -5

1000+7
0%12
12%0
7777%1
7000%1000

7000 or -1000

-1%1
-1000%1000

7777 or -1
7

1%2

The
operator causes a Boolean inclusive OR to be performed bit by
bit between the left-hand term and the right-hand term.
(The
inclusive OR is explained in Cliapter
1
of
INTRODUCTION
TO
PROGRAMMING.) For example:
!

if A=l and B=2
then A!B=0003

The & operator causes a Boolean AND to be performed bit by bit between
the left and right values.
The operation is the same as that
indicated by the memory reference instruction AND.
SPACE has special significance depending on the context in which it is
used.
When it is used to separate two permanent symbols or two
user-defined symbols, as in the following example:
SMA CLA

it causes an inclusive OR to be performed between them.
In this case,
SMA=7500 and CLA=7600. The expression SMA CLA is assembled as 7700.
When SPACE is used following pseudo-operators and memory reference
instructions, it merely delimits the symbol.

User-defined
example:

symbols

are

treated

operate

instructions.

For

A»333

222
B»

CIA

Possible expressions and their values using the symbols just defined
are shown below.
Notice that the assemhiler reduces each expression to
one 4-digit (octal) word:

A
B

A+B
A-B
-A
1-B
B-1
Al B
-71

0333
0222
0555
0111
7445
7557
0221
0333
7707

(an inclusive OR is performed)

5-15

If the information generated is to be
counter is incremented. For example:

loaded,

the

current

location

b-7;a+4;a-b
produces three words of information; the current location
incremented after each expression. The statement:

counter

HALT=HLT CLA
produces no information to be loaded (it produces an association in
and hence does not increment the current location
the symbol table)
counter.
*4721
TEMP,
TEM2,

The location counter is not incremented after the line TEMP,; the two
symbols TEMP and TEM2 are assigned the same value, in this case 4721.

Since a PDP-8 instruction has an operation code of three bits as well
as
an indirect bit, a page bit, and seven address bits, the assembler
must combine memory reference instructions in a manner somewhat
differently from the way in which it combines operate or lOT
instructions. The assembler differentiates between the symbols in its
permanent symbol table and user-defined symbols.
The following
symbols are used as memory reference instructions:

AND
TAD

0000
1000
2000
3000
4000
5000

ISZ

DCA
JMS
JMP

Logical AND
Two's complement addition
Increment and skip if zero
Deposit and clear accumulator
Jump to subroutine
Jump

When the assembler has processed one of these
following it acts as an address field delimiter.

symbols,

the

space

*4100
JMP A
A,

CLA

A has the value 4101, JMP has the value 5000, and the space acts as
field delimiter. These symbols are represented as follows:

A
JMP

100 001 000 001
101 000 000 000

The seven address bits of A are taken, e.g.:
000 001 000 001

The remaining bits of the address are tested to see if they are zeros
(page zero reference) ; if they are not, the current page bit is set:

5-16

000 oil 000 001

The operation code is then ORed into the JMP expression to form;
101 Oil 000 001
or, written more concisely in octal:

5301
In addition to the above tests, the page bits of the address field are
compared with the page bits of the current location counter.
If the
page bits of the address field are nonzero and do not equal the page
bits of the current location counter, an out-of-page reference is
being attempted and the assembler will take action as described in
Section 5.11, Link Generation and Storage.

5.8.2 Special Characters
In addition to the operators described in the previous
section, PALC
recognizes several special characters which serve specific functions
in the assembly process.
These characters are:

equal sign
comma
*
asterisk
dot
.
"
double quote
parentheses
(
square brackets
[]
/ slash
semicolon
;
<>
angle brackets
dollar sign
$
,

)

The equal sign,
comma,
asterisk,
slash,
and semicolon have
previously described. The remainder will be described next.

been

The special character dot (.) always has a value equal to the value of
the current location counter.
It may be used as any integer or symbol
(except to the left of an equal sign) , and must be preceded by a space
when used as an operand. For example:

iMP

.+2

is equivalent to JMP 0202.

Also,

*300
•

*-2400

will produce in location 0300 the quantity 2700.

2200
CALL»JMS
0027

•

5-17

Consider:

The second line (CALL=JMS I.) does not increment the current location
counter,' therefore, 0027 is placed in location 2200 and CALL is placed
in the user's symbol table with an associated value of 4600 (the octal
equivalent of JMS I)
If a single character is preceded by a double quote
("),
the 8-bit
value of ASCII code for the character is used rather than interpreting
the character as a symbol (ASCII codes are listed in Appendix A) .
For
example

CLA
TAD

("A

The constant 0301 is placed in the accumulator.
The code

will be assembled as 0256. The character must not be a carriage
return or one of the characters which is ignored on input (discussed
at the end of this section)
Left and right parentheses
member is optional)

()

enclose a current page literal (closing

*200

CLA
TAD INDEX
TAD (2)
OCA I NDEX

The left parenthesis is a signal to the assembler that the expression
following is to be evaluated and assigned a word in the constants
table of the current page. This is the same table in which the
indirect address linkages are stored.
In
the above example, the
quantity 2 is stored in a word in the linkage and literals list
beginning at the top of the current memory page. The instruction in
which the literal appears is encoded with an address referring to the
address of the literal, A literal is assigned to storage the first
time it is encountered; subsequent reference to that literal from the
current page is made to the same register. The use of literals frees
symbol storage space for variables and makes programs much more
readable.
If the programmer wishes to assign literals to page zero
the current page, he may use square brackets,
[and]

parentheses. This enables the
literal from any page of memory.

programmer to
For example:

*200
TAD [2]

*500
TAD [2]

5-18

rather than
in place of
reference a single
,

The closing member is optional.
forms:
constant term, variable
another literal.

Literals may take
term,
instruction,

the
following
expression, or

NOTE
Literals can be nested, for example:
*200
TAD (TAD (30

This type of nesting may be continued in
some cases to as many as 6 levels,
depending on the
number
of
other
literals on the page and the complexity
of the expressions within the nest.
If
the limits of the assembler are reached,
the error messages BE (too many levels
of nesting)
or PE (too many literals)
will result.

Angle brackets are used as conditional delimiters. The code enclosed
angle brackets is to be assembled or ignored contingent upon
in the
the definition of the symbol or value of the expression within the
IFDEF,
IFIMDEF,
angle
brackets.
(The
IFZERO,
and
IFNZRO
pseudo-operators are used with angle brackets and are described in
Section 5.10.9.)
The dollar sign character ($) is mandatory at the end of a program and
It may however occur
is
interpreted as an unconditional end-of-pass .
interpreted
in a text string, comment or " term, in which case it is
in the same manner as any other character.
The following characters are handled by the assembler for the
listing, but are otherwise ignored:

FORM FEED
LINE FEED
RUBOUT

pass

Used to skip to a nev/ page
Used to create a line spacing without causing a
carriage return
Used by the EDITOR to allow corrections in the
input file.

Nonprinting characters include:
SPACE
TAB
RETURN

These characters are used for format control and have been
explained in Section 5.5.

5-19

previously

INSTRUCTIONS

5.9

There are two basic groups of instructions: memory reference and
microinstructions.
Memory reference instructions require an operand,
microinstructions do not.

5.9.1

Memory Reference Instructions

In PDP-8 computers, some instructions require a reference
to memory.
They are appropriately designated memory reference instructions , and
take the following format:

OPERATION

CODE
1

ADDRESS

7
1

INDIRECT ADDRBSING )

MEMORY PAGE

Memory Reference Bit Instructions
Bits
through 2 contain the operation code of the instruction to be
performed.
Bit 3 tells the computer if the instruction is indirect
(see Section 5.9.2). Bit 4 tells the computer if the instruction is
referencing the current page or page zesro. This leaves bits 5 through
In these 7 bits,
200
octal
11 (7 bits) to specify an address.
(128
decimal) locations can be specified; the page bit increases accessible
For a list of the memory
locations to 400 octal or 255 decimal.
reference instructions and their codes, see Appendix C.
In PALC a memory reference instruction must be followed by
tab(s),
an optional I or Z designation, and any valid
It may be defined with the FIXMRI instruction as explained
5.10.12, Altering the Permanent Symbol Tc±>le. Permanent

be defined using the FIXTAB instruction and may
fields as shown below:

used

a
space (s)
expression.
in Section
symbols may
in
address

FIXTAB
TAD

5.9.2

Indirect Addressing

When the character I appears in a statement between a memory reference
instruction and an operand, the operand is interpreted as the address
the
(or location) containing the address of the operand to be used in
Consider:
current statement.

5-20

TAD 40

which is a direct address statement, where 40 is interpreted as the
location on page zero containing the quantity to be added to the
accumulator.
References to locations on the current page and page
zero may be done directly. An alternate way to note the page zero
reference is with the letter Z, as follows:
TAD

This is an optional notation, not differing in effect from the
previous example.
Thus, if location 40 contains 0432, then 0432 is
added to the accumulator. Now consider:
TAD

which is an indirect address statement, where 40 is interpreted as the
address of the location containing the quantity to be added to the
accumulator. Thus, if location 40 contains 0432, and location 432
contains 0456, then 456 is added to the accumulator.
NOTE

Because the letter I is used to indicate
indirect addressing, it is never used as
Likewise the letter Z,
a variable.
which is sometimes used to indicate a
page zero reference, is never used as a
variable.

5.9.3

Microinstructions

Microinstructions are divided
into
two
groups :
operate
and
Input/Output
Transfer
(lOT)
microinstructions.
Operate
microinstructions are further subdivided into Group 1, Group 2, and
Group 3 designations.
NOTE
If a programmer mistakenly specifies

combination
illegal
of
microinstructions, the assembler will perform
for
an
inclusive
OR between them;
example
CLL SKP is interpreted as SPA
(7100)

(7510)

(7410)

Operate Microinstructions
Within the operate group, there are three groups of microinstructions
Group 1 microinstructions perform clear,
which cannot be mixed.
complement, rotate and increment operations, and are designated by the
presence of a
in bit 3 of the machine instruction word.

5-21

CLA

CLL

CMA CML

BSW

lAC

ROTATE AC AND
ROTATE AC AND
D/^TATC

(BSW

RIGHT

LEFT

D/-^CITI/-^

t
O D /~\ciTir\MC

BITS 8,9 ARE 0)

1-CLA
3-IAC

LOGICAL SEQUENCE:

Group

2 -CMA, CML

CLL

4-RAR,RAL,RTR,RTL,BSW

Operate Microinstruction Bit Assignments

Group 2 microinstructions check the contents of the accumulator and
continue to or skip the next
and,
based on the check,
link
Group 2 microinstructions are identified by the presence
instruction.
in bit 11 of the machine instruction word.
of a 1 in bit 3 emd a

1
1

CLA SMA SZA SNL

OSR

HLT

REVERSE SKIP SENSING OF BITS 5,6,7 IF SET

LOGICAL SEQUENCE:

(BIT

0)-SMA OR SZA OR SNL
- SPA AND SNA AND SZL
I

)

2 -CLA

3- OSR, HLT

Group

Bit Assignments

Operate Microinstruction

register.
They
the
MQ
are
Group 3 instructions reference
differentiated from Group 2 instructions by the presence of a 1 in
bits 3 and 11. The other bits are part of a hardware arithmetic
option.
2

OPERATION

CODE
1

CLA MQA

CONTAINSAITO

WQL

SPECIFY GROUP 3

KE8-E EXTENDED

ARITHMETIC

CONTAINS A

SPECIFY GROUP 3

ELEMENT

Group

Operate Microinstruction Bit Assignments

Group 1 and Group 2 microinstructions cannot be combined since
determines either one or the other.

5-22

bit

;

within Group 2, there are two groups of skip instructions.
be referred to as the OR group and the AND group.

OR Group

AND Group

SMA
SZA
SNL

SPA
SNA
SZL

They

can

in bit 8, amd the AND group by a 1
The OR group is designated by a
OR and AND group instructions cannot be combined since bit
in bit 8.
8 determines either one or the other.

the programmer does combine legal skip instructions,
If
important to note the conditions under which a skip may occur.
1.

—

OR Group If these skips are combined in a statement,
the inclusive OR of the conditions determines the skip.
For example:
SZA SNL

The next statement is skipped if the
contains 0000 or the link is a 1 or both.
2.

accumulator

—

AND Group If the skips are combined in a statement, the
logical AND of the conditions determines the skip.
For
example
SNA SZL

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

the

accumulator

Input/Output Transfer Microinstructions
These microinstructions
effect an information
Input/Output device (s);
The Permanent
printer.

initiate operation of peripheral equipment and
transfer between the central processor and the
and line
i.e., cassettes, console terminal,
Symbol Table in Appendix C lists PALC's lOT's.

5.9.4 Autoindexing

Interpage references are often necessary for obtaining operands when
processing large amounts of data. The PDP-8 computers have facilities
When one of the absolute
to ease the addressing of this data.
locations from 10 to 17 (octal) is indirectly addressed, the contents
of the location is incremented before it is used as an address and the
This allows the
number is left in the location.
incremented
programmer to address consecutive memory locations using a minimum of
statements.

5-23

It must be remeinbered that initially tliese locations (10 to 17 on page
0) must be set to one less than the first desired address.
Because of
their characteristics, these locations are called autoindex registers.
No incrementation takes place when locations 10 to 17 are addressed
directly. For example, if the instruction to be executed next is in
location 300 and the data to be referenced is on the page starting at
location 5000, autoindex register 10 can be used to address the data
3,3

f OlXOWS *

0276*
0277
0300

1577

TAD C4777

3010

DCA 10
TAD I 10

1410

/=5000-l
/SET UP AUTO INDEX
/INCREMENT TO 5000
/BEFORE USE AS AN ADDRESS

0377
4777
C4777,4777
When the instruction in location 300 is executed, the contents of
location 10 will be incremented to 5000 and the contents of location
5000 will be added to the contents of the accumulator.
When the
instruction TAD I 10 is executed again, the contents of location 5001
will be added to the accumulator, and so on.

5 . 10

PSEUDO-OPERATORS

The programmer uses pseudo-operators to direct the assembler to
perform certain tasks or to interpret subsequent coding in a certain
manner.
Some pseudo-ops generate storage words in the object program,
other pseudo-ops direct the assembler how to proceed with the
assembly.
Pseudo-ops are maintained in the permanent symbol table.
The function of each PALC pseudo-op is described below.

5.10.1

Indirect and Page Zero Addressing

The pseudo-operators I and
addressing to be performed.
Section 5.9.2.

5.10.2

are used to specify the type of
These have been previously discussed in

Radix Control

Numbers used in a source program are initially considered to be octal
However, the programmer may change or alternate the radix
numbers.
interpretation by the use of the pseudo- operators DECIMAL cuid OCTAL.
The DECIMAL pseudo-op interprets all following
until the occurrence of the pseudo-op OCTAL.

numbers

decimal

The OCTAL pseudo-op resets the radix to its original octal base.

5-24

5.10,3

Extended Memory

The pseudo-op FIELD instructs the assembler to output a field setting
so that it may recognize more than one memory field.
This field
setting is output during pass 2 and is recognized by the Run (or Load)
command, which in turn causes all subsequent information to be loaded
into the field specified by the expression. The form is:

FIELD n
n is an integer, a previously defined symbol, or an expression

within

the range 0<=n<=7.

This field setting is output on the binary file during pass 2 followed
by an origin setting of 200. This word is read when the Run (or Load)
command is executed and begins loading information into the new field.
The field setting is never remembered by the assembler and no initial
field setting is output.
A binary file produced without field
settings will be loaded into field
(or
when using the Run
Load)
command.

NOTE

A symbol in one field meiy be used to
reference the same location in any other
field.
The field to which it refers is
determined by the use of the CDF and GIF
instructions.
(The programmer who is
unfamiliar with thelOT'sbut wishes to
use them should refer to the PDP/8E
SMALL COMPUTER HANDBOOK and experiment
with several short test programs to
satisfy himself as to their effect.)
CDF and CIF instructions must be used
prior to any instruction referencing a
location outside the current field,
as
shown in the following example:

*200
TAD P301
CDF 00
CIF 10
JMS PRINT
CIF 10
JMP NEXT
P301 ,

NEXT,

P302,
PRINT,

301

FIELD 1
*200
TAD P302
CDF 10
JMS PRINT
HLT
302
TLS
TSF

5-25

.-1

J'^p

CLA

RDF
TAD PS203
DCA .+1
000
.JMP

PS203,

6233

When FIELD is used, the assembler follows the new FIELD setting with
For this reason, if the programmer wants
an origin at location 200.
to assemble code at location 400 in field 1 he must write:
FIELD
*400

/CORRECT EXAMPLE

The following is incorrect and will not generate the desired code:
*42i0

/INCTORfiECT

FIELD

5.10.4

End-of-File

PAUSE signals the assembler to stop processing the file being read.
The current pass is not terminated, and processing continues with the
next file.
The PAUSE pseudo-op should be used only at the physical end of a file
and with two or more segments of one program. When a PAUSE statement
remainder of the file is ignored and processing
is reached the
continues with the next input file. PAUSE must be present or a PH
error will occur.

5.10.5 Resetting the Locatioh Counter
The PAGE n pseudo-op resets the location counter to the first address
of page n, where n is ein integer, a previously defined symbol, or a
symbolic expression, all whose terms have been defined previously and
to 37 inclusive. If n is not specified, the
whose value is from
For
location counter is reset to the next logical page of memory.
example:

PAGE
PAGE

sets the location counter to 00400
sets the location counter to 01400

an argument and the current
If the PAGE pseudo-op is used without
location counter is at the first location of a page, it will not be
In the following example, the code TAD B is assembled into
moved.
location 00400:
*377
J MP

.-3

PAGE
TAD B

5-26

If several consecutive PAGE pseudo-ops are given, the first will cause
the current location counter to be reset as specified.
The rest of

the PAGE pseudo-ops will be ignored.

5.10.6 Entering Text Strings

The TEXT pseudo-op allows a string of text characters to be entered as
data and stored in 6-bit ASCII by using the pseudo-op TEXT followed by
a space
or spaces,
a delimiting character
(must be a printing
character) , the string of text, and the Scime delimiting character.
Following the last character, a 6-bit zero is inserted as a stop code.
For example:
TAG,

TEXT/123*/

The string would be stored as:
SI 62
63 52

0000

5.10.7 Suppressing the Listing

Those portions of the source program enclosed by XLIST pseudo-ops will
not appear in the listing file; the code will be assembled, however.
Two XLIST pseudo-ops may be used to enclose the code to be suppressed
first XLIST with no argument will suppress the
in which case the
listing, cind the second will allow it again.
XLIST may also be used
with an expression as an argument; a listing will be inhibited if the
expression is equal to zero, or allowed if the expression is not equal
to zero.

5.10.8

Reserving Memory

ZBLOCK instructs the assembler to reserve; n words of memory containing
zeros, starting at the word indicated by the current location counter.
It is of the form:
ZBLOCK n
For example:
ZBLOCK 40

causes the assembler to reserve 40 (octal) words.
If n=0 , no locations are reserved.
expression.

5-27

The

may

S.10.9

Conditional

A:-iseinb"ly

The IFDEF pseudo-op takes

tlie

Pseudo- Operators

form:

iFDEF symbol

"^soui'ce;

coda>

If the symbol indicated is previously defined, the code
contained in
the angle brackets is assembled; if the symbol is undefined, this code
is ignored.
Any number of statements or lines of code may be
contained in the angle brackets.
The format of the IFDEF statement
requires a single space before and after the symbol.

The IFNDEF pseudo-op is similar in form to IFDEF and is expressed;

IFNDEF symbol

< source

code>

If the symbol indicated has not been previously defined,
the source
code in angle brackets is assembled.
If the symbol is defined, the
code in the angle brackets is ignored.

The IFZERO pseudo-op is of the form:

IFZERO expresson <source ccde>
If the evaluated (arithmetic or logical) expression is equal to zero,
the code within the angle brackets is assembled; if the expression is
non-zero, the code is ignored. Any numlDer of statements or lines of
code may be contained in the angle brackets.
The expression may not
contain any imbedded spaces and must have a single space preceding and

following it.
IFNZRO is similar in form to the IFZERO pseudo-op and is expressed:
IFNZRO expression < source code>
If the evaluated (arithmetic or logical) expression is
not equal to
the source code within the angle brackets is assembled; if the
zero,
expression is equal to zero, this code is ignored.

Pseudo-ops can be nested, for example:
IFDEF SYM <IFNZRO X2 <«..>>
The evaluation and subsequent i.nclusion or deletion of
done by evaluating the outermost pseudo-op first.

5.10.10

statements

Controlling Binary Output

NOPUNCH causes the assembler to cease binary output
assembling code.
It is ignored except during pass 2.

but

continue

ENPUNCH causes the assembler to resume binary output after- NOPUNCH,
For example, these two
and is ignored except during pass 2.
pseudo-ops might be used where several programs share the same data on
When these programs are to be loaded and executed
page zero.
together, only one page zero need be output.

5-23

5.10.11

Controlling Page Format

The EJECT pseudo-op causes the listing to jump to the top of the next
page.
A page eject is done automatically every 55 lines; EJECT is
useful if the user requires more frequent paging.
If this
pseudo-op
is followed by a string of characters, the first 40 (octal) characters
of that string will be used as a new heaider line.

5.10.12

Altering the Permanent Symbol Table

PALC contains a table of symbol definitions for the PDP-8 and CAPS-8
peripheral devices.
These are symbols such as TAD, DCA, and CLA,
which are used in most PDP-8 programs. This table is considered to be
the permanent symbol table for PAI.C; all of the symbols it contains
are listed in Appendix C.
If the user purchases one or more optional devices whose
instruction
is not defined among the permanent symbols (for example EAE or an
A/D converter) , he would want to add the necessary symbol definitions
to
the permanent symbol table
in every program he assembles.
Conversely, the user who needs more space for user-defined symbols
would probably want to delete a] 1 definitions except the ones used in

set

his program.
For such purposes , PALC has three pseudo-ops that can be
used to alter the permanent symbol table.
These pseudo-ops are
recognized by the assembler only during pass 1. During either pass 2
or pass 3 they are ignored and have no effect,

EXPUNGE deletes the entire permanent symbol table, except pseudo-ops.
FIXTAB appends all presently defined symbols to the permanent symbol
All symbols defined before the occurrence of FIXTAB are made
table.
part of the permanent symbol tcible until the assembler is reloaded.
To append the following instructions to the symbol
generates an ASCII file called SYMS.PHL containing;

mY-lAP.5
DVI=7407
CLSK:6131
FIXTAB

table,

the

user

/MULTIPLY
/DIVIDE
/SKIP ON CLOCK IMTERRUPT
/SO THAT THESE WON'T BE
/PRINTED IN THE SYMBOL TABLE

The ASCII file is then entered in PALC's input designation.
The user
may also place the definitions at the beginning of the source file.
This eliminates the need to load an extra file-

Each time the assembler is loaded, PALC's permanent symbol table is
restored to contain only the permanent symbols shown in Appendix C.
The third pseudo-op used to alter the permanent symbol table in PALC
FIXMRI.
is
FIXMRT is used to define a memory reference instruction
and is of the form;

FIXMRI name:-value

5-29

The letters FIXMRI must be followed by one space, the symbol for the
instruction to be defined, an equal sign, and the value: of the symbol.
The symbol will be defined and stored in the symbol table as a memory
reference instruction. The pseudo-op must be repeated for each memory
reference instruction to be defined.
For example:

EXPUNGE
FIXMRI
TAD:100f!
FIXMRI
DCA=5000
CLAr7200
FIXTAB

When the preceding program segment is read into the assembler during
pass 1,
all symbol definitions
are deleted and the three symbols
listed are added to the permanent symbol table. Notice that CLA is
not a memory reference instruction.
This process can be performed to
alter the assembler's symbol table so that it contains only those
symbols used at a given installation or by a given prcgram. This may
increase the assembler's capacity for user-defined symbols in the
program.

A sximraary of the PALC pseudo-ops is provided in Appendix C.

5.11

LINK GENERATION AND STORAGE

In addition to handling symbolic addressing on
the current page of
memory,
PALC automatically generates links for off-page references.
If reference
is
made to an address not on the page where an
instruction is located, the assembler sets the indirect bit (bit 3)
and an indirect address linkage will be generated on the current
memory page.
If
the off-page reference is already an indirect one,
the error diagnostic II (illegal indirect)
will be generated.
For
example:
*?. 1

CLA

*2S00
JMP

In the example above, the assembler will recognize that
the register
labelled A is not on the current page (in this case 2600 to 2777) and
will generate a link to it as follows;

word

In location 2600 the assembler will place the
which is equivalent to JMP I 2777.

In address 2777
(the
last available location on the
current page) the assembler will place the word 2117 (the
actual address of A)

5777

During pass 3, the octal code for the instruction will be followed
an apostrophe (') to indicate that a link was generated.

Although the assembler will recognize and generate an indirect address
linkage when necessary, the programmer may indicate eui explicit

5-30

indirect address by the pseudo-op I. The assembler cannot generate a
link for an instruction that is already specified as being as indirect
reference.
In this case, the assembler will print the error message
For example:
II (illegal indirect) .
*21 17

CLA

*2600
JMP I A
The above coding will not work because A is not defined on the
where JMP I A is attempted, and the indirect bit is already set.

page

Literals and links are stored on each page starting at page address
(relative)
(relative)
and extending toward page address
177
Whenever the origin is then set to another page, the literal buffer
This does not affect later execution.
for the current page is output.
There is room for 160 (octal) literals and links on page zero and 100
(octal) literals on each other page of memory.
Literals and links are stored only as far down as the highest
Further attempts to define literals will
instruction on the page.
error
(page zero exceeded)
or ZE
result in a PE (page exceeded)
message.

5.12

CODING PRACTICES

A neat printout (or program listing, as it is usually called) makes
subsequent editing, debugging, and interpretation much easier than if
The coding practices
the coding were laid out in a haphazard fashion.
cind
will result in a readable,
listed below are in general use,
orderly listing.
1.

A title comment begins with a slash at the left margin.

Pseudo-ops may begin at the left margin; often, however,
they are indented one tab stop to line up with the
executable instructions.

They
Address labels begin at the left margin.
separated from succeeding fields by a tabulation.

Instructions, whether or not they are
label field, are indented one tab stop.

A comment is separated from the preceding field

preceded

are

by one
(as required) and a slash; if the comment
or two tabs
occupies the whole line it usually begins with a slash at
the left margin.

5-31

PROGRAM PREPARATION AND ASSEMBLER OUTPUT

5.13

The following program was generated using the
CAPS-8 EDITOR and was assembled with PALC.

TAB

function

the

*200
/EXAMPLE OF INPUT TO THE FORMAT
/GENERATOR PROGRAM
BEGIN,
/START OF PROGRAM
KCC
KSF
/WAIT FOR FLAG
JMP .-1
/FLAG NOT SET YET
KRB
/READ IN CHARACTER
DCA CHAR
TAD CHAR
TAD MSPACE
/IS IT A SPACE?
SNA CLA
HLT
/YES
JMP BEGIN+2
/NO: INPUT AGAIN
CHAR,
/TEMPORARY STORAGE
-2 40
MSPACE,
/END OF EXAMPLE
S

The program consists of statements and pseudo-ops and is terminated by
the dollar sign ($) .
If the program is large, it can be segmented by
placing it into several files; this often facilitates t:he editing of
the source program since each section will be physically smaller.

The assembler initially sets the current location cov.nter to
This counter is reset whenever the asterisk (*) is processed.

0200.

The assembler reads the source file for pass 1 and defines all symbols
used.

During pass 2, the assembler reads the source file and generates the
binary code using the symbol table equivalences defined during pass 1.
The binary file that is output may be loaded by the Load command.
This binary file consists of an origin setting and data: words.
During pass 3, the assembler reads the source file and generates the
code from the source statements.
The assembly listing is output in
ASCII code.
It consists of the current locatior, counter,
the
generated code in octal, and the source statement. The 5-digit first
column is the field number and 4-digit octal address (current location
counter) ; the 4-digit second column is the assembled object code.
The
symbol table is printed at the end of the pass. The peiss 3 output is:
*200

PALC-Vl

03/06^73

0200

*200
/EXAMPLE OF INPUT TO THE FORMAT

0000
6032
6031
5202
6036
3213
1213
1214
7650

BEGIN,

PAGE

/GENtRATQP PROGRAM
00200
00201
00?02
00203
00204
00205
00206
00207
00210

/START OF PROGRAM
KCC
KSF
JMP
KRB
OCA
TAD
TAD
SNA

.-1

CHAR
CHAR
MSPACE
CLA

5-32

/WAIT FOR FLAG
/FLAG NOT SliT YET
/READ IN CHARACTER
/IS IT

SPACE?

00311
00212
00213
TttiZlH

7«02
5202
0000
7540

HLT
JMP BEGIN + 2

/YES

/NOHNPUT AGAIN

CHAR,
MSPACE, -240
/END OF EXAMPUE

/TEMPORARY STORAGE

PALC-Vl

•200

03/08/73

PAGE 1-1

BEGIN 0200
CHAR
0213
MSPACE 0214

5.13.1 Terminating Asseinbly

PALC will a) terminate assembly, b) print a +C, and c) wait for the
user to mount the System Cassette on drive
and type iC, under any of
the following conditions:

—

Normal exit The $ at the end of the source program was
executed on pass 2
(or pass 3 if a listing is being
generated)

Fatal error One of the following error conditions
found and flagged (see the next section)

—

BE
3.

5.14

"fC

was

— If typed by the user, control turns to the Monitor.

PALC ERROR CONDITIONS

PALC will detect euid flag error conditions and generate error messages
on the console terminal.
The format of the error message is:
CODE ADDRESS

where CODE is a 2-letter code which specifies the type of error, and
ADDRESS is either the absolute octal address where the error occurred
or the address of the error relative to the last symbolic tag
(if
there was one) on the current page.
For example, the following code:

BEG,

TAD LBL
ZTAD LBL

5-33

would produce the error message:
IC BEG+0001

since

is an illegal character.

If at ciny time PALC prints tc, the user should make certain
that the
System Cassette is mounted on drive
and then type + C to return to
the Monitor.
He should examine each error indication to determine
whether correction is required.

On the pass 3 listing, error messages are output as 2-character
messages on the line just prior to the line in which the error
occurred.
The following table lists the PALC error codes.
Those
labeled Fatal Error are followed immediately by an effective +C.

Table 5-3 PALC Error Codes

Error Code

Explanation

Two PAL-C internal tables have overlapped,
error assembly cannot continue.

Device error. An error was detected when trying
to read or write a device.
Fatal error assembly
cannot continue.

Device
full,
continue

Illegal character. The character is
the assembly continued.

Illegal redefinition of a symbol. An attempt was
made to give a previously defined symbol a new
value by means other than the equal sign.
The
symbol is not redefined.

Illegal equals an equal sign was used in the
wrong context.
Considered a warning and may not
indicate an error but rather an undefined symbol
at that point.

Illegal indirect

Fatal

—

Fatal

error

— assembly

cannot

ignored

and

—

— an off-page reference was made.
Illegal pseudo-op — a pseudo-op was used m the
wrong context or with incorrect syntax.

—

Illegal page zero reference the pseudo-op Z was
found in an instruction which did not refer to
page zero.
The Z is ignored.

Current non-zero
made to:

page

5-34

exceeded

— an

attempt

was

Table 5-3

PALC Error Codes (Cont'd)

Error Code

Explanation

Override a literal with an instruction

Override an instruction with a literal

Use more literals than the assembler allows on
that page.

This can be corrected by decreasing either the
number of literals on the page or the number of
instructions on the page.
PH

—

Phase error either no $ appeared at the end of
the program, or < and > in conditional pseudo-ops
did not match.
Fatal error assembly
cannot
continue.

—

Redefinition a permanent symbol has been defined
with =. The new and old definitions do not match.
The redefinition is allowed.

Symbol table exceeded too many symbols have been
defined for the amount of memory available. Fatal
error assembly cannot continue.

—

Undefined origin an undefined symbol has occurred
in an origin statement.

Undefined symbol a symbol has been processed
during pass 2 that was not defined before the end
of pass 1.

Page
exceeded
to page 0.

—

— same as PE except with

5-35

reference

CHAPTER
CASSETTE Bi\SIC
(5

6. 1

INTRODUCTION

Cassette BASIC is an interactive programming language derived from
Dartmouth BASIC and designed to run vinder the Cassette Keyboard
Monitor.
The BASIC language is aimed at facilitating communication
between the user and the computer. The user types his program as a
series of numbered statements, making use of common English words and
familiar mathematical notations. Because the BASIC language involves
learning only a small number of commands, it is a very easy language
to use.
As the user gains familiarity with BASIC, he can add the
advanced techniques available to perfoinn more intricate manipulations
or express a problem more efficiently and concisely.
Cassette BASIC provides approximately 1.7 to 2K of memory for program
storage.
1Important
features
include
and
2-dimensional
subscripting, user-coded functions, program chaining, use of cassettes
for program storage,
and use of line printer, if available, for
output

Beginning programmers may find a more fundamental approach to
language prograimming in Chapter 1 of THE EDUSYSTEM HANDBOOK,

6.2

BASIC

CALLING BASIC (.R BASIC)

Using the Cassette Keyboard Monitor, BASIC is called from
Cassette by typing:

System

the

^R BASIC

When it is first loaded into memory, BASIC asks the user
use run-time file input and output as follows:
USING RUN-TIME FILE

will

/0?(Y OR N)

The user responds with Y or N followed by a carriage return.
Choosing
the run-time I/O feature leaves the user approximately 1.7K of memory
for program storage, whereas a response of N frees the space used by
the run-time I/O routines and provides an additional . 3K of memory
(enough for approximately 20-25 statements
or
75
variables)
Statements associated with the run-time I/O feature are:

OPEN... FOR INPUT
OPEN. ..FOR OUTPUT
CLOSE
IF END#
PRINT*
INPUT*
COMMAS
NO COMMAS

6L-.1

If any of these statements are used witJiout the
rvm-time I/O option
having been chosen during BASIC'S initial dialogue, BASIC will print a
NO FILES ERROR message at run-time.

BASIC then asks:
NEW OR OLD-

The user responds NEW if he intends to create a program at the
keyboard, and must respond with the name of the new program when BASIC
requests:
NEW PROGRAM NAME-

The program name is typed as a standard system filename (6 characters
or less) and an optional extension (1 to 3 characters) ; a program name
is entered even if the user does not intend to save
the program for
future use.
(A
response of only a carriage return causes BASIC to
repeat the NEW PROGRAM NAME request.
If the user types an ALT MODE in
response to this request, the name NONAME.BAS is assigned by BASIC.)
When the new program name has been entered, BASIC indicates that it is
ready
to accept input by issuing a carriage return/line
feed
combination.
If the user responds OLD to BASIC'S initial
dialogue, BASIC assumes
that the program has been previously saved on a cassette and will ask:

OLD PROGRAM iVAMEUNIT#(0-7):
The user must respond with the correct program name and file extension
(if
any) , and then must specify which cassette unit drive the file is
stored on.
(An incorrect response will return an error message.) When
this interaction is complete, BASIC will type:
READY.
and the user may edit or run his program.

6.3

NUMBERS

Cassette BASIC treats all numbers (in both integer and real formats)
real, or floating point, numbers.
as
That is, BASIC e.ccepts as input
any number containing a decimal point and assumes a decimal ppint
after any integer number entered.
In addition to integer and real formats, a third format is
recognized
and accepted by BASIC in order to express numbers outside the range
.01<=x<1000000. This format is called exponential or E-type notation.
format, a number is expressed as a decimal nuimber times some
In
this
power of 10, as follows:

6-2

where E represents "times 10 to the power of".
A number in
exponential notation is then read "xx times 10 to the power of n"; for
example:
23.4E2 = 23.4*(10 to the power of

= 2340

Data may be input in any one or all three of these forms.
Internal
computations are carried out in floating point (real) format.
Results
of computations within the range .01<=x<1000000 are output as either
real or integer decimal numbers (whichever is the correct but more
concise format)
results outside this range are output in exponential
format.
BASIC handles seven significant digits in normal operation
and input/output, as illustrated below:
;

Same Value
Output By BASIC

Value Typed In
.01
.0099

.01

9.900000E-3
999999
l.OOOOOOE+6

999999
1000000

BASIC automatically suppresses the printing of leading and trailing
zeros in integer and decimal numbers and, as shown above, prints all
exponential numbers in the form;
(sign)

x.xxxxxx E (+ or -) n

where x represents the number carried to six decimal places, E stands
10
for "times
to the power of", and n represents the exponent.
For
example
-3.470218E+8.is equal to -347021800
7.260000E-4 is equal to .000726

6.4

VARIABLES

which

A variable in BASIC is a symbol
formed by
example

single

letter

Acceptable Variables
I

represents a number and is
letter followed by a digit. For

Unacceptable Variables
2C - A digit cannot begin
a variable
AB - Two or more letters

cannot form a variable
X

6-3

The user may assign values to variables either by computing the values
in a LET statement or by inputting the values
as data; these
operations are discussed later.

6.5

ARITHMETIC OPERATIONS

BASIC performs addition, subtraction, multiplication, division and
exponentiation,
as well
as more complicated operations explained in
detail later in the chapter. The five operators used in writing most
formulas are

Symbol
+
*

/
f

Meaning

Example

Addition
Subtraction
Multiplication
Division
Exponentiation
(Raise A to the
Bth power)

A + B
A - B
A * B
A / B
A + B

Priority of Operations

6.5.1

In
any given mathematical formula,
BASIC
performs
operations in the following order of evaluation:

arithmetic

Parentheses receive top priority. Any expreession within
parentheses
is
evaluated before an unpcirenthesized
expression.

In absence of parentheses, the order of priority is:

Exponentiation

Multiplication and Division (of equal pr;Lority)

Addition and Subtraction (of equal priority)

If either 1 or 2 above does not
clearly dessignate the
order of priority, then the evaluation of expressions
proceeds from left to right.

The expression AtB-^C is evaluated from left to right as follows:
1.

A+B

(result of step

= step 1

= answer

1) "tc

The expression A/B*C is also evaluated from left
multiplication and division are of equal priority:
1.

A/B

= step 1

(result of step 1)*C

= answer

6-4

right

since

Parentheses and Spaces

6.5.2

Parentheses may be used by the progranmier to change the order of
priority
(as
listed in rule 2 of the previous section) . Since
expressions within parentheses are always evaluated first,
the
programmer
can
control
the order of evaluation by enclosing
expressions appropriately. Parentheses may be nested, or enclosed by
a second
set (or more) of parentheses.
In this case, the expression
within the innermost parentheses is evaluated first, and then the next
innermost, and so on, until all have been evaluated.

Consider the following example;
A=7*C<Bt2+4>/X)
The order of priority is
1.

Bf2

= step 1

(result of step l)+4

= step 2

(result of step 2)/X

= step

(result of step 3)*7

= A

Parentheses also prevent any confusion
expression is evaluated. For example:

doubt

how

the

A*Bt8/7+B/C+Dt2
C(A*Br8)/7)+f CB/C)+Dt2)

Both of these formulas will be executed in the same way.
However,
most users will find that the second is easier to understand.
Spaces may be used in a similar manner.,
ignores spaces, the two statements:
LET B = Dt2 +

Since

the

BASIC

compiler

LETB=Dt2+l
are identical, but spaces in
reading.

6.5.3

the

first

statement

provide

ease

Relational Operators

A program may require that two values be compared at some point to
discover their relation to one another. To accomplish this, BASIC

6-5

makes use of the following relational operators:
=
<

equal to
less than
less than or
equal to

greater than

>= greater than or
<>

equal to
not equal to

Depending upon the result of the comparison, flow of program execution
may be directed to another part of the program, or the: validity of the
(indicating a FALSE condition)
relationship may cause a value of
or
(indicating a TRUE condition) to be assigned to a variable.
1
For
example:
15

X=Y</',

This statement assigns the value 1 to X if Y is greater than Z.
Relational operators are used primarily in conjunction with IF and LET
statements, both of which are later discussed in detail.
In
algebraic
The meaning of the equal sign (=) should be clarified.
the
notation,
formula X=X+1 is meaningless. However, in BASIC (cind
most computer languages), the equal sign designates replacement rather
Thus, the formula X=X+1 is actually translated: "add
than equality.
one to the current value of X and store the new result back in the
same variable X"; whatever value has previously been assigned to X
will be combined with the value 1.
An expression such as A=B+C
instructs the computer to add the values of B anc: C and store the
result in a third variable A; the variable A is not being evaluated in
terms of any previously assigned value, but only in terms of B and C.
Therefore, if A has been assigned any value prior to its use in this
statement, the old value is lost; it is instead replaced by the value
Finally, the equal sign may be used in relational testing as
of B+C.
illustrated in the previous example.

6.6

IMMEDIATE MODE

Commands are available which allow Cassette BASIC to act as a
calculator that is, the user types an algebraic exjiression which is
This is called
to be calculated and BASIC types back the result.
Immediate Mode since the user is not required to write a detailed
program to calculate expressions and equations, but cem use BASIC to
produce results immediately. The commands used in Immediate Mode are
These are
PRINT, LET and occasionally the FOR-NEXT combination.
explained in the following paragraphs.

—

6.6.1

PRINT Command

The PRINT command is of the form:

PRINT expression

BASIC is instructed to compute the value of the expresssion eind print
The expresision is a normal
the result on the console terminal.

6-6

arithmetic expression v/hich may include nvimbers, variables, arithmetic
functions (discussed in Section 6.8.12). A string of
operators,
eind
For example:
text may also be printed (see Section 6.8.5 PRINT),

—

l/8t8
5.9604 6'!)E-08

PRIiNJT

6.6.2

LET Command

Values may be assigned to variables by
follows;

use

the

LET

command

LET variable=expression
The computer does not type anything in response to this command, but
computes the expression and assigns the value to the variable. The
variable may then be used in another computation or may be output
using the PRINT command. For example:

LET PI =3. 141 59

PRINT Pl*4t2

6.6.3 Looping PRINT and LET Commands
It is possible to include PRINT and LET commands in a loop so that
Looping
variables and results may be stored or printed in a series.
FOR-NEXT statements in which the FOR
is accomplished by means of
statement sets the limits of the loop and the NEXT statement
increments the count by 1. The only restriction in Immediate Mode
looping is that the command and the looping statements must appear on
character
(\)
This is accomplished by using the backslash
one line.
(The backslash is produced
to separate multiple statements on a line.
on an LT33 or 35 Teletype by pressing the SHIFT and L keys
Other types of terminals provide a separate key.) For
simultaneously.
example:

LET Pl=3. 14159
FOR 1=1 TO 3 SPRINT PlflNNEXT

This combination will print the results of 3.14159 to
and 3rd powers respectively.

the

1st,

2nd,

More information on looping in general is provided in Section 6.8.7.

6-7

EXAMPLE RUN

6.7

The following Example Run is included at this point as an illustration
of Cassette BASIC'S initial dialogue, the format of a BASIC program,
the ease in editing and running it, and the type of output that may be
The user calls in the program AVER from cassette drive 1
produced.
Execution is halted by a SYNTAX ERROR at line
and attempts to run it.
The user lists the program, finds the mistake in line 30, and
30.
He corrects these errors by
also notices a mistake in line 85.
retyping the lines, and then reruns the program. After execution he
saves the corrected program on drive 1 under the original name.

Following sections cover the statements and
programming.

commands

used

.R BASIC
USING RUN-TIME FILE I/0?CY OR N)N

MEW OR OLD -OLD

OLD PROGRAM NAME-AVER
UNIT#C0-7)
:

READY.

HUN
HOW MAMY STUDENTS^ HOW MANY GRADES PER STUDEMT
SYXfTAX ERROR AT LINE 30

5,4

LIST
10 REM - PROGRAM TO TAKE AVERAGE OF
15 REM - STUDENT GRADES AND CLASS GRADES
20 PRINT "HOW MANY STUDENTS > HOW MANY GRADES PER STUDENT
30 INP(JT AjIB
40 LET 1=1
50 FOR J=I TO A
55 LET V=0
60 PRINT "STUDENT NUMBER =";j
7 5 PRINT "ENTER GRADES"
76 LET D=J
80 FOR K=D TO D+(B-1)
81 INPUT G
82 LET U=V+G
85 NEXT L
90 LET V=V/3
95 PRINT "AVERAGE GRADE =";V
96 PRINT
99 LET Q=Q+V
100 NEXT J
101 PRINT
102 PRINT
103 PRINT "CLASS AVERAGE =";Q/A
10^ STOP
40 END
1

&-.8

BASIC

READY.
30 INPUT A*B
85 NEXT K

RUN
HOW MANY STUDENTS^ HOW MANY GRADES PER STUDENT ?5>4
STUDENT NUMBER = 1
ENTER GRADES
?78
?86
?88
?74

AVERAGE GRADE

81.5

STUDENT NUMBER
ENTER GRADES

?59
?86
?70
?87

AVERAGE GRADE

7 5.5

STUDENT NUMBER
ENTER GRADES

?58
?64
?75
?g0

AVERAGE GRADE

69.25

STUDENT NUMBER
ENTER GRADES

= 4

?88
?92
?85
?79

AVERAGE GRADE

STUDENT NUMBER
ENTER GRADES

?60
?78
?85
?80

AVKWGE GRADE = 75.75

CLASS AVERAGE

77.6

READY

SAVE
UWIT#(0-7):l

READY.

6-9

;

6.8 BASIC STATEMENTS

The statements described in this section are used in creating BASIC
These statements make up the body of the program; they
programs.
perform arithmetic calculations and input and output operations , and
control the order of program execution.

6.8.1

Statement Numbers

An integer number is placed at the beginning of each line in a BASIC
program.
BASIC executes the statements in a prograir in numerically
consecutive order regardless of the order in which they have been
typed. A recommended practice is to number lines by fives or tens, so
that additional lines may be inserted in a program without the
(BASIC programs may
necessity of renumbering lines already present.
be created using either the BASIC Editor as described here, or the
If the CAPS-8 EDITOR is used, the programmer must make
CAPS-8 EDITOR.
certain to type his program in numerically consecutive order, as BASIC
will not sort it in this case.)

Multiple statements may be placed on a single line by separating each
statement from the preceding statement with a backslash (SHIFT/L)
This feature is particularly useful since statement numbers require
if unnecessary statement numbers are
space in the symbol table;
eliminated by use of the backslash, there will be more room for
program storage. For example:
10

A=5\B=.3\C=3\PR1NT "ENTER DATA"

All of the statements in line 10 will be executed before BASIC
Only one statement number at the
continues to the next line.
However,
it should be
beginning of the entire line is necessary.
noted that program control cannot be transferred to a statement within
in which it is
a line, but only to the first statement of the line
contained (see Section 6.8.9, Transfer of Control Statements).

6,8.2

The
or
The
The

Commenting the Program (REM)

REM or REMARK statement allows the programmer to insert comments
remarks into a program without these comments affecting execution.
BASIC compiler ignores everything on a line beginning with REM.
form is
(line number)

REM (message)

eind
15
are REMARK statements
In the Example Run program, lines 10
It is often useful to put the name
describing what the program does.
of the program and information relating to its use at the beginning
Remarks throughout the
where it is available for future reference.
body of a long program will help later debugging by explaining the
purpose of each section of code within the program.

6-10

Terminating the Program (END and STOP)

6.8.3

The END statement (line 140 in the Example Run program) ,
if present,
must be the last statement of the entire program. The form is:
(line number) END

Use of the END statement is optional.
of the program and BASIC prints:

If executed, it signals the end

READY.

Variables and arrays are left in an undefined state,
any values they have been assigned during execution.

thereby

losing

The STOP statement is used synonymously with the END statement to
terminate execution, but while END occurs only once at the end of a
program, STOP may occur any number of times. The format of the STOP
statement is:
(line number)

STOP

This statement signals that execution is to be terminated at that
point in the program where it is encountered leaving variables in a
defined state.
(Variables will contain the values assigned when the
statement is encountered.)

6.8.4

The Arithmetic Statement (LET)

The Arithmetic (LET) statement is probcibly the most commonly used
BASIC statement.
It causes a value to be assigned to a variable and
is of the form:
(line number)

(LET)

x = expression

where x represents a variable, and the cjxpression is either a number,
cinother
variable,
or an arithmetic expression.
The word 'LET' is
optional; thus the following statements are treated the same:

LET A=AtB+10
A=AtB+10

LET C=F/G
C=F/6

As mentioned earlier, relational operators may be used in a LET
statement to assign a value to a varialsle depending upon the validity
If the statement is FALSE, the value
of a relationship.
is assigned
For example:
to the variable; if TRUE, the value 1 is assigned.
IW'^

A=l

105
110
120
130
140
150

B=a

C=A=B
D=A>8
E=A<>B
PRINT C,D,K
EMD

6-11

Translated, this actually means "let C=l if A=B (0 otherwise) ; let D=l
if A>B (0 otherwise)" and so on.
Thus, the values of C, D, and E are
printed as follows
RUN
1

READY.

There is no limit to the number of relationships that may be tested in
the statement.

6.8.5

Input/ Output Statements

Input/Output statements allow the user to bring data into a program
The console
and output results or data at any time during execution.
terminal keyboard, (LT33 Teletype reader and punch units, if present),
cassettes,
and line printer are all available as I/O devices in
Cassette BASIC. Statements which control their use are described
next.

READ and DATA

READ and DATA statements are used to input data into a program.
One
statement is never used without the other. The form of the READ
statement is:
(line number)

READ xl,x2,...xn

where xl through xn represent variable names.
10

For example:

READ A>B^C

Variables
A,B, and C are variables to which values will be assigned.
READ statements are
in
a READ statement must be separated by commas .
generally placed at the beginning of a program, but must at least
logically occur before that point in the program wheire the value is
required for some computation.
Values which will be assigned to the variables in a READ statement are
supplied in a DATA statement of the form:
(line number)

DATA xl,x2,...xn

where xl through xn represent values. The values must be separated by
commas and must occur in the same order as the variables which are
statement
A DATA
listed in the corresponding READ statement.
appropriate for the preceding READ statement is:
73

DATA 1^2»3

Thus, after executing the READ statement, A=l, B=2 , and C=3.

6-12

(before
The DATA statement is usually placed at the end of a program
where it is easily accessible to the programmer
the END statement)
should he wish to change the values.

A READ statement may have more or fewer variables than there are
The READ statment causes BASIC to
values in any one DATA statement.
search all available DATA statements in consecutive line number order
until values are found for each variatile in the READ. A second READ
If at
statement will begin reading values where the first stopped.
some point in the program an attempt is made to read data which is not
present or if the data is not separated by commas, BASIC will stop and
print the following message on the console terminal:
DATA ERROR AT LINE XXXX

where XXXX indicates the line
caused the error.

number

the

READ

statement

which

RESTORE
If it should become necessary to use the same data more than once in a
program,
the RESTORE statement will make it possible to recycle
through the DATA statements beginning with the lowest numbered DATA
The RESTORE statement is of the form:
statement.

(line number)

RESTORE

An example of its use follows:
15 READ

B^C>D

55 RESTORE
60 READ E»F>G

80 DATA 6>3*4>7>9>2

100 END
In this example, the READ statements in lines 15 and 60 will both read
If the RESTORE
the first three data values provided in line 80.
statement had not been inserted before line 60, then the second READ
would pick up data in line 80 starting with the fourth value.

In recycling through data with a RESTORE statement, the programmer may
the same variable names the second time through the data, or not,
as he chooses , since the values are being read as though for the first
skip unwanted values, the programmer may insert
In order to
time.
replacement (or dummy) variables. Consider:

use

6-13

REM

PROGRAM TO ILLUSTRATE USE OF RESTORE

20 READ N

PRINT "VALUES OF X ARE:"
30 FOR 1=1 TO N
40 READ X
50 PRINT X,
60 NEXT I
70 RESTORE
185 PRINT
190 PRINT "SECOND LIST OF X VALUES'"
200 PRINT "FOLLOWING RESTORE STATEMENT:"
210 FOR 1=1 TO N
220 READ X
230 PRINT X..
240 NEXT I
25

2 50

DATA A, I,

251 DATA 3^4
300 END

1212

RUN
VALUES OF X ARE:

SECOND LIST OF X VALUES
FOLLOWING RESTORE STATEMENT:
4

READY.

The second time the data values are read, the variable X
(line 220)
picks up the value originally assigned to N in line 20 , and as a
result, BASIC prints:

To circumvent this, the programmer could insert a dummy variable
(for
example, 205 READ Z ) , which would pick up and store the first value,
but would not be represented in the PRINT statement.
In this case the
output would be the same each time through the list.

INPUT

The INPUT statement is used when data is to be supplied by the user
from the console terminal keyboard while a program is executing, and
is of the form:
(line number)

INPUT xl,x2,...xn

where xl through xn represent variable names.

For example:

25 INPUT A*B*C

This statement will cause the program to pause during execution, print
a question mark on the console terminal, and wait for tlie user to type
three numerical values. The user must separate the values by commas;
they are entered into the computer by pressing the RETURN key at the
end of the list.

6-14

If the user does not
insert enough values to satisfy the INPUT
statement, BASIC prints another question mark and waits for more
values to be input.
When the correct number has been entered,
execution continues.
If too many values are input, BASIC ignores
those in excess of the required number.
The values are entered only
when the user types the RETURN key.

OPEN
Input and output files may be stored on cassette, and may be accessed
during run-time (providing the user has chosen the run-time I/O option
during BASIC'S initial loading dialogue) .
Before an I/O file is
accessed however, the user must first open it via one of the following
commands
(line number) OPEN "n:xxxx" FOR INPUT

or
(line number) OPEN "nixxxx" FOR OUTPUT

where n represents the cassette drive numlDer (0-7) , and xxxx is any
legal filename
characters or less, and optional extension of 3
(6
characters or less) . Input files are created either by using BASIC or
the CAPS-8 EDITOR (see Section 6.8.6), and must have been previously
stored on cassette before being accessed. For example, the statement:
815 OPEN "1 :TEST.DAT" FOR INPUT

opens an input file named TEST. DAT on cassette drive

Only one input and one output file may be open at any time,
and only
one file either input or output may be open on a given cassette
drive at one time.

—

CLOSE
The CLOSE statement is used to close a currently open output file, and
is of the form:
(line number)

Suceeding OPEN FOR INPUT statements will perform an automatic close on
open input file; however, the user should take note of
a previously
the following cases:
1.

If the user attempts to open an input file on a cassette
which is currently open for output, BASIC will return an
I O ERROR, as the same cassette drive cannot be open for
both input and output at the same time.

If the user has an input file open on a cassette, and is
end-of-file
has been
its
(that is,
a CTRL/Z
at
detected) , BASIC will allow him to open an output file

6-15

the
same
cassette,
since the input file is
theoretically "closed". However, if the usier has an
input file open on a cassette and is not at its
end-of-file, an I O ERROR will occur if he then tries to
open an output file on the same cassette.
(See Section
6.8.9, IF END#, for more information on BASIC'S method
of detecting an end-of-file.)
on

If the user tries to open an output file and an output
file is already open on any cassette, BASIC will return
a "FILE OPEN ERROR"; before opening a new output
file,
the current output file must be closed.

A close is automatically performed on both open input and open output
files by STOP, END and CHAIN statements, as well as by all errors
detected at run- time.

INPUT

Once an input file has been opened using the open statement, data can
be called into a program using the INPUT* statement.
The form of this
statement is:
(line number)

INPUT# xl,x2,...xn

where # signifies that the file is stored on cassette under the
filename and drive number specified in the last "C1PEN...FOR INPUT"
statement; xl through xn represent variable names.
When the BASIC program reaches the INPUT# statement during execution,
automatically called into the program from cassette and
the data is
INPUT # statements and INPUT statements may be
execution continues.
interspersed throughout a program. The input file need only be opened
once before it is referenced.

PRINT
The PRINT statement is used to output results
comments, values of variables, or plot points
console terminal. The format is:
(line number)

cf computations,
cf a graph on the

PRINT expression

When no expression is indicated in the statement line, a blank line is
For example:
output.

MS PRINT
810

PRI'\)T

By using
Two blank lines will be output on the console terminal.
certain kinds of expressions and the control chaiacters colon and
semicolon, the user can create fairly sophisticated formats

6-16

In order to print out the results of a computation and the value of a
variable, the user types the line number, PRINT, and the variable
name(s) separated by a format control character (in this case, commas)
as follows:
5

A=16\B=5\C=4
PRINT A*C+B,SQR<A)
print
value
above
A are

In BASIC, an output line is formatted into five columns (called
The control character comma causes a
zones)
of 14 spaces each.
In the
to be typed beginning at the next available print zone.
example,
the value of A, the sum of A+B, and the square root of
printed in the first three print zones as follows:

RUN
4

A statement such as in line number 10 in this next example:
5

A=2.3\B=21\C=156.7 5\D=1 .134\E=23.4
A^BjC^D^E

10 PRINT

the

causes the values of the variables to be printed in
using all five zones:
RUN
2.3

same

format

1.134

23.4

When more than five variables are listed in the PRINT
sixth value begins a new line of output.

statement,

156.75

the

The PRINT statement may also be used to output a message or line of
The desired message is simply placed in quotation marks in the
text.
PRINT statement as follows:
10

PRINT "THIS IS A TEST"

when line
printed:

encountered

during

execution,

the

following

THIS IS A TEST

A message may be combined with
variable as follows:

result

the

calculation

80 PRINT "AMOUNT PER PAYMENT ="^R

Assuming R=344.96, when line 80 is encountered during
results are output as
AMOUNT PER PAYMENT

execution,

the

344.96

If a number following a printed message is too long to be printed on a
single line, the number is automatically moved to the beginning of the
next line.

The
It is not necessary to use the standard 5-zone format for output.
control character semicolon (;) causes the text or data to be output

6-17

immediately after the last character printed
(separated from that
character by a space and followed by another space) .
If neither a
comma nor a semicolon is used, BASIC assumes a semicolon.
Thus both
of the following;
80 PRINT "AMOUNT PER PAYMENT ="R
80 PRINT "AMOUNT PER PAYMENT =";R

result in:

AMOUNT PER PAYMENT

344.96

The PRINT statement can also cause a constant to be printed on the
console terminal.
(This
is
similar to the PRINT command used in
Immediate Mode.) For example;

.234>SQR< 10014)

causes the following to be output at execution time:
1.834

100.07

Any algebraic expression in a PRINT statement is evaluated using the
current value of the variables. Numlaers are printed according to the
format discussed in Section 6.3.
The following example program illustrates the use of the control
characters comma and semicolon in PRINT statements . The user may also
wish to refer to Section 6.8.12 for information pertaining to three
functions available for additional character control TAB, PUT, and
GET:

—

10 READ A.,B,C

S0 PRINT A>B^C >At2 ,Bt2..Ct2
30 PRINT
40 PRINT AiBJC ;At2 JBf2:!Ct2
50 DATA 4 ,5,6
60 END

RUN
4

36
4

READY.

Another use of the PRINT statement is to combine it with an
statement so as to identify the data expected to be entered.
example, consider the following program;

6-18

INPUT
As an

REM

PROGRAM TO COMPUTE INTEREST PAYMENTS

20 PRINT "INTEREST IN PERCENT'S
25 INPUT J
26 LET J==J/100
30 PRINT "AMOUNT OF LOAN"i
35 INPUT A
40 PRINT "NUMBER OF YEARS";
45 INPUT N

PRINT "NUMBER OF PAYMENTS PER YEAR";
INPUT M
LET N=:N*M
LET 1 = J/M

55
60
65
70
75
78

LET B = 1+1
LET R ==A*i/(i-:l/BtN>
=

80 PRINT "AMOUNT PER

PAYMENT =";R
85 PRINT "TOTAL INTEREST
=";r*isi-a
88 PRINT
90 LET B =:A
95 PRINT " INTEREST
APP TO PR IN
100 LET L,=B*I
110 LET P =R-L
120 LET B =B-P
t

]

BALANCE"

130 PRINT L/P,B
140 IF B> =RGO TO 100
150 PRINT B*I,R-B*I
160 PRINT "LAST PAYMENT ="B*I+B

200 END

HUN
INTEREST IN PERCENT?
AMOUNT OF LOAN72 500
NUMBER OF YEARS72
NUMBER OF PAYMENTS PER YEAR?4
AMOUNT PER PAYMENT
TOTAL INTEREST

344.9617

= 2 59.. 6932

APP TO PRIN
288.7117
295.2077
301 .8498
43.1 1182
308.6415
36.32019
315.5859
29.37576
322.6866
22.27508
329.947
15.01463
337.3708
7.590824
LAST PAYMENT = 344.9608

INTEREST
56.25
49.75399

BALANCE
2211 .288
1916.081
1614.231

1305.589
990.0035
667.317
337.3699

READY.

As can be noticed in this example, the question mark is grammatically
useful when several values are to be input by allowing the programmer
to formulate a verbal question which the input values will answer.

6-19

PRINT*

The PRINT* statement is similar to the PRINT statement with the
exception that data and messages are sent to the current output file
on cassette rather than to the console terminal.
The form of the
statement is:
(line number)

PRINT# xl,x2,...xn

where # signifies that the output will be sent to the cassette drive
number and filename of the currently open output file, and xl through
xn represent data variables.
(The current open file is determined by
the OPEN FOR OUTPUT statement, as detailed earlier in this section.)
If the user attempts to save data on a full cassette, BASIC prints
an
error message and returns control to its editing jahase. The data
already output is lost, and the user will have to rerun his program
using a different output cassette.

COMMAS and NO COMMAS

Data stored in an output file on cassette is often called later as
input by another or the same program.
(This is i.n fact the only
method of passing data between segments of a chained program.)
In
order to be used as input, this data must be in the scime format as it
would appear if written in a DATA statement. Cassette BASIC provides
two statements for formatting this output COMMAS and NO COMMAS.

—

In order to be used as data, individual values must be
separated by
the COMMAS statement inserts a comma after each item of data;
commas;
(unless the COMMAS statement is inserted in the program prior to
PRINT# statement, data will be output in the foirmat illustrated
earlier under the PRINT statement.) The form is:

(line number) COMMAS

A NO COMMAS statement will set the format back to its original state.
The COMMAS and NO COMMAS statements do not affect output on either the
console terminal or line printer.
The following example
reads the
"OUT. DAT",
console terminal.

writes out four values in a file called
values back into memory and prints them on the

10 OPE!>J "1 :OfJT.DAT" FOR
15 COMMAS

OUTPUT

20 PHINT# l;2J3;4
30 CLOSE
40 OPEN "1:OOT.DAT" FOR INPUT
50 INPUT# I:»J>K,L
60 PRINT IjJ>K>L
70 ElNJD

Output appears as follows
RUN
1

READY.

6-20

)

The COMMAS statement is not necessary if the user is only sending one
value per line.
The preceding example could have been coded as
follows, with the same results:
10 OPEN "ItOQT.DAT" FOR OUTPUT

20 FOR 1=1 TO 4
30 PRINT* I
40 NEXT I
50

60
70
80
90

CLOSE
OPEN "1: OUT. DAT" FOR INPUT
INPUT* I^J^KiL
PRINT 1,J,K,L
END

In this case the file OUT. DAT would appear;
1

2
3

whereas in the first case it would appear as follows:

U2j3*4
The user must take care when inputting data from cassette files.
example, if the file OUT. DAT is in the form:

For

1^2,3*4
and the user attempts
statement:
53 INPUT*

input

these

values

using

the

following

I^J^K

the proper values for I, J, and K will be read, but the rest of the
line will be lost as far as satisfying any future variables just as
it would be lost if these values were input from the console terminal.
INPUT statement in this
(Refer to the information concerning the
section.

—

LPT

The LPT statement is used to generate output on the line
one is available) and is of the form:
(line number)

printer

(if

LPT

all subsequent
By inserting this statement anywhere in a program,
output, with the exception of error messages, will be printed on the
The LPT statement is particularly advantageous for
line printer.
outputting large amounts of calculated data, as can be seen from this

6-21

and following examples:
100
110
120
130
140

LPT
FOR F=33 TO 60 STEP
PRINT F^Fta
NEXT F
END

HON
30
33
3fe

39
HZ
«5
aa
51
5a
57
60

900
10«9
1296
1521
176a
2055
230a
2601
2916
32a9
3600

When the END statement is encountered in
device is reset to the console terminal.

the

program,

the

output

TTY OUT
The console terminal may be placed under program control so that
during execution of a program output may be sent alternately between
the console terminal and the line printer (if one is availcible on the
system)

Control is originally set with the console terminal. By issuing the
LPT statement discussed previously, all subsequent outjput can be sent
to the line printer. To return control to the console terminal from
within the program, the statement:
(line number) TTY OUT

(Cassette I/O always returns control to the last device
indicated, so that the TTY OUT statement need only be used when the
line printer is involved.)

is inserted.

The following program makes use of almost all the availcible I/O
devices.
The console terminal and line printer output Ls included.
HEM PROUF?AM TO DEMOMSTHATE ALL I/O DEVICES
REM AVAILABLE IN CASSETTE BASIC
15 REM
20 PRINT "PROGRAM TO CALC'JLATE SQUARES AND SQUARE ROOTS"
25 PRINT
27 HEM GET LOOP LIMITS FROM USER
30 PRINT "INPUT LOWER LIMIT"
35 INPUT L
'!10
PRINT "INPUT UPPER LIMIT"
A5 INPUT U
50 PRINT "INPUT STEP"
55 INPUT S
57 HEM CREATE A CASSETTE FILE OF SQUARES OF NUMBERS
60 OPEN "1 :SnUARE.DAT"FOR OUTPUT
5

IP)

6-22

65 LPT
66 HEM PRIWT A FORM FHIRD OM LINEPRIMTEK
70 T=P'JTCia)
75 PRINT "TABLH: OF M'JMBERS AND THEIR SOMAHES"
80 PRINT
81

82 PRIMT •• X'S" XtH"
83 PRINT
85 FOR X = L TO 'I STEP S
91^

PRINT X^X»^

95 REM ALSO SEND SO'JARES TO
100 PRINT* Xta
135 ^JEXT X
11^6

CASSETTE FILE

110 T=P'JT(ia)
11 1

TTY

O'lT

112 PRINT
113 LPT
115 PRINT
13PI

125
126
127
128
130
135
136
l^lO)

150
155
160
165

"TABLE OF SO'JARES COMPLETE"

"TABLE OF N'JMBRRS AND THEIR SO'JARE ROOTS"
OPEN "1 :SO'TARE.DAT"FOR INPiJT
PRINT
PRINT
PRINT " X"*" SORCX)"
PRINT
FOR X=L TO 'I STEP S
INPIT* J
PRINT JjSORCJ)
NEXT X

T=P'IT(12)

TTY O'JT
PRINT "PROGRAM COMPLETED"
END

nuN
PROURAM TO CALC'JLATE SO'JARES AND SO'JARE ROOTS
IN^'JT

LOWER LIMIT

INP'IT

tJPPER LIMIT

?5^
INP'JT

STEP

TABLE OF SO'JARES COMPLETE

6-23

TABLE

flF

MJHBtRS ANO THfclR SQUARES
X-d

4
3

h
7

155/

^4iii1.

5PI

TAbue OH NUMHtWS ANO TMfclk SfOUAkE WQOTS
SOk(X)
1

3
4

(t.4

«1

r'4F:l

49
SI?

6-24

NOTE

Teletype is used as the
If an LT33
terminal and it includes a
console
reader and punch, these devices may be
used for I/O operations at any time; no
special statement is required. To read
in data from the reader, position the
tape over the sprocket wheel; when input
is required, set the reader to START and
To
the tape will begin reading in.
set the punch to ON and
punch a tape,
all Teletype output will be punched on
Using the paper tape I/O
the punch.
devices is, in effect, tJie same as using
Characters will
the Teletype keyboard.
be typed on the Teletype keyboard as
tapes are being read or punched.

6.8.6 Creating Run-Time Input Files

Data files stored on cassette and used for input during execution can
be created either by use of BASIC itself or by use of the CAPS-8
EDITOR.

Using BASIC, the programmer creates a program which accepts values
from the console terminal keyboard and then writes these onto the
Data files consist of consecutive ASCII
cassette as an output file.
If the useful data in a file is to end before the actual
characters.
end-of-file, the last useful character must be followed by a CTRL/Z.
inserted by BASIC when the user closes an output
(This character is
When later detected during input, BASIC sets an end-of-file
file.
the user can test an end-of-fil€i condition by using the IF-END#
flag;
statement.) The COMMAS statement is used to produce the correct format
for a data file when more than one value is on a single line.
The following program illustrates one method of doing this:
5 REM - PHOGRAM TO ACCEPT DATA FROM THE CONSOLE
10 REM - TERMINAL AMD CREATE A RUNTIME INPUT FILE
20 OPEN "0:RTIN.DAT" FOR OUTPUT
25 PRINT "INPUT A>B*CjD"i
30 INPUT A*B>C*D
35 COMMAS
40 PRINT* A>B*C>D
45 PRINT "INPUT FCI) FOR 1=1 TO 10"
50 DIM F(10)
52 REM - COMMAS NOT NEEDED SINCE ARRAY WILL
53 REM - BE OUTPUT ONE ELEMENT PER LINE
55 NO COMMAS
60 FOR 1=1 TO 10
70 PRINT "F("I")"i
7 5 INPUT FCn
80 PRINT# F(I)
85 NEXT I
90 PRINT "INPUT \}\,\J2.Z"
95 INPUT V\,V2.,Z
97 REM - COMMAS ARE NEEDED SINCE VU V2 AND Z
93 REM - WILL BE OUTPUT ON THE SAME LINE

6-25

100 COMMAS
105 PRINT# \}l,\J2^Z
1

1 1

CLOSE
END
rtUN

SAVE
UNlT#(0-7) :g

READY.

The
The CAPS-8 EDITOR can also be used to create an input file.
EDITOR first asks for input and output devices and filenames; then the
user types the file using EDITOR commands and making sure the format
The same data file in the above example can be
correct for BASIC.
is
created using the EDITOR as follows:

i.R

EDIT

* INPUT

FILE-

OUiVdl- FILE-

2rtfIN.DAT

J.A
1

.37»2.346j.-13.267^-1 .056

3.56
1 .436
38

9.386
23.067
89
54

12.467
-1

123,34567^789

IL
1.37,2.346>-13.8 67,-1.0 56
23

3.56
1 .436
38

9.026
83.067
89
54

12.467
-1

123*34567*789

6-26

6.8.7 Loops (FOR, NEXT and STEP)

A loop is a set of instructions which are repeated over and over
again, each time being modified in some way until a terminal condition
is reached.
FOR and NEXT statements define the beginning and end of a
STEP specifies an incremental value. The FOR statement is of
loop;
the form:
(line number) FOR v=xl TO x2 STEP x3

where v represents a variable name, and xl, x2 , and x3 all represent
formulas
(a
formula in this case means a numerical value, variable
name, or mathematical expression),
v is termed the index,
xl the
initial value, x2 the terminal value, and x3 the incremental value.
For example
15 FOR K=a TO 20 STEP 2

This loop will be repeated as long as K is less than or equal to 20.
Each time through the loop, K is incremented by 2 , so the loop will be
executed a total of 10 times.

variable used as an index in a
subscripted,
although a common use
subscripted variables using the value of
defined variable (this is
a previously
Subscripted Variables)

FOR

statement must not be
of loops is to deal with
the index as the subscript of
illustrated in Section 6.8.8,

The NEXT statement is of the form:
(line number) NEXT v

where v is the index of the FOR loop and signals the end of the loop.
When execution of the loop reaches the NEXT statement, the computer
adds the STEP value to the index and checks to see if the index is
If so, the loop is executed
less than or equal to the terminal value.
If the value of the index exceeds the terminal value,
again.
control
falls through the loop to the following statement, with the value of
the index equaling the value it was assigned the
final time through
(Note that this method of handling loops varies among other
the loop.
versions of the BASIC language.)
(Since +1 is
If the STEP value is omitted, a value of +1 is assumed.
the usual STEP value, that portion of the statement is frequently
omitted.) The STEP value may also be a negative number.

This loop is
The following example illustrates the use of loops.
executed 10 times: the value of I is 10 when control leaves the loop.
+1 is the assumed STEP value,
10 FOR 1=1 TO 10
20 NEXT I
30 PRINT I
40 END

RUN
10

READY.

6-27

If line 10 had been:

10 FOR 1=10 TO

STEP

-1

the value printed by the computer would be 1.

used in the FOR statement are
As indicated earlier, the numbers
these formulas are evaluated upon first encountering the
formulas;
While the index, initial, terminal and STEP values may be
loop.
changed within the loop, the value assigned to the initial formula
remains as originally defined until the terminal condition is reached.
To illustrate this point, consider the previous example. The value of
I (in line 10) can be successfully changed as follows:
10 FOR

1=1 TO 10
15 LET 1=10
80 NEXT I

The loop will only be executed once since the value 10 has been
reached by the variable I and the terminal condition is satisfied.
If the value of the counter variable is originally set
equal to the
terminal value, the loop will execute once, regardless of the STEP
value.
If the starting value is beyond the terminal value,
the loop
will also execute only once.

It is possible to exit from a FOR-NEXT loop without the index reaching
the terminal value.
This is known as a conditional transfer and is
explained in Section 6.8.9. Control may only transfer into a loop
which has been left earlier without being completed, ensuring that the
terminal and STEP values are assigned.

Nesting Loops
loops within a loop.
This
It is often useful to have one or more
technique is called nesting, cind is allowed as long as the field of
(the numbered
lines from the FOR statemisnt
the
one loop
to
corresponding NEXT statement, inclusive) does not cross the field of
another loop. A diagram is the best way to illustrate acceptable
nesting procedures

ACCEPTABLE NESTING
TECHNIQUES

UNACCEPTABLE NESTING
TECHNIQUES

Two Level Nesting
1

FOR

FOR
pFOR

-FOR

h^IEXT

'-NEXT

pFOR

-NEXT

'-NEXT

6-28

Three Level Nesting

— FOR

—-FOR
FOR

FOR

pFOR

r-FOR
•-NEXT
f-FOR

L-NEXT

pFC
FOR

EXT
NEXT
NEXT

H-NEXT
L-NEXT

A maximum of eight (8) levels of nesting is permitted,
limit will result in the error message:

Exceeding that

FOR ERROR AT LINfE XXXX
where XXXX is the number of the line in which the error occurred.

Subscripted Variables

6.8.8

In addition to single variable names, BRSIC accepts another class of
variables called subscripted variables. Subscripted variables provide
the programmer with additonal computing capabilities for handling
tables, matrices, or any set of related variables.
lists,
Variables
are allowed one or two subscripts.
A single letter forms the name of
the variable,
followed by one or two integers in parentheses,
separated by a comma, indicating the place of that variable in the
list.
Up to 26 arrays are possible in any program (corresponding to
the letters of the alphabet) , subject only to the amount of memory
space available for data storage.
For example,
a list might be
described as A(I) where I goes from 1 to 5 , as follows:
A(l) ,A(2),A(3),A(4) ,A(5)

This allows the programmer to reference each of the five elements in
the
list A.
A two dimensional matrix A (I, J) can be defined in a
similar manner, but the subscriped variable A can only be used once
(i.e.,
A(I)
and A(I,J)
cannot be used in the same program).
It is
possible however, to use the same variable name as both a suliscripted
and am unsubscripted variable.
That is, both A and A(I) are valid
variable names for use in the same program.

Subscripted variables allow data to be input quickly and easily, as
illustrated in the following program (the index of the FOR statement
in lines 20, 42 and 44 is used as the subscript)
10
11

15
18
P.0

25
30
35
38
39
40
HI
zjg

REM - PROGRAM DSMOMSTRAT IMU READ I Mb
RKM - OF S'IBSCRIPTED VARIABLES
DIM A(5),B(2*3)
PRINT "ACn WHERE A = TO 55"
FOR 1 = 1 TO 5
READ ACI)
PRIMT ACn;
MEXT I
PRINT
PHIMT
PRINT ••B(l,J) WHERE 1 = TO P.:"
PRINT
AND J=l TO 3:"
FOR 1 = TO 2
l

••

6-29

43 PRINT
FOR J=l TO 3
48 READ B(I,J)

Zl^i

50 PRINT R(I*J);
55 NEXT J

56 NEXT
60 DATA

>8>3>4*5*6*7^8
DATA 8^ 7 ^6^5^4*3^2^!
65 END
1

H'JN

WHERE A=l TO

AC I )
1

5 J

B{I>J) WViERE 1 = 1 TO 3:
AND J=l TO 3:
6
8

7
7

8
6

READY.

DIM
From the preceding example, it can be seen that the use of subscripts
requires a dimension (DIM) statement to define the maximum number of
elements in the array. The DIM statement is of the fonri:
(line number)

DIM vl(nl), v2(n2,m2)

where v indicates an array variable name and n and m are integer
numbers indicating the largest subscript value required during the
program.
For example;
15 DIM AC6>10)

The first element of every array is automatically assumed to have a
subscript of zero.
Dimensioning A(6,10) sets up room for an array
with 7 rows and 11 columns. This matrix can be thought of as existing
in the following form:
AO ,
AO , 1 ...
A1,0 Al,l ...
A2,0 A2,l ...

A0,10
Al,10
A2,10

A6,0 A6,l ...

A6,10

and is illustrated in the following program:

6-30

10 REM - MATRIX CHECK PROGRAM
15 DIM A(6*10)
20 FOR 1=0 TO 6

LET A(Ij0)=I
FOR J=0 to 10
LET A(0;.JJ=J
PRINT A(I>J);
3 5 NEXT J
40 PRINT
4 5 NEXT I
50 END
22
25
28
30

RUN
1

2
3

4
5
6

READY.

Notice that a variable assumes a value of zero until another value has
been assigned.
If the user wishes to conserve memory space by not
making use of the extra variables set up within the array, he should
set his DIM statement to one less than necessary, i.e.
DIM A(5,9).
This results in a 6 by 10 array which may then be referenced beginning
with the A (0,0) element.
More than one array can be defined in a single DIM statement:
10

DIM A(20>> B<4>7)

This dimensions both the list A and the matrix B.

A number must be used to define the maximum size of the array. A
variable inside the parentheses is not acceptable and will result in
run-time.
The amount of memory not
an error message by BASIC at
filled by the program will determine the amount of data the computer
In some programs
can accept as input to the program at any one time.
occur, indicating that memory will not hold an
a TOO-BIG ERROR may
In that event, the user should change
array of the size requested.
his program to process part of the datei in one run and then chain to
another section to process the rest (see Section 6.8.10).

6.8.9

Transfer of Control Statements

Certain control statements cause the execution of a program to jump to
line either unconditionally or as a result of some
a different
condition within the program. Looping is one method of jumping to a
designated point until a condition is met. The following statements
give the programmer added capeibilities in this area.

6-31

Unconditional Transfer (GOTO)
The GOTO (or GO TO) statement is an unconditional stattsment
direct program control either forward or back in a program.
of the GOTO statement is:

used to
The form

(line number) GOTO n

where n represents a statement number. When the logic of the program
reaches the GOTO statement, the statement (s) immediately following
will not be executed; instead execution is transferred to the
statement beginning with the indicated line number.
The following program never ends; it does a READ, prints something,
and j lamps back to the READ via a GOTO statement.
It atempts to do
this over and over until it runs out of data, which is <in acceptable,
though not advisable, way to end a program.
10 REM
11. REM

30
35
30
35
40

PHOtiRAM ENDIfOU WITH KRROR
MESSAUE WHi^M O'JT OF DATA

READ X
PRINT "X=*'X*"Xta = "Xt8
GO TO 80
DATA 1/5^10*15^20*85
END

H'JN

X=
X=
X=
X=
X=
X=

Xf8 =
Xt8 =
Xt8 =
Xt8 =
Xt8 =
X»8 =

10
15

80
35

85
100
885

400
685

DATA ERROR AT LINE 20
jitADY.

Conditional Transfer (IF THEN and IF GOTO)
two values be compared at some
point; control of program execution may be directesd to different
In computing,
procedures depending upon the result of the comparison.
values are logically tested to see whether they are equal, greater
than, less than another value, or possibly a combination of the three.
This is accomplished by use of the relational operatoirs discussed in
Section 6.5.3.

A program sometimes requires that

statements allow the programmer to test the
numbers,
or
(variables,
formulas
between
two
relationship
the
IP
Providing the relationship described in
expressions) .
statement is true at the point it is tested, control will be
transfered to the line number specified, or the indicated operation
will be performed. The statements are of the form:
IF THEN and IF GOTO

(line number)

IF vl <relation> v2 GOTO [or THEN]

6-32

;

where vl and v2 represent variable names or expressions, and x
represents a line number or an operation to be performed. The use of
either THEN or GOTO is acceptable.
The following two examples are equivalent (the value of the variable A
is changed or remains the same depending upon A's relation to B)

100 IF A>B THEN 120
110 A=AtB-l
120 C=A/D

100 IF A<=B THEN A=AtB-1
110 C=A/D

IF END#

The IF END# statement is used to verify cin end-of-file
during run-time input. The form of this statement is:
(line number)

condition

IF END# THEN n

IF END# instructs BASIC to perform a check on the validity of the last
INPUT*
statement referencing the currently open input file; n
represents a line number or operation to be performed.
If an
end-of-file
(CTRL/Z)
was detected during the last INPUT* statement,
BASIC transfers control to the specified line number or performs the
indicated operation.
If an end-of-file was not detected, then no
operation occurs. For example:

150 OPEN "l:UALUE" FOR INPUT

200 INPUT* A#B*C
210 IF END# THEN 530
215 LET X=SGNCA)
530 PRINT "INPUT FILE- -NOT ENOUGH DATA'
53 5 STOP

6-33

In this example the programmer provides his ovm error message if there
an insufficient number of values for his variables.
is
If there are
two valid numbers remaining in the input file when staitement 200 is
then the variables A and B will receive valid input. When
reached,
BASIC will detect an
the program attempts to input a value for C,
end-of-file and return a value of zero for C. As it executes the IF
END# statement, BASIC will note that it has jusit reached the
end-of-file, and will transfer control to statement number 530, as the

user intended.

However, assiame that as line 200 is executed there is only one valid
data value left in the input file. An end-of-file is detected this
When
time when BASIC tries to read a value for B; B is set to zero.
BASIC attempts to continue reading a value for C, an EOF ERROR will be
returned (see Section 6.12) and program execution will terminate since
A good way of
the user has tried to read past the end-of-file.
circumventing this condition is to include both the INPUT # and the IF
Using this
END# statements in a loop and input one value at a time.
method allows the programmer's own error message to be printed before
BASIC is allowed to read past the end-of-file.

6.8.10 Program Chaining (CHAIN)

Since Cassette BASIC allows at most only 2K words of memory for
program storage, it is possible that a program may be too large to fit
However, Cassette BASIC compensiates for this
in memory at one time.
by allowing different segments of a program to be stored on cassette
and called as needed. Although each program segment is restricted to
The form
2K of memory, total program length is effectively unlimited.
of the CHAIN statement is
(line number) CHAIN "niXXXX"

where n is the cassette drive number, and XXXX is the name of the file
The CHAIN statement should be the last statement in
to be chained to.
When BASIC transfers to the progrcim specified in
the user's program.
Data is not
it removes the old program from memoiry.
the statement,
passed in memory during the chain, so the user should be careful to
(See Section
save any data he will need in an output file.
6.8.5 PRINT#.) The chain automatically closes any open output file,
transfers control to the lowest statement number in tJie new program,
and continues execution.

—

For example, the following section of a program stores some
values on an output cassette and chains to a file calltid PART2:

OPEN "ItDATA" FOR OUTPUT
COMMAS
460 PRINT* B>C*D*G*H*Z
465 NO COMMAS
473 FOR 1=1 TO 10
475 PRINT* A<n
480 NEXT I
485 CLOSE
490 CHAIN "1:PART2"
4 50

^155

6-34

data

The values stored by this section of the program in the cassette file
DATA can be read in by the second section of the program PART2 and
can continue to be used.
PAPT2 might appear as follows:

—

DIM AC 10)
OPEN "1:DATA" for INPUT
10 INPUT# B,C>D^G>H>Z
1

15 FOR 1=1 TO 10
80 INPUT# AC I)
25

6.8.11 Subroutines

(GOSUB and RETURN)

A subroutine is a section of code performing some
required at more than one point in the program.
I/O operation for a volume of data, a mathematical
too complex for a user-defined function, or
processes may best be performed in a subroutine.

operation that is
Often a complicated
evaluation which is
any number of other

Subroutines are generally placed physically at the end of a program,
usually before DATA statements,
if any, and always before the END
statement.
Two statements are used exclusively in BASIC to handle
subroutines; these are the GOSUB and RETURN statements.

A program begins execution and continues until it encounters
statement of the form:
(line number)

CX)SUB

GOSUB x

where x represents the first line number of the
For example:
then transfers to that line.

subroutine.

Control

50 GOSUB 200

When program execution reaches line 50, control transfers to line 200,
and the subroutine is processed until execution encounters a RETURN
statement of the form:
(line number)

RETURN

The RETURN statement causes control to return to the statement
Before transferring to the sxibroutine,
following the (MSUB statement.
BASIC internally records the next statement to be processed after the
thus the RETURN statement is a signal to transfer
GOSUB statement;
different
In this way, no matter how many
control to this statement.
subroutines are called, or how many times they are used, BASIC always
knows where to go next.
The following program demonstrates a simple subroutine:

6-35

REM - THIS PROGRAM ILLUSTRATES GOSUB A^5D RETURN
DEF FNA<X)=ABSC1NTCX))
INPUT A^B^C
GOSUB 100
LET A=FNA(A)
50 LET B=FNA(B)
60 LET C=FNACC)
70 PRINT
80 GOSUB 100
90 STOP
100 REM - THIS SUBROUTINE PRINTS OUT THE SOLUTIONS
110 REM - OF THE EQUATION: ACXt2) + BCX) + C =
"A"*Xt2
+
+
120 PRINT "THE EQUATION IS
"B"*X
130 LET D=B*B-^*A*C
140 IF D<>0 THEN 170
150 PRINT "ONLY ONE SOLUTION... X ="-B/<2*A)
160 RETURN
170 IF D<0 THEN 200
180 PRINT "TWO SOLUTIONS... X =";
185 PRINT (;-B+SQRCD))/(8*A)"AND X =" ( -B-SQRC D) )/<«*A)
190 RETURN
200 PRINT "IMAGINARY SOLUTIONS... X = C";
205 PRINT -B/(2*A)"^"SQRC-D)/(2*A)") AND C";
207 PRINT -B/(2*A)","-SQRC-D)/(2*A)")"
210 RETURN
1

10
20
30
40

900 END

RUN
?1^ .5^-.

THE EQUATION IS
TWO SOLUTIONS... X

+
*Xt2
AND X =-1

-.5

*Xt2
1
THE EQUATION IS
IMAGINARY SOLUTIONS... X =

+
<

)

+
*X
AND (

>-l

READY.

Line 100 begins the subroutine. There are several places in which
control may return to the main program, depending upon the flow of
control through the various IF statements. The subroutine is called
from line 30 and again from line 80. Vvlien control returns to line 90,
the program encounters the STOP statement and execution is terminated.
is important to remember that subroutines should generally be kept
It
distinct from the main program.
The last statement in the main
program should be a STOP or GOTO statement, emd subroutines are
normally placed following this statement. A useful practice is to
assign distinctive line numbers to subroutines. For example, if the
main program is numbered with line numbers up to 199, 1:hen 200 and 300
could be used as the first numbers of two subroutines.

Nesting Subroutines
Nesting of subroutines occurs when one subroutine calls another
subroutine.
If a RETURN statement is encoxintered during execution of
statement follov/ing the GOSUB
a subroutine, control returns to the

6-36

which called it. From this point, it is possible to transfer to the
beginning or any part of a svibroutine, even back to the calling
Multiple
entry points and RETURN statements make
subroutine.
subroutines more versatile.
levels,
The mciximum level of GOSUB nesting is about ten (decimal)
Exceeding
which should prove more than adequate for all normal uses
this limit will result in the message:
.

GOSUB ERROR AT LINE XXXX

An
where XXXX represents the line number where the error occurred.
Execution has been stopped by
example of GOSUB nesting follows.
Stopping a
(see Section 6.11.4,
typing a CTRL/SHIFT/P combination
Run) , as the program would otherwise continue in an infinite loop.
10

REM

FACTORIAL PROGRAM USING GOSUB TO
COMPUTE THE FACTORS

15 REM - RECURSIVELY
^0 INPUT N
50 IF N>20 THEN 120
60 X=l

70 K=l
80 GOSUB 900
90 PRINT "FACTORIAL •N'ft —ft X
110 GO TO 40
120 PRINT "MUST BE 10 OR LESS'
130 GO TO 40
200 X=X*K
210 K=K+1
220 IF K<=N THEN GOSUB 200
230 RETURN
240 END

RUN
?2

FACTORIAL

= 2

FACTORIAL

120

FACTORIAL
7

STOP.
READY.

6.8.12 Functions

BASIC defines several mathematical calculations for the programmer,
eliminating the need for tables of trig functions, square roots, and
logarithms. These functions have a 3-letter call name, followed by an
which can be a number, variable, expression, or another
x,
argument,
BASIC.
Teible 6-1 lists the functions available in Cassette
function.
described
in
and
are
not
that
are
those
self-explanatory;
Most are
greater detail are marked with an asterisk.

6-37

Table 6-1 Cassette BASIC Functions

Meaning

Function

Sine of x (x is expressed in radians)
Cosine of x (x is expressecl in radians)
Tangent of x (x is expressed in radians)
Arctangent of x (result is expressed
in radians)
e to the xth power (e=2.71£;282)
Natural log of x (loggx)
Sign of x assign a value of +1 if x is
positive,
if X is zero, or -1 if x
is negative
Integer value of x
Absolute value of x (|x|)
Square root of x /x)
Random number
Print next character at space x
Get a character from input device
Put a character on output device
User-defined function
User-coded function (machine language

SIN(x)
COS(x)
TAN(x)
ATN(x)

EXP(x)
LOG(x)
*SGN(x)

—

*INT(x)
ABS(x)
SQR(x)
*RND(x)
*TAB(x)
*GET(x)
*PUT(x)
*FNA(x)
*UUF(x)

(

code)

Sign Function (SGN(x))
if
The sign function returns the value +1 if x is a positive value,
For example, SGN(3.42)=1,
and -1 if x is negative.
zero,
X is
SGN(-42)=-l, cind SGN (23-23) =0. The following example illustrates the
use of this function:
10

REM

SGN FUNCTION EXAMPLE

20 READ A>B
25

PRINT "A="A,"B="3

30 PRINT "SGNCA)="S6N(A)*"SGMCB)="SGN(B)
40 PRINT "SGNCINTCA) )="SGNCINT(A))
50 DATA -7.32> .44
63 END

Integer Function (INT(x))
The integer function returns the value of the nearest integer not
greater than x. For example, INT (34. 67) =34 . By specifying INT(x+.5)
the INT function can be used to round numbers to the nearest integer;
INT can also be used to round numbers to any
INT (34. 67+. 5) =35.
thus,
given decimal place by specifying:
INT (X*10 +D+. 5) /lO -fD

where D is the number of
program illustrates this
typing a CTRL/SHIFT/P

decimal places desired,
function; execution has

6-38

The following
been stopped by

10 REM - INT FUNCTION EXAMPLE
20 PRINT "NUMBER TO BE ROUNDED"
30 INPUT A
40 PRINT "NO. OF DECIMAL PLACES";
50 INPUT D
60 LET 3=IMT(A*10tD+.5)/10tD
70 PRINT "A ROUNDED = "B
80 GO TO 20
90 END

RUN
NUMBER TO BE ROUNDED? 55. 6534l2
NO. OF DECIMAL PLACES72
55.65
A ROUNDED =
NUMBER TO BE R0UNDED778 .375
NO. OF DECIMAL PLACES? -2
100
A ROUNDED =
NUMBER TO BE R0UNDED?67 .89
NO. OF DECIMAL PLACES?-!
A ROUNDED =
70
NUMBER TO BE ROUNDED?
STOP.
READY.

negative number, the value returned is the
largest negative integer
(rounded to the higher value) contained in
the number.
For example, INT (-23) =-23 but INT (-14.39) =-15.
If the argxjinent is a

Random Number Function (RND(x))
The random number function produces a random number n which is in the
range 0<n<l.
The nvimbers are not reproducible, a fact the programmer
should keep in mind when debugging or checking his program.
The
argument x in the RND(x)
function call can be any number, as that
value is ignored. The following program illustrates the use of this
function to generate a table of random numbers.
10

REM

RANDOM NUMBER EXAMPLE

25 PRINT "RANDOM NUMBERS"
30 FOR 1=1 TO 30
40 PRINT RNDC0)^
50 NEXT I
60 END

RUN
RANDOM NUMBERS
.7759228
.4857633
.6156673
.3796163
.9547609
.05880478
READY.

.08069808
.4192038
.5921191
.2023254
.2890875
.3859534

.5008833
.1433537
.01170888
.7974058
.1416765
.8404774

6-39

.2790171
.08728769
.7411813
.9635064
.2482717
.5692836

.1661529
.2335427
.341708
.6043865
.2145417
.8514056

It is possible to generate random nvunbers over any range by using
following formula:

the

(B-A)*RND(0)+A
This produces a random number (n) in the remge A<n<B.
For exeunple, in
order to obtain random digits in the range 0<n<9, line 40 in the
previous example is changed to read:
40 PRINT 9+RNDC0),

To obtain random integer digits , the INT functi on is used in
conjunction with the RND function (using the same values for A and B
above) as follows:
40 PRINT INT(9*RNDC0))>

When the program is run, the results will look as folli^ws:
HUN
RANDOM NUMBERS
4

8
2
8

8
8

7
7

8
7

8
5
8
4
2
5

READY.

Notice that the range has changed to 0<=n<9. This is because the INT
function returns the value of the nearest integer not greater than n.

Tab Function (TAB(n))
The TAB function allows
characters anywhere on the
positions can be thought of
console terminal line (1 to
The form of this
to right.

the user to position the printing of
teleprinter (or line printer) line. Print
as being numbered from 1 to 72 across the
80 across the line printer line) from left
function is:
TAB(n)

(from 1 to the total
where the argument n represents the position
number of spaces available) in which the next character will be typed.
For example, TAB (3) causes the character to be printed at position 3.

Each time the TAB function is used, positions are counted from the
beginning of the line, not from the current position of the printing
For example, the following statement:
head.
10 PRINT "X

=";TABC3>r'/";3. 14159

will print the slash on top of the equal sign, as shown below:
RUN
X * 3.14159

6-40

The following is an example of the sort of graph
with BASIC using the TAB function:

that

can

drawn

30 FOR X=0 TO 15 STEP .5
40 PRINT TABC30+15*SIN<X>*EXP(-.1*X));"*"
50 NEXT X

RUN
*

*
*
*

*
*
*
*

PUT and GET Functions (PUT(x) , GET(x))

Cassette BASIC provides two additional functions, PUT and GET, to
increase input/output flexibility on the console terminal or line
Using these statements, the programmer can "PUT" an ASCII
printer.
character on the current output device, or "GET" a character from the
(ASCII character codes are listed in Appendix
current input device.
A.) GET is of the form:
GET(x)

where the argument x is a dvurany variable which may be any value.
will be assigned the decimal value of the ASCII code of the
GET(x)
next character input on the current input device.
For example, if the following statement appears in a program:
10 LET L=GET<0)

6-41

and the next character input is an M, the variable L will be
the value 77 (decimal).

assigned

PUT is of the form:
PUT(x)

where the argument x represents either the decimal value of the ASCII
code of the character to be output, or the characte:r itself.
For
example, the statement:
15 L=PUTCGETCV>)

will wait for a character to be read from the current input device and
then print it on the current output device. A statement such as;
30 PRINT PUT<Q)

will print the character typed as well as the decimal value of the
ASCII code for that character.
(Since both the character and the
decimal value are typed, PUT and GET statements should not be used
with cassette files.)
NOTE
If the user is inputting characters from
paper tape via the paper tape reader on
cm LT33 Teletype, he should be
careful
to
position the tape on the first
character to be input. Otherwise blank
tape
may
be
entered,
which
is
interpreted as a "BREAK" and stops a
running program.

The PUT function can also be used to format output. For example,
to
print a trig table on the line printer with a heading and 50 data
lines per page, the form feed character (12 decimal) can be "puT" to
the printer as follows:
100
110
120
125
130
140
150
160
165
170
180
190

LPT

GOSUB 1030
GOSUB 500
REM - SET UP TRIG TABLE
FOR J=0 TO 360 STEP .5
LET L=L+1
LET B=J/180*3.14
PRINT J»SIN(B)>COS<B)>TAN(B).ATtg(B)
REM - PRINT 50 ENTRIES IN TABLE
IF L=50 THEN GOSUB 500
NEXT J
GOSUB 1000
200 GOSUB 1000
210 STOP
500 REM - PRINT HEADER
50 5 GOSUB 1000
510 PRINT
520 PRINT
530 PRINT "ANGLE". "SINE"/"COSINE"»"TANGENT". "ARCTANGENT"
540 PRINT
550 RETURN
1000 REM - PRINT FORM FEEDS TO ADVANCE PAPER
1005 X=PUT(ia)
1010 L=0
1020 RETURN
1030 END

6-42

The beginning of the line printer output from this program follows.
The first page of the table continues through an angle of 24.5
degrees: then the header and the next 50 entries are printed on the
next page,
and so on until the values have been output (in steps of
.5) for all angles through 360 degrees.
ANGLE

SINE

COSINE

TANGENT

ARCTANGENT

6,722444E- 03
.01744621
.02617264
.03490305
,04363878
,05238116
,06113134
,06989125
,07866164
,08744408
,09623993
,1050506
,1138774
,1227217
,131585
.1404687
,1493741

a.722001E-03
,01744268
,0261607
,03487474
.0435835
.05228564
.06097986
,06966486
.07833935
,08700204
,09565166
.1042869
,1129067
,1215095
,1300944

«.5

.1131461
,1218079
.1304604
.139103
.147735

,999962
,9998479
,9996577
,9993915
,9990492
,9986309
.9961367
.9975665
.9969205
,9961986
.9954009
,9945274
,9935764
,9925537
,9914535
,9902779
,989027

2«.5

.414496

,9100512

,4554645

,4038923

e,7a2ll2E-03
.01744356
,02616368
.03468181
,04359729
,05230945
,06101763
.06972117
.0784194
.08711167
,09579731
.1044757

.5
1

1.5

2.5
3

3.5
a

tt.5

5,5
6

6.5
7

7.5
B

FNA" Function

,13666
,1472052

(DEF FNA(x))

In some programs it may be necessary to execute the same mathematical
formula in several different pj.aces.,
Cassette BASIC allows the
programmer to define his own function in the BASIC language and then
call this
function in the same manntjr as the square root or a trig
function is called.
Only one such user-defined function may be
included per program. The function is defined once at the beginning
of the program before its first use, and consists of a DEF statement
in combination with a 3-letter function name, the first two letters of
which must be FN. The format of the DEF FNA statement is as follows:

(line number)

DEF FNA(x) =formula(x)

The A in the FNA portion of the statement may be any letter.
The
argument (x) has no significance; it is strictly a dummy variable but
must be the same on each side of the equal sign. The function itself
be defined in terms of numbers, several variables, other
can
functions, or mathematical expressions. For example:

DEF FNA(X)=Xt2+3*X+4

6-43

20 DEF FNCCX)=SQR(X+4)+l

The function

DEF FNL(S)=St2

will cause the later statement:
20 LET R=FNA(4>+1

to be evaluated as R=17.

The user-defined function can be a function of only one variable.

User-Coded Function (UUP)
The user-coded function is explained in detail in the next section.

6.9 IMPLEMENTING A USER-CODED FUNCTION

(UUF)

A special user-coded function is available in Cassette BASIC for the
prograiraner who
is familiar with the PD:p-8 instruction set and 27-bit
mantissa floating-point format. BASIC'S internal format is 27-bit,
sign-magnitude
mantissa floating-point; thus, all user-generated
values must be in that format and all coding must be compatible with
The user codes the function in the PDP-8 series machine language
it.
instructions, assembles it with the PAL(3 Assembler, and loads the
resulting binary file as an overlay to one of the existing functions
(ATAN, LOG, etc.) Thus, while BASIC is running, this special
function
can be requested and used in a fashion analogous to the built-in BASIC
functions.
The user-coded function, if present, is specified in the
BASIC program as:
UUF{n)

where n can be any BASIC expression.

6.9.1 Coding Formats
Due to memory restrictions, the user-coded function must replace one
or more of the existing Cassette BASIC functions. Table 6-2 lists the
functions which may be overlaid and the areas of memory they occupy.
Also listed is the transfer table address through which BASIC calls
the given extended function.

6-44

Table 6-2 Function Addresses

Function

Locations Occupied

Transfer Tadjle Address

FNA
ATN
SQR
RND
TAB

5453-5546
6200-6271
5412-5452
5350-5406
5547-5572

1131
1134
1137
1143
1147

The functions SIN, COS, and TAN are interdependent, but all three may
be deleted as follows:
SIN
COS
TAN

5600-5674

1132
1133
1144

Almost a full page is freed by deleting the following:
FNA
SQR

5412-5572

1131
1137
1147

TAB

For each function replaced by the UUF, the user must set the
corresponding transfer table location to point to an error routine so
calls to that function will generate an error
that accidental
condition rather than a spurious call to the UUP. The \iser does this
by inserting a statement such as the following in his UUF:
+ 1143
64/!ll

ADDHESS FOR R^JD
/P0IMT5R TO SYN)TAX ERROR RO'JTINE
/TABL'=:

requd.red
for the
To include a user-coded function, all conventions
PALC Assembler must be observed. The coding language is PDP-8 machine
the
modified
in
language code, but can include instructions
floating-point package, which is described later in this chapter in
Section 6.10.

When floating-point statements are to be included in the program, it
necessary only to indicate the start of floating-point notation by
is
including the following operator:

FENTER
immediately before the first floating-point statement.
floating-point coding is terminated by the operator:

Similarly

FEXIT

immediately after the last floating-point statement. There can be as
many sections of floating-point code as necessary in the. program, but
each must be delimited in this mcinner.

6-45

6.9.2 Floating-Point Format
The floating-point format used by Cassette BASIC allocates three
storage words in sign magnitude convention as follows
(in sign
magnitude convention the sign bit rather than the mantissa, expresses
the sign of the entire number)

WORD 2

EXPONENT
-SIGN BIT

Five memory locations are
accumulator, as follows:

used

represent

the

floating-point

Table 6-3 Floating-Point Accumulator

Location Name

Value

ACS

0024

Sign

ACE

0025

Exponent (200 octal biased;
i.e.
the constant 200 is added
to the exponent to make the
range 0-377)

ACl

0020

High order word

AC2

0017

Mid order word

AC 3

0016

Low order word

Contents

All of BASIC'S mathematical operations are in floating-point format;
therefore, if any temporary storage locations are required by the UUF
subroutine, they must specify three words. For example;

UTEMP>0;0;0

6.9.3 Incorporating Subroutines with UUF

When adding a user function, it becomes necessary to reference some of
Cassette BASIC'S subroutines at specific times in the coding. Most of
these calls are needed in order to preserve a compatible format
throughout the system. The BASIC subroutines which may be referenced
(The complete BASIC symbol table is included as
are described below.
Tcible 6-7 at the end of this chapter.)

6-46

BEGFIX
If a value is to be returned to the accuiniulator as a result of the
user function, tliat value must be in noiinalized floatin<j-point format.
If floating-point arithmetic is used throughout the user
function,
then
the value in the FAC
(floating-point accumulator)
is
in
normalized floating-point format and need not be converted.
If
fixed-point arithmetic is used anywhere in the function, then the
subroutine BEGFIX must be referenced before the value (::loating-point)
is
saved in order that the storage locations are properly initialized
to accept a floating-point value.
Using this procedure, the five FAC
locations are prepared accordingly. However, because the value to be
stored only requires 12 bits, a subsequent DCA AC3 statement is
BEGFIX is located at 3760 and is called via a JMS
sufficient.

instruction.

ANORM
If a fixed-point value is added to the FAC, ANORM normalizes
the
in
order that it be in a format suitable for Cassette BASIC.

FAC
The
routine supplies the acceptable values for the locations ACE, ACS, ACl
and AC2.
ANORM is assigned the location 4600.

FIX
To convert a value in the FAC to an integer, as when printing
character, the subroutine FIX is called; it is located at 4744.

6.9.4 Writing the Program

A user-coded function must respt one of Cassette BASIC'S tables to
recognize the function, otherwise, UUF is considered to be an
undefined fionction. The pointer is at location 1150; a statement such
as the following is required:
*1150
UUF

Procedures for loading a user-coded function are contained in
Examples of user-coded functions follow.
6.11.5.

Section

6.9.5 Examples of User-Coded Functions

—

Example 1 This program calculates squares and square
series of values. The BASIC program is as follows:
100
110
120
130

FOR A=33.1 TO 33.9 STEP
PRINT A*'rJF(A>*SQR(A)
NEXT A
END

6-47

roots

for

The user-coded function is
PALC-V/l

18/87/72

PAUB'

/'JSER-CODED FiJiMCTION TO CALCaLATE
/SQtJARES OF NUMBERS
/

4435
2000
0200
6000
0000
01 134

6441
1134
6441

01 150

6200

06200
06801

06208
06803
06804
06805
06806
06207
06810

/THE FUNCTION LOADS INTO FIELD
/INTO THE AREA OCCUPIED BY THE 'ATN'
/FUNCTION
FENTEP[=4435
FST=2000
FWD=800
FMP=6000
FEXIT=:0000
SXERR=:6441

*U34
SXERR
*1150

150

6200
0000
4435
2204
6803
0000
5600
0000
0000
0000
0001
3000

/SO REFERENCES TO ATN WILL
/YIELD AN ERROR

/DEFINE

UfJF

IJ'JF

FUNCTION TABLE

*6200
UIJF,

FENTER /INTO FLT.PT.PKG.-A
FST+FWD+X-.
/SAVE A
FMP+FWD+X-.
/A*A
FEXIT
JMP I
UUF
/ALL DONE
X*

FIELD
3000

;

IN FAC

;

/TO START BASIC WHEN LOADED

PALC-Vl

FENTER 4435
FEXIT 0000
6000
FMP
2000
FST
0800
FWD
SXERR 6441
6800
TJF
6806
X
output after execution is:
HUN
1095.61
33.1
33.2
1 108.24
33.3
108.89
33.4
1 1 15.56
33.5
1 188.85
33.6
188.96
33.7
135.69
33.
148.44
33.9
1 149.81
1

1
1

5.75386
5.761944
5.770615
5.779873
5.787918
5.796551
5.80517
5.813777
5.888371

READY

6-48

18/27/78

PAUE 1-1

—

Example 2 The following program tests a student's ability to convert
the octal value in the console switches to its decimal equivalent.
Line 120 will set P equal to the decimal value of the setting.
Line
130 determines if the correct answer was typed:
100
110
180
130
140
150

PRINT "WHAT DECIMAL VAL'JE DO THE SWITCHES EQiJAL?"
INP'JT

LET P = 'J'JF(0)
IF P = JJ THEN 800
PRINT "TRY A(iAIN"
GO TO 100
200 PRINT "CORRECT"
300 END

The user-coded function is:
PALC-Vl

13/37/73

PAtiE

/'.ISER-CODED F'INCTION TO READ THE CONSOLE
/SWITCHES AMD COMVERT TO FLOATIML. POIMT
/

/THE FWCTION LOADS IMTO FIELD ZERO
/INTO THE AREA PREyio'jsLY occ'jpie:d by
/THE •H^JD F'JMCTIOM-THE RANDOM NvFMBER
/UENERATOR
/

3300
4435
0030
4030
8030
0230
3763
4630
3016
6441
1

FIELD
FeNTER=4435
KEXIT=3333
FAD=4003
FST=a030
FWn=333
3E(jFIX = 3760
AHOHM=4603
AC3=16
SXERR=6441

143

SXERR

01113

6441

aiisn

5353

iJ'IF

053S!1
!?53S1

5353
3300
4756

*5353

PI535a

7604

LAS

PI5353

3316

DCA

05354
05355
05356
05357

4757
5750
3760
4630
0031
3033

JMS
JMP

/SO REFERENCES TO H.MD
/WILL YIELD AN ERROR

*1 153

150

'DF,

/DEFINE

'JiJF

IN F'INCTION

JMS

'IBEUFIX /PREPARE FOR

/INTEUEH VALJE
/UET CONTENTS
/OF SW. REli.
/SAVE IN LOW
/ORDER FAC

ACS
I

')ANORM

:j'JF

/NORMAL
/RET JRN

;1E

'JBElJFIX.BEUFIX
lANORM, AMOHM

FIELD
*3330

/TO START

')P

BASIC JHE.M LOADED
PALC-yi

3316
ANORM 4603
BEUFIX 3763
4030
FAD
FENTER 4435
FEXIT 0033
2300
FST
3P03
FWD
SXERR 6441
JANOHM 5357
JBEGFI 5356
5353
lUF
AC 3

6-49

ia/27/7a

page i-i

An exeunple of a run
swi tches f ol lows

which

200 (octal)

was

set

;Ln

the

console

RUN
WHAT DECIMAL VALUE DO THE SWITCHES; EQUAL?
?120
TRY AGAIN
WHAT DECIMAL VALUE DO THE SWITCHES EQUAL?
?ia8

CORRECT
READY.

6.10 FLOATING-POINT PACKAGE

Information concerning the PDP-8 modified Floating-Point Package which
the programmer will find useful in coding a function follows.

6.10.1 Instruction Set
The legal instructions in the modified Floating-Point Package used
Cassette BASIC are explained in Table 6-4:

Table 6-4 Floating-Point Instructions

Meaning

Instruction Value
FST

2000

FLD

3000

FAD
FSB

4000
5000

FMP

6000

FDV
FJMP
FENTER
FEXIT

7000
1000
4435
0000

FWD

0200

BKWD

0600

FSNE
FSEQ
FSGE
FSLT
FSGT
FSLE

0040
0050
0100
0110
0140
0150

Store the contents of the floating accumThe contents of the
(FAC) .
ulator
FAC are not changed.
relative
with contents of
Load FAC
address.
Add contents of relative address to FAC.
address
Subtract contents of relative
from FAC.
Multiply the contents of the FAC by the
contents of the relative address.
Divide FAC by contents of relative address.
Floating-point jiamp to relative address.
Start floating-point code.
Return to PDP-8
Exit floating-point code.
code.

Access a relative location in the forward
direction.
Access a relative location in the backward
direction.
Skip if FAC <>
Skip if FAC =
Skip if FAC =>
Skip if FAC <0
Skip if FAC >0
Skip if FAC <=

6-50

The following instructions require indirect (and relative)
addressing
and therefore only address field 1.
Their operation is the same as
the corresponding direct instruction.

Table 6-5 Relative Addresses

Instruction

Valu

Operation

FSTI
FLDI
FADI
FSB I
FMPI
FDVI
FJMPI

2400
3400
4400
5400
6400
7400
1400

Store
Load
Add
Subtract
Multiply
Divide
Jump

6.10.2 Addressing

The Floating-Point Package uses relative addressing.
Thus,
all
statements that address a location must include one of the operators
FWD or BKWD plus a reference to the current location.
Such a
reference is generally in the form:
op code instruction + FWD (BKWD) + LTEMP-.
The operator FWD is used when the address of the location to be
referenced is numerically greater than the current address; BKWD is
used when the address of the location to be referenced is numerically
less than the current address.
LTEMP-.
in conjunction with the FWD
or BKWD operator defines the relative address of the location to be
(LTEMP)
operated on
with respect to the current location. This
relative displacement is then used by tiie Floating-Point Interpreter
This can best be
to access the contents of the three wo3rds at LTEMP.
seen in an example:

4010 fad+fv;d+ltemp-.
4363 LTEMP»0;0;0

locations forward
The contents of that location which is (4063-4010)
from the current address, (i.e. the contents of LTEMP) , are added to
Similarly:
the FAC.
146 ALOC>0;0;0
«

152 FMP+BKWD+.-ALOC

At line 152 the contents of FAC are multiplied by the contents of the
(152-146)
locations backward from the current
location that is
address.

6-51

6.11 EDITING AND CONTROL COMMANDS

Errors made while typing at the console keyboard are easily corrected.
BASIC provides jspecial commands to facilitate the editing procedure.

6.11.1 Erasing Characters and Lines
(SHIFT/0, RUBOUTS, NO RUB OUTS , ^iLTMODE)

There are two methods available for erasing a character or series of
characters one at a time. Typing a SHIFT/O causes the deletion of the
(or
last character typed and echoes as a back arrow («-) on the LT33
(—
Teletype, or as an underscore
on most other console
35)
terminals. One character is deleted each time the key is typed.
)

The RUBOUT key (or DELETE key on some terminals) may also be used
deletion of characters one at a time providing the command:

for

RUBOUTS
This
has been typed on the keyboard before the editing is done.
command eneibles the RUBOUT key to be used and must be typed each time
If the user has neglected to type
this
a new program is in memory.
command, he may not use the RUBOUT key. A later command of:
NO RU)30UTS

disables the key for use.
For example
10 LEB-T

A=10*B

The user types a B instead of T and immediately notices the mistake.
He may type SHIFT/O (or RUBOUT key, if enabled) once to delete the B,
are to be
(and as many times more as characters, including spaces,
After the correction is made, he may continue typing the
deleted).
The typed line enters the computer only when this RETURN key is
line.
Before that time any number of correctionis can be made to
pressed.
the line.
20 DEN F---F FNA(X*y)=Xt2+3*Y

When the RETURN key is typed, the line is input as:
20 DEF FlMA(X>Y)=Xt2 + 3*Y

Notice that spaces, as well as printing characters, may be erased.
The user may erase an entire line (provided the RETUR]^ key has not
been typed) by typing the ALTMODE key (ESCAPE key on some keyboards)
BASIC echos back:

6-52

;

DELETED
at the end of the line to indicate that the
line has been removed.
The user continues as though it were a new line.
If the RETURN key
has already been typed, the user may still correct the line by simply
typing the line number and retyping the line correctly. He may delete
the line by typing the RETURN key immediately after the line number,
thus removing both the line number and line from his program.
If the line number of a line not needing correction is
accidentlally
the SHIFT /O or RUBOUT key may be used to delete the number (s)
typed,
the user may than type in the correct numbers.
Assume tile line:

10 IF

A>5 GOTO 230

is correct.

The programmer intends to insert a line 15,

but

instead

types
10 LET

He notices the mistake and makes the correction as follows:
10

LET-—---5 LET X=Z-3

Line 10 remains unchanged, and line 15 is entered.

Following cin attempt to run a program, error messages may be output on
the console terminal indicating illegal characters or formats, or
other user errors in the program. Most errors can be corrected by
typing the line number (s)
and correction (s) and then rerunning the
program. As many changes or corrections as desired may be made before
runs.

6.11.2 Listing a Program (LIST, LIST and LPT)

An indirect program or data can be listed on the active output
by typing the command:

device

LIST

followed by the RETURN key.
listed.

The entire

program

(or

data)

A part of a program may be listed by typing LIST followeid

will

by a line
This causes that line and all following lines in the program
number.
For example:
to be listed.
LIST 100

will list line 100

cuid

all remaining lines in the progrcim.

6-53

The LIST command may be used in conjunction with the
follows:

LPT

command

This will list the current program on the line printer.
Control
reset to the console terminal after the listing is completed.

LPT
LIST

6.11.3 Running a Program (RUN, RUN and LPT)
a BASIC program has been typed and is in memory, it i;
This is accomplished by simply typing the command:

RUW
followed by the RETURN key. The program will begin execution.
If
errors are encountered,
appropriate error messages will be typed on
the keyboard; otherwise, the program will run to completion,
printing
whatever output was requested.
When the END statement is reached,
BASIC stops execution and prints
READY.
The line printer, if available, can be used in
RUN command, as follows:

conjunction

with

the

LPT

RUM

After this command is issued, all output during progreim execution is
diverted from the console terminal to the line printer, eliminating
the need of inserting the LPT statement within the program.
The
output device is reset to the console t€:rminal after execution.

6.11.4 Stopping a Run (CTRL/C, CTRL/0, CTRL/SHIFT/P, BREAK)

To Stop a program during execution or to return to the Keyboard
Monitor at any time, type a CTRL/C (by pressing the CTRiLi key and the C
key simultaneously) . This causes the current operation to be eiborted
immediately and the Cassette Keyboard Monitor to be re-bootstrapped
from the System Cassette.
(produced by typing the CTRL and
keys
O
The command CTRL/0
The
is used to stop teleprinter output temporarily.
simultaneously)
program will continue to execute but output will not be printed unless
an error occurs or unless BASIC is waiting for a command or for data
is
In the latter case, the console terminal
from an input stiitement.
the expected input device. This feature is particularly useful for
request
a
programs that print lengthy introductions and then
user-specified parameter. Typing CTRL/0 after the program is started
will cause BASIC to bypass printing the introduction and wait until

6-54

the parameter is specified, thereby saving the time required to print
the message.
A second CTRL/0 will resume output.

NOTE
For most programs that do not wait for
input from the terminal, processing of
the program after an initial CTRL/0 will
be completed before a second CTRL/0 can
be typed.
Thus, it is veiy possible for
no output to be printed rather than the
anticipated partial output.

Certain terminals (such as Teletype models LT33 and 35)
are equipped
with a BREAK key which may be used in Cassette BASIC to interrupt
program execution. Pressing the BREAK key causes a halt in execution
and a return to the BASIC Editor for more commands.
For those systems
containing terminals not equipped with the BREAK feature, the same
result can be produced by pressing the CTRL, SHIFT, and P keys
simultaneously.

6.11.5 Loading a User-Coded Function

A user-coded function is created using the CAPS-8 EDITOR; it is
assembled using PALC. The resulting binary file is loaded with BASIC
using the Monitor Run or Load commands as follows:
.R BASIC, drive #:filename

or
.L BASIC, drive #:filename

UUF.BIN is stored on cassette
drive 3.
Assume also that the file UUF.BIN has been coded so as to
include the correct starting address for BASIC. The user runs BASIC
loading the function as follows

Assiame a user-coded function called

BASIC^UUF

The starting address for BASIC is included in the program and coded as
follows
FIELD i
•31300
S

The new function may now be used in any files the user wishes to
and run.

6.11.6 Erasing a Program in Memory (SCRATCH)
The command;

SCRATCH

6-55

edit

SCR
is provided to
allow the programmer to clear his storage area,
deleting any commands or a program which may have been previously
entered, and leaving a clean area in which to work.
If the
storage
area is not cleared before entering a new program, lines from previous
prograuns may be executed along with the new program, causing errors or
misinformation. The SCRATCH command eliminates all old statements cind
numbers and should be used before ciny new programs are read into
memory or created at the keyboard.

Note that the SCR command does not clear the program name.
If
the
user wishes to create a new program with a new name, he should use the
NEW command which also performs a SCRATCH.

6.11.7

Renaming a Program (NAME)

The user may change the name of the program in memory by
command

issuing

the

NAME
BASIC responds by asking:
NEW PROGRAM NAME-

The user specifies a new filename (and extension, if desired) .
This
changes the name of the program without, affecting its image in memory.
All subsequent references to the program must use this new name.

6.11.8

Saving a Program (SAVE)

Once the user hais created or edited a program, he may \jant to save the
new version on a cassette for later use. He does this by typing:

SAVE

BASIC asks;
UMIT #<0-7):
to which the user responds with the number of the cassette drive on
which he wishes the program to be stored. The progrcim is saved under
its current name that is, the name used in BASIC'S initial dialogue,
(If
or its new name if the NAME command has been used to change it.
the
the filename is the same as one already present on the cassette,
old file is replaced by *EMPTY in the directory and the new file is

—

6-56

written onto the cassette.) After the program has been
still in memory eind may be RUN or edited further.

saved,

Attempting to save a program on a full cassette causes BASIC to return
to the editing phase; the user must save the program on another
cassette.
If the user does not specify a name for his program in the initial
dialogue
(by
responding with an ALT MODE to the NEW PROGRAM NAME
request) , the program will be saved under the
assigned
name
NONAME.BAS.

If the user SCRATCHes
a program,
creates another program without
assigning a name to it by use of the NEW or NAME commands, and then
attempts to save it, it will be saved under the name of the last
program which was in memory, possibly deleting that program if saved
on the same drive.

6.12 CASSETTE BASIC ERROR MESSAGES

BASIC checks all commands before executing them.
If for some reason
it cannot execute a command, BASIC indicates this by typing one of the
following error messages and the number of the line in which the error
occured. The form is:

ERROR MESSAGE AT LINE XXXX
Table 6-6 lists
execution.

the

errors

BASIC

checks

for

reports

and

before

Table 6-6 Cassette BASIC Error Messages

Message

Meaning

ARGUMENT ERROR

CHAIN ERROR

A cassette error occurred while doing
program chaining; the user should not
attempt to run the prograni in memory

function has been
argument; for example:

given an
SQR(-l)

illegal

again.

DATA ERROR

There were no more items in

EOF ERROR

An attempt was made to reeid past the
end-of-file
during
run- time
input.
Program execution terminates and control
returns to the Keyboard Monitor.

EXPRESSION ERROR

One of BASIC'S internal lists overflowed
while
attempting
to
6'valuate
an
expression.

FILE NAME ERROR

A mistake or illegal character was found
in the user's specification of a cassette
drive # or file name in either a CHAIN or
an OPEN statement.

6-57

thie

data list.

Table 6-6

Cassette BASIC Error Messages (Cont'd)

Message

Meaning

FILE OPEN ERROR

The user attempted to open a run-time
output file when one was alre.ady open, or
a hardware error occurred.

FOR ERROR

FOR loops were nested too deeply.

FUNCTION ERROR

The user attempted to call
which had not been defined.

GOSUB ERROR

Subroutines were nested too deeply.

function

ERROR

The user attempted to do run--time input
and output to the same cassette at the
same time.

IN ERROR

A cassette error occurred while attempting
to carry out an OLD command or while doing

run- 1 ime input

LINE TOO LONG

LINE

ERROR

A line of

more than 80 characters was
entered; BASIC ignores the whole line and
waits for the user to enter a new line.

A GOTO, GOSUB, or
nonexistent line.

referenced

LOOKUP ERROR

BASIC could not find a run-time: input file
on the drive specified.

NEXT ERROR

FOR and NEXT statements were not
paired.

NO FILES ERROR

The user attempted to do run- time file I/O
without first specifying so during BASIC'S
initial dialogue.

OUT ERROR

occurred
An error (proba!bly end-of-tape)
while doing cassette output either during
If the
a SAVE or during run-time output.
error occurred during a SAVE, the user
should retry the SAVE to a. different
cassette.
If
the error occurred during
he should re- run his
run- time output,
program using a different cassette for
output.

RETURN ERROR

A RETURN statement was issued
under control of a GOSUB.

SUBSCRIPT ERROR

A subscript has been used which is outside
the bounds defined in the DIM statement.

6-58

properly

when

not

Table 6-6

Cassette BASIC Error Messages (Cont'd)

Message

Meaning

SYNTAX ERROR

TOO BIG, LINE IGNORED

The combination of program size and number
of variables exceeds the capacity of the
computer.
Reducing one or the other may
help.
Otherwise, the user must break his
program into
parts
and
chain
them
together.
A
large
number
of DATA
statements might be put into a run-time
input file.

command did not correspond to
the
language
syntax.
Common examples of
syntax errors are misspelled commands,
unmatched
parentheses,
and
other
typographical errors.
Reference to an
undefined
UUF will also produce this
diagnostic.

The following programming errors are not reported by Cassette
BASIC, but instead are used in the computation as specified. They
are included here for the programmer's reference.
1.

Attempting to use a number in a computation which is too
large for BASIC to handle will produce a result which is
meaningless.

Attempting to use a number in a computation which is too
small for BASIC to handle will result in the value zero
being used instead.

Attempting to divide by zero will produce a result which
is meaningless.

6.13 CASSETTE BASIC SYMBOL TABLE

Table 6-7 lists the Cassette BASIC symbols and their values.
This information is useful when writing user-coded functions.

6-59

Table 6-7 Cassette BASIC Symbol Table

/POP-8/fc CASStTTE BASIC

ACE

fciy^S

AcN

a« 1 7

ACS

0He::4

AC)

tJMaV!

AC?
AC^

^P 1 7

CLUSt
CLOSED
CMSwCH
cnamst
CNCLk
CNtRP
CNTFnO

B«lh

C ^J r L

AHCDEF

Ann

RES

1763

P7 1

biiPlB

OvLOOP b245

117^'

Owi?IT

0176
na5a
0141
05W1

ECHO
EOIT

7a« 7

1301

UUh*)

LNilO

1U6M
314

CnuELO I?!0P'4
COLUMN «130
COMCK
P?77

ALi

AMATCH
ANOPM
AhGERR

^hf^t
«*)5a

LdiiMAS 61715

bSkJ^!

LOMKON 3377

ahyia

COi-'ON

7-^47

ARi-LOC

<A'^i^:i

Ak 1

4aK?

ASKAGN WS"^
ATLINt b4b)

11?3
13b7
CONST
COkEIN PI423
COS
Stl6
L (Vv T

14 3

AT^^HIG
ATNilOW

^^t""!

URlF
LkLFU

6531
52S7

6<?£e0

CPLFPi*

37'^fc

AT^NPt

bP.-i?

HaOCHN

7i,?b4

CK wDS
KEr.t-ix

a "d

t-Hifib
CTklC
CTKLCJ 7604
LTHLZI ^fcSe?
CTH/CK 'Ml 3
CTKZhP wH'i5i?
tvlLOO "^ViP.e

fiKfAK

bS,?,P

hSKIP

^73S

rtLiFtMD

b?/it1

UFCExP H043
uECFHA <343
UftPEK ^I53lri

MljE&T

bat.'tl

UEF

lb75

LELKTE

*>b01

L'FVCOH

rsba

A T f^

(:<

^ t" B

s?*?'-!

CAM
7t'r'V
CAPKET Shha
C ASINi

hbl 4

CaSOUT 6/i/3
OHaf'
CCNT«
CGtT
be.bt
C M A 1 M
ChA(.-Nt

A 1 AEK

Ibl, UP

317 6
6b^7

/ i1 i 1

I It

6 tt 7 ri

«l'Vl

iy 1

CHAW OK a>>al,
ChtCKw e;i4U
CHK.en f>4^^ifl
ChN:FWh( 358P

HF LA

blVLP
OIvxTt
UOITNU
uPuEN
SW

FATiNTT

biiSl

4/H5

FulGIT
FDV

3 335

i>l

I/-I

CMNMS

3 56 i

DCK'iCi^T

Chftr-ET

04 1 /

uor7E«^ 6576

CKhKAK t34a

u P r L A t>

C K C, T W Z
r, L E A » V

uf.Uf.TX

C L I- V

CLOS

b
kii^^b

6 ">

0746
00ki0
FtXlT
FEXPCl 6072
FtXPC2 6075
Ft)(PC3 6100
Ft XHC4 6 103
FtXPC5 6106
FE)(PC6 6111

Ft^(P

l^'

3i^!42

334^
3162

uOuHTK "6 2'D
I'P

C-h)

6bS7

ICK

7.<3/

F'DWl

OfUb

it'ic3

000
7400
FtNTfcP 4435

3341
1247

Ci-f-'G

4 1 4
(? a b a

FATNAX 627 3
FA PNC
6337
FaTNCH 634?
FATnCJ 6345
FATNCl 6304
FAFNC? 6307
FATNC3 6312
FATNC4 6315
FATNC5 6320
FATNC6 6323
FATNC7 6326
FATNCa 6331
FATNC9 6334
FaTnSX 6?/2
FATNT
6276

6 7 f?

64 4

FALT

VihlH 3«e21
UlulMl 3^?2
U Ib I T

6731
7023
2412
2400

ENOLIN 57fc)2
EMINM
733?
EM3NUM 3321
ENOPDL 5743
EMEP 6404
EOFAO
4526
EOFkTN 665M
EHTR
k)060
EKKOR
4136
EVAL
1000
EvALGO 1004
EXECljT 0213
2407
EXIT
6H00
EXP
EXPGOO b242
ExPcnN 5764
EXPOK
5265
EXTLOC 0224
FAO
4000
FAOEXT 1314
4 400
FAO I

CNlLOZ «134

ALLOC

ALTMOD

EM.)

It^bV'

ALf<^:LP
AL L ^

l?/Z7/12

PAi.a-v8

6-60

PAGE 51

FEXPF
FEXPI
FEXPU
FHER
FILALT
FILNAM
FILNR
FILl
FINOIT
FINOLU
FIOER
FIX
FIXEXI
FIXITU
FIXLIN
FIXLUP
FIXUP
FJMP
FJMPI

6067
6061
6064
5117
0367
0600
1356
0606
0560
0566
7135
4 7 44
4 7 73

5200
2135
4750
5143
1000
1400
FJUMp1130
5000
FLD
FLUI
3400
FLOGCl 6172
FLQGC2 6153
FLOGCS 6156
FL0GC4 6161
FMP
6000
FMPT
6400
FMTENF 5121
FMTl
5123
FMT2
5051
FMT3
5126
FN
5453
FNtRH
5172
FNEXIT 1200
FOR
0415
FOHCT
0065
FOROON 0663
FORERR 0503
FORLIM 0721
FORLIS 5744
FORSTE 0724
FORVAR 0454
FOUND 0576
FPAOO 4456
FP&nUR 4504
FPOIV
466/
FPOOIT 4237
FPFLAG 0154
FPGOrn 4273
FPJMP
4317
FPJUnP 4274
FPLAC 4351
FPLOOP 4202
fPMUL 4530

Table 6-7 Cassette BASIC Symbol Table

/P0P-8/£ CASSETTE BASIC
FPNOAD
FFOPER
FPPG7
FPSKIP
FPSTQ
FPSue

4305

GETOPR
uFTUNi

a?.?.!

tjEfVAR

a31«
4322
4U55
420H

1243

bEfWD
bLOnp
uNtXT
GObOTH
bOLIST
bn&UB
GOIEMP
bOTiT

12fol

U-OTITI

5n0a
1?P2
2101

i^OTSS

PAL«-V8

12/27/72

r-Vlf,?.

1557

0573
0434
4034
4076
0553
0272
4007
7316
2027
lNSt<T5 2025
6434
INT
IM»IDTM 4136
lONAM
0227
lOUNJT 1301
IPNDPE 4024
ISDEF2 3511
ISUIG
6532
ISOIM
1472
4564
ISIT
ISITOF 0551
ISITFU 1105
ISITLI 4100
4422
ISITl
ISLIT
4127
ISSDME 1643
ISU^^IN 1010
ITSDEF 3513
ITSOP
3217
ITSt
3253
nSOP 1220
ITSP
3270
6660
lUNlT
jBPtNT 3707
JISOIG 3344
JMATCH 2770
JPUTCH 0763
JUST0
3142
JUST0F 3152
JUSTBP 3155
3137
JUSTl
JUST2 3141
KbUiN 0421
KbDINP 7626
KHUFEN 6762
KbUFST 6737

f-itX

Pf-ifc 1

XFl

KfcPTW

GfeTADD

14C.".''

FPT

a27(7i

FPTfcMP 457f>

FPTH
FPZOIV
FPINP
FRINPI
FRMDx
FROUT
FkSTNE
FSB
FSBI
FSFQ

0061
4V3fe

50fc'0

5400
a^lb?!

FSGfe

0l0fi

F s (.- T

i/'lau

FSINCI
FSIMC3
FSIKC4
FSlNCb
F8IMC6
FSINC/

bTlS
b7l6
57?!
5/24
5727
5732
FSItviM4 5735
FSI'vjOK 5657
5705
FSlNZ
FSINZZ 5710
FSIN10 5b41
1.31 5W
FSLt
FSLT
ann
FSNtfc

I3B4P

FSOkX
54P7
2i:S0C'
FST
24P0
FSTI
FT4NT1 567'
FTANT2 57i^2
Fu^JTAB

1131

FUPKCI 5Vb2
Fwo
/isrc^
FVXPFX fei123
7242
GALT

GhTbLK I7t»
r, P.

2 Cn»

GhTCHk tin/
GtTCS «7 12
Gfcinf

k?27 5

GtTj

17b5

GtTLIN 2^tl2
GtTL«t 2577

I^LC)OP

11^12
0^240
C1303
1^177

INUUPF
INPUUP
INPPTR
InPSET
INPTN
INPUT
I\PUTN
INSERT

2711
«b07
0534
5764
PI507
P'tiSS

7207
721^
Gtno
M521
GOiOPK 1202
11^.71

GOTSTE 0634
bOUT
7244
GPTR
KKfe2
b«tJ
7223
GPUELA 7221
GSriEND S777
bSBPTW f*163
GSSl
1555
GSS2
155b
GToKLP 1722
GTtMP
727115
ijTJMH
0442
btjMPl v^42/f
oTPTR 0(^36
HAP
043 7
PI451
HALF
filGHwD 4333
MLOOP
?t>77
27 31
nLOPl
HLP
4163
HMOL«<
h800
nPfP
0063
lAMLES 2103
ii'SiOO
6764
lAO

1257

iCASEP 5157
iruiJNT ^062
JEKR
6663
iti(TL.C

02 35

0372
0403
IGMOkE 2137

ImmEl)

007 7
0231
KICiNOP 1676
KEYlAiU

n55

KM200 ZI/ilS
KM4H0a 2170
K50M0
2167
Kb201
7005
LAStKK bfel2
LttEGIN 5622
LtftP
3355

IMMEOA 1155
iN
3430
iNCHN
7 403
(^131
JNUPV
iMUFxi ''nn4
lNUEx2 0015
iN'LCTM 4t!77

6-61

(Cont'd)

PAGE 51-1
LET
LETDO

LETTER
LFXLUP
LHALF
LIMIT
LINBUF
LINENO
LINFIX
LIST
LISTAL
LISTLU
LISTSO
LIST2
LIST3
LIST4
LISTS
LITRAL
LJMS
LKER
LKERR
LLSOUT
LNQENO
LOADED
LOCCTR
LOCTEM
LCCTMP
LCG
LCGACE
LCGFwO
LC'GOKW
LC'OK

LOOKER
LOOKUP
LOWLOC
LPTQUT
LLIKERR

LUNIT
LLIP

LUPF
L4LUP
MAYZER
MEiHEAK

0304
0205
3445
2331
3067
1600
5551
0054
2326
3600
3610
3612
3611
3636
3655
3661

3676
3123
7255
1312
0330
7400
3626
4123
0045
0671
1677

6114
6165
6164
6167
0306
7310
7002
2166
7347
0326
0332
3404
0430
3664
4612
7603

MENOLI 00<11
MENOPD 2361
MGOLIS 0720
MGSrtEN 0527
m:;nus
1316
MLBEGI 0171
MLEMD 0172
MLINbU 0040
MNSONE 0736
MONITR 0100
MOREDI 6470
MQREIN 4000

Table 6-7 Cassette BASIC Symbol Table

/P!)P-8/t LASStTTK F^ASIC

PAl.b-v8

MOkfRO lt£C

rjO'HER

Movfc

^aic'i

^OIKkU

MOVLUP
MPkJNT

<il^t

NOT MOW

011100

fct!!c3

fjUrsUN

Oil

MPY

b ?? 1

MpVLUH ubb?
MfOA

0'437
PI3P5

1776
3271
MOITXT P236
IMOIVAK
NOlXll^

^^236

MUL

/St;l
7ac'l

MSTt-ei

a^iS

Nsr MTA

M7 X y 1 T

i 1 7 3
"'37 1

inTCmAN

122i(;

J5?b7

NIILiM

1201^

MinHIJf-'

MULCLrt
MUL^-XH

MULxTt iiatfi
MULXl
33/1
MU5TBE aShfe
NAM
ti3^?
KAMCHK 0hSl

N(UYtT 6741
53

MAMfcK

003?

UCbUNT

5335
M7?b
3124
4435
2574
5205
8761

NAMLOC

i<l316

uEh'R

67 5/

MCTHL;£

hTi'i

UIH

HfW

UJUMH

7^5 7
1276

1ii5 7

Nfc'.'JflO

U-ibi!

ULUdO

10h2

NtWLlN

'dhi'h

lU:^

ULL.KLr,
UL'JMfcS

Pi.'ifS

Mfci-'MES

Nt^T

ff. ().-.)

ULUnP

('!H7ii

NtXTfeR Pfo/3

ULL'3

NtXTR

UML

11 PIP''
1^147

(-1

10 3 7

U 7

NUPCHK
Mi/ULMS

JtCO
uCAStff
UC:C

t'l.

t > T V A

M-MtS

t7b7
0^37
g^t:7

Nt-DPEN b3bS
N'M
lf143
NOPLiMP 463?
^OCHNiG 304k1

MOCOM
NDCOMM
NOCk
NHNbLN
MONZEK
NHPAWE
NOPCP
NOPE
NOBLFT
NORMED
NORMIT
NORUHO

4C156

3104
5KH4
103?

UPtRAN
OPNERR 1354
UPUTAB 71316

i???0

UPS

l?026

7147

OPl

Vi0?'i

S?.i<i

ap2
0P3
OTtMP
0T£MP1
OTHER
OUNIT

^0Z^
0021

b207
5574
1457
N'OSSl
N0SS2
1452
NOT
3426
NOTbAD 2153
NDTl^lG 4620
MGTCP
3P123
NOTEM 6626
NOTFUL 6712

2 7 72

077

1562
2356
^762
2745
514 4
3352
0027
3353
0064

07700
u7706A
O7706C
07715
07725A
07725»
07737
07740
07741
07743
07745
07/53
07762
07763A
07/63B
07764A
07764R
07764C
07766
07770
07771
07772
07773
U7774
07776
PACN

1151

0153
3350
5344
0175
01/4
02 3
1366
Oc'i3
3770
0240
0051
0253
5145
0255
5146
0256A
5153
0256B
6575
0260
0012
02/
3345
0305
5147
032
3115
036
2771
03734
1152
03737B 0776
03755
1273
0377
00/3
04
0156
040
2777
04014
1153
042
3103
04200
3102
04213
1154
05400
5347
0046
06203
07
0074
0700
1272
O7000A 2565
O7000B 3473
07077
1275
0/520
5150
07545 4777
0/570 6456
07577
4577

12P1K
1/075

uPuTC

07600
07603
07610
O7640A
076408
07673

0200
O2040A
02062
0212
0215

3575

1314

2171
3547
506
2357
0067

02
02

Pfc30

fea?3

0013

0177
017/0

UMtDIM U'61
ONtSS
1B73
OrLVl
5312
UC76l^0 5452
00/736 2324
OPuONE 1203

1271

7012
3(^00

6760
OUPSET 1026
OUTDEV 0133
QurD2 013?
UUTNUM 5000
UurOK
1332

6-62

PAGE 51-a

Ola

01 /4B

OPt
OPtN
UPtNl

6)76
ti3(?7

1^/27/7?

0110
012
0122
013
014
O140A
0140a
017

\\IA?.

(Cont'd)

PAD

PAOOQN
PAKBUF
PALI

PANOKM
PAKGER
PARI

PASSCR
PBARKD
PBEGFI
PCCUNT
PCHKFI
PCLOS
PCOMMA
PCQwT
POL

POLIST
PEOIT
PENON
PENONM
PERMSY
PERROR

4345
2774
5345
0754
2765
3306
0140
2610
6544
3472
2775
3075
3346
3116
0056
3743
4743
0160
3101

2325
0761
3076
1274
3077
3351
5151
0057
5152
5154
5346
1561
3347
4/42
0347
0741
0763
0146
0144
0047
0145
0474
2773
1773
0744
0161
0143
0273
0137
0036
5703
0122
0271
0365
5111
0101

Table 6-7 Cassette BASIC Symbol Table

CASSfcTTP BASIC

/f'(iF-8/fc
P 1. 1^ s; w

H /a7

KKV AL

a 1 k' 3

P f- X k C U

P (- X P

5776

Pe 1

i-Ji

PPNEPhi

Ui 5

u'
"jSab

PFPLCO «5/S
PtETAIJ t?tta
PGfcTBL 0117
HLitTCH fcCJiS

PRETLI

aw^

PPKXgO
PPcNT
PKtStT
HPINbL
KKlNCn
PPINKX
PPINHA
PRINQU
PPIMSK
PPJNT
PRINTC
P»lMTG
KRiMrh

PAL6-V8
\\bi
S5ib
Ml3h

^?6feJ

?3?0
?17?
^^07
?t>Hb

0:?b'5

P I ^ T

b^78

PRM

Pi.'^iTL
PL ''» GI

:m7:^
v^ 1 /?

HPuGiMA

PLtrnO

t1?(;,ii

PLfcTTt 31 CM
PL J f- IT eS^b
PL I^HU

fe737

PL INK I

PL I ST

P L t T I? A

lb?

^b/n
33b u

da3

1114
PPoUbP 37??
i

tMP

l^ t^

PPTXPt 37?0
PSAve
?4b3
PSIjN
S675
PSKIPI Iblfe
PSLHUP «l?f.
PSPACE lbb0
p.") TICK
0l?3
tSlOP
3776

PLU?

b7yb
13iy

PMHk'EA

iiSbi;;

PMPY

blb5

psrovtt, 0114
PSxE«;k" 011712

^^Mrt^6

blbfi

pr.

PNe.u,LI

117 7

VMTA
PTAhOE

PNONBL
PNOTMQ
PNUMBU
POADU
PDIP
POP
POPERA
P0P3
POUINU
PPASSC

0124
db73

PTABf-L Sb71
PTArtLE 2776

iia'ia

PTtN
PTtXT
PTUBIG
PUatPP
PUbH

015((1

PIJTCH
PijTEK

07 4 1

PLL'L.

PPOHS

01bb
a035
ixXh^
31.?1

aa3a
0121
011.?
k51c7
i?b72
i,7ai

PPERMS
PPPLOn
PPFORL 17ba
PPINT 606?l
PPOP
01i?j7
PPRINT 011f)
PPWINLI Bl?5
PPUSH 0106
PPUTCH 0333

S:3ERR
S:5FIX
SI50NE
SSTi^Q

0771

K C H hi

i-;"?:^

Pf.OLTS 21^2
PC-OTPP icM 11

QMK

RtAD
1622
PhADIT 6664
WtADLQ 80'»6
WtADY
6525
PELATfc 1342
WfcMPAC 3043
i^tCEER 6700
PeStTl 7072
HtSTOk 3771
PtTNEK 0713
HtTUPN 0677
PhALF
3071
RIGHT
0433
RIP
6661
RI^LtPT 6413
RMJ
5353
HNOJMP 5350
RTBEND 1600
PTilUF
1400
HTIOME 3103
RUBO
5573
RUN
2457
RUMC
2456
RUMIN 2510
PUNLUP 2472
RU^^INuT 2504
RIjN2IN 2550
RUN2LU 2521
RUN2N0 2544
SAVE
1000
SAVtl
2461
SCHMUR 1656
5CRATL 2445
SCRATl 0332
StARCH 1657
SETINC 0200
StrSGN 4512
St-N
0726
5IMPLV 3465
SIN
5624
SJUMP
0241
S^IPIT 0471
SKPSYM 2762
SLASH
1332
SLOOP
2675
SLSHTM 1337
SNUMFL 0066
SPACER 1163
SPLtFT 0142
SQEXIT 5450

Pir.r-.:(jw

P 1. 1 T V A

SQLOOP 5435
SQR
5412

P3l?b

Pr"??

at;s2
'ib70

0100
3021
SSas
2362
PIJTCOF 7014
7000
3b50
0647
eb57
3744
3117
?b71
3120
3122
2567
PZtWDO 65«5
PUTJ
PWhEPE
PXPORL
PXLlNb
PXXCKL
PXXFnF
PXXEXI
PXXLIT
PXxThE

6-63

PAGE 51-3

P7640 0722
QtPKOP 1571

??lb

•-HLP

1.S76

\?J?im

RBSwCH 0135

.?31^e?

?^?a
PPlNTr-' 73P^
PSiMTx 370^
PPIMI? PI 74
PkiMjM ?74b
PRi^Vw 3h51
PWLOOP 371

pr,tTnp

(Cont'd)

6763

STAR
S'^ARTH

STICKI
S'^OBUF
S'^QP

S"ORCH
S-OVAR
SWP
SXER
SKERR
TAB
TaSDES
TAriDO

TaBFLG
TaBL
TaBTHP
TAN
THEGFI
TEMP
TEMPS
TEN
TMESKI
TLSDUT
TMP
TOOLON
TPRINT
TRALUP
THANSF
TRYAGI
TRYAL
TRYALT
THYQLO
TRYSTE
TTYO
TTYOUT
TUBIG
TWIOTH
TWOLF
TWOSS
TVTPAK
TVQUES
UDOPER
UCIHl

UJM8
UMOPER
UMOERF
UNIT
UPARRO

1563
4/75
0336
0337
3005
1327
3000
6430
0747
2401
0704
0333
7521
0551
6441
5547
6375
6350
2343
3652
2360
5600
5572
0003
3102
0000
1353
7402
0031
5162
6376
2131
2126
5131
0270
0271
3075
0626
7024
7350
1173
2355
3557
1074
3046
1145
1363
3561
0004
1321

4645
0012
6457

Table 6-7 Cassette BASIC Symbol Table (Cont'd)

/PDP-8/fe CASSETTE BASIC

PALB-VS

UPARRX 5740
1,IPARR2 4365
nSERFN Ifel?
UTEH
0411
UTEMl
0021

XKTAN 5204
XXTeXT 5540
X)1THEN 5305
XXTO
5lfc5
XXTTYO 5437
XxUNA« 5542
XXUPAR 5122
X>:UUF
5253
X10
0010
ZCNTLO 7147
ZtMOON 5142
7.t«0
0150
ZHXtX 4767

yf.KSTl

(-.533

XGf<LiS7

VISIT

?270
71?4

XXbOSU 5321
*XbOTO 5300
XXCiT
514?
XXiF
5312
XXINPT 5332
*XlNPU 5337
XXINT
5231
XXLbRA 5163
XXLE
5124
XXLET 527a
*XLIS
5502
XXUIST 5476
XXLIT0 5545
XXLOG
5212
5i»tti4
xVLPT
XXUT
5145
XXMINU 5114
AXNAM S534
xvNiOMt 5530
XXNCOM 5447
XXMh;
5132
*VNEW
5525
XXNEXT 5326

VlSjn

0S2'^

JiXNHUB 5467

l.iUJMP

0ari0

laUHS

0401

ULiUJMS 0416

VAk

0335

VAi^TEM 0554

VSCHIN 3S23
VbCHLU 34ya
VSCHNO 3517
l^iAJT
6200
VUITR 6601?WOIEMP 1072
UjO»D
005E
I'iTEM
6613
xexfccu 0aia
XKISIT Ml"^

XNOST
/ay/
XMUSTl 05al
xptG2
0i^'ii
XHirC
0010
VkPlT
PCI 11
yxAhS
52<r3
XXATN
520/
XXf^?LS 5260
XxChAN 5a27
XXCLOS 5155
VxClSE 5U16
XXfJJMA

5ii55

yyCUMM 5151
XXCfj.S

5201

XXCRLE 5256
yxi:ATA

54ti2

XXOrF
XXDIM

53/2
5355
5135

XXt[>

xxtL
VXENO

514r'i

vyf•:NO^

54ij6

5454

b54l
514i
XxExIT 55aa
yxF.XP
5215
XXKINl 5543
XXFN
5176
vyfoP
5315
XXGF-;
5127
524S
Xxr,|-,T
XXf-nP
XXf-U

xxuDi

0005

xxQr)(J

0i/iP6

xxan3
XXULU
XXUPt>
XXUPN

0007
5522
5161
5412
XXUIJTP 5u22

XXHLUS 5ll<^
XXKRIN 52h7
xXHRNt 5262
XXPUI
5242
XXRBRA 5157
xxkEAD 537b
XXREM 53^6
XXkETR 534a
XXKMl)
5234
aXRSTU 5361
XXHue
5462
XXKUN S505
S517
xkSav
r.vSAvK 5513
Ay&r.hi
S51n
XViiEMl
xxb(iN
AXSlNi

SI 53

522b
5237
AX6LA3 5i20
AXbQK 5220
XXSTrtR 5116
xxSTtP 5171
xv.'^roP 53S1
xxlAp
5250

6-64

12/27/72

PAGE 51-4

CHAPTER 7
USING CAPS- 8 CODT

Using CODT, the programmer can run his binary program on the computer,
control its execution, and make alterations to his program by typing
at the Teletype keyboard.
CODT occupies any four pages of core, in the same field, that the user
desires. The user may change the location of these four pages of core
If the user progreun resides in the
by reassembling the source.
first
few pages of memory, then CODT should be loaded in the upper pages of
any
memory, and vice versa. The user progrcim cannot occupy (overlay)
location used by CODT, including the breakpoint locations (locations
4, 5, and 6 on page zero).

7.1

FEATURES

octal
CODT features include location examination and modification;
core dumps to the Teletype using the word search mechanism; and
The
instruction breakpoints to return control to CODT (breakpoints) .
user's program can run with interrupts on. CODT may reside in any
field, not necessarily the same as the user's field.

When debugging
The breakpoint is one of CODT's most useful features.
a program, it is often desircible to allow the program to run normally
up to a predetermined point, at which the programmer may examine and
possibly modify the contents of the accumulator (AC) , the link (L)
or various instruction or storage locations within his program,
depending on the results he finds. To accomplish this, CODT acts as a
monitor to the user program.
The user decides how far he wishes the program to run and CODT inserts
an instruction in the user's program v^hich, when encountered, causes
CODT immediately preserves in
control to transfer back to CODT.
designated storage locations the contents of the LINK and AC at the
breedc.
It then prints out the location at which the break occurred,
CODT will
as well
as the contents of the LINK and AC at that point.
then allow excunination and modification of any location of the user's
program (or those locations containing the AC cind L) . The user may
also move the breakpoint and request that CODT continue running his
This will cause CODT to restore the AC and L, execute the
program.
trapped instruction and continue in the user's program until the
breakpoint is again encountered or the program is terminated normally.

7-1

7.2

USING CODT

When the programmer is ready to start debugging a new program
computer, he should have at the console:

the

A binary copy of the new program on a cassette.

A complete octal/symbolic program listing.

A binary copy of the CODT program (previously assembled so as
not to interfere with the user's program).

RUN PROG, CODT

The binary of CODT must be the
automatically begins in CODT.

7.2.1

last

file

run.

Execution

Commands

SLASH (/)

— OPEN PRECEDING LOCATION

The location examination character (/) causes the location addressed
by the octal number preceding the slash to be opened eind its contents
printed in octal. The open location Ccin then be modified by typing
the desired octal number cind closing the location. Any octal number
Typing a fifth digit
from 1 to 4 digits in length is a legal input.
is an error and will cause the entire modification to be ignored cuid a
Typing / with no preceding
question mark to be printed by CODT.
argument causes the latest named location to be opened (again)
Typing 0/ is interpreted as / with no argument. For example:

400/6046
400/6046 2468?
400/6046 12345?
/6046
The memory field referenced is that field specified by the location in
CODT symbolically referenced by F. For example, if the contents of F
were 20, then the command

423/

would examine location 423 in memory field

7-2

RETURN

— CLOSE LOCATION

If the user has typed a valid octal numlDer, after the
content of a
location is printed by CODT, typing the RETURN key causes the binary
value of that number to replace the original contents of the opened
location and the location to be closed.
If nothing has been typed by
the user, the location is closed but the content of the location is
not changed.
For example:

location 400 is unchanged
location 400 is changed to contain 2345,
replace 6046 in location 400.

400/6046
400/6046 2345
/2345 6046

Typing another command
example

will

400/6046 401/6031 2346
400/6046 401/2346

LINE

also

opened

For

location 400 is closed and unchanged and
401 is opened and changed to 2346.

FEED— CLOSE LOCATION, OPEN NEXT LOCATION

The LINE FEED key has the same effect as the RETURN KEY, but,
in
addition,
the next sequential location is opened and its contents
printed.
For example:
400/6046
0401/6031 1234
0402/5201

location 400 is closed unchanged and 401
is opened.
User types chcuige, 401 is
closed containing 1234 and
402
is

opened

SEMICOLON

— CLOSE LOCATION, AND UNOBTRUSIVELY OPEN NEXT LOCATION

The SEMICOLON key has the same, effect as the LINEFEED key except that
the location and contents of the next sequential location are not
printed.
Therefore,

400/6046 3211; 4162; 5000
has the same effect as

400/6046 3211
401/6031 4162
402/5201 5000
This makes it convenient for the user
locations.

(SHIFT/N)

— CLOSE LOCATION, TAKE CONTENTS

change

several

MEMORY

sequential

REFERENCE

AND

OPEN SAME
The up arrow (circumflex) will close an open location just as will the
RETURN key.
Further, it will interpret the contents of the location
as a memory reference instruction, open the location referenced and
print its contents . For exetmple :

7-3

404/3270+
0470/0212 0000

«-

3270 symbolically is "DCA, this page,
relative location 70," so CODT opens
location 470.

(SHIFT /O) CLOSE LOCATION, OPEN INDIREICTLY

The Back arrow (or iinderscore) will close the currently open location
and then interpret its contents as the address of the location whose
contents it is to print cind open for modification. For exeimple:
365/5760+
0360/0426^
0426/5201

nnnnG—TRANSFER CONTROL TO USER AT LOCATION nnnn
Clear the AC then go to the location specified before the G (in the
All indicators and registers will be
specified by F) .
field
Typing G
initialized and the breakpoint, if any, will be inserted.
alone will cause a jump to location 0.

nnnnB

— SET BREAKPOINT AT USER LOCATION nnnn

Instructs CODT to establish a breakpoint at the location specified
If B is typed alone, CODT
before the B (in the field specified by F) .
the
removes any previously established breakpoint and restores
original contents of the break location. A breakpoint may be changed
to another location, whenever CODT is in control, by simply typing
nnnnB where nnnn is the new location. Only one breakpoint may be in
effect at one time; therefore, requesting a new breakpoint removes any
previously existing one.

A restriction in this regard is that a breakpoint may not be set on
any of the floating-point instructions which appear as arguments of a
For example
JMS .
TAD
DCA
JMS
FADD

BrecUcpoint legal here.

Breakpoint illegal here.

may not be set on a CIF instruction, nor on cui
instruction which is meant to be executed between a CIF and its
corresponding JMP or JMS instruction.

A breakpoint

A breakpoint may not be set on a memory
references an auto-index register.

reference

instruction

which

A breakpoint may not be set on a two-word EAE instruction, nor may
be set on ciny of the following instructions

7-4

SKON
ION
lOF

The breedcpoint (B) command does not make the actual exchange of CODT
instruction for user instruction, it only sets up the mechemism for
doing so. The actual exchange does not occur until a "go to" or a
"proceed from breakpoint" command is executed.
When, during execution, the user's program encounters the location
containing the breakpoint, control passes immediately to CODT (via
location 4, 5, and 6).
The C (AC)
and C(L)
at the point of
interruption are saved in special locations accessible to CODT. The
user's data field is stored in location D and his instruction field is
stored in location F as well as internally by CODT. The user
instruction that the breakpoint was replacing is restored; before the
address of the trap and the content of the LINK amd AC: are printed.
The restored instruction has not been executed at this time.
It will
not be executed until the "proceed from breakpoint" command is given.
Any user location, including those containing the stored AC and Link,
can now be modified in the usual manner.
The breakpoint can also be
moved or removed at this time.
An example of breakpoint
ITERATE LOOP...".

usage

follows

the

section

'CONTINUE

AND

— OPEN C(AC)

When the breakpoint is encountered the C(AC) and C(L)
are saved for
Typing A after having encountered a breakpoint
later restoration.
opens for modification the location in which the AC weis saved and
prints its contents. This location may now be modified in the normal
manner (see Slash) and the modification will be restored to the AC
when the "proceed from breakpoint" command is given.
Similarly, other key locations in CODT may be examined and modified as
follows

— OPEN CONTENTS OF LOCATION L (LINK)

F— OPEN CONTENTS OF LOCATION F

— OPEN CONTENTS OF LOCATION D (USER'S DATA FIELD)

7-5

NOTE

Whenever any of the locations A, L, F,
D,
M are referenced, CODT automatically
sets the value of F to be the field of
CODT.

— PROCEED (CONTINUE) FROM A BREAKPOINT

Typing C, after having encountered a breakpoint, causes CODT to insert
the latest specified breakpoint (if any) ; restore the contents of the
previous
AC and Link; execute the instruction trapped by the
breakpoint;
and transfer control back to the user program at the
appropriate location. The user program then runs until the breakpoint
is again encountered.
Regardless of the value of F, the C command resumes program execution
The user's
the precise spot where it had been previously stopped.
data field is first set to that specified by location D.
at

NOTE
If a trap set by CODT is not encountered
running the object
CODT
is
(user's) program, the insstruction which

while

causes the break to occur will not be
removed from the user's program.

nnnnC

— CONTINUE AND ITERATE LOOP nnnn TIMES BEFORE BREAK

The progrcimmer may wish to establish the breakpoint at some location
Since loops often run to many
within a loop of his program.
iterations, some means must be available to prevent a break from
occurring each time the brecik location is encountered. This is the
After having
function of nnnnC (where nnnn is an octal number) .
encountered the breakpoint for the first time, this command specifies
how many additional times the loop is to be iterated before another
The brecik operations have been described
is
to occur.
break
previously in the section on the B command.

Given the following program, which increases the value of the AC by
increments of 1, the use of the breakpoint command may be illustrated.

7-6

*200

0200
0201
0202
0203
0204
0205
0206
0207

A
B

CNT
ONE

7300
1206
2207
5202

CLA CLL
TAD ONE
ISZ CNT
JMP B
JMP A
HLT

5201
7402
0001 ONE ,1
0000 CNT ,0
0201
0202
0207
0206

0201B
200G
0201 (0;0000
C

0201 (0;0001
C

0201 (0;0002
4C
0201 {0;0007

CODT has been loaded and started.
A breakpoint is inserted at
location 0201 and execution stops here showing the AC initially set to
0000 and the link 0.
The use of the Proceed command (C) executes the
program until the breakpoint is again encountered (after one complete
loop) and shows the AC to contain a value of 0001.
Again execution
continues, incrementing the AC to 0002. At this point, the command 4C
is used, allowing execution of the
loop to continue 4 more times
(following the initial encounter) before stopping at the breakpoint.
The contents of the AC have now been incremented to 0007,

M— OPEN SEARCH MASK
Typing M causes CODT to open for modification the location containing
the current value of the search mask and print its contents.
Initially the mask is set to 7777.
It may be changed by opening the
mask location and typing the desired value after the value printed by
CODT then closing the location.

LINE FEED

— OPEN LOWER SEARCH LIMIT

The word immediately following the mask storage location contains the
location at which the search is to begin. Typing the LINE FEED will
open for modification the first location after the mask, and its conInitially,
the lower search limit is set to
tents will be printed.
0001.
It may be changed by typing the desired lower limit after
that
printed by CODT, then closing the location.

7-7

LINE FEED

— OPEN UPPER SEARCH LIMIT

The next sequential word contains the location with which the search
to terminate. Typing the LINE FEED key to close the lower search
is
limit causes the upper search limit to be opened for modification and
Initially, tlie upper search limit is the
contents printed.
its
beginning of CODT itself, 7000 (1000 for low version). It may also be
changed by typing the desired upper search limit after the one printed
by CODT, then closing the location with the RETURN key.

nnnnW

— WORD SEARCH

The command nnnnW (where nnnn is eui octal number) will cause CODT to
conduct a search of a defined section of core, using the mask and the
lower and upper limits which the user has specified, as indicated
The searching operations are used to determine if a given
above.
quantity is present in any of the locations of a particular section of

memory
The search is conducted as follows: CODT masks the expression nnnn
which the user types preceding the W and saves the result as the
quantity for which it is searching. CODT then masks each location
within the user's speci f ied limits with C (M) and compares the result
If
the two quantities are
to the quantity for whi ch it is searching.
identical,
the addres s and the actual unmasked contents of the
matching location are printed and the search continues until the upper
limit is reached. The search occurs in the memory field specified by
F.

For example:
of any location.
Search location 3000 to 4000 for all ISZ instructions regardless of
what location they refer to (i.e. search for all locations beginning
with an octal 2)

A search never alters the contents

FOOlO
M7777

7453/0001

3000

7454/7000

4000

7000

2000W
0200/2467
3057/2501
3124/2032

7.3

Set the field to 2
Chcmge the mask to 7000, open lower
search limit.
Change the lower limit to 3000, open
upper limit.
Change the upper limit to 4000, close
location.
ISZ
for
the
search
Initiate
instructions
These are 4 ISZ instructions in
this section of core.

ILLEGAL CHARACTERS

Any character that is neither a valid control character nor an octal
digit,
or is the fifth octal digit in a sequence, causes the current
ignored and a question mark printed. For example:
be
line to

7-8

7.4

7.4.1

4:?
4U?

CODT opens no location.

0406/4671 67K
/4671

CODT ignores modification
location 406.

cind

closes

ADDITIONAL TECHNIQUES

TTY I/O- FLAG

CODT automatically notes the status of the TTY flag after encountering
a breakpoint and restores it after performing a CONTINUE.,

7.4.2

Interrupt Program Debugging

CODT executes an lOF when a breeikpoint is encountered.
{It does
not
do this when more iterations remain in an nnnnC command.) This is done
so that an interrupt will not occur when CODT prints the breakpoint
information.
CODT thus protects itself against spurious interrupts
and may be used safely in debugging programs that turn on the
interrupt mode.
CODT restores the interrupt facility to its former
state when it resumes execution.

7,4.3

Octal

Diomp

By setting the search mask to zero and typing W, all Locations
(in
field F) between the search limits will be printed on the Teletype.

7.4.4

Indirect References

When an indirect memory reference instruction
actual address may be opened by typing + and
respectively)

7.5

is
-<-

encountered,

the

(SIIIFT/H and SHIFT /O,

ERRORS

The only legal inputs are control characters and octal digits.
Any
other character will cause the character or line to be ignored and a
question mark to be printed by CODT. Typing G alone is an error.
It
must be preceded by an address to which control will be transferred
This will elicit no question mark also if not preceded by an address,
but will cause control be transferred to location 0.

7-9

7.6

7.6.1

OPERATION AND STORAGE
Storage Requirements - CAPS-8 System

(octal)
CODT can be run in a standard CAPS-8 system and requires 1000
core locations and three locations (4,5,6) on page zero of every field
which uses a breakpoint. CODT is page-relocatable.

The source tape can be re-origined to the start of any memory page
except page zero and assembled to reside in the four pages following
that location, assuming they are all in the same memory bank.

7.6.2

Programming Notes Summary
page

CODT must begin at the start of a memory page (other than
and must be completely contained in one memory field.
The user's program must not use or reference
occupied or used by CODT and vice versa.

any

core

zero)

locations

Breakpoints are fully invisible to "open location" commands; however,
breakpoints may not be placed in locations which the user program will
modify in the course of execution or the breakpoint will be destroyed.
If a trap set by CODT is not encountered by the
breakpoint instruction will not be removed.

user's

The user may type CTRL/C at any time to return to the
(assuming his program did not destroy CAPS-8).

7-10

program,

CAPS-8

the

Monitor

7.7

COMMAND SUMMARY

nnnn/

Open location designated by the octal
nnnn.

Reopen latest opened location.

RETURN key

Close previously opened location.

LINE FEED key

Close location ajid open the
one for modification.

+ (SHIFT/N)

(SHIFT /O)

Illegal character

number

sequential

Close
location
and
allow
modification of the next location.

immediate

Close location, take
contents
that
of
location as a memory reference and open it.

Close location, open indirectly.

Current line typed by user is
types: ? (CR/LF)

Ignored,

CODT

nnnnG

Transfer program control to location nnnn.

nnnnB

Establish a brecikpoint at location nnnn.

Remove the breakpoint.

Open for modification the location in which
contents of the AC were stored when the
breakpoint was encountered.
the

Open the location storing the link.

Proceed from a breakpoint.

nnnnC

Continue from a breakpoint and iterate past
the breakpoint nnnn times before interrupting
program
the
the user's
at
breakpoint
location.

Open the search mask.
LINE FEED key

Open lower search limit.

LINE FEED key

Open upper search limit.

nnnnW

Search the portion of core as defined by the
upper and lower limits for the octal value
nnnn.

Open location F.

Open location

7-11

CHAPTER 8
CAPS- 8 UTILITY PROGRAM

8.1

INTRODUCTION

The CAPS-8 Utility Program (UTIL) allows the user to take files stored
on paper tape and transfer them to cassette,
using either the
high-speed or low-speed reader. The Utility Program will transfer
both ASCII and BINARY files.

8.2

CALLING AND USING THE UTILITY PROGFIAM

To call the Utility Program from the system cassette, the user types:
.R UTIL/OPTIONS

in response to the dot

8.2,1

(.)

printed by the Keyboard Monitor.

Utility Program Options

There are two options available for use with the Utility Program;
these options are discussed in Table 8-1.
(Options usage is explained
in Chapter 2, Section 2.4.3.)

Table 8-1
Utility Program Options

Option

Meaning

The /H option is used to designate the
high-speed reader as the input device. Note
that the high-speed reader is the default
input device.
That is, if no option is
specified the program assumes
that
the
high-speed reader is the input device.

The /L option is used to designate
low-speed reader as the input device.

8-1

the

)

Input and Output Specifications

8.2.2

Before indicating the input and output devices to be used in the file
transfer, the user must ensure that the proper reader is ready and
that the cassette the file is to be copied onto is write-enabled.
When this has been done, the user is ready to begin the file transfer.

After UTIL has been called from
following:

the

system

cassette,

asks

the

MODEThe user responds with a single character (A or B) to indicate whether
the file being put on the cassette is ASCII or BINARY.

OUTThe user responds by typing the drive number the output cassette is
mounted on and the name of the output file to be put onto it, i.e.,
3:F00.
In B mode, .BIN is the default extension.

After these two queries have been answered UTIL prints the following:
f

The user responds by typing any character; this response starts the
file transfer.
(If
/L had been typed, the user merely turns on the
low-speed reader.

8.3

UTILITY PROGRAM ERROR MESSAGES

Errors which occur during the Utility Program operation may be of two
types: User errors and cassette errors.
User errors may be corrected
with the appropriate action as detailed in Table 8-2. Cassette errors
normally require the user to use another cassette to complete the copy
operation. Control does not return to the Keyboard Monitor when a
Utility Progreim error occurs. The user may use CTRL/C to return to
the Monitor if he cannot correct the indicated error.

Table 8-2
Utility Program Error Messages
Message

Ifeaning

UNIT n NOT READY

There is either no cassette on the cassette
drive specified or no such drive exists.

OUTPUT ERROR ON UNIT n

An output error has occurred on the cassette
drive specified.
The user should try the
tremsfer operation using another cassette.
Or perhaps, the user tried to write data when
the write protect tab of the cassette on the
drive specified was write- locked.

8-2

ENTER ERROR ON UNIT n

An error occurred while trying to open a
cassette file.

UNIT n FULL

There was not enough room on the cassette.

CLOSE ERROR ON UNIT n

An error occurred during a close operation.

INPUT ERROR

In binary mode, the paper tape reader stopped
or ran out of tape before a checksum was
encountered.

CHECKSUM ERROR

In binary mode, the checksum did not
agree;
probably a hardware read error. Try again.

Whenever cin error occurs, the program writes a
open cassette if possible.

8-3

new

sentinel

new

the

CHAPTER 9
BOOT

BOOT is used to make it convenient to bootstrap from one system to
another, or from, one device to another by typing commands on the

keyboard.

BOOT can run conveniently from CAPS-8 and other monitor systems,
i.e., OS/8 and COS-300.
9.1

OPERATING PROCEDURES

To run BOOT from CAPS-8 the user types:
.R BOOT

the system will respond by typing a slash, at which time the user

responds with the device mnemonic.
If an illegal mnemonic is typed, the system types "NO"

slash to allow the user to try again.

and prints a

In this case, the user can

type RUBOUT to erase a line and try again.
If a legal mnemonic was given, but the system configuration does not

include the corresponding device (or the device is not ready) , the

bootstrap may hang.
The following is a list of legal mnemonics;

System or Comments
CA

TA8E cassette

CAPS-8

Any disk (RF08,

OS/8, COS-300

DF32, RK8E, RK8)
DL

L INC tape

DIAL-V2, DIAL-MS

RF08 or DF32

Disk Monitor

OS/8, COS-300

Any tape (TC08,
TD8E, LlNCtape)
L INC tape

PTBE Papertape

Loads BINLDR into field

OS/8, COS-300

9-1

System or Comments

Mnemonic

Device

RK8E disk

OS/8, COS-300

RF08, DF32 disks

OS/8, COS-300

RK8 disk

OS/8, COS-300

TD8E DECtape

OS/8, COS-300

TC08 DECtape unit

TC08 DECtape

Typeset Bootstrap
types boot's version number
OS/8, COS-300, Disk monitor,
DEC library system, and others

Zeroes core (field

If the device mnemonic is followed by a period, the program will load

the correct bootstrap into core and then halt.

Hitting continue

branches to the bootstrap.
Example
^R BOOT
/DT
The preceding bootstraps onto a DECtape system (on DECtape unit 0)
The underlined characters were typed by the computer.

9-2

APPENDIX A
ASCII CHARACTER SET

Character
A
B
C
D
E
F

G
H
I

J
K
L

M
N
O
P
Q
R
S

T
U

V
W
X
Y
Z
1
2
3
4

5
6

7
8
9

8-Bit
Octal

7-Bit
Octal

301
302
303
304
305
306
307
310
311
312
313
314
315
316
317
320
321
322
323
324
325
326
327
330
331
332
260
261
262
263
264
265
266
267
270
271

101
102
103
104
105
106
107
110
111
112
113
114
115
116
117
120
121
122
123
124
125
126
127
130
131
132
260
261
262
263
264
265
266
267
270
271

Character

#
$
%

&
1

(
)

+
»

•

/
•
•
1

=
>

7
@
[

\
]

i
-^

Leader/Trailer
BELL
TAB
LINE FEED
FORM
CARRIAGE RETURN
CTRL/Z
SPACE
RUB OUT
BLANK

A-1

8~Bit
Octal

7-Bit
Octal

241
242
243
244
245
246
247
250
251
252
253
254
255
256
257
272
273
274
275
276
277
300
333
334
335
336
337
200
207
211
212
214
215
232
240
377
000

241
242
243
244
245
246
247
250
251
252
253
254
255
256
257
272
273
274
275
276
277
133
134
135
136
137

240

APPENDIX B
ERROR MESSAGE Al^D COMMAND SUMMARIES

The following summaries are provided for the user's convenience;
they
are grouped in alphabetical order according to the SyEtem Program to
which they pertain. As these are only summaries the useir is referred
to the appropriate chapters for details.

KEYBOARD MONITOR (Chapter

Error Messages
Message

Meaning

BAD COMMAND

The user has failed to follow the
correct syntax for Monitor commands.

FILE NOT FOUND

The Monitor could not locate the file
(or files) specified.

10 ERROR ON UNIT n

An I/O error has occurired on the
cassette unit drive specified.
The
user should try the I/O transfer
specifying another cassette.

UNIT n NOT READY

There is no cassette on the unit
drive specified, or no such drive
exists.

UNIT n WRITE LOCKED

The user tried to write data when the
write protect tab of the cassette on
the drive specified was wjrite- locked.

Commcinds

Command

Explanation

DATE

Allows the user to enter the month,
day,
and year.
This date is then
represented in directory Listings.

DELETE

Causes the file named in the command
line to be deleted from the cassette
drive specified.