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DEC-8I-RZPA-D

December 1971

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PDP-8 Family

Commonly Used
Utility Routines
(Dumps, Verifier, Duplicator^

Conversion and Printing Routines)

For additional copies, order NO. DEC-8I-RZPA-D from the
Program Library, Digital Equipment Corporation, Maynard,
Mass, 01754.

PDP-8
LIBRARY

Fi rsl-

Frlif-ion,

Jamifirv

19 71

This volume is a collection
of manuals printed 1965-1970

@ 1971 by

Digital Equipment Corporation

The following are trademarks of Digital

Equipment Corporation, Maynard, Mass.
DEC

PDP

COMPUTE RLAB

FLIPCHIP

FOCAL

UN I BUS

DIGITAL

Or^NIBUS

PREFACE
This document is a collection of proven routines for
the PDP-8 family of computers.

These routines in themselves

are useful to many programmers and are all illustrative of

assembly language programming techniques.

The user is advised

to first investigate the sections on assembly language pro-

gramming in Programming Languages and Introduction to Pro gramming 19 70
.

CONTENTS

Chapter

RIM Loader

1=1

Chapter

Binary Loader
(33-ASR, High-Speed Reader)

2-1

Chapter

RIM Punch

3-1

(33-ASR, High-Speed Punch)

Chapter

Binary Punch
(33-ASR, High-Speed Punch)

4-1

Chapter

Octal Memory Dump
(33-ASR, High-Speed Punch)

5-1

Chapter

Teletype I/O Subroutines

6-1

(33-ASR)

Chapter

Master Tape Duplicator/Verifier
(High-Speed Reader/Punch)

7-1

Chapter

^"1

Chapter

Incremental Plotter Subroutine
(Type 350 Control and Plotter)
Decimal to Binary Conversion and Input
(Single Precision, Signed or Unsigned,

9-1

33-ASR)

Chapter 10

Decimal to Binary Conversion and Input
(Double Precision, Signed or Unsigned,

10-1

33-ASR)

Chapter 11

BCD to Binary Conversion, Single Precision

11-1

(33-ASR)

Chapter 12

BCD to Binary Conversion, Double Precision

12-1

(33-ASR)

Chapter 13

Unsigned Decimal Integer Print, Single
Precision (33-ASR)

13-1

Chapter 14

Signed Decimal Integer Print, Single
Precision (33-ASR)

14-1

Chapter 15

Unsigned Decimal Integer Print, Double
Precision (33-ASR)

15-1

Chapter 16

Signed Decimal Integer Print, Double
Precision (33-ASR)

16-1

Chapter 17

Binary to BCD Conversion

17-1

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i-> J- 1 i. >^ J- jf

4-/-\

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/^^*-.TT^ v-r- J.
-i^i-»
v^>^ii V c: J- o

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(

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-i- \
i-tJ-^J-'—J

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1Q_1
w J.

Formerly

DEC-08-LRAA-D
CHAPTER

RIM LOADER

ABSTRACT

The

Re6.d.— In

Mode ^RIM^

Loa.d.er

miniinuiTi— sized

routine for

reading and storing into core information contained in Read-InMode coded tapes via the 33-ASR perforated tape reader or high speed
perforated tape reader.
1.2

REQUIREMENTS
The RIM Loader requires 17^^

..^

—

_-„^

C21o)

core locations and is used

family computer with a 33-ASR Teletype v-^

a high

speed perforated tape reader is optional.

USAGE

1.3.1

To place the RIM Loader into memory via the console switches,

proceed as follows:
a.

Set 7756 in the switch register (SR)

Press LOAD ADDress.

Set the first instruction (6032

Press DEPosit.

Set the next instruction (60 31 for 33-ASR)

Press DEPosit.

Repeat steps e. and
deposited.

for 33-ASR)

until all instructions have been

S tar t-up /Entry

1.3.2
a*

Place the i^erf orated tape which m.ust be in RIM form.at in the
perforated-tape reader.

PDP Procrramjned Data Processor- is a rei^istered trademark of
the Digital Equipment Corporation.
;

©P.'eletype is a trademark of the Teletype Corporation.

1-1

Make sure the reader is set to LINE.

Place the starting address (7756) in the switch register.

Press the LOAD ADDress key.

Press the START key.

If the 33-ASR version is used, move the reader control
to START.

There are no error stops in this routine.
1.4

DESCRIPTION
This is a basic routine that alternately assembles an address

from two successive characters on tape, then assembles data contained
in the next two characters and stores this data at the associated

address

Because a tape in RIM format is twice as long as a comparable
tape in binary format, it is suggested that the RIM Loader only be

used to load the Binary Loader.

After this, the Binary Loader should

be used.

Any tapes to be read by this program must be in Read-In-Mode
coded format.

Leader tape for RIM format tapes should be about two feet of

leader-trailer codes; i.e., any code with channel

punched,

preferably code 200.

keys simultaneously

(Depress ALT MODE, CTRL, and

to punch 200 leader trailer.)

Characters representing the absolute, machine language program
are arranged in an alternating pattern of address, contents, address,

contents, etc.
punched.

Addresses have channel

punched, channel

Contents have no punch in channel

Trailer tape should be the same as leader tape.

1-2

not

1.5

EXAMPLE OF READ-IN-MODE CODED FORMAT

Channels

Tape Channel

and

Indicate

87 654 S 321

10 000
01 Al
00 A3

00 Dl
00 D3

.
.

Leader code is always tound first.

000
A2
A4

Absolute octal Address of data in next
two characters.

D2
D4

Octal Data to be stored at preceding
address.

This pattern repeats in similar four character groups until
the concluding Trailer Code is
10 000
000
encountered.
.

Note that a 3-bit group
by the notation Al above.

single octal character) is designated

The

in this notation indicates that this

particular octal character is used as the most significant three bits
in specifying the absolute address into which following data is

deposited.

Correspondingly, A2

A3, and A4 designate successively

less significant octal characters in the absolute address.

The remarks above apply equally to data as specified by the

notation Dl, D2

D3,

and d4.

1-3

1.6

PROGRAM LISTING

1.6.1

33-ASR Version

Abs
Addr.

Octal
Contents

1156,
1151
1160,
1161,
1162,
1163,
7764,
1165,
1166,
1161
1110,
1111,
1112,
1112,
lllA,
1115,
1116,
1111

6032
6031
5357
6036
7106
7006
7510
5357
7006
6031
5367
6034
7420
3776
3376
5356

Comments

Instruction
BEG,

KCC
KSF
JMP .-1
KRB
CLL RTL
RTL
SPA
JMP BEG+1
RTL
KSF
JMP .-1
KRS
SNL
DCA I TEMP
DCA TEMP
JMP BEG

TEMP,
JMP start of
BIN loader

1.6.2

High-speed Version

Abs
Addr.

Octal
Contents

7756
7757
7760
7761
7762
7763
7764
7765
7766
7767
7770
7771

6014
6011
5357
6016
7106
7006
7510
5374
7006
6011
5367
6016

7772

7420

SNL

7773

3776

DCA

7774
7775
7776
7777

3376
5357

DCA TEMP
JMP BEG+1

Instruction
BEG,

TEMP,

1-4

/read, do not clear
/checking for address
/store contents
/store address
/next word
/temp storage

Comments

RCF
RSF
JMP .-1
RCC
CLL RTL
RTL
SPA
JMP TEMP -2
RTL
RSF
JMP .-1
RCC

/clear AC and flag
/skip if flag = 1
/looking for char
/read buffer
/ch8 in ACO
/checking for leader
/found leader
/0K,ch7 in link

TEMP

/clear flag and fetch char.
/skip if flag = 1
/wait for fetching to be done
/put char. in AC; fetch another
/rotate channel 8 to
/bit j? of AC
/was it set (leader-trailer)?
/yes - leader trailer
/no - rotate channel 7 to link
/character fetched yet?
/no - wait for it
/yes - add it to AC; fetch
/another
/is 12-bit word in AC an
/address?
/no - store in last stored
/address
/yes - store new address
/get next word
/temporary storage
/start of binary loader
.

1.7

OTHER POSSIBLE RIM LOADERS
Variations of the RIM Loader may prove useful in special cases

where, due to circumstances, RIM must be located in a different

section of core.
On the other hand, the equipment involved may make it necessary
to use a variation of RIM tailored specifically to a particular situation.

As an example of this, consider a special-purpose PDP-8 system

used for text editinfT*

In this system., no 33— ASR's are used*

In-

stead, several typewriters which use a different code (including

provision for upper and lower case) are time-shared with respect to
input and output with a central PDP-8.
Please consult the Applied Programming Department at Digital

Equipment Corporation for details of other RIM Loaders currently
available or for assistance in special cases.

1.8

USE OF PDP-8 SYSTEM PROGRAMS

Certain system programs^ such as the DECtape Library System
require that the RIM Loader be used precisely as
(DEC-08-SUCO)
,

listed in section 1.6.
1.9

USING THE RIM LOADER WITH EXTENDED MEMORY
The RIM Loader as described in section 1.6 can run in any

memory field provided that it is loaded into memory following a
slightly different procedure than that described in 1.3.1. The
Instruction Field register and the Data Field register must both be
to 7) where N indicates the memory field
set to N (a number from
in which the RIM Loader is to be placed.

This is easily done.

Set the DATA FIELD extension of the switch register to N.
Set the INSTRUCTION FIELD extension of the switch register
to N.

Follow procedure in steps a through g in section 1.3.1.

1-5

Formerly
DEC-0 8-LBAA-D

CHAPTER 2
BINARY LOADER
2 .

ABSTRACT
The Binary Loader is a short routine for reading and storing informa-

tion contained in binary-coded tapes, using the

3 3-ASR

reader or the

High-Speed Reader.
The Binary Loader accepts tapes prepared with the PAL III, PAL-D,
PALS, or riACRO-8 assemblers.

Diagnostic messages may be included on

tapes produced when using either PAL or MACRO.

The Binary Loader ignores

all diagnostic messages.
2 .

REQUIREMENTS
This program occupies 94, q

(136o)

core locations.

The Binary Loader can be used with a system consisting of the

PDP-8 and a

3 3-ASR

Teletype only.

On the other hand, the same program

operates with systems including the High-Speed Tape Reader

Memory Extension Control.

and/or the

This loader is compatible with the 552

DECtape Library System and the TCOl DECtape Library System.
2.3

LOADING PROCEDURES
The Binary Loader is brought into memory by the RIM or Read-In=

Mode Loader.

This requires that the Binary Loader tape itself be in

RIM format.

See Introduction to Programming and Chapter

for dis-

cussions of the RIM Loader and RIM format.
NOTE:

Memory Extension users; refer to Special Requirements
section.

Proceed as follows:
a.

Load the RIM Loader for the type of reader which is to load
the Binary Loader.

Place the Binary Loader tape in the reader.

Make sure that the reader is on-line.

Place the starting address of the RIM Loader (7756) in
the SWITCH REGISTER.

Press the LOAD ADDRESS key.

Press the START key.

If the 33-ASR is the chosen reader, move the READER CONTROL

switch to the START position.
2-1

Switch Setting
NOTE: Memory Extension users see "Special Requirements"
section.

2.3.1

2.4

USING THE PROGRAM
a.

Place the tape to be loaded (which must be in binary format)
in either the 33-ASR Tape Reader or the High-Speed Reader,
with leader-trailer under the read head. When using the
33-ASR, make sure the reader is on-line. When using the
High-Speed reader, make sure the reader is on.

Place the starting address of the Binary Loader (7777) in the
SWITCH REGISTER.

Press LOAD ADDRESS key.

When using the High-Speed Reader, change the SWITCH REGISTER
to 3777 (bit 0=0).
Omit this step if using the 33-ASR.
d.

Press console START key.

When using the 33-ASR, move the READER CONTROL switch to
START.

2 .

ERRORS

When any of the PDP-8 assemblers is used to produce a binary tape,
a checksum is automatically punched at the end of the binary tape.

checksum is the sum

The

of all data on the tape including the origin word.

To be more specific, it is the sum of all data contained on tape

that will enter the accumulator

(AC)

in bit positions

through 11 from,

for example, the 33-ASR Reader buffer.

The sum is accumulated charac-

ter by character and not word by word.

Overflow

carry out of the

most-significant bit position of the AC) is ignored both when calculating a checksum (which is done by the assembler used) and when the
Binary Loader accumulates a checksum while loading a tape.
If the checksum accumulated while using the Binary Loader does

not agree with the last two characters on the tape (i.e., the checksum
on the tape calculated and placed there by the assembler)

an error

has occurred.

When the computer halts, the display lights will be static, the
memory buffer (MB) will contain 7402, and the contents of the AC will
be unequal to zero if a checksum error has occurred.

2-2

Restart the computer after the tape has been repositioned by
pressing the CONTINUE key.
2.6

DETAILS OF OPERATION AND STORAGE

This program furnishes the basic means by which the contents of
binary-coded tapes are loaded into core.
The heart of the program is a short subroutine (tagged BEGG) which
operates in outline as follows:
The incoming character is tested to see if it is a "rubout"
eight tape channels punched)

(all

If this is the case, all subsequent information coming from the

reader is ignored until another rubout is detected.
This is the mechanism by which assembler diagnostic messages are
detected.
They are preceded and followed by a single rubout char-

Within a diagnostic message, in contrast to the rules concerning
the balance of the binary tape, any character is valid except, of course,

acter.

a single rubout

character which would prematurely conclude the

diagnostic message.

Note that two consecutive rubouts within a diagnostic
message would, in effect, be ignored.

Next the character is tested to see if it is leader or field setting.
These tests are listed in the order in which they are performed.
If none of the actions indicated have occurred upon exit from the BEGG
subroutine, the character is part of the origin address, contains part
of a data word, or is a part of the checksum, and the appropriate
course is followed by the main routine.
2.7

2.7.1

SPECIAL REQUIREMENTS OR FORMATS

External Format
Tapes to be read by this program must be in binary-coded format

and have about 1 foot of leader- trailer code

punched; preferably code 200)

2-3

(any code with channel

The first two characters represent the address (origin) into which
the first command on the next portion of the tape will be placed.
Successive coramands are placed in memory at addresses:

origin+l,origin+2

,origin+n.

The initial character of the origin has no punch in channel 8,
while channel 7 is punched. The second character designating the origin
has no punches in either channel

A concluding 2-character group representing the checksum has no
punches present in channels 8 or 7.
Trailer tape is similar to leader.
Reference to Program Listing indicates that after the BEGG subroutine tests to see if the character just read was leader/trailer,
a test is made to determine whether the character is a "field setting."
This is a reference to the fact that the assemblers produce tapes on

which characters of the form
11 XXX 000

indicate the memory field into which the following data is to be
If, for example XXX were 101, all data following the field
loaded.
Unlike origins and
designator should be loaded into memory field five.

other data, field settings are not included in the checksum.
2.7.2

Example of Binary Loader Format

Tape Channel
87 654 S 321
10 000

01 000
00 000
00 Ill
00 000
00 oil
00 Ill

Channels 8 and
7 I ndicate

Program
Proper

Notes

000

Leader

010
000

Origin

In octal the origin 0200.
Loading will start at 0200

010
000

Contents of 200

Yes

The command 7200 or CLA.

010
110

Contents of 201

Yes

The command 3276 or

DCA
2-4

76.

Example of Binary Loader Format (Cont.)
Tape Channel

Program
Proper
Yes

The command 7402 or HLT.

Mr^

Thfi

87 654 S

321

00 111
00 000

100
010

Contents of 202

,««

no 010

010

10 000

000

Notes

Channels 8 and
7 Indicate

i.„,

nrnaram determines
that these two characters
are the checksum since
trailer follows.

Trailer

The octal checksum in this example is 0422.
this is the following sum:
102
000
072
000
32

076
074
002
422

Note that

Origin
First word
Second word

Third word

Memory Extension Usage
exist in field 0. This
It is recommended that the Binary Loader
and 7755 which
ensures a permanent program lining around location 7754
The loader can exist in any field, though
are used for TCOl DECtape.
(this
7755 in field
caution must be taken not to use location 7754 and
proper field is chosen
applies only to DECtape users). Also, when the
already be in that field.
it should be noted that the RIM Loader must
2.7.3

Binary Loader Loading Procedure for E xtended
a.

b.
"

Place the Binary Loader tape in the reader.
LISTER
Place the proper FIELD in the INSTRUCTION FIELD
(7756)
Loader
^^Ht-ocq
of
RIM
..^-^^
iu^
^4-^^4--ir,rT
thf?
v^^^-.^^^
—
wnen puT-i-j.xig L.iie o ucu. i—
in the SWITCH REGISTER.
Press the LOAD ADDRESS key.

—

L-ii-tj

Memory Users

Press the START key.
press READER CONTROL to start.
33-ASR:
Start the reader.
should already be ready to start.
High-Speed Reader:

2-5

Operat ion and Usage for Extended Memory Users
a.

Place the tape to be loaded (tape must be in binary
format)
the reader.
When using the 33-ASR, make
sure reader is on-line. When using the High-Speed
make sure reader is on and tape is positioned with Reader,
leader/ trailer over read head.
In the DATA FIELD register place the field in
which
program is to be loaded. In the INSTRUCTION FIELD the
register place the field that the Binary Loader is in.
Press LOAD ADDRESS key.
When using the High-Speed Reader, change the SWITCH
REGISTER TO 3777 (bit 0=0). Omit this step if using

Press console START key.

Starting Program

After program has been successfully loaded, place
starting
address of program in SWITCH REGISTER. Place the
field
where program exists in the FIELD INSTRUCTION
REGISTER.
Press LOAD ADDRESS key.
Press START key.

2-6

2.8

PROGRAM LISTING
DIGITAL ^JJIP^It^^f
^ASSACHJSSrrS
/BINARY AND DECTAPE LOADERS FOR
/555 CONTROL
/COPr aciHf 1971

Ui^f'jKm 1 jN

/-^AfMA^D^

7612
7613
7614
7615
7616

0000
0000
0000
0000
0000

*7612
SWITCH,
r^EMTEM,

CHAR,
CHKSUM,
ORIGIN,

*7626
/T? VrtTD
/EXTRACT
/iliAiKAC
7» /-I

7626
7627
7630
7631
7632
7633
7634
7635
7636
7637
7640
7641
7642
7643
7644
7645
7646
7647
7650

0000
3212
4260
1300
7750
5237
2212
7040
5227
1212
7640
5230
1214
0274
1341
7510
2226
7750
5626

7651
7652
7653
7654
7655
7656
7657
7660
7661
7662
7663
7664
7665
7666
7667
7670
7671
7672

1214
0256
1257
3213
5230
0070
6201
0000
0000
6031
5262
6036
3214
1214
5660
6011
5270
6016

ERRORS, FIELD, L/T

BEGG,

DCA SWITCH
JMS READ
TAD M376

SPA SNA CLA
JMP .+4
ISZ SWITCH
CMA
JMP BEGG+1
TAD SWITCH
SZA CLA
JMP BEGG+2
TAD CHAR
AND MASK
TAD M200
SPA
ISZ BEGG
SPA SNA CLA
JMP I BEGG
TAD CHAR
AND FMASK
TAD CHANGE
DCA MEMTEM
JMP BEGG+2
FMASK,
CHANGE
READ
LOR,

HIR,

/SET SWITCH
/GET A CHARACTER
/TEST FOR 3 77
/NO
/YES: COMPLEMENT SWITCH

/NOT 377
/IS SWITCH SET?
/YES; IGNORE
/NO; TEST FOR CODE
/TYPES

/DATA OR ORIGIN
/DATA, ORIGIN, or L/T

/FIELD SETTING

/CONTINUE INPUT

CDF

KSF
JMP .-1
KRB
DCA CHAR
TAD CHAR
JMP I READ
RSF
JMP .-1
RRB RFC

2-7

/WAIT FOR FLAG

JMP LOR+3

7673
7674

5265
0300

I^IS
1616
7677
7700
7701
7702
7703
7704
7705
7706
7707
7710
7711
7712
7713
7714

4343
7041
1215
7402
6032
6014
6214
1257
3213
7604
7700
1353
1352
3261
4226
5313

7715
7716
7717
7720
7721
7722
7723
7724
7725
7726
7727
7730

3215
1213
3336
1214
3376
4260
3355
4226
5275
4343
7420
5336

7731
7732
7733
7734
7735

3216
1376
1355
1215
5315

7736
7737
7740
7741
7742

0000
3616
2216
7600
5332

MEMFLD

7743
7744
7745
7746
7747
7750
7751
7752

0000
1376
7106
7006
7006
1355
5743
5262

ASSEMB,

MASK,
/traile:
BEND,

M376,
BEGIN,

GO,

CHEX,

300

JMS ASSEMB
CIA
TAD CHKSUM
HLT
KCC
RFC
RDF
TAD CHANGE
DCA MEMTEM
CLA OSR
SMA CLA
TAD HIRI
TAD LORI
DCA READ+1
JMS BEGG
JMP .-1

DCA CHKSUM
TAD MEMTEM
DCA MEMFLD
TAD CHAR
DCA WORDl
JMS READ
DCA W0RD2
JMS BEGG
JMP BEND
JMS ASSEMB
SNL
JMP MEMFLD
DCA ORIGIN
TAD WORDl
TAD W0RD2
TAD CHKSUM
JMP GO
DCA I ORIGIN
ISZ ORIGIN

M200,

LORI,

7600
JMP CHEX

TAD WORDl
CLL RTL
RTL
RTL
TAD W0RD2
JMP I ASSEMB
JMP LOR

2-8

/SAVE FIELD INSTRUCTION

/IGNORE LEADER

/LOOK AHEAD
/TRAILER, END

1153
7754

0006
0000

7755

0000

1111

5301

ASSEMB
BE GG
BEGIN
BEND
CHANGE
CHAR
CHEX
CHKSUM
FMASK

7743
7626
7701
7675
7657
7614
7732
7615
7656
7715
7670
7753
7662
7752
7674
7736
7613
7741
7700
7616
7660
7612
7776
7755

HIR-LOR

HIRI,

W0RD1=111^
W0RD2
*7777

HIR
HIRI
LOR
LORI
MASK
MEMFLD

MEMTEM
M200
M376
ORIGIN
READ
SWITCH
WORDl
WORD 2

JMP BEGIN

2-9

Formerly
DEC-OS-PMPO-D

CHAPTER

RIM PUNCH

3.1

ABSTRACT
The RIM Punch program provides a means of punching information

contained in selected blocks of core memory as RIM-coded tape via the
33-ASR Perforated Tape Punch or 75E High Speed Punch.

The punch pro-

gram may occupy either low or high memory depending on the version used.
3.2

REQUIREMENTS
The RIM Punch program will run on any PDP-8

with

family computer

33-ASR (Teletype) or 75E (high-speed) punch.

This program requires 61^^

^"^^p^

memory locations.

Program tapes are as follows:

High-speed Punch Version

33-ASR Version
Low Memory Binary
Low Source
High Memory Binary
High Source

Low Memory Binary
Low Source
High Memory Binary
High Source

DEC-0 8-PMPl-PB
DEC-0 8-PMPl-PA
DEC-0 8-PMP2-PB
DEC-0 8-PMP2-PA

DEC-0 8-PMP4-PB
DEC-0 8-PMP4-PA
DEC-0 8-PMP3-PB
DEC-0 8-PMP3-PA

LOADING PROCEDURES
See Introduction
This routine is loaded using the Binary Loader.
to Programming or Programming Languages for a complete description of
(This routine cannot be called as a subroutine.)
the Binary Loader.
3.3

3.4

USING THE PROGRAM
The SWITCH REGISTER is used to enter the initial and final address

of each block of core memory to be punched.

Make sure 33-ASR or 75E punch is on.

3-1

Set the starting address 0041 (or 7441 if using the highmemory version) into the SWITCH REGISTER and press the
LOAD ADDRESS key. Next press the START key.

The computer halts.
Set the initial address of the block
to be punched into the SWITCH REGISTER and press the
CONTINUE key.

The computer halts.
Set the final address of the block
to be punched into SWITCH REGISTER and press the CONTINUE
key.

3.5

Note that the final address must be larger than the initial
address.
A block of leader (code 200) tape is punched followed
by the selected block of data in RIM format.

The computer halts.
Steps (c) and (d) can now be repeated
to punch as many blocks of data as desired.
To terminate
the tape, proceed as described in (g) below.

Set the terminating address 0074 (7474) into the SWITCH
REGISTER and press the LOAD ADDRESS key. Next press the
START key and a block of trailer tape is punched.

DETAILS OF OPERATION AND STORAGE

Reference to section 1.7, Flow Chart, will illustrate the following discussion.

After entry, a short subroutine is entered to punch a block of
leader.
Next the initial address is picked up and the six most

significant bits are rotated right, masked out, added to 0100 (in
order to punch channel 7)
and punched.
The least-significant six
,

bits of the address are next masked out and punched.

A similar process is followed to punch the data associated with
the corresponding address except 010

is not added before the first

character is punched.
This process is repeated until the final address is reached; then
the computer halts at the starting address.
If more blocks of data
are to be punched, this is done as explained in step

(f)

above.

The routine is entered at a different address to punch the final
trailer.

3-2

3.6

EXTERNAL DATA
See Chapter

of Introduction to Programming for a description

of RIM paper tape format.

3.7

FLOW CHART

LEADER DATA BLOCK ENTRY

BEG

HALT

PUNCH TRAILER

LOAD
ADDRESS

INITIAL

HALT

LOAD
FINAL ADDRESS

PUNCH LEADER

LOAD ADDRESS

PA DO

SHIFT RIGHT 6

ADD CHANNEL 7
PUNCH
LOAD RIGHT HALF
ADDRESS
PUNCH

LOAD CONTENTS

PCON

SHIFT RIGHT 6

PUNCH

LOAD RIGHT HALF
CONTENTS

PUNCH

^,y^ BLOCK \s^

PROCESSED

J>
:s

TRAILER ENTRY

•

i
INCREMENT
ADDRESS

3-3

J-IJ. <-« J. J. j.>(

/ClPY^IaHf IJll

744!
7442

7443
7444
7445
7 446
7447
7 450
7 451

7452
7 4 53

7454
7455
7456
7457
7 460
746 1

7462
7463

7464
7465
7466
7467
7470
7471
7472
7473
7474
7475

7402
7604
332S
7402
7 604
3323
4276
1322
4306
1326
4314
1322
0325
4314
1722
4306
4314
1722
0325

747 6
7 47 7

1327

7500

3324

7501
7 502

7503
7504
7505
7506
7507
7510
7511
7512
7513

1330

JMS
TAD
CIA
TAD
SNA
JMP

CO^r^ jkA F I J.nj

PUN
lA
FA
CLA

/TEST FOR END

.+4
lA
I SZ

JMP PADD
JMS LTS
JMP BEG

/ENTRY FOR L/T

LTS*

MORE*

4314
2324
5301
5676
0000
7012
7012
7012
0325
5706

£JuI.^vi^,Mr

/DEC-08-Pr^P2-PA
/KIM PUNCH 33-ASK HIGH MEMORY
*7441
BEG*
HLT
/Ei\'TRY FOR LEADER DATA BLOCK
LAS
/SET INITIAL ADDRESS
DCA lA
HLT
LAS
/SET FINAL ADDRESS
DCA FA
JMS LTS
/GO TO L/T SUBROUTINE
PADD*
TAD I A
/PUNCH ADDRESS
J.MS SHFT
TAD CH7
JMS PUN
TAD I
AND SL6
JMS PUN
PCON,
TAD I I A
/PUNCH CO>JTENTS
JMS SHFT
JMS PUN
TAD I I
AND SL6

4314
1322
7341
1323
7650
5275
2322
5250
4276
5241
0000

DIGITAL

/L/T SUBROUTINE
TAD
DCA
TAD
JMS

M10!
CTR
C200
PUN
I SZ
CTR
JMP MORE
JMP I LTS

/MORE L-T CODES

SHFT*

/SHIFT RIGHT
RTR
RTR
RTR
AND SL6
JMP I SHFT

3-4

7514
7515
7516
7517
7520
7521
7522
7523

7524
7525
7526
152.1

7530

0000
6046

/PUNCH SUBROUTIiME

PUN,

TLS
TSF
JMP
CLA
JMP

6041
5316

7200
57 14

0000
0000
0000
0077
0100
leil
0200

-1
T

HI It>j

FA>

Z1R>
SL6,
CH7*
•M 1

100
-101
200

1 *

C200*

/COPy^lGHf 1971
/-lAYMAnJD,

DIGITAL Z^JlP^Z^l CO-^POKAflOM

.^ASSACH JSri: f IS

/DIGITAL-8-4-U-RIM
/RIM PUNCH 33 LOW MEMORY
0041
0042
0043
0044
0045
0046
0047
0050
0051
0052
0053
0054
0055
0056
0057
0060
0061
0062
0063
0064
006 5
0066
0067
0070
0071
0072
0073
0074
0075

7402
7604
3122
7402
7604
3123
4076
1122

*41
BEG

PADDj

4106
1126

4114
1122
0125
4114
1522

4106
4114
1522
0125
4114
1122
7041
1123
7650
5075
2122
5050
4076
5041

PCONj

HLT
LAS
DCA lA
HLT
LAS
DCA FA
JMS LTS
TAD lA
JMS SHFT
TAD CH7
JMS PUN
TAD lA
AND SL6
JMS PUN
TAD I lA
JMS SHFT
JMS PUN
TAD I lA
AND SL6
JMS PUN
TAD lA
CIA
TAD FA
SNA CLA
JMP • +4
ISZ lA
JMP PADD
JMS LTS
JMP BEG

/ENTRY FOR LEADER DATA BLOCK
/SET INITIAL ADDRESS
/SET FINAL ADDRESS
/GO TO L/T SUBROUTINE
/PUNCH ADDRESS

/PUNCH CONTENTS

/TEST FOR END

/ENTRY FOR L/T

3-5

0076
0077
0100
0101
0102
0103
0104
0105
0106
0107
0110
0111
0112
0113
0114
0115
0116
0117
0120
0121
0122
0123
0124
0125
0126
0127
0130

0000
3124
1130
4114
2124
5101
5476
0000
7012
7012
7012
0125
5506
0000
6046
6041
5116
7200
5514
0000
0000
0000
0077
0100
7677
0200

/L/T SUBROUTINE

LTS^

1127

MORE*

TAD M101
DCA CTR
TAD C200
JMS PUN
ISZ CTR
JMP MORE
JMP I LTS

/SHIFT RIGHT

SHFT*

RTR
RTR
RTR
AND SL6
JMP I SHFT
/PUNCH SUBROUTINE

PUN*

TLS
TSF
JMP .-1
CLA
JMP I PUN
I A*

FA,
CTR*
SL6*
CH7*

M101*

77
100
-10]

C.200*

200

/c OR r UGH r

19 71

/DIGITAL-8-4-U-RIM
/HIM PUNCH 7 5 HIGH
7441
7442
7 443
7444

7445
7446
7447
7450
7451
745f?

7453
7454
7455
7456
7^57
7460
7461

746S
7463
7^64

7402
7604
3322
7 402
7604
3323
4276
1322
4306
1326
4314
1322
0325
4314
1722
4306
4314
1722
0325
4314

/MORE L-T CODES

*7441
BEG»

PADD,

PCON,

1 G I r

AL £ ^ J I f:a h:.nj r C J.^POf^ ATI.J M

i^lENORY

HLT
LAS
DCA lA
HLT
LAS
DCA FA
JMS LTS
TAD lA
JMS SHFT
TAD CH7
JMS PUN
TAD lA
AND SL6
JMS PUN
TAD I lA
JMS SHFT
JMS PUN
TAD I lA
AND SL6
JMS PUN

/ENTRY FOK LEADER DAT
/SET INITIAL ADDRESS
/SET FINAL ADDRESS
/GO TO L/T SUBROUTINE
/PUNCH ADDRESS

/PUNCH CONTENTS

3-6

RLOCK

7465
7466
7467
7470

1322
7041
1323
7650

7471
7472

5275
2322
5250

7473
7474
7475
7476
7477
7 500

427 6
5241

0000

1330

4314
2324

751 1

7512
7513
7514
7515
7516
7517
7520
7521
7522

7523
7524
7525
7526
7527
7530

PADD
LIS
BEG

TAD 1^101
DCA CTR
TAD C200
JMS PUN
ISZ CTR
JMP MORE
JMP I LTS

MORE^

/ENTRY FOR L/T

/MORE L-T CODES

/SHIFT RIGHT

SHFT*

RTR
RTR
RTR
AND SL6
Ji^P I SHFT

/PUNCH SUBROUTINE

PUN

PLS
PSF
JMP .-1
CLA
JMP I PUN

6021
5316
7200
5714

0000
0000
0000
0077
0100
7677
0200

/TEST FOR END

. + 4

/L/T SUBROUTINE

5301
5676

0000
7012
7012
7012
0325
5706
0000
6026

CLA

Ji^P

1327

7501

LIS

3324

7 502

7503
7504
7505
7506
7507
7510

TAD
CIA
TAD
SNA
JMP
ISZ
JMP
JMS

FA*
CTR>
oLo*

CH7#
M101
C200

100
- 10]

200

/COPYilGHT 1971
/>lArNA^D>

OlGlfAL SJUIP-ICNf

COiif'Oii^ilO^i

/iASSACHJS.EirrS

/DIGITAL-8-4-U-RIM
/RIM PUNCH 7 5 LOW MEMORY
*41

0041
0042

0043
V

t-*

—1 —

0045
0046
0047

0050
0051
0052

7402
7604
3122
7 402
7604
3123
4076
1

122

4106
1126

BEi

PADD,

HLT
LAS
DCA
HLT
LAS
DCA
JMS
TAD
JMS
TAD

/ENTRY FOR LEADER DATA BLOCK
/SET INITIAL ADDRESS
lA

/SET FINAL ADDRESS
FA

/GO TO L/T SUBROUTINE
/PUNCH ADDRESS

LTS
lA

SHFT
CH7
3-7

0053

41 14

00 54

122

0055
0056
0057
0060

0125

0061

41 14

0062
0063
0064
0065
0066
0067
0070
0071
0072
0073
0074
0075
0076
0077
0100
0101

0102
0103
0104
0105
0106
0107
01 10
01 1 1
01 12
01 13
01 14
01 15
01 16
01 17

0120
0121

0122
0123
0124
0125
0126
0127
0130

41 14

1522

PCON,

4106

122

7041
1

123

130

MORE,

2124
5101
5476

TAD
DCA
TAD
JMS
ISZ
JMP
JMP

M101
CTR
0200
PUN
CTR

MORE
I
LTS

/MORE L/T CODES

SHFT*

/SHIFT RIGHT
RTR
RTR
RTR
AND SL6
JMP I SHFT

PUN

/PUNCH SUBROUTINE
PLS
PSF
JMP .-1
CLA
JMP I PUN

6021
5116
7200

5514
0000
0000
0000
0077
0100
7677
0200

/ENTRY FOR L/T
/L/T SUBROUTINE

41 14

0000
7012
7012
7012
0125
5506
0000
6026

/TEST FOR END

LIS

127

3124
1

/PUNCH CONTENTS

SHFT
JMS PUN
TAD I lA
AND SL6
JMS PUN
TAD lA
CIA
TAD FA
SNA CLA
JHP . + 4
TSZ lA
JMP PADD
JMS LTS
JMP BEG

1522

7650
5075
2122
5050
4076
5041
0000

PUN
lA
SL6
PUN
lA
I

Ji^S

0125
4114
1

JMS
TAD
AND
JMS
TAD

FA,

CTR,
SL6,
CH7,
M1

77
100
,

C200,

-101
200

3-8

Formerly
DEC-0 8-YXYA-D
CHAPTER

BINARY PUNCH
(Binary Core Dump to High-speed or

Teletype Punch)

4.1

ABSTRA.CT

This program provides a means of punching information con-

tained in selected blocks of core memory as binary-coded paper tape
using the high-speed or Teletype punch.

4.2

REQUIREMENTS
This program occupies

"75,^

(113g)

core memory locations.

The Binary Punch program runs on the basic PDP-8, 8/S

8/1,

8/L,

or 8/E with standard 33-ASR Teletype or standard high-speed punch.

Program tapes are as follows

4.3

33-ASR Binary

DEC-0 8-YXlA-PB

33-ASR Source

DEC-0 8-YXlA-PA

High-speed Binary

DEC-0 8-YX2A-PB

High-speed Source

DEC-0 8-YX2A-PA

LOADING PROCEDURES
This

program is loaded by means of the Binary Loader.

See

Introduction to Programming o r Programming Languages for a complete
discussson of the Binary Loader and its use.

(This program

cannot be called as a subroutine.)
The SWITCH REGISTER is used to enter initial and final addresses
of blocks to be punched as well as the number of blocks to be punched,

This program is used in the following manner:

4-1

Assuming the program is in memory as listed in 4.7, place
the starting address 7465 in the SWITCH REGISTER and press
the LOAD ADDRESS key.

Press the START key.
Leader tape is punched and the computer
halts.
Set the number of blocks to be punched into the
SWITCH REGISTER and press the CONTINUE key.

Set the initial address of the block
The computer halts.
to be punched into the SWITCH REGISTER and press the CONTINUE
key.

The computer halts.
Set the final address of the block to
be punched into the SWITCH REGISTER and press the CONTINUE
key

Note that the final address must be greater than the initial
address.

The indicated block of data is punched.
If only
has been called for, the trailer tape is punched
If more than one block has been
computer halts.
the computer halts at step (a) waiting for a new
address.
The second block is punched following
of steps (c) and (d)
etc.

one block
and the
called for,
initial
completion

4 . 4

METHOD
This is a basic program used to produce tapes acceptable by the

Binary Loader.

With each punched block of data, an initial address (into which
that data is to be loaded)

is punched as the first two characters.

Following the initial address, each 2-character group represents the
binary contents of a computer word.

At the end of each block, a 2-

character checksum is punched.
Reference to Section 4.6, Flow Chart, will illustrate the com-

putational approach.

Basically data is picked up from memory, the

most significant half shifted right and punched, and the least
significant half masked out and punched.

A similar process is followed with respect to the initial address
and the checksum^ which is accumulated character by character as a

block is punched.

4-2

See Chapter

of Introduction to Programming for a complete

discussion of tape format.
4.6

FLOW CHART
,

tion, not connectives.

PLOT

PUNCH LEADER

ENTER NUMBER
OF BLOCKS

ENTER BLOCK
lA AND FA

PUNCH 2
BINP

4-3

)

CHARACTERS
INCREMENT CUSM

, , -I-

.,•

r, -.

4. /

FKUCiKAJyi IjibTliSHo

A listing of this program with BPUN located at 7465 is as
follows:

/COPfUGHr
A^lAf,NJA:<i),

7465
7466
7467
7470
747

7300
6026
3366
4330
7402

19/1

DIGir-^L E:5JIP^£iviT CO-JPOnriQiNl

r-IASiACH JS-iriS

/BIN PUNCH HIGH SPEED PUNCH (PC03> PP8I> PP8L)
*7465
CLA CLL
BPUN^
/INITIAL PUNCH
PLS
/CLEAR CHECK-SUM
DCA CKSM
/GO PUNCH LEADER CODES
JMS PLOT
/SET SWITCHES=NUMBER OF
HLT
BLOCKS
LAS
CIA
/STORE MINUS NUMBER OF
DCA NB
BLOCKS
NXBL>
HLT
/SET SWITCHES = IN IT lAL ADDRESS
OF BLOCK

7472
7473
7474

7604

7475

7402

7476
7477
7500

7604
3370
7402

LAS
DCA lA
HLT

7501

7604
7001
3371
1370
7120

LAS

7041

3367

/SET SWITCHES=FINAL ADDRESS
OF BLOCK

7502
7503
7504
7505
7506
7507
7510
751 1

7512
7513
7514
7515
7516
7517
7520
7521

7522
7523
7524
752 5
7526
7527
7530
7531
7532

4341

lAC

PUNL^

1370
7041
1371

7650
5320
1770
7100
2370
5306
2367
5275
1366
7100
4341
4330
7402
5265
0000
7300
13 72

DCA FA
TAD lA
STL
JMS BINP

TAD
CIA
TAD
SNA
JMP
TAD
CLL
ISZ
JMP
ISZ
JMP
TAD

/TO PUNCH lA AS ORIGIN
/GO PUNCH WORD AS TWO LINES
OF TAPE

CLA
.+5
IIA
lA

/AC=FA-IA
/WAS IT LAST WORD OF BLOCK?
/IT WAS THE LAST WORD
/GET WORD TO PUNCH
/NOT AN ORIGIN
/JUST INDEX lA

PUNL
NB

NXBL
CKSM

/IS THERE ANOTHER BLOCK?
/HANDLE NEXT BLOCK

CLL
JMS BINP
JMS PLOT
HLT
JMP BPUN

/GO PUNCH CHECK SUM
/GO PUNCH TRAILER CODES
/DONE

PLOT:*

CLA CLL
TAD M212

4-4

/TO PUNCH 212 OCTAL LEADER
TRAILER CODES

7533
7534
7535
7536
7531
1

DCA CTRl
TAD C200
J MS PUN
ISZ CTRl
JMP .-2

3373
1374
4361

2373
5335

J-^ICI

7541

7542
7543
7544
7545
7546
7547

0000
3375
1375
7012
7012
7012
0376

/LEADER TRAILER CODE
/PUNCH C (AC)
/ANOTHER L-T CODE OR NO
/GO PUNCH ANOTHER
/ EXIT

B I NP >

DCA TEMl
TAD TEMl
RTR
RTR
RTR
AND SL 7

/FIRST TWO OCTAL DIGITS IN
AC 5-11

7550
7551

7552
7553
7554

PUN
CKSM
CKSM

J MS

4361
1366

TAD
DCA
TAD
AND

3366
1375
0377

TEMl
SL6

/PUNCH

(AC)

/LAST TWO OCTAL DIGITS

AC 6-11

7555
7556
7557
7560

JMS PUN
TAD CKSM
DCA CKSM
JMP I BINP

4361
1366

3366
5741

PUM^

7561

0000

7562
7563
7564
7565
7566
7567
7570

6021
53 62

PSF
JMP

.-1

6026

PLS
JMP

757

7572
7573
7574
7575
7576
7577

4.8

5761

0000
0000
0000
0000
7566
0000
0200
0000
0177
0077

PUN

/PUNCH

(AC)

/EXIT
/ROUTINE TO PUNCH C (AC)
/AND EXIT WITH C (AC)
/UNALTERED
/PUNCH IT
/EXIT

CKSM,
NB,
lf\>

FA,
M212>
CTRl >

-212

C200>
TEMl,
SL7,
SL6,

200
177
77

33-ASR TELETYPE PUNCH PROGRAM
To use this program with the 33-ASR Teletype, make the following

changes

7466
7562
7564

6046
6041
60 46

TSF
TLS

/AND EXIT WITH C
/PUNCH IT

4-5

(AC )

Formerly
DEC-0 8-YPPA-D

CHAPTER 5
OCTAL MEMORY DUMP
(Octal Core Dump to Paper Tape)

This program enables the user to dump, in octal, any or all
data in any memory field to either the Teletype or high-speed paper

During dumping the absolute address of each location
being dumped is held in the accumulator. When dumping is completed
output devices and memory fields can be changed to dump another
tape punch.

section of memory.
5.2

REQUIREMENTS
This program requires one core page; initially 7400-7577.
The Octal Memory Dump program runs on any PDP-8 family computer

with at least 4K words of core, a 33-ASR Teletype and/or high-speed
paper tape punch.
The program leaves the

No additional software is required.
BIN and RIM Loaders untouched.

5.3

The program tapes are as follows:

Binary

DEC-0 8-YPPA-PB

Source

DEC-0 8-YPPA-PA

USAGE
The program is supplied in ASCII format on punched paper tape,

and

can be assembled by any 4K PDP-8 assembler (i.e., PAL III,

MACRO- 8, or PAL-D)
Vv J.

uii

i^iiC

e lJj:

•-'

The origin of this program (7400)

iiiJ-'w j. j-\^

j-it^^i. v^v^ j.

j-xx

v^x. <wxC: j.

<^\^

\^ vaxhj^

can be changed

j.>j>^»^»,j.%^*i~

-->-

._?.

(See the appropriate assembler section of Programming Languages for

assembly instructions.)
5.3.1

The program is loaded into core with the Binary Loader (see
Introduction to Programming or Programming Languages for loading

procedures)

and can be loaded into any available memory field.
5-1

5.3.2

Operating Procedures
The SWITCH REGISTER on the PDP-8 console is used to control the

program; all options are determined by the position of bit

The

program can be interrupted by depressing the STOP switch.

With Octal Memory Dump program in core:
a.

Set the SWITCH REGISTER to the starting address (7400) and
the INSTRUCTION FIELD to the field containing the Octal
Dump.
Set DATA FIELD to the field containing the code to
be dumped.
Press the LOAD ADDRESS key.

Set SWITCH REGISTER bit
to 1 for a core dump to the
when dumping via the high-speed
Teletype punch, or to
paper tape punch.

Press the START switch.

Set the SWITCH REGISTER to the starting address of the
section of core to be dumped.

Press the CONTINUE switch.

Set the SWITCH REGISTER to the final core address of the
section of core to be dumped.

Press the CONTINUE switch; dumping commences and stops
after dumping the contents of the final core address
specified in step (f) above.

The computer halts.

Another dump can be performed at this time by continuing at
step

(a)

when the output device or data field is to change.

wise, continue at step

Other-

(d)

The program halts after each dump.
The preceding operations are illustrated in Figure 5-1.

5 .

INPUT/OUTPUT
The program contains its own

Teletype and high-speed punch

output, and there are no external I/O handlers used.

bit

determines the output device.

5.5

FUNCTIONAL DESCRIPTION
The program is written in the PAL III language.

are used in the program:

5-2

SWITCH REGISTER

Four routines

Load BIN Loader
and Press STOP

c
rrx

Set Start

\zy

)

liigh-Speed

Set SR Bit

jZf

Starting Address and
Data Field of
Octal f4aTDry Dunp

iMdress In SrI

Teletype

= jg

Set SR Bit

jZf

= 1

^ Press START ^

I
I

Ccnputer

Halts

Set Start Address
of Dunp In SR
Press

COsiT

HHEZH
I

Coiputer

Halts

Set Ending Address
of Dump In SR

Press

CDOT

I
Specified Memory Is
Being Dunrped

-»(

Figure 5-1

Finish^

Operating Procedures

5-3

The TOCT routine causes a number to be formatted for a
typeout or punchout.

The TCR routine outputs a carriage return-line feed.

The TSP routine outputs a space.

The TCHAR routine is the output routine for both the
Teletype and the high-speed punch.

The main routine begins with the initialization of variables, and
the two address arguments are picked up from the switch register.

Two

carriage return- line feeds are performed, followed by the, starting
address and several spaces.
of eight memory locations
to be output, a JMP to

A loop is then entered to type the contents

(if eight remain) .

LPjZ(2

If more data remains

repeats the process.

If during this loop

the routine finds that it has processed the last memory location, the
loop exits, a carriage return line feed is performed, a JMP to LPi?j2f is

executed, and the program halts.
See the program listing that follows for more precise information.
5.6

PROGRAM LISTING

OCTAL MEf^ORY DUMP PROGRAM

COPYRIGHT 1969
DIGITAL EQUIPME'^T CORP.
/ MAYXfARD^ MASS.
/TO OPERATE:
/
LOAD ADDRESS 7400 ISi SR
/
TO CKOSE OUTPUT DEVICE:
/
SET BIT 0=0 EOR H. S. PUlMCH OUTPUT OR
/
SET BIT 0=1 EOR TTY OUTPUT TtlE'M PRESS START
/
SET STARTIiMG ADDRESS AMD DATA EI ELD I Nf SR -PRESS
/

ONTIWUE

SET

DUMP^

*7400
CLA OSR

/EXAMIME SR EOR OUTPUT DEVICE

SMA
TAD
TAD
DCA

/STORE A "SKP" IM SKPZ IF H.

E^XIDIINJG

ADDRESS AMD DATA FIELD

TIWUE

7400
7401
740 2
7403
7404
MCH
740 5

7604
7700
1265
1270
3325
LI

,P00.

HL T

SR -PRESS COM

CLA
010
C7400
SK PZ

T PUT

7402

I'M

/STOP.

5-4

EMTER DUMP START IMG ADDRESS

740 6
7407
7410

7 60 4

741 1

7 60 4

7412
7413
7414
PED
7415
7416
7417
7420

7040

7421
7422

7423
7424
7425
7426
7427
7430
7431

7432
743 3
7434
7435
7436
7437
7440
7441

4312
4312

A DDR
DCA I.MDEX

LP01^

126 1

4272
4320
4 320
4 320

LF02:»

1661

4272
2262
7410

JMS
JMS
TAD
JMS
JMS
JMS
JMS
TAD
JMS

TCP
TCR
A DDR
TOCT
TSP
TSF
TSP
I
A DDR
TOCT

ISZ

IiNJDE.K

JMP OUT
I SZ
A DDR
TAD A DDR

0263
7640

A^\ID

5 22 3

1261

JMP LP02
TAD A DDR

0264

A\ID

C7
SZA CLA

5222

4324

OUT.

1267
127 1

3262
4324
2262
5254

/ u- u u L\/

r u rs

.\)

u iv

j_.

uu o

t? c

JJ L

/TYPE CR-LES

/OUTPUT STARTING ADDRESS IM OCTAL
/OUTPUT 3 SPACES
/GET CONiTEMTS OE LOC
/TYPE OUT CC^TEMTS
/DOME DUMPINJG?
/YES. EXIT
/MO. KICK ADDRESS UP

/HAVE WE OUTPUT
/MO.

LOGS OM

A LT.^E?

JMP LP02-1
TAD A DDR
AXfD C177
SZA CLA
JMP LP01
JMP LP01-1
JMS TCR
TAD C214
JMS TCHAR
TAD M20
DCA IiMDEX
JMS TCHAR
ISZ

1261

VARIABLES

SPACE OVER

OiVE

A.\ID

GET MEXT

/OUTPUT CR/LF

THEj.nJ

^E\n

ADDRESS

/OUTPUT CR/LF

/OUTPUT A FORM FEED
/THEM OUTPUT 20 BLAiMKS OE TRAILER

IiVDEK

JMP .-2
TAD A DDR
JMP LP00

5205

746
0000
PED
7462 0000
DUMPED

DUMP E^DIMG ADDRESS

C3
SZA CLA

7 640

0266
7640
5216
5215
4312

E!\1TER

SKP

5247
2261
1261

7451
7452
745 3

/STOP.

CMA
TAD

3262

126 1

746

DC A A DDR

HLT
LAS

1261

7442
744 3
7444
7445
7446
7447
7450

7454
7455
7456
7457

LAS

3261
7 40 2

Ai^JD

/LEAVE WITH FIlnJAL ADDRESS IM AC
/GO TO HALT FOR POSSIBLE RESTART
COiMSTA^MTS

ADDR^

/LCC OF STARTIMG ADDRESS TO BE DUM

Ii\)DEX.

/COUJMTER FOR DUMBER OF LOGS TO BE

5-5

7463
7464
7465
7466
7467
7470
747 1
UT

000 3
0007
0010
0177
0214
7400
7760

C3^
C7.

C10^
C177^
C214>
07400^
M20^

7472
7473
7474
7475
7476
7477
7500
7501

7502
7503
7504
7505
7506
7507
7510
751 1

i000

7104
3344
1352
3345
1344
7006
7004
3344
1344
0264

7513
7514
7515
7516
7517

LP0

WORD
M4

ISZ

:\IDX

LEFT

/SET DUMBER OF DIGITS PER WORD

MDX

WORD

/ROTATE WORD

LEFT

WORD
WORD
/MASK BITS 9- 1
/ADD 260 FOR OUTPUT
/OUTPUT DIGIT
/DOXIE FOUR?
/IMO. PICK UP A'MOTHER DIGIT
/YES. RETURM

C260
TCHAR

ROUTIME TO OUTPUT A CARRIAGE RETUR-M/L I :^E FEED

TCR^

TAD
JMS
TAD
JMS
JMP

346

4324
5712

0000
1350
4324
5720

DCA
TAD
DCA
TAD
RTL
RAL
DCA
TAD
AMD
TAD
JMS

JMP LP03
JMP I TOCT

7520
7521
7522
7523

/FORM FEED
/USED TO FORM SKP COMMA^XfB
/COU-MTER FOR .\fUM OF BLANKS TO OUTP

CLL RAL /ROTATE ADDRESS

4324
2345
5277
5672

214
7400
-20

OCTAL TYPEOUT ROUTIME

1351

0000
1347
4324

10
1 77

TOCT.

75] 2

/MASK VALUES

3
7

0215
TCHAR
C212
TCHAR
I
TOR

/OUTPUT A

/OUTPUT A L.

ROUTINE TO OUTPUT A SPACE

TSP^

TAD 0240
JMS TCHAR
JMP I TSP

/OUTPUT

5-6

SPACE

75 24

7525

0000
7000

ROUTI-^E TO OUlPul A ChAHACTFR

TCHAR^
SKPZ^

0"^^

TTY OR H.

MOP

/CHA'XIGED TO A "SKP"

JMP TCHl
PLS
OLA
TAD ADDR

/OTHERWISE GO TO TTY

PO.\]CH

IF H.

OUTPU

7526
7527
7530
7531

5335
6026
7200

7532
7533
7534
7535
7536
7537
7540

6021

7541

7542
7543

126 1

5332
5342
6046

TCHl^

7 200

1261
6041
5340
7200

TCH2^

5724
/

PSF
JMP
JMP
TLS
CLA
TAD
TSF
JMP
CLA
JMP

VARIABLES

/KEEP ADDRESS

I;.\J

OUTPUT

AC WHILE PUNCHIIMG

.-1

TCH2
/TTY OUTPUT ROUTIME

ADDR
.-1
I

TCHAR

AinJD

C0l\) STAiM

7544

0000

WORD.

/STORAGE FOR DIGIT TO BE FORMATTED

7545
7546

0000
0212
0215
0240

NDX.
C212.
C215.
C240.
C260.
M4.

/COU'^ITER

7547
7550
7551
75 5 2

260
77 74

212
215
240
260
-4

FOR MUM OF DIGITS OUTPUT
/code for lime feed
"
"
carriage returm
/
/

"
"

space;

formatting digits
/number of digits per word

5-7

CHAPTER 6
TELETYPE I/O SUBROUTINES

6 .

ABSTRACT
The routines described in this chapter are illustrative of the

procedures to be followed in creating I/O routines to be used with
The user is advised to peruse these routines
the ASR-33 Teletype.
prior to writing I/O routines tailored for his particular needs.
Subroutines are provided which perform input and output of character

These routines are

strings and single alphanumeric characters.

illustrative and by no means exhaustive of routines to handle the
ASR-33 Teletype.
6.2

REQUIREMENTS
The routines as supplied require

124^

(174^)

core locations.

The Teletype I/O Subroutines run on any PDP-8 family computer

with an ASR-33 Teletype console.

The program is distributed as an

ASCII tape as follows:
DEC-0 8-FIKA-PA

6 .

6.3.1

USAGE

Assembly
The routines as supplied will be automatically assembled onto

the first available core page.

There is no

character at the end

of the tape; although a PAUSE statement is present to allow for the

later loading of additional programs, if any.

This collection of subroutines can be assembled with PAL III,
PAL-D, PALS, or MACRO-8.

(If using the tape

with TSS/8, remove the

PAUSE statement from the end of the tape.)
If the routines are to be assembled separately

program), they will assemble at location 200.

6-1

(without a user

In this case, the

user should append a separate tape with a

character to the end

of the Teletype I/O Subroutines tape before assembly.
If the routines are to be assembled with a user program (such
as the example program in section 6.6), the Teletype I/O Subroutines

tape should be loaded after the user program and the whole

followed by a tape with a

character.

In this case, the I/O sub-

routines will fit on the first available free core page and will
not overlay the user program.
(Tapes can be loaded after the I/O
routines if allowance is made for the length of the routines or by
assigning a specific address to the beginning of the I/O routines.)

Calling Sequence

6.3.2

The calling sequence for the Subroutines is designed so that
the user can easily incorporate messages into his program.

The

user inserts a series of JMS instructions to the I/O routines
followed by the address of the message to be transmitted.
The subroutines the user is likely to call are as follows:

Subroutine
TYPX

Purpose

Calling Sequence

Prints a message. Message is
coded by programmer if using
PAL III, or set in a labeled
TEXT pseudo-op statement if
using PAL-D, PALS, or MACRO- 8.

ENTRY,

TLSX

Prints a single character, used
by TYPX to print message, character by character.
Subroutine is
entered with character to be
printed in AC bits 6 to 11.

KREAD

Inputs a message.
KREAD accepts ENTRY,
8-bit ASCII and does not convert
to 6-bit ASCII, therefore TYPX
cannot directly cause a message
read by KREAD to be printed,
although a simple routine to do
so can be written by the user.
Remember, the size of the input
buffer must include the carriage
return character.

6-2

JMS TYPX

POINTER

/ADDR OF
/MESSAGE

/EXIT IS TO
/ENTRY+2 WITH
/AC CLEAR
JMS TLSX
/CHAR IN AC
/BITS 6 TO 11

JMS KREAD

POINTER

/ADDR OF
/INPUT BUFFER
-LENGTH /-SIZE OF
/INPUT BUFFER
/EXIT IS TO ENTRY+3
/WITH AC CLEAR
/ZERO PLACED AT
/BUFFER END

Subroutine

Purpose

KRBX

Inputs single character from
Teletype, exits with character read in the AC.

'^t-iicj.

J- v-(i-i

ojLiico

pjLuvj.cicu.

Callincr Se'^uence

j.iiuj.uu.fc;

j\x%.uiD ,

ENTRY,

JMS KRBX

/EXIT IS TO
/ENTRY+1 WITH
/CHAR READ IN AC
wiixuii ufcjxeteb

tue ±asT:

character in the input buffer when the RUBOUT key is typed. This
routine is not necessary to Teletype I/O but allows for erasing
of typing mistakes and also performs echoing.

If the user rubs

out characters past the beginning of the input buffer, a
carriage return/line feed is performed as a warning.
6.4

RESTRICTIONS
The user program must initialize the teleprinter flag before

calling these subroutines.
CLA
TLS

Initialization is performed as follows

/SET AC TO ZERO, GOOD PRACTICE
/INITIALIZE TELETYPE

The routines can only be called from the memory field in which
they reside.
The following characters have special meaning to the output
subroutines

6-bit value

Character

Purpose
Marks the end of a message; supplied via
the TEXT pseudo-op when using PAL-D,
PALS, or MACRO-8.
Must be supplied by
user if using PAL III.
Causes a carriage return-line feed to be
output to the Teletype.

The following characters have special meaning to the input

subroutine:

6-3

Character

Purpose

212

LINE FEED

Ignored on input.

000

null

Ignored on input.

377

RUBOUT

Deletes the previous character typed,
echoes a backslash after the first
RUBOUT typed and a closing backslash after the first non-RUBOUT
character typed.

215

RUBOUT

Echoes a carriage return/line feed
and exits from the input subroutine
to the user program (calling
program)

8-bit value

On input buffer overflow while reading characters into the

Teletype buffer, characters echo as "bell"
Teletype rings)

(the bell within the

All characters other than RETURN and RUBOUT

are lost if typed while "bell" is being rung as a warning.
6.5

DESCRIPTION

Table 6.1 shows the ASCII values of the characters which can
be used with the supplied Teletype I/O Subroutines.

When using

PAL III, the user must code these ASCII values at the location

referenced by the output routine. The PAL III assembler reads
the ASCII codes directly as octal numbers.
PAL-D, PALS, and MACRO- 8 can use the TEXT pseudo-op to

directly format alphanumeric characters into ASCII code.

The TEXT

pseudo-op puts the desired message into 6-bit ASCII format; the
routines convert the 6-bit ASCII to the printable 8-bit ASCII and
then output the message.

If the user were outputting the message HELLO, it would be

done as follows, where MESG is the location given for the message:

PAL III
MESG,

PAL-D, MACRO- 8, or PALS
10j2f5

1414
17j?j?

/HE
/LL
/O END OF
/MESSAGE CODE

MESG, TEXT/HELLO/

6-4

TABLE

6 .

6-BIT ASCII CHARACTER SET FOR INPUT WHEN USING THE
PAL III ASSEMBLER, 8-BIT ASCII FORMAT IS ALSO SHOWN FOR
COMPLETENESS.

Character

6-BIT
Value

8-BIT
Value

n
UX
02
03
04
05
06
07
10
11
12
13
14
15
16
17
20
21
22
23
24
25
25
27

oux
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

-1

i-i

B
C
D
E
F
G
H
I

J
K
L

M
N
P

R
S

V
w
X
Y
Z

1
2
3

5
6
7
8
9

30
31
32
60

61
62
63
64
65
66
67
70
71

Character
•
II

#
$
%
&
1

(

8-BIT
Value

A 1
IX
42
43
44
45

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
212
215
240
377
000
207
211
214

46
47
50

51
52
53

54,

)

/
•

7
<'

\
>
'?

h
[

]

i
<-

leader tape
LINE FEED
RETURN
SPACE
RUBOUT
blank
BELL
TAB
FORM

6-5

6-BIT
Value

55
56
57
72
73
74
75
76
77
00
33
34
35
36
37

The same results are achieved in both cases.

The TEXT pseudo-

op performs all of the necessary operations in the case of PAL-D,

PALS, and MACRO- 8 which the programmer must perform if using

PAL III.
The input routines echo characters typed at the keyboard,
accept 8-bit ASCII characters (as they come from the Teletype
keyboard) for internal storage, and allow character editing via
Once the RETURN key is typed, no further input
the RUBOUT key.
is accepted from the keyboard until the next time such input is

requested by the calling program.

Additional information on these routines and their usage can
be found by reading through the listing (section 6.7) and by
reading Chapter 5 in Introduction to Programming 1970.
,

6.6

EXAMPLE PROGRAM
The following example program was assembled with the Tele-

type I/O Subroutines as shown in section 6.7

(PROGRAM LISTING).

The demonstration program was loaded prior to the I/O routines.
If no program had preceded the I/O routines they would, of

course, have started at location 200 (instead of location 400)

The output of the demonstration program is shown below:

FLEASE TYPE YOUR NAME
HERMAN
IT IS A

PLEASURE TO MEET YOU* HEP^AN

The computer causes

PLEASE TYPE YOUR NAME
and a carriage return/line feed to be output.

The user types

his name on the keyboard, enters it with the RETURN key, and
the computer then prints a carriage return/line feed followed by
IT IS A PLEASURE TO MEET YOU, HERMAN

6-6

The program as input to the Assembler

(PAL-D in this case)

looks as follows

/DEMONSTRATION OF TTY I/O SUBROUTINES
/

*200
START*

LOOP*

DONE*

TLS
JMS TYPX
MESGl
JMS KREAD
INAREA
-20
JMS TYPX
MESG2
TAD (INAREA-1
DCA 10
CLA CLL
TAD I 10
SNA
JMP DONE
JMS TLSX
JMP LOOP
HLT
JMP START

/ADDRESS OF START OF PROGRAM
/INITIALIZE TELEPRINTER FLAG
/PRINT A MESSAGE
/••PLEASE TYPE YOUR NAME''
/READ IN REPLY
/UP TO 16 CHAR* 1 PER WORD
/BEGINNING IN INAREA
/PRINT SECOND MESSAGE
/••IT IS A PLEASURE TO MEET YOU* "
/SET AUTO INDEX REGISTER 10 TO
/ADDRESS WHERE NPME IS STOREDC-1)
/BEGIN PRINTING THE NAME
/GET A CHARACTER
/TEST FOR ZERO
/IF ZERO* ALL DONE--QUIT
/ELSE PRINT A CHARACTER

/IT IS A GOOD PRACTICE TO PUT
/A JMP TO SOMEWHERE AFTER THE
/HLT AT THE END OF A PROGRAM
/IN CASE SOMEONE INADVERTANTLY
/HITS •'CONTINUE^^.
MESGl*
TEXT /^-PLEASE TYPE YOUR NAME-/
MESG2*
TEXT /-IT IS A PLEASURE TO MEET YOU* /
INAREA*
/INPUT AREA FOR NAME

The demonstration program assembled with PAL-D
looks as
follows

/DEMONSTRATION OF TTY I/O SUBROUTINES
*200
0200
0201
0202
0203
0204
0205
0206
0207
0210

6046
4777
0222
4776
0256
7760
4777
0236
1375

START.

TLS
JMS TYPX
MESGl
JMS KREAD
INAREA
-20
^^S TYPX
MESG2
TAD (INAREA-1

OF START OF PROGRAM
/INITIALIZE TELEPRINTER FLAG
/PRINT A MESSAGE
/••PLEASE TYPE YOUR NAME**
/READ IN REPLY
/UP TO 16 CHAR* 1 PER WORD
/BEGINNING IN INAREA
/PRINT SECOND MESSAGE
/••IT IS A PLEASURE TO MEET YOU*
/SET AUTO INDEX REGISTER 10 TO

6-7

0212
0213
0214
0215
0216
0217
0220
0221

0222
0223
0224
0225
0226
0227
0230
0231
0232
0233
0234
0235
0236
0237
0240
0241
0242
0243
0244
0245
0246
0247
0250
0251
0252
0253
0254
0255
0256

3010
7300

LOOP,

1410

7450
5220
4774
5212
7402
5200

DONE,

3720
1405
0123
0540
2431
2005
4031
1725
2240

MESGl,
LE
AS

1601
1505

3700

NA
ME
-/

/ADDRESS WHERE NAME IS STORED(-l)
/BEGIN PRINTING THE NAME
/GET A CHARACTER
/TEST FOR ZERO
/IF ZERO, ALL DONE-- QUIT
/ELSE PRINT A CHARACTER
/IT IS A GOOD PRACTICE TO PUT
/A JMP TO SOMEWHERE AFTER THE
/HLT AT THE END OF A PROGRAM
/IN CASE SOMEONE INADVERTANTLY
/HITS "CONTINUE".

TEXT /-P

TY
PE
Y

OU
R

3711

MESG2,

2440

1123

4001
4020

1405

0123
2522
0540
2417
4015
0505
2440
3117
2554
4000
0000

DCA 10
CLA CLL
TAD I 10
SNA
JMP DONE
JMS TLSX
JMP LOOP
HLT
JMP START

TEXT /-I

UR
E
TO
M
EE
T

YO
U,
/
I

N AREA,

/INPUT AREA FOR NAME

6-8

6.7

PROGRAM LISTING
As explained in section 6.6, this listing of the I/O routines

was made following the example program shown in that section.
These routines can start at any address if the user changes the

starting address or will start at the beginning of the first free
page after any programs loaded previously.

/BASIC TELETYPE I/O SUBROUTINES
/REVISION: 18-JAN-7 1
/GWB

DIGITAL EQUIPMENT CORPORATION
MAYNARD* MASSACHUSETTS 01754

/THESE SUBROUTINES ILLUSTRATE TYPICAL METHODS OF USING THE

/STANDARD TELETYPE TO INPUT AND OUTPUT ALPHANUMERIC DATA
/ON A PDP-8 FAMILY COMPUTER.

--NOTES—

/
/
/

PRINTER FLAG BEFORE CALLING THESE SUBROUTINES.

/
/

(2) THESE ROUTINES MAY ONLY BE CALLED FROM
THE FIELD IN WHICH THEY RESIDE.

(1) THE USER PROGRAM MUST INITIALIZE THE TELE-

/ORIGIN TO NEW PAGE

*.-l

177+1

/SUBROUTINE TO TYPE MESSAGES.
/THIS SUBROUTINE PRINTS A MESSAGE TO BE STORED IN STRIPPED
/SIX=BIT ASCII, TWO CHARACTERS PER WORD.

THIS FOP-MAT

/CAN BE EASILY GENERATED BY USING THE "TEXT" PSEUDO-OP IN
/PROGRAMS ASSEMBLED BY PALD* PAL8, OR MACRO-8.
/ENTRY* JMS
TYPX
POINTER
(ADDRESS OF MESSAGE)
/EXIT IS TO ENTRY+2 WITH THE AC CLEAR.

6-9

—

NOTE
/THE FOLLOWING CHARACTERS HAVE SPECIAL MEANINGS:
COMMENTS
/VALUE CHARACTER
MARKS THE END OF MESSAGE* THE TEXT
/ 00

/
/

PSEUDO-OP INSERTS THIS CHARACTER.
CAUSES A CARRIAGE RETURN/LINE FEED

TO BE OUTPUT.

0400
0401
0402
0403
0404

0000
7300

0405
0406
0407
0410
0411
0412
0413

1616

TYPX*

CLA CLL
TYPX
TAD I
TYPNT
DCA
TYPX
ISZ

1600
3216
2200

TYPXl*

7012
7012
7012
4217
1616
2216

0414
0415

4217
5205

0416

0000

/GET POINTER
/AND SAVE IT LOCALLY

TYPNT

/GET LEFT HAND CHARACTER
/THIS CAN BE CHANGED TO A
/BYTE SWAP ON THE PDP-8E!

ISZ

TYPY
TYPNT
TYPNT

/CONVERT AND TYPE
/GET RIGHT HAND CHARACTER
/MOVE POINTER TO NEXT WORD

JMS
JMP

TYPY
TYPXl

/CONVERT AND TYPE
/CONTINUE UNTIL DONE.

TAD
RTR
RTR
RTR
JMS
TAD

/POINTER TO STRING

TYPNT*

/THIS SUBROUTINE IS CALLED BY "TYPX" (AND "HRBX"!)-/ENTER WITH THE CHARACTER TO TYPE IN AC6- 1 1
/
(1) TESTS FOR TERMINATOR (00)
/
(2) TESTS FOR CR-LF (37) CHARACTER
/
(3) CONVERTS CHARACTER TO 8-BIT ASCII AND TYPES IT
0417
0420
0421
0422
0423
0424
0425
0426
0427
0430

0000
0236
7450
5600

0431
0432
0433
0434
0435

7510

TYPY*

AND
SNA
JMP
TAD
SZA
JMP
TAD
JMS
TAD

1237

7440
5231
1240

4244
1241

1242
1243

4244
5617

TYPYl*

SPA
TAD
TAD
JMS
JMP

TK77
I

TYPX
TKM37
TYPYl
TK215
TLSX
TKM125

TK100
TK237
TLSX
TYPY

6-10

/MASK OFF CHARACTER
/TEST FOR TERMINATOR
/EXIT IF TERMINATOR
/TEST FOR CR-LF
/NOT A 37
/TYPE A -CR-

/CONVERTS TO A -LF- (212)
/TEST RANGE
/RANGE IS 301-336
/RANGE IS 240-277
/TYPE CHARACTER

0436
0437
0440
0441
0442
0443

mil
7741
0215
7653
0100
0237

TK77*
TKM37*
TK215*
TKM125*
TK100,
TK237*

/MASK FOR AC6-11
/TEST FOR CR-LF CHARACTER
/ASCII VALUE OF -CR/THIS PLUS 337 = 212 -LF/CONVERT TO RANGE 301-336
/CONVERT TO RANGE 240-277

-37
215
-125
100
237

/TELETYPE OUTPUT SUBROUTINE.
/ENTER WITH CHARACTER IN THE AC.
/
--NOTE-/THE TELETYPE FLAG MUST BE INITIALIZED
/BEFORE CALLING THIS SUBROUTINE!
0444
0445
0446
0447
0450
0451

0000
6041
5245
6046
7200
5644

TLSX,
TSF
JMP
TLS

CLA
JMP

-1

/WAIT FOR TELETYPE READY

TLSX

/TELETYPE INPUT SUBROUTINE.
/EXIT WITH CHARACTER READ IN THE AC.
0452
0453
0454
0455
0456

0000
6031
5253
6036
5652

KRBX*

KSF
JMP
KRB
JMP

.-1
I

/WAIT FOR CHARACTER

KRBX

/TELETYPE INPUT SUBROUTINE.
/THIS SUBROUTINE DEMONSTRATES HOW TO INPUT
/ALPHANU-MERIC CHARACTERS FROM THE TELETYPE.
IT READS
/THE CHARACTERS INTO A BUFFER, ECHOES CHARACTERS TYPED,
/AND PERFORMS MINOR EDITING:
/
(1) CHARACTERS NULL(200 AND 000) AND LINE FEED
/
ARE DELETED ON INPUT.
/
(2) CHARACTER RUBOUT (377) DELETES THE PREVIOUS
CHARACTER TYPED. IT ECHOES AS A BACKSLASH FOLLOWED
/
/
/

BY THE CHARACTER DELETED (MULTIPLE RUBOUTS DO NOT
ECHO BACKSLASH AFTER THE FIRSTS A NON-RUBOUT CHAR-

ACTER CAUSES A "CLOSING" BACKSLASH TO BE PRINTED).

/THE CHARACTt«CAKRl AGE RETURN TEP?MINATES INPUT.
/ECHOES AS A CARRIAGE RETURN FOLLOWED BY A LINE FEED.

6-11

KREAD
/ENTRY* JMS
(ADDRESS OF INPUT BUFFER)
POINTER
-LENGTH
(MINUS SIZE OF INPUT BUFFER)
/EXIT IS TO ENTRy+25 ON EXIT:
/
( 1)
AC IS CLEAR.
/
(2) A TERMINATING WORD OF ZERO IS PLACED IN THE
/
INPUT BUFFER (THE CARRIAGE RETURN IS NOT ENTERRED
/
IN THE BUFFER).
/
/

--NOTE--

/ON BUFFER OVERFLOW* CHARACTERS WILL BE ECHOED AS "BELL"
/TO INFORM USER THAT BUFFER IS FULL.
ALL CHARACTERS*
/OTHER THAN CARRIAGE RETURN AND RUBOUT* ARE LOST.

/THIS SUBROUTINE IS WRITTEN TO CO-RESIDE WITH THE TELETYPE

/OUTPUT SUBROUTINES "TYPY" AND "TLSX".
0457
0460
0461
0462
0463
0464
0465

0000
7300

0466
0467
0470
0471

4252
3616

KREAD*

CLA CLL
TAD I
KREAD
KREAD
ISZ
DCA
KRPNT
KREAD
TAD I
DCA
KRCNT

1657

2257
3216
1657

3200

1360
3345

KRBl*

JMS
DCA I
TAD
DCA
/ENTER SCANNING

KRB3*

TAD

/GET CHARACTER
/SAVE CHARACTER
/LOAD POINTER TO TABLE
/INTO TEMP. STORAGE

KRPNT
KRBKS

/ADD IN CURRENT CHARACTER
/ADVANCE INDEX TO JMP WORD

0472

1616

2345

ISZ

0474

7650
5745
2345

SNA CLA
KRBKS
JMP I

1745

TAD
SZA
JMP

047 5

0476
0477
0500
0501

7440
5272

0502
0503
0504

4345
2200
5312

0505
0506
0507
0510

4244
7240

0511

1356

1200
5265

ISZ
I

/SET UP POINTER
/GET SIZE OF BUFFER
/SET UP COUNTER

KRBX
KRPNT
KRTAB
KRBKS
LOOP.

047 3

/GET ADDRESS OF BUFFER

KRBKS
KRBKS
KRB3

/CALL SPECIAL ROUTINE
/GO ON TO NEXT ENTRY
/GET TABLE ENTRY
/ZERO MARKS END OF TABLE
/CONTINUE SCAN

/NORMAL CHARACTER ROUTINE
/CHECK FOR BUFFER OVERFLOW* ECHO CHARACTER* AND
/RETURN TO FETCH NEXT CHARACTER.
JMS
KRBKS
/ECHO BACKSLASH IF NEEDED
ISZ
KRCNT
/TEST FOR BUFFER OVERFLOW
JMP
KRB6
/NORMAL ROUTE
/BUFFER OVERFLOW
TAD
TK207
/ECHO "BELL"
KRB5*
JMS
TLSX
CLA CMA
/DECREMENT CHAR COUNTER
TAD
KRCNT
JMP
KRBl/RETURN TO GET NEXT CHAR
6-12

0512
0513
0514
0515

1616
2216
4244
5266

KRB6^

TAD

ISZ
JMS

JMP

KRPNT
KRPNT
TLSX
KRBl

/GET CHARACTER
/ADVANCE BUFFER POINTER
/ECHO CHARACTER
/RETURN TO GET NEXT CHAR

/RUBOUT ROUTINE-/THIS ROUTINE IS CALLED WHEN A RUBOUT IS typed; IT DELETES

0516
0517
0520
0521
0522
0523
0524
0525
0526
0527
0530
0531
0532

7240
4345
2355
1657
7041
1200
7650
5333
7240
1216
3216
1616
5306

0533
0534
0535

4217
4345

0536

5266

1243

0537

4345

0540
0541
0542
0543
0544

1243
4217
3616
8257
5657

/THE LAST CHARACTER IN THE BUFFER, RESET THE POINTERS*
/AND DOES SOME FANCY ECHOING.
KRUB>
CLA CMA
/REVERSE RUBOUT FLAG TEST
JMS
KRBKS
/EHCO BACKSLASH IF NEEDED
ISZ
KRFLAG
/SET RUBOUT FLAG
TAD I
KREAD
/CHECK FOR "EMPTY" BUFFER
CIA
TAD
KRCNT
/BY COMPARING COUNTERS
SNA CLA
JMP
KRUBl
/NO RUBOUT PAST BEGINNING
CLA CMA
TAD
KRPNT
/DECREMENT BUFFER POINTER
DCA
KRPNT
TAD I
KRPNT
/GET CHARACTER TO ECHO
JMP
KRB5
/ECHO CR-LF- BACKSLASH ON ATTEMPT TO RUBOUT PAST THE START
/OF THE INPUT BUFFER.
KRUBl,
TAD
TK237
/LOOKS LIKE A "-"!
JMS
TYPY
/FORCES A CR-LF
JMS
KRBKS
/ALWAYS FORCES A BACKSLASH
JMP

KRBl

/CARRIAGE RETURN ROUTINE-/THIS ROUTINE IS CALLED WHEN A CARRIAGE RETURN IS TYPED;
/ECHOES CR-LF> DEPOSITS
IN INPUT BUFFER* AND EXITS.
KRCR*
JMS
KRBKS
/ECHO BACKSLASH IF NEEDED
TAD
JMS
DCA

TK237
TYPY
KRPNT

/LOOKS LIKE A
/FORCES A CR-LF
/STORE ZERO IN BUFFER

KHEAD
KREAD

/AND EXIT.

IS2

JMP

6-13

/THIS SUBROUTINE ECHOES BACKSLASH WHEN KRFLAG IS NON-ZERO
/NOTE-- LOCATION "KRBKS" IS ALSO USED AS A TEMPORARY
0545
0546

0000

0547

7640

0550
0551
0552
0553
0554

7440
4244
3355
5745

0555

0000

KRBKS*

KRFLAG
TAD
SZA CLA
TK334
TAD
SZA
TLSX
JMS
KRFLAG
DCA
KRBKS
JMP I

1355
1357

/GET FLAG

/BACKSLASH CHARACTER

/TYPE A BACKSLASH
/CLEAR FLAG
/EXIT
/SET TO +1 IF A RUBOUT WAS

KRFLAG*

/LAST CHAR* OTHERWISE 0.

0556
0557

0207
0334

/SAVE A COUPLE LOCATIONS BY USING TYPX AND TYPNT.
/POINTER TO INPUT BUFFER
KRPNT=TYPNT
/MINUS NO. OF WORDS LEFT
KRCNT=TYPX
/BELL IS ASCII 207
207
TK207*
/BACKSLASH IS ASCII 334
334
TK334*
/SPECIAL CHARACTER TABLE/ENTRIES IN THIS TABLE ARE TWO WORDS LONG;
-VALUE OF CHARACTER
/
(WORD 1)
JMP TO PROPER ROUTINE
(WORD 2)
/
/THE TABLE IS TERMINATED BY AN ENTRY OF 0.

0560

0561
0562
0563

5266
7600
5266
7 566
5266
7563
5337
7401
5316
0000

0564
0565
0566
0567
0570
0571
0572

KRTAB*

/NULL -- IGNORE

JMP KRBl
-2005
JMP KRBl
-2125
JMP KRBl
-2155
JMP KRCR
-3775
JMP KRUB

/NULL -- IGNORE

/LINE FEED -- IGNORE

/CARRIAGE RETURN -- EXIT
/RUBOUT -- DELETE CHARACTER
/DENOTES END OF TABLE.

PAUSE

6-14

Formerly
Digital-8-16-S

CHAPTER 7

MASTER TAPE DUPLICATOR/VERIFIER

ABSTRACT

This program duplicates and verifies 8-channel paper tapes using
a PDP-8 family computer with high-speed reader and high-speed punch.
the punch to operate at maximum speed.
The program accumulates two types of checksums while reading and
punching: 1) the number of nonzero characters on the tape, and 2) the

sum of characters on the tape (both are taken modulo 4096)

When duplicating, the program compares the checksums at the end
If
of the tape with the checksums accumulated by the read routine.
these differ, a reader error has occurred and a message is printed.
Tapes are verified by reading them and comparing accumulated checksums

with those at the end of the tape. Only master tapes produced by the
program can be duplicated. The master tape has the two checksums
punched at the end.
7.2

REQUIREMENTS
The program uses all of memory, except for the last page, as a

buffer.
The Master Tape Duplicator program runs on any PDP-8 family

computer with high-speed reader and high-speed punch.

The program

tapes are as follows:

7 .

7.3.1

Binary

DIGITAL-8-16-S-BIN

Source

DIGITAL -8-16-S-ASC

USAGE

Loading
The program is loaded with the Binary Loader (see Introduction
7-1

to Programming or Programming Languages for details)

To Produce a Master Tape

7.3.2

A tape is read and duplicated by the punch. When the tape has
run out of the reader, the accumulated checksums are punched.
The
tape that has been punched is the master tape used for duplication.
It should be compared against the original to ensure that the tape was
read correctly.

7.3.3

To Duplicate the Master Tape

The master tape that has been produced (see 7.3.2) is reproduced

by the punch.

Checksums are accumulated by the read routine and are
compared with the checksums at the end of the tape. Checksums are

punched and are used for verification (see 7.3.4).
If the master tape
is short enough to fit into the buffer, the program will notify the
operator that more copies can be made without rereading the master.
Blank tape is punched between copies.
7.3.4

Verify Duplication

Similar to duplication, but no punching takes place. Tapes are
read and the accumulated checksums are compared against the checksums

punched at the end.

7 . 4

OPERATION PROCEDURES
a.

Set the SWITCH REGISTER to 200.

Press the LOAD ADDRESS key; press the START key; the
program halts.

Set SWITCH REGISTER for the mode of operation as follows:

0=1
Bit 1=1
Bit 2=1
Bit

Make master tape

Duplicate master tape

Verify duplication

Place tape in reader starting on blank tape (all modes of
operation must be started with blank leader tape in the
reader)

Turn reader on.

Press the CONTINUE key.

The program prints a message when the operation has been
completed and then halts.

Turn punch on.

7-2

7.5

Proceed from step
made

(c)

unless multiple copies are being

DESCRIPTION

This program uses the program interrupt to keep the reader and
the punch running at full speed.
The reader fills a buffer and the
punch punches from it.
Checksums are accumulated by both the reader
and the punch routines.
7-fi

KTHTF OM "PYTPa

RT.aM'K'

PT?aMT?c:

r\rTDT Tr'T^nrcr^

mTvn-dC

The Master Tape Duplicator does not check for extra blank frames
in the duplicate tape.
A future version of this program will perform

such a check.

Until this version is released, users with tape
Digital-8-16-S having difficulty with binary tapes which load and
verify properly but do not run properly should order tape and document

number 5-10 from the DECUS Program Library. The document is called
Paper Tape Reader Tester.
It is a program for the PDP-5, but will run
on the PDP-8 and should be used as a second verifying operation.
Programs which are too long for the space left in core should be

broken into two or more shorter tapes for this operation.

7-3

PROGRAM LISTING
OIGir^L £jJIf^'1i^f

/COPf^IGHT 1971
/;vjAr^lAK':)>

COr^r^O <A FI O.M

^AS:i^GHJ5^rfS

/TAPE DUPLICATOR FOR PDP-5/S
/
-DEC-1/15/65
/SINGLE BUFFERING-HEAD AND PUNCH UTILIZING
/PROGRAiV} INTERRUPT
/COMPUTE A CHARACTER COUNT AND CHECK SU'^
/FOR EACH TAPE-COMPARE WITH CHECKS AT
/END OF TAPE
/CHECKS ARE ALSO COMPUTED DURING PUNCHING
/AND COMPARED
/THREE MOOES OF OPERATION:
ON-MAKE MASTER TAPE
/A. SWITCH
ON-DUPLICATE MASTER TAPE
/B. SvaiCH
/C. SWITCH 2 ON- VERIFY DUPLICATION
/DURING DUPLICATION, THE PROGRAM WILL NOTIFY
/THE OPERATOR WHETHER OR NOT MORE COPIES
/CAN BE MADE WITHOUT RE-READING THE
/MASTER
/DEFINITIONS OF INTERRUPT LOCATIONS:
/FOR THE PDP-8J INTER=0
/FOR THE POP- 5; INTER=1
/PAGE
INTER=0
1

*INTER+
3001

0002
0003
0004

5020
0632
0600
0615

0016
0017
0020

0000
0000

0021
0022

7410
5431

0023
0024
0025
0026
0027
0030
0031
0032
0033
0034
0035
0036
0037

6021

601 1

7410
5434
4567
0000
5400
0000
6014
5027
0000
6026
7230
5027

NPNT,

JMP HNDL
DPRT

El,
E2,

TES2

/HANDLE INTERRUPT

TESl

*16
NDXR,

/AUTO-INDEX REGISTER
/AUTO-INDEX REGISTER

iMDXP,

HNDL,

DSMS*

RSF
SKP
JMP
PSF
SKP
JMP
JMS
ION
JMP

READ

/750 CAUSED INTERRUPT

PNC
CRLF

INTE

/7 5A PUNCH CAUSED INTERRUPT
/EXTRANEOUS-CLEAR FLAGS
/ENABLE INTERRUPT
/RETURN
/CALLED AS A
/SUBROUTINE TO PROVIDE
/RETURN ADDRESS
/CALLED AS SUBROUTINE
/PROVIDES RETURN

READ,

RFC
JMP DSMS
PNC,

PLS
CLA
JMP DSMS

7-4

0040
0041
0042
0043
0044
0045
004 6
0047
00 50
0051
00 52

0053
0054

0055
0056
0057
0060

1417
7510
5570
3143
1

143

7440
2145
7000
1

147

3147
1

143

4034
5040
6012
3J42
5105
1

7440
2144

00 63

70'30

0064

0065

3146

0066
0067
00 7
007 1
00 72

0073
0074
00 7 5

0076
0077
0100
0101

0132
0103
0134
0105
0136
0107
01 10
01 1 1
01 12

RSTl*

146

160

3157
7410
5155
1

RDl

142

0062

0061

PNCH*

RST2#

J,^P

3416
2163
7410

;M64
5055
7240
3175
5040

JiMP

FRST,

161

7640
5060
1

153

01 13
01 14

3057
5060
1142

0115

162

01 16

7640

0117
0120
0121
0122

Si 23

1154
3057
5060

/GO GET NEXT
/READ 750 BUFFER
/SAVE IT
/OF "SCND" OR "THRD"

/COUNT MODULO 409 6

/ACCUMULATE SUM
/RESET END-OR-TAPE TIMER

/GET CHARACTER
/PUT IN BUFFER
/IS BUFFER FULL?
/NO
/YES
/FETCH NEXT CHARACTER
/DELAY START OF PUNCHING

5571
4031

/COUNT NON-ZERO CHARACTERS
/MODULO 409 6
/ACCUMULATE SUM MODULO 4096

TAD HLDl
DCA
NDXR
ISZ RCNT
SKP
JMP I FUL
J>1S READ
ISZ STRT

142

1142

/GET NEXT CHARACTER
/IF IT IS 7777, IT
/IS END OF TEXT

TAD I NDXP
SPA
JMP I PDUN
OCA HLD2
TAD HLD2
SZA
ISZ ZROP
NOP
TAD CHKP
OCA CHKP
TAD HLD2
JMS PNC
JMP PNCH
HRB
DCA HLDl
Jf^P FRST
TAD HLDl
SZA
ISZ ZROR
NOP
TAD CHKR
DCA CHKR
TAD TIME
DCA 1 1 MR
SKP

SCiMD*

RDl

CLA CMA
OCA SCON
Ji^P PNCH
TAD HLDl
TAD TSTl
SZA CLA
JHP RST1^1
TAD TRY2
DCA RSTl
JMP RSTl+1
TAD HLDl
TAD TST2
SZA CLA
JHP • i-4
TAD TRY3
DCA RSTl
JMP RSTl+1

/START PUNCHING
/TEST TO SEE IF
/CHARACTER IS FIRST
/IN CHECK- SUM IDENTIFIER
/IF IT IS-SET SWITCH
/TO TEST FOR SECOND
/CHARACTER NEXT
/CHECK FOR SECOND CHARACTER
/IDENTIFIER - IF FOUND
/TEST FOR THIRD NEXT

7-5

0123
0124
0125
0126
0127
0130
0131

0132
0133
0134
0135
0136
0137
0140
0141

0142
0143
0144
0145
0146
0147
0150
151

0152
0153
0154
0155
0156
0157
0160
0161

52
5121
142
1161
7 6 40
1

5123
7240
3416
4541
3151
4541
3150
5 540
0303
0565
0000
0000
0000
0000
0000
0000
0000
0000
5105

THRD,

TAD
JMP
TAD
TAD
SZA

HLDl
TSTl
CLA

J(^P

.-5

TRYl
.-3

CLA CMA
OCA I iMDXR
JMS I GETl
DCA MCHK
J.VJS

/GET 12-BIT WORD

NON-ZERO READ
NON-ZERO PUNCHED
/CHECK SUM - READ
/CHECK SUM - PUNCH
/#0F NON-ZERO MEASURED
/CHECK SUM - MEASURED
/f^OF
/itOV

i^CHK,

TIMR*
TIME*
TSTl,

7526

0162

7653

TST2*

7653

0163
0164
0165
0166
3167
0170
0171
0172
0173
0174
0175
0176
0177

0000
0000
7000
7410
0345
0000
0320

RCiMT*

0000
0000
0000
0377
0002

/MEASURED ZERO-COUNT

HLDl,
HLD2*
ZROR>
ZROP*
CHKR,
CHKP,
^ZRO,

5055
0000
0000
7526

00 7 7

/MEASURED CHECK- SUM

GETl

GETU

4031

5125

/SET END-OF PUNCH FLAG

DCA MZRO
JMP I .-n
SWT
GET

TRYl*
TRY2>
TRY 3*
VY*

51 14

/TEST FOR THIRD CHARACTER
/l^ IDENTIFIER - IF FOUND
/READ CHECKS FROM TAPE
/IF NOT - RESET FOR FIRST

STRT*
NOPT*
SKIP>
CRLF*
PDUN,
FUL,
BIT6,
DCON,

JMP FRST
JVJP

scm

JMP THRO
JMS READ
JMP RDl

/WHEN VERIFY I NG-DON' START
/PUNCHING

/2'S COMPLEMENT 1ST AND
/THIRD IDENTIFIER
/TWO'S COMPLEMENT OF 2ND
/IHENTI FI ER

NOP
SKP
CFLG
8FUL
007 7

VCt^T*

SCON,
0311
TWO*

/START OF PUNCHING FLAG
037 7

0002

7-6

*2i

0200
0201
0202
0203
0204
020 5
ltJC-)£J

0207
0210
021

7200
3174
7200
3144
3145
3146
O 1

3173
6012
6022
7200
3175
3057

0221

3303

022 5
0226
0227
0230
0231
0232

0233
0234
0235
0236

152
166

3070
1

166

1341

3164
7402
7604
7004
7430
5250
7 004
7430
7402
7004
7630

L0P1>

3303

0243
0244
0245
0246

3070
1342
3336

024 7
0250
0251

526 1
7200
343

02 52
02 53

3336
3174

0254
0255
0256
0257
0260

5261
7200
1344
3336
3174

/RESET PUNCH* READER
/COi^PUTED CHECKS

r«LJiy^o

/RESET BUFFER OVER FLAG
/CLEAR HARDWARE FLAGS

DCi

SCON
TRYl
Z RSTl
Z SKIP
Z RST2
Z SKIP
SwTl
DLAY
Z STRT

/RESET START PUNCH FLAG
/SET PROGRA^I SWITCHES

/SET START OF PUNCHING DELAY

OSR

SZL

/BIT 0=1* CREATE MASTER

SZL
JiV]P

7040
5224
1

DCA
RRB
PCP
CLA
DCA
TAD
DCA
TAD
OCA
TAD
DCA
TAD
DCA
HLT
CLA
RAL

/RESET VERIFY COUNT

JMP CRTE
RAL

5241

023 7
0240
024
0242
1

-7

/. "7

0212
0213
0214
0215
0216
0217
0220
0222
0223
0224

LOOP*

CLA
DCA Z VCiMT
CLA
DCA ZROR
DCA ZROP
DCA Z CHKR

165
165

CRTE*

OUP.

DUP

RAL
SZL
JHP
CM A
JMP
TAD
DCA
TAD
DCA
TAD
DCA

LOPl
NOPT
SWTl

J.'-IP

/BIT 1=1* DUPLICATE

CLA
.+3

/BIT 2=1* VERIFY
/ERROR SET C(AC)=7777
/NO PUNCHING - DON'T
/WAIT FOR PUNCH

NOPT
RST2
VRPT

/DON*T START PUNCHING

CO.^JR

/SET-UP RETURN FOR END

CLA
TAD CRPT
DCA COiMR
DCA Z VCi^iT
JMP GO
CLA
TAD DUPT
DCA CONR
nnA 7 UCiMT

/SET-UP RETURN FOR END

7-7

026

0P62
0263
0264
0265
0266
026 7
0270
027

4345
3016
1337

3017
1340
3163
1333
3000

0272
0273

3157

02 7 4

4031

027 5

5055
2157
5276
3000
7240
3416
7410
5736
1336
3170

02 7 6

0277
0300
0301
0302
0303
0304
0305
0306
0307
0310
031

0312
0313
0314
0315
0316
0317
0320
0321
0322
0323
0324
0325
0326
0327
0330
0331

0332
0333
0334
0335
0336
0337
0340

160

SAT>

7700
5315
0000
7200
5313
1334
3000
5102
7240
3416
2173
1335
3170
5307
1341

SWT W

0312
0326
0000

0342

0400

CFLG
BUF

/CLEAR FLAGS

iMDXR

/SET-UP BUFFER
/POINTERS FOR
/READ AND PUNCH

BUF
NDXP
OVH
RCNT
SA

/SET BUFFER- FULL COUNT

I.NITER

/INITIALIZE INTERRUPT

TIME
TIMR
READ

/SET END-OF-TAPE TIMER
/START READING

Z RDl
ISZ Z TIMR
I

.- 1

/END-OF-TAPE

CMA

CLA
OCA
SKP
JMP
TAD
DCA
TAD
SMA
JMP

COiMR

iSJDXR

CONR
PDUN
Z SCON
CLA

/DID WE START PUNCHING?
/NO /YES - WAIT FOR PUNCHING

.<-4

BFULi

CLA
JMP
TAD
DCA
JMP
CLA
DCA

/SET END-OF- PUNCHING FLAG
/OR NOP FOR VERIFY
/SET RETURN FOR PUNCH DONE

ION
.-1

/START PUNCHING

SAl

INTER
Z FRST-3
CMA
I

iVDXR

ISZ Z DCON
TAD RET
DCA Z PDUN
JMP BFULTAD DLAY
DCA STRT
DCA Z SCON
PCF
JMP GO+1
SAT
8FUL-6
FILL

/BUFFER-FULL
/SET-UP END-OF-PUNCHING FLAG
/•FILL'

FILL#

3164
3175
6022
5262
027 6

JMS
TAD
DCA
TAD
DCA
TAD
DCA
TAD
DCA
TAD
DCA
JMS
JMP

JMP

175

1063
1274
7760

034

GO,

1337

SA,
SA1#
RET*

CONR,
BUF*
OVR*
DLAY*
VRPT*

/ENTER WHEN BUFFER
/OVERFLOWED AND HAS

/BEEN PUNCHED

X-1

/START OF BUFFER
/BUFFER-FULL COUNT
/DELAY START OF PUNCHING
/DONE POINTERS

X + 210

1169
VRFY

)

7-8

0343
0344
0345
34 6

0347
0350
0351

404

0445
0000
6042
6072

CRPT,
OUPT*
CFLG,

HRFT
DUPL

6 7 72

0353

6502
6732
7 320

03 54

70 12

0355

6722
7004
6702

6502
6732
CLA CLL CML
RTR
6722
RAL

3 52

0356
0357
0360
0361

0362
0363

04 10
041

3000
1325
403 4

04 12
04 13
04 14

0415
0416
0417
420
0421
0422
0423
0424
042 5

6652
6534
KCC
JMP I CFLG

6534
6032
5745

21 74

PAUSE
*400
VRFY*

4403
536 1
5351
4404

CRET*

5345
4314
1327

1326

4034
1325
4034
1
1

144
177

JtVJP

i^ER

JMS
TAD
OCA
TAD
JMS
TAD

3LNK
HERE

423
4314
1

PNC

T2
PNC

TAD Tl

Ji^S

/10101010
/PUNCH CHECKS
/ALTER CHECKS

PiMC

TAD ADl

4734

J<4S

PrvNT

57 33

Ji^lP

LOP

143

HLOP

/PUNCH BLANK TAPE

RL.^K

Ji^S

133 5

SIX,

/PUNCH NUMBER IN AC

)0 '9

0432

3143

DCA

MA33

T An.

0434

7012

i'43S

7^il2

04 3^

RTn
RTR
RTR

012

/SET INTERRUPT POINTER
/PUNCH CHECKSUM
/IDENTIFIER CODES
/BIT PATTERN IS:
/ 10101010

liVTER
Tl

042 6
0427
0430

/COMPUTED VS PLEASURED CHECKS
/VERIFY ERROR
/VERIFY OK
/CO.^PUTED VS PUNCHED
/ME.viORY ERROR

TAD CHKR
TAD C3 7 7
Ji^S SIX
TAD / ZkOR
TAD Z TWO
j^yis SIX

ISZ Z VCNT
JMS I El
JMP VER
JMP VOK
JMS I E2

J;^s

146
176

423

/DISABLE WCO FLAG C 57A)
/SET C(AC)=4000
/DISABLE TCR FLAG ( 57A)
/LINE-PRINTER FLAG
/1 33 ADC FLAG
/KEY- BOARD C AND AC)

6 7 02

6 6 52

0400
0401
8402
0403
40^
0405
0406
040 7

/CLEAR FLAGS
/TELEPRINTER
/LIGHT PEN
/Mi CRO TAPE
/PLOTTER
/DISABLE ERF FLAG (57A)

TCP
6072

U, l>

7-9

0437
0440
044
0442
0443
0444
0445
1

0446
0447

Z
Z

BIT6

Z
Z
Z

HL02
BIT6

0172
4034

AND
JNS
TAD
AND
JMS

563

JiAP

SIX

OUPL

Jf«1S

J(AP
Ji^S

R£R

GOl

vJi'^P

i^ER

0172
4034
1

143

4403
5347
4 404

5345

PNC

P.MC

04 50
0451
0452
0453
0454

3000
1325
4034

TAD HERE
DCA INTER
TAD Tl
J>1S Z PNC

0455

1146

TAD

0456
0457
0460

4231
144
4231

Ji^S

SIX

TAD

04 6 1
0462

4314

J>1S
Ji^S

0463
04 6 4

7640
5356

0465
0466

1324
7 6 40

SIX
BLNK
TAD Z DC ON
SZA CLA
JMP DOK
TAD DCNT
SZA CLA

0467

;d305

JMP TST4

0470
0471
0472
0473

1336

4734
7 402
7604

TAD AD2
Jt^S I PRNT
HLT
CLA OSR

04 7 4

7 04 1

C(^A

0475
0476
0477

3324
3170

DCA DCNT
TAD HEKl
DCA Z PDUN

0500

1360
3017
3145
3147
5040
2324
7410
5356
1337
4734
7 602
5330

TAD BF
DCA Z NDXP
DCA Z ZROP
DCA Z CHKP
J.^P Z PNCH
DCNT
ISZ
SKP
JMP DOK
TAD AD3
JMS I PRNT
HLT CLA
jMP TST4-5

132 7

/COMPARE COMPUTED VS
/f^EASUKED CHECKS
/HEADER ERROR
/COi^PARE COMPUTED VS
/PUNCHED CHECKS
/MEMORY ERROR

/PUNCH THIRD IDENTIFIER
/READER STOPPED WHEN THIRD
/IDENTIFIER
/HAS BEEN FOUND, IE IT IS

CHKK

/NOT IN THf BJS'FFR

173

ZkOR
/PUNCH BLANK TAPE

/BUFFER OVERLAP-NO MORE DUp.

/STARTED MULTIPLE
/DuPLICAI US)??
/MULTIPLE DUPLICATION HAS
I

/SI A'<IED

501

0502
0503
0504
0505
0506
0507
0510
051 1

0512
0513

1332

TST4,

/READ NUMBER FROM SR

/SET RETURN FOR PUNCHING
/DONE
/RESET BUFFER POINTER
/RESET PUNCH-COMPUTED CHECKS

/START PUNCHING
/ARE WE DONE YET?
/YES
/NO
/HALT
/MAKE NEXT COPY

7-10

0514
0515

0000

516
0517

3 157

0520

/SUBROUTINE TO PUNCH
/BLANK TAPE

BL.^K*

TAD
DCA
JMS
ISZ

1323

4034
2157

tVjCiMT

Z
Z
Z

Tli^R

JMP I
7600

BLiMK

PNC
Tli^iR

CO 1 T

0522
0523
0524
0525
0526
0527
0530
0531
0532
0533
0534
0535
0536
0537
0540
0541
0542
0543
0544

0545
0546
0547
05 50
0551
0552
0553
0554
0555
0556
0557
0560
056
0562
0563
0564
0565
1

5714
7600
0000
0252
0125
0530
7200
5330
0447
0202
0673
0741
0751
1007
1017
1026
1036
1045
1054
1342

T .
12,

0252
0125

HERE*

HERE^-l

HEHl,
LOP,
PRNT*
AOl,
AD2,
AD3*
AD4,
AD5>
AD6,
AD7>
AD8*
MER,
RER*

174

VOK,

4402
1340
4734
5733
1341

5354
1063

DOK>

174

BF*
VER>

4402
1344
5354
0000

GET*

4031

057

0572
0573
0574
0575

7006
7006
3142
4031
6012

057 6
0577

5765

6012
7 106

142

/IDENTIFIERS

CLA
JMP .-1

5354
1343
5354

0566
0567
0570
1

MCNT*
DCNT*

GOl

LOOP
PR I.
TABl
TAB2
TAB3
TAB4
Si

/MASTER CREATED
/PRINT TABLE
/PRINT TABLE
/VERIFY OK
/DUP OK
/MEMORY ERROR
/READER ERROR
/VERIFY ERROR

TABS
TAB6
TAB7
TABS
TAD AD6
JMP VOK+3
TAD AD7
JMP V0K^3
TAD Z VCiMT
JMS I iNJPNT
TAD AD4
JMS I PRNT
JMP I LOP
TAD AD5
JMP VOK+3

/VERIFY OK

/DUPLICATION OK

X-1

/VERIFY OK

TAD Z VC.MT
JMS I Z NPNT
TAD ADS
JMP VOK+3

/ROUTINE TO READ 2-6 BIT
/CHARACTERS
JMS Z READ
RRB
CLL RTL
RTL
RTL
DCA Z HLDl
JMS Z READ
KRB
TAD Z HLDl
JMP I GET

7-11

0600

0000

0601

7 200

0608
060 3
0604
060 5
060 6
0607
0610

144
7041
150
7 6 40

^oWid
TESIj.

/COMPAHE READER COi^PUTED
CLA
TAD Z ZROR
CMA I AC
TAD Z i^ZHO
SZA CLA
JMP I TESl
TAO Z CHKK

5600
1

146

CiMA

061 1

151

TAD

0612
0613
0614
0615

7650
2200
5600
0000

0616
0617
0680

7 200

0621

0622
0623
0624
062 5
0626
062 7
0630
0631
0632

AC
>1CHK

CLA
ISZ TESl
TESl
J^AP
I

/COMPARE PUNCH COMPUTED
/SUMS

T?rs ?.>

145
7041
1 144
7 6 40

CLA
TAD

C-V)A

1146
7041
147

7650

/CONVERT BINARY WORD IN AC

06 3 7

1263

0640
0641
0642
0643
0644
0645
0646
0647
0650

3245

TAD ADDR
DCA XYZ<-3
SKP
DCA Z HLD2
CLL
TAD Z HLD2
TAD CON
SZL
ISZ Z HLDl
SZL
JHP XYZ
CLA
TAD Z HLDl
TAD C260
JMS TYPE
DCA Z HLDl
ISZ XYZ + 3
ISZ CNT
JMP xyz-f-2

06 51
06 52

0653
0654
0655
0656
06 57
06 60
0661

74 10

143

7422
7430
2142
7430
5242
7200
142
127 1
1

4325
3142
2245
2272
5244

DIGIT UNSIGNED DECIMAL
/NUMBER AND TYPE IT

/TO

HLD2
DC A Z HLDl
TAD CNTR
DCA C.MT

DCA

3143
7100

RETURN TO CALL^- 2
/OTHERWISE RETURN TO CALL*-

/IE EQUAL*

DKK T,

3143
3142
1264
3272

0633
0634
0635
0636

/TO READER COMPUTED SUMS

ZHOP

TAO Z ZROK
SZA CLA
JMP I TES2
TAD Z CHKk
Ci^A I AC
TAD Z CHKP
SNA CLA
ISZ TES2
JiMP I TES2

5615

2215
5615
0000

SiMA

/TO MEASURED SUMS
/IF EOUAL> RETURN TO CALL+ ^
/OTHERWISE RETURN TO CALL+

XYZ.»

/IDENTICAL TO ROUTINE IN
/LI BRARY

'-12

0662
0663
0664
0665
0666
0667
06 70

0671

0672
0673
0674
0675
0676
06 7 7
SIR IN G

0700
0701

0702
07 03

0704
0705
0706
0707
07 10

0711

0712
0713
07 14

0715
0716
0717
0720
721

0722
0723
0724
0725
726
0727
0730
0731
07 32

0733
0734
0735
0736
0737
0740
0741
7 42
0743

5632
7422
7774
6030
7634
7766
7777
0260
0000
0000
3143
1543
7450
5320
7012
7012
7012
4310
1543
4310
2143
5275
0000
0172
1334
7510
1335
1336
4325
5710
1337
4325
1340
4325
5673
0000
6046
6041
5327
6042
7200
5725
7740
0100
0240
0215
0212
1501

2324
522

JMP
ADOH,

DPHT

CON>

TAD CO.N
7774
6030
7634
7766

C260>

0260

CiMTR^

nil
CtMT,

PRIiM,

OCA
TAO

^
I

/ROUTINE TO PRINT A STRING
/OF PACKED ASCII PM AC APTCLJ
/ENTER WITH S.A. OF STRING

HL02
KLD2

SiMA

JMP CR

/IN AC: EXIT ON
/IN STRING

RTR
RTR
RTR
JMS GPRT
TAD I Z HLD2
JMS GPRT
ISZ Z HLD2

/AFTER TYPING CR-LF

PRIN+2

JtMP

/THIS ROUTINE CONVERTS
/6BIT TO ASCII

GPRT,

CR>

ELE^vjr.NJx

Z BIT6
M40

AND
TAD
SPA
TAD
TAD
JMS
JMP
TAO
JMS
TAO
JMS

C100
C200
TYPE
I
GPRT
CAR
TYPE
LF
TYPE
PRIN
I

Ji^P

/TYPE CR-LF

/TYPE CHARACTER IN AC

TYPE*

TLS
TSF
JMP .-1
TCF
CLA
J,^P

fv!40*

7745

C100^
C200*
CAR>
LF*
TAB1>

0100
0240
0215
0212

TYPE

)

/PRINT TABLES

150]

2324
0522

7-13

07 4 4

0745
0746
0747
0750
07 51

0752
0753
0754
0755
0756
0757
0760

4003
2205
0124
3504
0000
2305
2440
2327

4003
2205
124

TAB2»

0504
0000
2305
2440
2327

124

1124

0310
0523
4024

0310

0762
0763

1740
1625
1502
0522

1740
1625
1502

07 64

401 7

0765
0766

0317

07 6 7

0770
0771
0772

0523
4024
1740
0205
4015
0104

07 6

07 7 3

0774
0775
0776
07 7 7

1000
1001

1002
1003
100 4
100 5
1006
1007

523

4024

0522
4017
0640
0317

640
1

2011
0523
4024

17 40

0205
4015
104

540

0540
2022
0523
2340
0317

2022
0523
2340
031 7

1624
1116
2505

0000
2022

1624
1116
2 50 5

TAB 3>

0000
2022

1010

523

10 11

2340

1012
1013
1014
1015
1016
1017
1020

031 7

2340
0317

0000
4040
2605

1624
1116
2505

1624
1116

TAB45

2505
0000
4040
2605

1021

221 1

1022
1023
1024

63 1

063

4017
13 40

401 7
1340

\i^p-r>

0000

7-14

1026
1027
1030

2014

0425
2014

103
124

0124

1117
1640
1713

42 5
1

1031

1032
1

133

1034
1035
1036
1037
10^0
1041

1042
1043
1044
1045
1046
104

1051

1052
10 53

1354
1055
1056
1057
1060
1061
10 62

1063
1364

0000
150 5
1517
2231
400 5

AB6>

103

0000
1505
1517
2231
400 5

2222

1722

1722
0000
2205
0104
0522
4 005
2222
1722
0000
4040
2605

0000
2205
i

TAR 7,

1522

10 50

TAB5>

4005
2222
1

722

0000
4040
2605

TABS

221 1
0631

4005
2222

1722
0000
0000

0000

1722

/START OF BUFFER

7-15

Formerly
DIGITAL-8-12-U

CHAPTER 8
INCREMENTAL PLOTTER SUBROUTINE

ABSTRACT

8.1

The Incremental Plotter Subroutine moves the pen of a type
350 plotter to a new position along the best straight line.

The

pen can be raised or lowered during the motion.

REQUIREMENTS

8.2

The subroutine requires one memory page of storage (12 8,

The routine works on any PDP-8 family computer
or 200o words)
o
equipped with a type 350 Plotter Control and Plotter.
.

The routine is distributed as an ASCII source tape as follows

Digital- 8-12-U-ASCII
USAGE
8.3.1

Loading and Assembly
The source tape as supplied has no origin setting and ends

with a PAUSE statement.

This tape can be assembled with a user

program (which supplies an origin setting) or assembled by itself

The tape can be assembled with any of the PDP-8 family asiKI i^i T-c
c Cimrv
I

i-1

Calling Sequence

8.3.2

The plotter routine is called by executing a JMS PLOTX.

The contents of the accumulator specify the operation of the

subroutine as follows
C(AC)

= -1

The location registers internal to the
subroutine are reset to zero and the
pen is raised.
Control returns to the
instruction following the calling JMS
instruction.

CCAC)

The pen is lowered (if it was up) and
is moved to the new located as described
below.

C(AC)

= 1

The pen is rai s ed (if it was down) and
is moved to the new location as described
below.

The two locations following the calling JMS instruction

contain, respectively, the new X coordinate and the new Y co-

ordinate in steps (these values must be less than 4096)
The
pen is moved from the previous location to the new location
.

along the best straight line with the pen up or down depending

upon the contents of the accumulator when the subroutine is

Control returns to the instruction following the Y

called.

co-

ordinate.
8.3.3

Examples

Initialization of Plotter:
CLA CMA
JMS I PLOT
return

PLOT, PLOTX

/AC = -1, INITIALIZE ROUTINE AND PEN UP
/JUMP TO PLOTX ROUTINE, PAGE INDEPENDENT
/CONTROL RETURNS TO THIS ADDRESS

/CONTAINS ADDRESS OF PLOTX ROUTINE

\-2

Plot with Pen Down:

CLA
JMS I PLOT
X coordinate
Y coordinate
rerurn

/AC = 0, PEN DOWN

/MUST BE IN RANGE -4096<X<4096
/-4096<Y<4096

PLOT, PLOTX

Plot with Pen Up

CLA lAC
JMS I PLOT

/AC = 1, PEN UP

X coordinate
Y coordinate

/-4096<X<4096
/-4096<Y<4096

return

PLOT, PLOTX

8.4

DESCRIPTION
The routine has two registers which contain the location of

the last position plotted.

When the subroutine is entered, the

accumulator is tested to determine if initialization is being
performed; if so the location registers are set to zero, the pen
raised, and the subroutine exits.

If the routine is not being

initialized, the subroutine compares the current pen position (up

or down) with the requested one and raises or lowers the pen if
appropriate.

The new X and Y coordinates are retrieved from the

two locations follov/ing the calling JMS and placed in the location

registers.

The X and Y difference between the current location

and the desired location are computed and compared.

The subroutine

selects motion commands depending upon the quadrant of the new

location compared to the old.
to either the X-axis
a

combined motion.

The possible motions are now parallel

(drum motion) or the Y-axis

(pen motion)

The subroutine determines which of these motions

to use, and when the new location is reached, it exits.

1-3

The X and Y coordinates are specified in numbers of steps.
Increasing X corresponds to lowering the drum.
Increasing Y cor-

responds to moving the pen left.

The subroutine is limited by the speed of the plotter. The
minor subroutine, PLOTWT can be replaced, if necessary, by a
routine making use of the program interrupt.
8.5

PROGRAM LISTING

/COf YdlGHi 1971

iJIGIfAL EQ JI PiiSM f CO^^PO^AFUN

/DIGITAL 8-12-U
/PLOT SUBROUTINE
/CALLING SEQUENCE
/
/
/

/
/

0200
0201
0202
0203
0204
0205
0206
0207
0210
0211
0212
0213
0214
0215
0216
0217
0220
0221
0222
0223
0224
0225
0226

0000
7510
5220
1361
7112
7710
5227
7620
5214
3361
6504
5216
2361
6524
4370
5227
7200
6504
3361
3362
3363
4370
5600

C(AC)=-l;
INITIALIZE
C{AC)= 0;
PLOT WITH PEN DOWN
C{AC)= IJ PLOT WITH PEN UP
JMS PLOTX
X CO-ORDINATE (IN STEPS)
(RETURN
Y CO-ORDINATE (IN STEPS)

PL0tX»
SPA
JMP PLOTA
TAD PLOTPN
CLL RTR
SPA CLA
JMP PLOTl
SNL CLA
JMP .+4
DCA PLOTPN
PLPU
JMP .+3
ISE PLOTPN
PLPD
JMS PLOTWT
JMP PLOTl
PLOTA,
CLA
PLPU
DCA PLOTPN
DCA PLOTNX
DCA PLOTNY
jMS PLOTWT
JMP
PLOTX

/MOVE THE PEN?
/NO: CONTINUE
/ADD PEN STATUS
/ANY CHANGE?
/NO: CONTINUE

/LOWER THE PEN
/RAISE THE PEN
/LOWER THE PEN
/WAIT FOR FLAG
/CONTINUE

/RAISE THE PEN
/0 TO
/0 TO

X
Y

8-4

CO-ORDINATE
CO-ORDINATE

AC=-1)

/DIGITAL 8*12-U
/PAGE 2
/PICK UP ARGUMENTS
0227
0230
0231
02^2
0233
0234
0235
0236
0237
0240
0241
0242
0243
0244
0245
0246
0247
0250
0251
0252
0253
0254
0255
0256
0257
0260
0261
0262
0263
0264
0265
0266
0267
0270
0271
0272
0273
0274

1362
7141
1600
7420
7041
3364
7004
3367
1600
3362
2200
1363
7141
1600
7420
7041
3365
1367
7004
3367
1600
3363
2200
1364
7141
1365
7620
5275
1364
3366
1365
3364
1366
3365
7001
0367
1342
5300

PLOTl
CIA
TAD
SNL
ClA
DCA
RAL
DCA
TAD
DCA

/FETCH PREVIOUS

TAD PLOTNX
I

PLOTX

1367
7110
1345
3366
1766
3340
1367
1350
3367
1767

CO"0«DlNATE

/FORM NX-NPX
/L=0: NX<NPX

PLOTDX

/ABSOLUTE VALUE OF DIFFERENCE

PLOTMV
PLOTX
PLOTNX
IS2 PLOTX
TAD PLOTNY

/SAVE SIGN BIT
/SET NEW
/PREVIOUS X
/INCREMENT POINTER
/FETCH PREVIOUS Y CO-ORDINATE

CIA
TAD
SNL
CIA
DCA
TAD
RAL
DCA
TAD
DCA

CLL
PLOTX

ClA
TAD
SNL
JMP
TAD
DCA
TAD
DCA
TAD
DCA

CLL

PLOTDY
PLOTMV

PLOTMV
PLOTX
PLOTNY
ISZ PLOTX
TAD PLOTDX
I

/FORM NY-NPY
/<=0: NPY<NY

/ABSOLUTE VALUE OF DIFFERENCE
/SAVE SIGN BIT
/BIT 10(1)= DRUM-DOWN(POSITIVE)
/BIT 11(1)=PEN-LEFT (POSITIVE)
/SET NEW

/PREVIOUS Y
/INCREMENT POINTER

PLOTDY
CLA

PL0T2
PLOTDX
plotna
PLOTDY
PLOTDX
PLOTNA
PLOTDY

lAC

AND PLOTMV
TAD PLOTTl
jMP .+4

/L=0:

DELTA

/REVERSE NUMBERS

/SET MAJOR MOTION
/INSTRUCTION

/DIGITAL 8-12-U
/PAGE 3
0275
0276
0277
0300
0301
0302
0303
0304
0305
0306

CLL

TAD PLOTMV
PL0T2,
CLL RAR
TAD PL0TT2
DCA PLOTNA
TAD I PLOTNA
DCA PL0T4
/SET COMBINED MOTION
TAD PLOTMV
TAD PL0TT3
DCA PLOTMV
PLOTMV
TAD
I

!-5

0307
0310
0311
0312
0313
0314
0315
0316
0317
0320
0321
0322
0323
0324
0325
0326
0327
0330
0331
0332
0333
0334
0335
0336
0337

3331
1364
7110
3366
1364
7040
3367
2367
7410
5600
1366
1365
3366
1366
7140
1364
7630
5340
0000
1364
7041
1366
3366
4370
5316

DCA PLOTDB
TAD PLOTDX
CLL RAR
DCa PLOTNa
TaD PLOTDX
CMA
DCA PLOTMV
PL0T3,
IS2 PLOTHV
SKP
JMP
PLOTX
/ALL DONE
TAD PLOTNA
TAD PLOTDY
DCA PLOTNA
TaD PLOTNA
CMa CLL
TAD PLOTDX
S2L ClA
JMP PL0T4
/SINGLE MOTION
PLOTDB,
/COMBINED MOTION
TAD PLOTDX
CIA
TaD PLOTNA
DCA PLOTNA
jMS PLOTWT
JMP PL0T3

0340
0341

0000
5336

PL0T4,
JMP .-3

0342
0343
0344
0345
0346
0347
0350
0351
0352
0353
0354
0355
0356
0357
0360

0343
6511
6521
0346
6512
6514
0351
6513
6523
6515
4355
0000
6514
6521
5755

.+1
PLOTTl,
PLPR
PLPL
,*1
PL0TT2»
PLDU
PLDD
PL0TT3,
.I
PLDU PLPR
PLUD PLPL
PLDD PLPR
JMS .!

PLDD
plPl
JMP

/PEN-RIGHT
/PEN-LEFT
/DRUM-UP
/DRUM-DOWN

/UP-RIGHT
/UP-LEFT
/DOWN-RIGHT
/DOWN-LEFT

.-3

/DIGITAL 8-12-U
/PAGE 4
0361
0362
0363
0364
0365
0366
0367

0000
0000
0000
0000
0000
0000

PLOTPN,
PLOTNX,
PLOTNY,
PLOTDX,
PLOTDY,
PLOTNA,
PLOTMV,

8-6

0370
0371
0372
0373
0374

0000
6501
5371
6502
5770

PLOTWT,
PLSF
JMP .-1
PLCF
JMP
PLOTWT
I

/WAIT FOR DONE FLAG
/NOT YET
/CLEAR FLAG
/EXIT

PAUSE

PLOTA
PLOTDB
PLOTDX
PLOTDY
PLOTMV
plotna
PLOTNX
plotny
PLOTPN
PLOTTl
PL0TT2
PL0TT3
PLOTWT
PLOTX
PLOTl
PL0T2
PL0T3
PL0T4

022
0331
0364
0365
0367
0366
0362
0363
0361
0342
0345
0350
0370
0200
0227
0275
0316
0340

8-7

Formerly
Digital- 8-2 8-U-Syin

CHAPTER 9
DECIMAL TO BINARY CONVERSION AND INPUT
(Single Precision, Signed or Unsigned, 33-ASR)

9 .

ABSTRACT
This routine accepts a string of up to four decimal digits (single

precision for the PDP-8) from the Teletype keyboard and converts it to
the corresponding 2's complement binary number.
The string can contain as legal characters a sign (+,-, or space)
and the digits from

0-9.

If the first legal character is not a

sign, the conversion is unsigned

A back arrow

(

-«)

at any point in

the string erases the current string and allows the operator to reenter
the correct value.

Any character after the first, other than another

digit or back arrow, causes the conversion to terminate and is found in
location SISAVE within the subroutine.
9.2

REQUIREMENTS

This subroutine requires 74^^ (112^) core locations and runs on
any standard PDP-8 family computer with a 33-ASR Teletype console.

Program tape is labelled Single Precision Decimal Input,
Digital- 8-2 8-U-ASCII
9 .

9.3.1

USAGE

Loading
The symbolic tape provided can be assembled with the user's main

program by PAL III, r4ACRO-8, or PAL-D.

The symbolic tape has neither an

origin setting nor a terminating "$", but does have a PAUSE pseudo-

instruction at the end.
9.3.2

Calling Sequence

The subroutine is called by an effective JMS to location SICONV.
Return is to the location immediately following the calling JMS with
the binary number in the accumulator.

9-1

9.4

ERRORS IN USAGE
If a sign

(+,

or space) precedes the string of decimal

digits, the maximum decimal number correctly accepted is
2047

The sign, if any, must appear first.

If a sign

does not precede the string of decimal digits, the maximum decimal

number correctly accepted is 4095 (2 12 - 1)
If either of these
maxima is exceeded, the results are unspecified.
.

9.5

RESTRICTIONS
The status of the AC and link is not preserved.
This subroutine should not be used when the interrupt is on.

The magnitude restrictions on numbers are described in
Section 9.4.
9.6

DESCRIPTION

This subroutine converts to the binary equivalent a signed or
unsigned string of decimal numbers read from the console keyboard
of the PDP-8.

If a minus sign is specified, the results are in

2's complement negative form.
if it is a sign

(+,

The first character is examined and,

or space), a switch is set to provide the

correct sign for the conversion. Regardless, a switch is set after
the first character to terminate conversion if a character other than
a decimal digit or rubout appears.
If a back arrow appears at any
time, the conversion is reinitialized and the subroutine waits for
the correct entry.

The last four bits of the ASCII code for each of the decimal
digits are identical to the standard 8-4-2-1 BCD code. Thus, the

BCD digit is extracted from the 8-bit code by the AND instruction
with a "mask" of 17g. When the first BCD digit comes in, it is
added to a cleared location (SJHOLD) in memory and stored back in
that location. When the next legal character comes in, location

SJHOLD is multiplied by 10, then added to the BCD code of the
character and returned to location STORE. This sequence holds

9-2

true for a decimal number of any arbitrary length.

9.7

EXAMPLE
Since the PDP-8 can add and shift easily, the multiplication

by 10 can be accomplished in three instructions.
is equivalent to a multiplication by 2 ,

equivalent to a multiplication by

Since a shift left

a double shift left is

Assume that the number currently

in STORE is 5, and the new code just coming in is the number 1 stored
in HOLD.

The program sequence to perform the multiplication and

storage is as follows:

Instruction
Sequence

Contents of AC

Comments

CLA
TAD STORE

/Load C (STORE) into AC

CLL RTL

/Multiply C (STORE) by

TAD STORE

/Add STORE giving C (STORE) by

CLL RAL

/Multiply by

TAD HOLD

/Add in the next number

000 000 110 Oil

DCA STORE

/Store back into STORE and return
to wait for next character

000 000 000 000

000 000 000 101

0000000 10 100

000 000 Oil 001

giving C (STORE) by 10 000 000 110 010

The number residing in location STORE is 006 Sq or 0051,^.
If the next number to come in were "9", using the same sequence

and conditions, the result would be 001 000 000 111, the binary

equivalent of 519.

9 .

SCALING
This subroutine assumes an integral decimal number (signed or

unsigned) and yields an integral binary equivalent (signed or unsigned

respectively)

9 .

9.9.1

FORMAT
Input
The input string may or may not contain a sign (+, -, or space)

9-3

Any character other than a sign,

0-9, or back arrow causes the

subroutine to terminate, as does a sign in any but the first position.
9.9.2

Core Data
The terminating character is found in location SISAVE.

9.9.3

Output
Spacing, tabulation, carriage return, etc., are not provided

for in this subroutine.

See Chapter

for those purposes.

9-4

which contains short subroutines

9.10

FLOW CHART

(

ENTRY

INITIALIZE a ZERO

ASSEMBLY
LOCATIONS

ERASE NUMBER

WAIT FOR
INPUT FROM

KEYBOARD

YES

SET SIGN
INDICATOR
TO NEGATIVE

MULTIPLY PARTIALLY

ASSEMBLED
NUMBER BY 10

FORM 2'S
COMPLEMENT

ADD INCOMING
DECIMAL DIGIT

5>^
NUMBER IN AC

EXIT

D
9-5

PKUGKAiyi l.lbTl]N«a

/COPY UGH
/;vlAYNA:^D>

DIGIIAL ^^JIP-ISMr cor^pO'^ArioN
1971
.^ASS^CH JSH:TTS

/SINGLE PRECISION DECIMAL INPUT FROM KEYBOARD
/CALLING SEQUENCE: JMS SI CONV
/ACC IGNORED, RETURN WITH BINARY WORD IN ACC
0200
020
0202

0000
7300
1273

0203
0204
0205
0206
0207
0210

3232

021 1

3307

0212

1307

SI CONV,

CLA CLL
TAD SI SET

1273

3224
3310
331
5257
1

SIPROC,

DCA
TAD
DCA
DCA
DCA
JMP
DCA
TAD

/INITIALIZE PROGRAM SWITCHES

SI CTRL

SISETl +1
SIXSWl
SIHOLD
SINEGl
SINPUT
SI SAVE
SI SAVE

/CLEAR NEGATIVE SWITCH
/STORE AND THE PROCESS
/CHARACTER

0213

1301

02 14

7450

TAD SIRBUT
SNA

0215
0216
0217

5201
1302
7510

JMP SI CONV
TAD SIM260
SPA

0220

5232

JMP

0221

0222

1303
7740

TAD SIM271
SMA SZA CLA

0223

5232

JMP SICTRL

/IS IT GREATER THAN 27
/(IE. "9")?
/YES, TRANSFER TO SEE WHAT

0224

7300

CLA CLL

/CHAR. IT IS
/NO, FIRST CHARACTER WAS A

0225
0226
0227

1231

1777

TAD .+4
DCA .-2
TAD SINMBR

/DECIMAL DIGIT
/CLOSE SWITCH TO GO TO
/"SINMBR" NEXT
/SET SWITCH TO SENSE
/TERMINATING CHAR.

3232
5246
7300

DCA SICTRL
JMP SINMBR
CLA CLL

/IS IT A "BACK-ARROW"
/(IE. ERASE) KEY
+

/YES,

/IS IT LESS THAN 260
/CIE. "0")
/YES. TRANSFER TO SEE WHAT

SI CTRL

/CHAR.

0230
023
0232
0233
0234
0235
1

SIXSWl,

3224

1307
1304

SICTRL,

REINITIALIZE

IS
1

-1

/CONTINUE CHECKING

0236

7450
5273

TAD SI SAVE
TAD SIMSPC
SNA
JMP SISETl +1

0237
0240
0241

1305
7450
5273

TAD SI MPLS
SNA
JMP SISETl

0242
0243
0244

1306
7650
5273

TAD SIMMNS
SNA CLA
JMP SISETl

+ 1

9-6

/IS IT A SPACE?
/YES, SET SWITCH TO SENSE
/TERMINATING CHAR.
/IS IT A "PLUS"?
/YES, SET SW TO SENSE
/TERMINATING CHAR.
/IS IT A MINUS?
/YES, SET NEGATIVE XSWITCH
/AND TERM. SWITCH

0245

5264

0246

1310

0247

7106

0251

100A
3310

0252
0253
02 54

0255
0256
0257
0260

JMP
SINMBR,

1307

1310

3310

026 1
0262
0263

6036
6046

0264

7300

SINPUT*

131 1

0266

7010

/PICK UP CURRENT DIGIT
/MASK OFF THE HIGH ORDER

/BIT
/ADD TO ASSEMBLED NUMBER
TAD SIHOLD
/STORE BACK IN SIHOLD
DCA SIHOLD
/INPUT ROUTINE
KSF
JMP .KRB
TLS
JMP SIPROC
1

521 1

02 6 5

TAD SIHOLD
CLL RTL
TAD SIHOLD
RAL
DCA SIHOLD
TAD SI SAVE
AND SI MASK

0300

6031
5257

IT WAS A TERMINATING
/CHARACTER
/MULTIPLY CURRENT ASSEM/BLED NUMBER BY 10

/NO,

SI END

/TERMINATING ROUTINE
CLA CLL
SI END,
TAD SINEGl
RAR

/PUT NEGATIVE SWITCH INTO
/LINK

0267
0270

7 430

TAD SIHOLD
SZL

027 1

7041

CM A

0272
0273
0274
0275

5600
231 1

1310

/IS THE LINK "1"?
/YES, NUMBER NEGATIVE.
/COMPLEMENT
/RETURN.
/SET NEGATIVE SWITCH

JMP

7300

I
SI CON
ISZ SINEGl
CLA CLL

1777

TAD SINMBR -1

SISETl^

/CLOSE SW TO TRANSFER TO
/TERM.

DCA SI CTRL
JMP SIN PUT

0276
0277

3232
5257

0300
0301
0302

0017
7441
0057

SIMASK,
SIRBUT,
SIM260,

-337

0303

7767

SIM27 1,

- 1 1

0304
0305

7540
7765

SIMSPC,
SIMPLS,

-240

0306

7776

SIMMNS*

-2

0307
0310

0000
0000
0000

SI SAVE,

/CONSTANTS AND VARIABLES

0311

/CODE FOR ERASE
/NUMBER USED TO GENERATE
/CODE "260"
/NUMBER USED TO GENERATE
/CODE "271"

/NUMBER USED TO GENERATE
/CODE "253" (+)
/NUMBER USED TO GENERATE
/CODE "255" (-)
/STORAGE LOCATIONS

- 13

SIHOLD,
SINEGl,
PAUSE

9-7

Formerly

Digital-8-29-U-Sym

DECIMAL TO BINARY CONVERSION
AND INPUT
(Double Precision, Signed or Unsigned, 33-ASR)

ABSTRACT

10 .

This routine accepts and echoes a string of up to eight decimal
digits (double-precision for the PDP-8) from the Teletype keyboard
and converts it to the corresponding two's complement binary number.

The string may contain as legal characters a sign (+, -, or space)
If the first legal character is not a sign, the
and the digits 0-9.
at any point in the
conversion is unsigned A "back-arrow" ( ^
)

string erases the current string and allows the operator to re-enter
Termination of input is accomplished by typing one illegal
the value.

character which will then be found in location DIDSAV within the subroutine.

REQUIREMENTS

10.2

This subroutine requires 110-,q

(156 g)

core locations and runs on

The
any standard PDP-8 family computer with a 33-ASR Teletype console.
paper tape is labelled Double Precision Decimal to Binary Conversion,

Digital- 8-29-U- ASCII
10

10.3.1

USAGE

The symbolic tape provided can be assembled with the user's
main program with PAL III, MACRO- 8, or PAL-D. There is neither

origin setting nor terminating "$" on the symbolic tape, but a
PAUSE pseudo-instruction is the last line on the tape.

10-1

Calling Sequence

10.3.2

The subroutine is called by an effective JMS to location DICONV.
The location immediately following the JMS instruction contains the

address of the location where the high-order portion of the number is
to be stored.
(It is assumed that the low-order portion of the number
is in the location immediately following the high-order portion.)
Return is to the second location following the calling JMS with the AC
clear.

For example:

JMS DICONV
ADDR
HLT

ADDR,

ERRORS IN USAGE

10.4

If the string of decimal digits is preceded by a sign

space)

(+,

the maximum decimal number that is correctly accepted is

16777215 (2^^ -1)
If neither of these maxima is exceeded, the results are

unspecified.
10.5

RESTRICTIONS
The status of AC and link is not preserved.

This subroutine should not be used with the interrupt on.
The magnitude restrictions on numbers is described in section 10.4
10.6

DESCRIPTION

The discussion, example, and scaling information about the
conversion are given in Chapter 9. The only difference is that the

multiplications by "4" and "2" are performed by the arithmetic shifts
as described in the section on Arithmetic Shift Subroutines in the
PDP-8 Math Routines write up, DEC-0 8-FFAD-D.
Information on techniques used in this program can also be
found in Chapter 9 of this document.
10-2

FORMAT

10.7

10.7.1

Input Data

The input string may or may not contain a sign

Any character other than a sign,

- 9,

(+,

or space)

or rubout causes the subroutine

to terminate as does a sign in any but the first position.

10.7.2

Core Data

The high-order portion of the binary equivalent of the number
is found in the location specified by the address following the JMS

The low-order portion is found in the next successive location.
is the format compatible with the double-precision,

arithmetic subroutines.

fixed point

The terminating character is found in location

DIDSAV.

10.7.3

Output Data

Spacing tabulation, carriage return, etc.
for in this subroutine.

This

See Chapter

are not provided

which contains short sub-

routines for such purposes.
This subroutine is input limited at a maximum of 10 cps

10-3

FLOW CHART

10.8

INITIALIZE PROGRAM

SWITCHES AND ZERO
LOCATIONS FOR HOLDING
PARTIALLY-ASSEMBLED
DOUBLE-PRECISION NO.

FIRST CHARACTER
A TERMINATING

CHARACTER

PICK UP ADDRESS FROM

CALLING SEQUENCE FOR
STORING DOUBLE
PRECISION NUMBER

ERROR MADE
OPERATOR WISHES TO
ERASE NUMBER

COMPLEMENT THE
DOUBLE -PRECISION

WAIT FOR CHARACTER

FROM KEYBOARD
OR READER

NUMBER

THIS

TERMINATING
CHARACTER

SAVE INCOMING
CHARACTER IN
"
D DSAU

STORE RESULT IN
ADDRESS SPECIFIED BY
THE CALLING SEQUENCE

FIRST CHARACTER
WAS A DECIMAL DIGIT

SET SWITCH 'I

SET

CONTROL

SWITCH

YES

PICK UP PARTIALLYASSEMBLED, DOUBLE
PRECISION NUMBER

MULTIPLY BY FOUR
(IE DOUBLE SHIFT

LEFT TWICE)

PICK UP INCOMING

CHARACTER

ADD THE PARTIALLY
ASSEMBLED. DOUBLE
PRECISION NUMBER

MULTIPLY BY TWO
(!E

DOUBLE SHIFT
LEFT ONCE)

ADD THE INCOMING
DECIMAL DIGIT
TO THE RESULT

YES

SET NEGATIVE SWITCH

SET

CONTROL
SWITCH

YES

10-4

STORE SUM AS THE NEW
PARTIALLY-ASSEMBLED,
DOUBLE-PRECISION NO.

10.9

PROGRAM LISTING
/COPYRIGHT 197
/;iAY^JAf^D>

0200
020
0202
0203
0204
0205
0206

0000
7300
1324
3235
1324
3227
1600

0207
0210

3351
3352

0211
0212
0213
0214
0215
0216
0217
0220
0221
0222
0223

3353
3347
5275
3350

1350
1341
7450
5201
1342
7510

5235

DIGITAL £3 JI P^^ENi F COifOR^ilO^
^lASSACHJSEirS
1

/DOUBLE PRECISION DECIMAL-TO-BINARY CONVERSION AND INPUT
/AC IGNORED
/CALLING SEQUENCE:
/
JMS DICONV /SUBROUTINE CALLED
/
ADDRES /ADRESS TO STORE HIGH-ORDER \wORD
/
/LOW -ORDER WORD IN ADDRESS+1
DICONV^
CLA CLL /INITIALIZE PROGRATn SWITCHES
TAD DISETl+1
DCA DICTRL
TAD DISETl+1
DCA DIXSWl
/PICK UP ADDRESS TO STORE
TAD I DICONV
/HIGH-ORDER WORD
DCA DIGET
/CLEAR LOCATIONS USED TO HOLD
DCA DIHIHD
/INCOMING
/NUMBER
DCA DILOHD
/CLEAR NEGATIVE SWITCH
DCA DINEGl
DIPROC^

JMP
DCA
TAD
TAD
SNA
JMP
TAD
SPA
JMP

DUN
/STORE CHARACTER

DIDSAV
DIDSAV
DIRBUT

/IS IT A "BACK- ARRO W" C I E. ERASE) KEY?
/YES^ REINITIALIZE
DICONV+1
DIM260
/IS IT LESS THAN 260 (IE. "0")?
/YES^ TRANSFER TO SEE WHAT
DICTRL
IS

/ uni-irii-io i rL,i

0224
0225

1343
7740

0226

5235

0227
0230
0231
0232

7300
1234
3227
1250

TAD DIM271
SMA SZA CLA

/IS IT GREATER THAN 271

241

3235
525
7200
1350
1344
7450
5 324

0242
0243
0244

1345
7450
5324

"9")?

/YES^ TRANSFER TO SEE WHAT
/CHARACTER IT IS
DIXSWl^ CLA CLL /N0:» FIRST CHARACTER WAS A DECIMAL DIGIT
TAD .+4 /CLOSE SWITCH TO GO TO "DINMBR" NEXT
DCA .-2
/SET SWITCH TO SENSE TERMINATING
TAD DINMBR/CHARACTER
DCA DICTRL
JMP DINMBR
/CONTINUE CHECKING TO DETERMINE CHAR.
DICTRL^ CLA
TAD DIDSAV
TAD DIMSPC
/IS IT A "SPACE"?
SNA
/YES^ SET SWITCH TO SENSE TERM.
JMP DISETi+i
/CHARACTER
TAD DIMPLS
/IS IT A "PLUS"?
SNA
/YES^ SET SWITCH TO SENSE TERM.
JMP DISETl+1
/CHARACTER

JMP DICTRL

•

0233
0234
0235
0236
0237
0240

(IE.

10-5

245
246
0247

1346
•7

/^,

i7i

5323

0250
0251

5302

0252
0253
0254
0255
0256
0257
0260
0261
0262
0263
0264
0265
0266
0267
0270
0271
0272
0273
0274

3354
1352
3355
4330
4330

7004
1352
1355
3352
4330
1350
0340
1353
3353
7430
2352

0275
0276
0277
0300
0301

6031
5275
6036
6046
5214

0302
0303
0304
0305
0306
0307
0310

7200
1347

1353

1353
1354
3353

71 10

0312
0313

1352
7430
7040
3751
1353
7430
7141

0314
0315
0316
0317

7430
2751
7000
2351

0320
0321
0322
0323

3751
2200

031 1

5 60

TAD DIMMNS
SNA CLA /IS IT A "MINUS"'
JMP DISETl
/YES^SET NEGATIVE SWITCH AND TERM
/SWITCH
JMP DIEND
/NO^ IT WAS A TERMINATING CHARACTER
DINNER^ TAD DILOHD
/STORE ASSEMBLED NUMBER
/TEMPORARILY
DCA DIXTMI
TAD DIHIHD
DCA DIXTM2
JMS DIDSPL
/MULTIPLY CURRENT BY "1
JMS DIDSPL
TAD DILOHD
TAD DIXTMI
DCA DILOHD
RAL
TAD DIHIHD
TAD DIXTM2
DCA DIHIHD
JMS DIDSPL
TAD DIDSAV
/PICK UP CURRENT DIGIT
AND DIXMSK
/MASK OFF HIGH-ORDER BITS
TAD DILOHD
/ADD REMAINDER TO CURRENT NUMBER
DCA DILOHD
SZL
/DID IT OVERFLOW?
ISZ DIHIHD
/YES^ CORRECT HIGH-ORDER WORD
/INPUT ROUTINE
DIIN^
KSF
JMP KRB
TLS
JMP DIPROC
/TERMINATING ROUTINE
DIEND^
CLA
/PICK UP NEGATIVE NUMBER
TAD DINEGl
CLL RAR /PUT IT INTO LINK. ("1" IF NEGATIVE)
/PICK UP HIGH ORDER PORTION
TAD DIHIHD
/IS LINK "1"?
SZL
CMA
/YES:. NUMBER NEGATIVE. COMPLEMENT IT
DCA I DIGET
/STORE IT
/PICK UP LOW-ORDER PORTION
TAD DILOHD
SZL
/IS LINK "1"?
/YES:. TWO'S COMP.IT. IF OVERFLOW^
CLL CMA lAC
/LINK=1
SZL
/IS LINK "1"?
/INDEX HIGH-ORDER PRTION
ISZ I DIGET
/TAKES CARE WHEN HIGH-ORDER PORTION =0
NOP
/INDEX POINTER FOR LOW-ORDER
ISZ DIGET
/PORTION
/STORE LOW-ORDER POTION OF NUMBER
DCA I DIGET
/INDEX FOR CORRECT RETURN
ISZ DICONV
/RETURN
JMP I DICONV
/SET NEGATIVE SWITCH
ISZ r^ T M
ISET
.

u' r:

10-6

0324
0325
0326
0327

7300
1250
3235
5275

330
0331
0332
0333
0334
0335
0336
0337

0000

0340
0341
0342
0343

0017
7441
0057
7767
7540
7765
7776
0000
0000
0000
0000
0000
0000
0000

0344
0345
0346
0347
0350
0351
0352
0353
0354
0355

1353
7104
3353
1352
7004
3352
5730

CLA CLL /CLOSE SWITCH TO TRANSFER TO TERMINATION
TAD DINMBRDCA DICTRL
JMP DUN
/JUMP TO WAIT FOR NEXT CHARACTER
/DOUBLE PRECISION LEFT SHIFT CX2)
DIDSPL'
TAD DILOHD
CLL RAL
DCA DILOHD
TAD DIHIHD
RAL
DCA DIHIHD
JMP I DIDSPL
/CONSTANTS AND VARIABLES
DIXMSK^ 17
/MASK FOR LAST FOUR BITS
DIRBUT^ -337
/CODE FOR ERASE
DIM260:* 57
/NUMBER USED TO GENERATE CODE "260"
DIM271^ -11
/NUMBER USED TO GENERATE CODE "271"
DIMSPC:» -240
/CODE FOR SPACE
DIMPLS^ -13
/NUMBER USED TO GENERATE CODE "253" C+)
DLMMNS^ -2
/NUMBER USED TO GENERATE CODE "255" C-)
DINEGl^
/STORAGE LOCATIONS
DIDSAV^
DIGET^
DIHIHD>
DILOHD>
DIXTMl^
DIXTM2^

10-7

Formerly
Digital- S-lO-U-Sym
CHAPTER 11
BCD TO BINARY CONVERSION, SINGLE PRECISION
(Binary Coded Decimal to Binary Conversion Subroutine)

ABSTRACT

11.1

coded-decimal numbers to their equivalent binary value.
is accomplished by "radix deflation".

Conversion

REQUIREMENTS

11.2

This subroutine requires 23, ^ ^27g) memory locations and runs
on any standard PDP-8 family computer with a 33-ASR Teletype console
The source paper tape is labeled BCD to Binary Conversion,

Digital-8-lO-U-ASCII
USAGE

11.3

11.3.1

Load the subroutine with the Binary or RIM Loader, as described
in either Introduction to Programming or Programming Languages
.

11.3.2

Calling Sequence

Call with the number to be converted in the AC.

Return will be

to the location following the calling JMS with the result in the AC.

11.4

DESCRIPTION
The method used is that of "radix deflation".

Upon entry, the

BCD number may be considered to be in the following form:
(a)

D^ 16^ + D

16 + Dq

What is desired is the number in the form:
(b)

D2 10^ + D^ 10 + Dq

11-1

A right shift is equivalent to

The PDP-8 can shift (rotate) and add.

division by a power of two. An appropriate series of shifts,
additions, and subtractions is used to convert the number from the
a

form of
11.5

(a)

to that of

(b)

EXAMPLE

Consider the BCD number
0101

1001

0001

representing the decimal number 519.
First the whole number is stored and then brought back into the
AC.

Next, the four most significant bits are masked out.

At this

point, the accumulator contains 16xl6xA or
0101

0000

A shift to the right of one bit yields
0010

1000

0000

This number is stored and then brought back to the AC, shifted right
two bits, and the stored value added as follows:
0000
0010

1010
1000

0000
0000

0011

0010

0000

Now the original number is added to this result
0011
0101

0010
0001

0000
1001

1000

0011

1001

and the most significant eight bits masked out as
1000

0000

0011

11-2

This is stored, brought back and shifted right once, and the stored

value added.
0100
1000

0001
0011

1000
0000

1100

0100

1000

Next the result of this addition is shifted right two places dividing
the number by four as follows

0011

0001

0010

negated and the original number added
1100
0101

1110
0001

1110
1001

0010

0000

0111

This result represents in binary 512 plus

plus

or 519,

the original number.

11.6

SCALING
This subroutine assumes an integral BCD number and yields an

integral binary equivalent.
11.7

PROGRAM LISTING

A listing of the subroutine with BCDBIN located at 0200 is
given below. To simplify mnemonics D^, D,
and D^ have been replaced
respectively with A, B, and C.

11-3

/BINARY-CODED-DECIMAL TO BINARY COhiVERSTON SUBROUTINE
*263
0263
0264
0265
0266
0267

0000
3314

02 70

3313
1313
7010
1315
7041
1314
3314
1314

027 1
0272
0273
0274
0275
0276
0277
03-1/

1314
031 1
71 12

!/';

]

0301
0302
0303
0304
030 5
0306
0307

7112
3313

03 1
031

5 6 63

'/'

0312
0313
0314

13 1

7010
i:-! 1

.-.

7041
1314

7400
7760
0000
0000

BOBBIN^

DCA TEMPH
TAD TEMPH
AND LDIGIT
CLL RTR
DCA COUNT
TAD COUNT
RAR
TAD COUNT
CMA I AC
TAD TEMPH
DCA TEMPH
TAD TEMPH
AND MDIGIT
CLL RTR
DCA COUNT
TAD COUNT
RAR
TAD COUNT
CMA I AC
TAD T EMPH
JMP I BCDBIN
LDIGIT:* 7400
MDIGIT^ 7760
COUNTS

/STORE INPUT

/160 H

/60 H

16 M + L

/EXIT

TEMPH:.

REFERENCES

11.8

11.8.1

DECUS Programs

See DECUSOPE January 1965, article entitled "Accelerated Radix

Deflation on the PDP-7 and PDP-8".
11.8.2

ACKNOWLE DGMENTS

Mr. Donald V. Weaver, Consultant, of New York City, who first

described the algorithm used by this subroutine in reference 11.8.1
has granted his kind permission to include this subroutine in the

PDP-8 library so that a detailed description may be available.

11-4

Formerly
Di'^i"'"3.1— 8— 11—^^

CHAPTER 12
BCD TO BINARY CONVERSION, DOUBLE PRECISION

ABSTRACT

12.1

This subroutine converts a 6-digit BCD number to its equivalent

binary value in two computer words
REQUIREMENTS

12.2

This subroutine requires 89,

(131„) memory locations and runs

on any standard PDP-8 with a 33-ASR Teletype console.

The source tape

is labeled Double Precision BCD to Binary Conversion,

Digital-8-ll-U-ASCII
USAGE

12.3

12.3.1

The subroutine is loaded with the Binary Loader.

The symbolic

code is either assembled with the user program or separately with the

proper origin setting.
Calling Sequence

12.3.2

This subroutine is called with an effective JMS DOUBLE followed
by the address of the high-order word of the double-precision BCD
number.

Control is returned to the following location with the high-

order part of the result in C(AC) and with the low-order part of the
result in C(LOW)
12.4

DESCRIPTION
Upon entry, the BCD number is in the form:
2

(16 D,

(each digit is

+ I6D2 + D^)

bits,

;

C16 D, + 16D^ + Dg)

= 16)

12-1

using the single

precision BCD to binary subroutine, this is

reduced to:
(lO^D^ + IOD2 + D3);(10^D^ + lOD^ + D^)

The high order part of the BCD word is effectively multiplied
by 1000 (=8(128

3))

and the low-order part is added, giving

lO^D^ + 10'^D2 + lO^D^ + lO^D^ + lOD^ + D

See Chapter 11.

12 5
.

EXAMPLES
GO,

HIGH,
LOW,

JMS I X
HIGH
HLT
DOUBLE
1001
1001
1001
1001

1001
1001

999,999

If this program were started at GO, the C(AC)

at the halt would

be 0364g and C (LOW) would be 1077g, i.e., 03641077g = 999,999^q.
12.6

PROGRAM LISTING
/COPYRIGHT 1971

/DIGITAL

DIGITAL EJJIPMSNf CO'^POKAriON

8-11-U-SYM

/DOUBLE PRECISION BCD TO BINARY CONVERSION
/CALLING SEQUENCE:
JMS DOUBLE
/
ADDRESS OF HIGH ORDER ARGUMENT
/
C(AC)=HIGH ORDER PART
RETURN:
/
CCLOW) = LOW ORDER PART
/
/ALSO CONTAINS SINGLE PRECISION BCD TO BINARY
/CALLING SEQUENCE:
CCAC) = 3 BCD CHARACTERS
/
/
JMS BCDBIN
ANSWER IN CCAC)
RETURN:
/

12-2

0200
020
0202
0203
0204
1

0205
0206
020 7

0210
(Tl

O
C 1 1
1

DOUBLE.
7300
1600
3271
2200
1671

4275
3272
2271

0212
0213
0214

4275

7 112

021 6

7012
7010
3275
1275
0327
3274
1275
7010
0325

0217

0220
0221
0222
0223
0224
0225
0226
0227
0230
0231
0232
0233
0234
0235
0236
0237
0240
0241
242
0243
0244
0245

0246
0247
0250
0251

0252
0253
0254
0255
0256
0257
0260
0261

0262

3271
1272

32 7 3
1272

7104
1272
7 141

1273

3273
7420

L_/

TAD
DCA
TAD
CLL
RAL
AND
DCA
TAD
CLL
RAL
DCA
TAD
RAL
AND
TAD

1274
3274
1273
0326
7100
127

3273
1274
7430

7001
5600

n*.i

L- »^ VV

/FETCH ADDRESS
/STORE
/INCREMENT RETURN
/FETCH HIGH ORDER
/CONVERT IT
/STORE
/INCREMENT POINTER
/ p r T Q u LOW
ORDER
/CONVERT IT
/STORE IT

CM A

0324

JMS BCDBIN
DCA LOWl
TAD HIGH
CLL PTP
RTR
RAR
DCA BCDBIN
TAD BCDBIN
AND K 177
DCA HIGH
TAD BCDBIN
RAR
AND K7600
DCA LOW
TAD HIGHl
CLL RAL
TAD HI GHl
CIA CLL
TAD LOW
DCA LOW
SNL

02 6 3
02 6 5

Tn
An

1274
3274
1274
7106
7004
0326
32 7 4
1273
7106
7004
3273
1273
7004

0264
0266
0267
0270

CLA CLL
TAD I DOUBLE
DCA LOWl
DOUBLE
I SZ
TAD I LOWl
JMS BCDBIN
DCA HIGHl
LOWl
I SZ

/MULTIPLY HIGH ORDER
/PART BY 128

/MULTIPLY HIGH ORDER
/BY THREE

/FORM 128*HI GH-3*HI GH

HIGH
HIGH
HIGH

/125*HI GH
/NOW MULTIPLY BY

/MASK

K7771

BITS

HIGH
LOW
RTL
LOW
LOW
/3 BITS

HIGH
DCA HIGH
TAD LOW
AND K777£

CLL
TAD L W
DCA LOW
TAD HIGH
SZL
I AC
I

BITS

/ADD LOW ORDER PART
/STORE LOW ORDER PART

JMP

RTL

/CARRY

DOUBLE

12-3

027
0272
02 7 3
1

0274

02 7 5

0276
0277
0300
0301
0302
0303
0304
0305
0306
0307
0310
031 1

0312
0313
0314
0315
0316
0317
0320
032
0322
0323
0324
0325
0326
0327
0330
1

0000
0000
0000
0000

0000
3274
1274

0330
7112
3273
1273
7010
1273

LOWl^
HIGHl,
LOW,
HIGH,

/SINGLE PREC;isiON
BCDBIN,
DCA HI GH
TAD HIGH
AND K7400

K7760,
K7,

K7600,
K7770,
K177*
K7400,

7600
7770

3274
1274
0323
71 12

3273
1273
7010

0007
7600
7770
0177
7400

/LEFT DIGIT

CLL RTR
DCA LOW
TAD LOW
RAR
TAD LOW
CIA
TAD HIGH
DCA HIGH
TAD HIGH
AND K 7 7 6
CLL RTR
DCA LOW
TAD LOW
RAR
TAD LOW
CIA
TAD HIGH
JMP I BCDBIN
7760

7041
1274

1273
7041
1274
5675
7760

co;

177

7400

12-4

Formerly
—
o
Digitalb-^^-u-bym
I

'^ '^

CHAPTER 13
UNSIGNED DECIMAL INTEGER PRINT

ABSTRACT

13.1

This subroutine permits the printing of the contents of a computer

word as a 4-digit, positive, decimal integer.
13

REQUIREMENTS

This subroutine requires 38,

core locations and runs on

^^^q^

any standard PDP-8 family computer with a 33-ASR Teletype console.

The

paper tape provided is labeled Unsigned Decimal Print Subroutine,
Digital- 8-22-ASCII
USAGE

13.3

13.3.1

The subroutine can be placed in core by use of the Binary Loader.
See Introduction to Programming or Programming Languages for full
The symbolic tape provided is either assembled with the

details.

user program or separately with the proper origin setting.

Calling Sequence

13.3.2

The subroutine is called by the usual JMS instruction with the

number to be printed in the AC.

Return to the location following that

of the calling JMS.

13.4

DESCRIPTION
This is a basic subroutine used to obtain decimal output corres-

^Kjn'ji.^i.LKj

UVJ

kjj.xi.CLS.

WKJJ-KJLO

±.11

luciin^J- _y *

xiLKZ

j^j. i^Cj J. dill

i^^Jc: J- CI w::^ o

j-ii

«.

o »-j. cij.'wj j.* <-

First the binary equivalent of 1000 is subtracted
from the original number until a negative result is obtained. A count
forward manner.

is kept of the number of subtractions necessary to accomplish this,

thus yielding the most significant decimal digit.

13-1

This process is

repeated, using the proper power of ten, to give the three remaining

decimal digits.
13.5

METHOD

This method of binary to binary-coded-decimal conversion is
compact and easily understood, if not sophisticated. The latter consideration is of little consequence, since the subroutine is output
limited.
13.6

OUTPUT DATA FORMAT

Output is in the form of four consecutive decimal digits. No
sign is printed.
Spacing, tabulation, carriage return, etc. are not

provided in this subroutine.

13.7

PROGRAM LISTING

0200
020
0202
0203
0204
0205
0206
0207
0210

0000
3243
3244
1235
3245
1234
3213
7410
3243

021
02 12
1

7 100

0213

1243
1236
7430

0214
0215
0216
0217
0220
0221
0222
0223
0224
0225
022 6

2244
7430
5210
7200
1244
1242
6041
5223
6046
7200

/COPY:<lGHr 1971
DIGITAL £2 JI PM^^sjx COr^POKA f I OnJ
/MArNARD, ^^ASSACHJSbfrS
/DIGITAL 8-22-U
/UiMSIGNED DECIMAL PRINT
/CALL WITH NUMBER TO BE TYPED IN CCAO
/RETURN TO LOCATION FOLLOWING THE JMS
DECPRT,
DCA VALUE
/SAVE INPUT
DCA DIGI T
/CLEAR
TAD CNTRZA
DCA CNTRZB
/SET COUNTER TO FOUR'
TAD ADDRZA
DCA ARROW
/SET TABLE POINTER
SKP
DCA VALUE
/SAVE
CLL
TAD VALUE
ARRO W.
TAD TENPWR
/SUBTRACT POWER OF TEN
SZL
ISZ DIGIT
/DEVELOP BCD DIGIT
SZL
JMP ARROW-3
/LOOP
CLA
/HAVE BCD DIGIT
TAD DIGIT
/GET DI GIT
TAD K260
/MAKE IT ASCI I
TSF
/OR TAD DIGIT
JMP .JMS TDIGITCSEE 8- 19-U)
/
TLS
/TYPE DIGIT
CLA
1

13-2

0227
0230
0231
0232
0233

3244
2213
2245
5212
5600

0234

1236

023 5
0236

7774
6030
7634
7766
7777
0260
0000
0000
0000

0237
0240
0241
02 42

0243
0244
0245

ADDRZA,
CNTRZA,
TENPWR.

DCA DIGIT
ISZ ARROW
ISZ CNTRZB
JMP ARROWTM D T
ViVrC DDT
TAD TEiMPWR
-4
-

/ONE THOUSAND
/ONE HUNDRED
/TEN
/ONE

750

-0144
-0012
-0001
K260,
VALUE,
DIGIT,
CNTRZB,

/CLEAR
/UPDATE POINTER
/DONE ALL FOUR?
/NO: CONTINUE
/YES: EXIT

260

13-3

Formerly
Digital-8-23-U-Syin

CHAPTER 14
SIGNED DECIMAL INTEGER PRINT
SUBROUTINE, SINGLE PRECISION

ABSTRACT

14.1

This subroutine permits printing the contents of a computer word
is a "1",

the remaining bits represent a negative integer in two's

equals "0", the remaining bits represent

complement form; if bit
a

positive integer.

If the number is negative, a minus sign is

printed; if positive, a space.

REQUIREMENTS

14.2

This subroutine requires 51,^ ^^^r^ core locations and runs on
any standard PDP-8 family computer with a 33-ASR Teletype console.
The program is provided on a source tape labeled Signed Decimal Print,

Single Precision,

Digital- 8-23-U-ASCII
USAGE

14.3

14.3.1

The symbolic tape provided is compatible with the PAL III, MACRO- 8,
or PAL-D assemblers.

It can be assembled with the user's program or

separately with the proper origin setting.

Neither origin setting

nor "$" terminating character exists on the symbolic tape provided.
14.2.1

Calling Sequence

The subroutine is called by an effective "JMS SSPRNT" with the

number to be printed in the AC.
ing that of the calling JMS.

The return is to the location follow-

The contents of neither the AC nor the

link are preserved, and return is with both active registers clear.

14.4

DESCRIPTION
This is a basic subroutine to obtain signed decimal output

(integer format)

corresponding to binary words in memory stored in

two's complement form.

First, the number is sensed to determine if

it is positive or negative.

If positive, a space is printed.

14-1

negative, a minus sign is printed and the number complemented to form
the absolute value in two's complement.

Then, the same algorithm is

followed as in the unsigned printout described in Chapter 13.

OUTPUT DATA

14.5

Output is in the form of four consecutive decimal digits preceded
Spacing, tabulation, carriage
by either a space or minus sign.
return, etc.

are not provided in this subroutine.

See Chapter 6,

which contains details on subroutines for such purposes.

This sub-

routine is output limited at 10 cps by the 33-ASR.

FLOW CHART

14.6

ENTRY
yes

CLEAR LINK
MODIFY CODE TQ"-"

^.^THE NUMBER \^

NEGATIVE

YES

TYPE OUT CHARACTER

SET LINK TO "l."
FORM
ABSOLUTE VALUE
PICK UP
CURRENT POWER
OF TEN

STORE NUMBER AWAY

SUBTRACT CURRENT
POWER OF TEN
FROM NUMBER

INITIALIZE COUNTERS.
POINTERS AND DIGIT

STORAGE REGISTER

INDEX DIGIT

INDEX INSTRUCTION
TO GET NEXT

YES

LOAD CODE
FOR "space"
INTO AC

POWER OF TEN

LOAD GENERATED
DIGIT INTO AC
TYPE IT OUT

SUBROUTINE
FINISHED

14-2

EXIT

14.7

PROGRAM LISTING
OIGIf^L EJJIP^SNr COrJPOKA
/COPr.^IGHF 1971
A^1AYNARD# NlASSACKUSEirS
/BINARY TO DECIMAL CONVERSION AND TYPEOUT

0200
0201
0202
0203
0204
0205

0000
7100
7510

0210

3253
3251
1250
3252
1244

0211
0212
0213
0214

3217
1246
7430
1247

DCA
TAD
SZL
TAD

0215
0216
0217
0220
0221
0222
0223
0224
0225
0226
0227
0230
0231

4235

7061

1253
1254
7510
5225
2251
3253

/SINGLE PRECISION
/AC CONTAINS BINARY WORD
/CALLING SEQUENCE:
/
JMS SSPRNT /SUBROUTINE CALL
/RETURN. AC AND L CLEAR
SSPRNT^
CLL
SPA
CML
DCA
DCA
TAD
DCA
TAD

0206
0207

SSXYZ>

JMS
TAD
TAD
SPA
JMP
ISZ

I
POSITIVE?
/IS IS
/NO^ SET LINK^FORM ABSOLUTE VALUE
CMA I AC
/STORE NUMBER AWAY
SSVAL
/SET DIGIT LOCATION TO ZERO
SSBOX
/INITIALIZE OUTPUT COUNTER TO "4"
SSCNTR
SSCNT
/INITALIZE INSTRUCTION TO GET
SSADDR
/FIRST 10
SSXYZ+1
SSPLUS
/GET CODE TO TYPE A "PLUS"
NUMBER NEGATIVE?
/IS THE
T
SSMNS
/YES> CHANGE CODE TF TYPE A
/"MINUS"
SSOUT
/TYPE IT OUT
SSVAL
/PICK UP NUMBER
SSCON
/SUBTRACT CURRENT POWER OF 10
/IS THE
RESULT NEGATIVE?
T
.+4 /YES^ INDEXING IS FINISHED
SSBOX
/NO^ INDEX THE DIGIT LOCATION
SSVAL
/STORE REMAINDER IN SSVAL
SSXYZ
/CONTINUE SUBTRACTING

3251
2217

DCA
JMP
CLA
TAD SSBOX
JMS SSOUT
DCA SSBOX
ISZ SSXYZ+1

0232
0233
0234

2252
5216
5600

ISZ SSCNT
JMP SSXYZ
JMP I SSPRNT

0235
0236
0237
0240

0000
1245
6046
6041
5240
7300
5635
1254

5216
7200
1251

4235

/PICK UP THE DIGIT NUMBER
/TYPE IT OUT
/SET DIGIT COUNTER TO "0"
/INDEX INSTRUCTION TO GET
/POWER OF 10
/have we typed "4" digits
/no^ continue
/yeSj return

/TYPEOUT ROUTINE

0241
0242
0243
0244

SSOUT:.

TAD
TLS
TSF
JMP
CLA
JMP
SSADDR> TAD

SSTWO
.-1

CLL
I
SSOUT
SSCON

/INSTRUCTION TO PICK UP FIRST
/POWER OF 10

14-3

0245
0246
0247
0250
0251
0252
0253

0254
0255
0256
0257

0260
7760
0015
7774
0000
0000
0000

SSTWO^
SSPLUS^
SSMNS^
SSCNTR^
SSBOX^
SSCNT^
SSVAL^

6030
7634
7766
7777

/TABLE OF POWERS OF 10
SSCON^
/-1000
6030
/-100
7634
/-10
7766
7777
/-I

260
-20
15

-4

/BASIC CODE FOR DIGITAL OUTPUT
/NUMBER USED TO GENERATE "SPACE"
/NUMBER USED TO GENERATE "MINUS"
/COUNT OF "4" DIGITS
/STORAGE REGISTERS

14-4

Formerly

Digital-8-24-U-Sym

CHAPTER 15
UNSIGNED DECIMAL INTEGER PRINT
SUBROUTINE, DOUBLE PRECISION

ABSTRACT

This subroutine permits printing a double-precision integer stored
The one excepin the usual convention for double-precision numbers*.
tion is that all 24 bits are interpreted as magnitude bits (i.e.,

The printout
the bit "0" of the high-order word is not a sign bit)
is in the form of an eight-digit, positive, decimal integer.
.

REQUIREMENTS

15.2

This subroutine requires 73^q (lllg) locations and runs on any
standard PDP-8 family computer with a 33-ASR Teletype console.

The source tape is labeled Unsigned Decimal Print, Double

Precision,

Digital- 8-24-U-ASCII
15 .

15.3.1

USAGE

The symbolic tape provided can be assembled with PAL III, MACRO-8,
It can be assembled with the user program or separately
or PAL-D.
"$"
with the proper origin setting. Neither origin setting nor

terminating character exists on the tape; the tape does have a PAUSE
statement on the end.
15.3.2

Calling Sequence

The
This subroutine is called by an effective JMS UDPRNT.
location immediately following the calling JMS contains the address
*For details on storage of double-precision numbers, see the Math
Routine s writeup available from the PDP-8 Program Library, section
oiT Double Precision Signed Multiply Routine.

15-1

uf the high-order portion of the double-precision integer stored in
the usual double-precision format.

DESCRIPTION

15.4

This is basic double-precision subroutine used to obtain
decimal output corresponding to double-precision binary words.
First, the binary equivalent of 10,000,000 is subtracted from the
original number until under-flow occurs. A count is kept of the

number of subtractions necessary to accomplish this, thus yielding
the most significant decimal digit.
Then this digit is added to 2608
and printed on the 33-ASR through the AC. This process is repeated
using the proper power of ten to give the seven remaining digits.
The numbers are interpreted and

printed

as integers.

See Chapter 13 for a discussion of the techniques used.
15

FORMAT

15.5.1

Core Data

The double-precision integers are stored in the usual doubleprecision formats with the exception that bit "0" of the high-order
word is interpreted as part of the number not a sign bit.
15.5.2

Output Data

Output is in the form of eight consecutive decimal digits. No
sign is printed.
Spacing, tabulatic^ carriage return, etc., are
not provided for in this subroutine.
See Chapter 6 which contains
details on short subroutines for such purposes.
,

This subroutine is output limited at 10 cps by the 33-ASR.

15-2

15.6

FLOW CHART

ENTRY

PICK UP ADDRESS OF
HIGH ORDER WORD FROM

Calling SEQUENCE

PICK UP DOUBLE
PRECISION NUMBER FOR

USE IN SUBROUTINE

INITIALIZE COUNTERS,

POINTERS AND STORAGE
REGISTERS

PICK UP CURRENT
POWER OF TEN FOR

USE IN SUBTRACTION

1
PERFORM DOUBLE
PRECISION SUBTRACT
FROM NUMBER

STORE REMAINING
PORTION OF DOUBLE
PRECISION NUMBER

PICK UP

GENERATED DIGIT
TYPE IT OUT

SUdKUUIINt
FINISHED

EXIT

15-3

INDEX TO PICK UP
NEXT POWER OF TEN.
PUT DIGIT COUNT
TO ZERO

15.7

PROGRAM LISTING

/COPYlIGHf 1971

DIGITAL

/M^i^^rio*

;^AssACH'jssrfs

/Ui^sISIGiMED

DECIi-WAL

/CALLING SEQUENCE:
/
/

0200
020
0202

0000
7 300

0203
0204

3267

020 5
0206
020 7

3261
2267

02 10
02 1 1

0212

3262
1255
3260

02 13

12 56

UDPRNT>
CLA CLL
TAD I UDPRNT

1600

DCA UDGET
TAD I UDGET

166 7

DCA UDHIGH
ISZ UDGET
TAD I UDGET
DCA UDLOW
TAD UDLOOP
DCA UDCNT
TAD UDADDR
DCA UDPTR
ISZ UDPRNT

1667

32 7

02 15

2200

12 16

167

0217
0220
022
0222
0223
0224

22 7

ISZ UDPTR

3263
1670
2270
3264
7100

DCA UDHSUB
TAD I UDPTR
UDPTR
I SZ
DCA UDLSUB
CLL

022 5
0226
022 7
0230
023
0232
0233

1264
1262
3266
7 004
1263

023 4

023 5

52 42
22 6 5

TAD
TAD
DCA
RAL
TAD
TAD
SNL
JMP
ISZ

1236

3261

DCA UDHIGH

1261

7420

Cj,<PO^^A fl O.nj

PRINT, DOUFJLE PRECISION
JMS UDPRNT /SUBROUTINE CALLED
HI AODR
/ADDRESS OF HIGH ORDER
/WORD
RETURN
/RETURN WITH AC AND L
/CLEAR

0214

£:j JIPM:£,^j f

UDARND,

UDDO

TAD

UDPTR

/PICK UP ADDRESS OF
/HIGH -ORDER WORD
/PICK UP BOTH WORDS FOR
/USE IN SUBROUTINE

/INITIALIZE DIGIT COUNTER
/FOR "8"

/INITIALIZE TO TABLE OF
/POWERS OF TEN
/INDEX LINKAGE FOR CORRECT
/RETURN
/PICK UP CURRENT
/POWER OF TEN FOR
/USE IN SUBTRACTION

/DOUBLE PRECISION
/SUBTRACTION

UDLSU3
UDLOW
UDTEML

UDHSUB
UDHIGH
UDOUT
UDBOX

15-4

/DID IT UNDERFLOW?
/NO, COUNT I S DONE
/YES, COUNT NOT DONE YET
/INDEX DIGIT
/DEPOSIT REMAINING PORTIONS
/OF WORD

023 7
0240
0241

1266
32 62
522 4

0242
024 3

TAD UDTEML
DCA UDLOiy\J
JMP UDDO

024 4

126 5
1257

0245
0246

6046
6041

CLA
TAD uDBOX
TAD UDTWO
TLS
TSF

02 4 7

52 4 6

J\AP

300
3265
2260
5216
5600

CLA CLL
DCA UDBOX

0250
02 51
02 52

0253
0254

0255
02 56
02 5 7
0260
02 6 1

0262
026 3
026 4
0265
026 6
026 7
0270
0271
027 2
0273

200

0260
0000
0000
0000
0000
0000
0000
0000
0000
0000
3166

UDTWO.

260

0302
0303
0304
0305
0306
0307
0310

UDCON

/INITIALIZE DIGIT TO "0"
/HAVE WE TYPED "8" DIGITS
/NO, DETERMINE NEXT DIGIT
/YES> SUBROUTINE DONE.
/RETURN
/COUNT OF "8" DIGITS
/INITIAL ADDRESS OF
/POWERS OF TEN
FOR DIGITS
/I CODE
/STORAGE LOCATIONS

UDCiMT,

UDHIGH,
UDLOW,
UDHSUB*
U0LS1J3.

UDBOX^
UOTEML,
UDGET*
UDPTR>
UDCONl,

4 600

7413
6 7 00

JMP UDARND
JMP I UDPRNT

7770
0271

7747
4540
7775
4360
7777
6030
7777
7634

•

/ADD "261 )" TO IT
/TYPE IT OUT

SZ UDCtMT

-10

02 7 5

02 7 7
300
030

UDLOOP^
UDADDR,

0274
0276

UDOUT^

/GO BACK AND SUBTRACT
/AGAIN

7 77 7

7766
7777
7777

/POWERS OF TEN

3166
4600
7413
6700
7747
4540
7775
4360
7777
6030
7777
7634
7777
7765
7777
7777

1/-X

rx rx ryi

r% r% r%

/ - iVJ > \D\OVJ> \OVJVJ

/- 1*000^000
/- 100*000
/- 10*000

/- 1*000
/- 100

/- 10
/- 1

PAUSE

15-5

Formerly
Digital-8-25-U-Syin

CHAPTER 16
SIGNED DECIMAL INTEGER PRINT
SUBROUTINE, DOUBLE PRECISION

This subroutine permits printing the contents of two consecutive computer words as one signed double-precision two's complement

number.

If bit

of the high order word is a "1", the remaining

23 bits represent a negative integer in two's complement form;

equals "0", the remaining bits represent a positive integer.
If the number is negative, a minus sign is printed; if positive, a

bit

space,

REQUIREMENTS

16.2

This subroutine requires 86, q

(126 g)

core locations and runs on

any standard PDP-8 family computer with a 33-ASR Teletype console.

The source tape supplied is labeled Signed Decimal Print Double

Precision,

Digital-8-25-U-ASCII
USAGE

16.3

16.3.1

The symbolic tape provided is compatible with PAL III, MACRO- 8,
and PAL-D assemblers.

It can be assembled with the user's program

or separately with the proper origin setting.

Neither origin setting

nor "$" terminating character exists on the symbolic tape provided,
but a PAUSE pseudo-instruction is the last line on tape.
16.3.2

Calling Sequence

The subroutine is called by an effective JMS SDPRNT.

The

location immediately following the calling JMS contains the address
of the high-order portion of the signed, double-precision integer

which is stored in the usual double-precision format.
16-1

For example:

JMS

SDPRNT

ADDR
HLT
ADDR,

|?123

4567

DESCRIPTION

This is a basic subroutine to obtain signed decimal output corresponding to a double-precision binary word storage in two consecutive
locations in memory.
First, the binary number is sensed to determine
if it is positive or negative.
If positive, a space is printed.
If
negative, a minus sign is printed, and the number complemented to form
the absolute value.

Then the same algorithm is followed as in the
unsigned double-precision printout described in Chapter 15.
The numbers are interpreted and printed as integers.

FORMAT

16.5

16.5.1

Core Data

The double precision integers are stored in the usual signed, doubleprecision format (see the Double Precision Signed Multiply section of the
Math Routines writeup, available from the PDP-8 Program Library.

16.5.2

Output Data

Output is in the form of seven consecutive decimal digits preceded
by either a space or a minus sign.
Spacing, tabulation, carriage
return, etc., are not provided in this subroutine.
See Chapter 6 which
contains details on subroutines for such purposes.
If the user wishes
to print a "+" sign instead of a space, he can change the contents of
location SDPLUS from "-15" to "-2".

This subroutine is output limited at 10 cps by the 33-ASR.

16-2

16.6

FLOW CHART
ENTRY

)

PICK UP ADDRESS OF

HIGH -ORDER WORD

PICK UP DOUBLE

PRECISION NUMBER FOR

USE IN SUBROUTINE

COUNTERS
AND POINTERS

INITIALIZE

}

PICK UP CURRENT

POWER OF TEN

\ r

PERFORM DOUBLE
PRECISION SUBTRACT

INDEX DIGIT

FROM NUMBER

INDEX TO PICKUP
NEXT POWER OF TEN.
PUT DIGIT COUNT
TO ZERO
i

i i

YES

Die IT

^N.

NO
1

STORE REMAINING
PORTION OF DOUBLE
PRECISION NUMBER

V
PICK UP
GENERATED DIGIT

TYPE IT OUT

y^l DIG! rs been\^ NO
TYPED OUT
?

YES

EXIT

16-3

16.7

PROGRAM LISTING
GHF 1971
Dibi
r COKrO^^A n OiV
D, i^ASSACHJSErrS
/SIGNED DECIMAL PRINT^r DOUBLE PRECISION
/CALL IN G SEQUENCE:
JMS SDPRNT /SUBROUTINE CALLED
/
HIADDR /ADDRESS OF HIGH ORDER WORD
/
RETURN /RETURN WITH AC AND L CLEAR
SDPRNT^
CLA CLL
TAD I SDPRNT
/PICK UP ADDRESS OF
/HIGH-ORDER WORD
DCA SDGET
TAD I SDGET
/PICK UP HIGH-ORER WORD
SMA CLA /IS IT NEGATIVE?
TAD SDPLUS
/NO^ GENERATE CODE FOR SPACE
TAD SDMNS
/YES^ GENERATE CODE FOR "MINUS"
JMS SDTYPE
/TYPE IT OUT
TAD I SDGET
/PICK UP HIGH-ORDER WORD AGAIN
SPA
/IS IT POSITIVE?
CMA CML /NO. COMPLEMENT IT. SET LINK
DCA SDHIGH
/STORE POSITIVE WORD FOR USE IN
/SUBROUTINE
ISZ SDGET
TAD I SDGET
/PICK UP LOW-ORDER WORD
SZL
/IS LINK SET?
CMA CLL I AC
/YES^ FORM TWO'S COMPLEMENT
SZL
/DID AC OVERFLOW FROM "lAC"?
ISZ SDHIGH
/YES^ CORRECT HIGH-ORDER WORD
DCA SDLOW
/STORE POSITIVE LOW-ORDER WORD
TAD SDLOOP
/INITIALIZE DIGIT COUNTER TO "7"
DCA SDCNT
TAD SDADDR
/INITIALIZE POINTER TO TABLE OF
/POWERS OF TEN
DCA SDPTR
ISZ SDPRNT
/INDEX LINKAGE FOR CORRECT RETURN
SDARND. TAD I SDPTR
/PICK UP POWER OF TEN FOR USE IN
/SUBTRACT
ISZ SDPTR
DCA SDHSUB
TAD I SDPTR
ISZ SDPTR
DCA SDLSUB
SDDO^
CLL
/DOUBLE PRECISION SUBTRACTION
TAD SDLSUB
TAD SDLOW
DCA SDTEML
RAL
TAD SDHSUB
TAD SDHIGH
SPA
/DID IT UNDERFLOW?
JMP SDOUT
/N0:» COUNT IS DONE
ISZ SDBOX
/YES> COUNT NOT DONE. INDEX DIGIT
ii^

0200
0201

0000
7300

0202

1600

0203
0204
0205
0206
0207
0210
0211
0212
0213
0214

3307

0215
0216
0217
0220
0221
0222
0223
0224
0225
0226

1707
7700
1276
1277
42 64
1707
7510
7060
3301

2307
1707
7430
7141
7430
2301
3302
1273

3300
1274

0227
0230
0231

3310
2200
1710

0232
0233
0234
0235
0236
0237
0240

2310
3303
1710
2310
3304
7100
1304
1302
3306
7004
1303

0241
0242
0243
0244
0245
0246
0247
0250

1301

7510
5255
2305

16-4

251

3301

DCA SDHIGH

0252

1306

TAD SDTEML

0253
0254
0255
0256
0257
0260
0261
0262
0263
0264
0265
0266
0267
0270

3302
5237
7200
1305
4264
3305
2300
5231
5600
0000

DCA
JMP
CLA
TAD
JMS
DCA

0271

0272
0273
0274
0275
0276
0277
0300

1275

6046
6041
5267
7300
5664
7771
031 1

0260
7763
7775

.qDnuT.,

ISZ

JMP
JMP
SDTYPE:.

0302
0303
0304
0305
0306
0307
0310

SDLOW^
SDHSUB^
SDLSUB^
SDBOX^

0312
0313
0314
0315
0316
0317
0320
0321
0322
0323
0324

0325
0326

/GO BACK AND SUBTRACT AGAIN

/PICK UP RESULTING DIGIT
SDBOX
/TYPE IT OUT
SDTYPE
/INITIALIZE DIGIT TO "0"
SDBOX
/HAVE WE TYPED "7" DIGITS
SDCNT
/NO^ DETERMINE NEXT DIGIT
SDARND
/YES:» SUBROUTINE DONE. RETURN
I
SDPRNT
/TYPEOU T ROUTINE
SDTWO

SDHIGH;,

031 1

SDLOW
SDDO

TAD
TLS
TSF
- 1
JMP
CLA CLL
JMP I SDTYPE
/COUNT OF SEVEN DIGITS
SDLOOP^ -7
SDADDR^ SDCONL /INITAL ADDRESS OF POWERS OF TEN
/BASIC CODE FOR DIGITS
SDTWO^r
2 60
/"SPACE ". TO TYPE " + 'S REPLACE BY "-2'
SDPLUS:» -15
-3
/"MINUS"
SDMNS:»
/STORAGE LOCATIONS
SDCNT^

0301

0000

/DEPOSIT REMAINING HIGH-ORDER
/PORTION
/RESTORE REMAINING LOW-ORDER
/PORTION

SDTEML,'

SDGET^
SDPTR:»

7413
6700
7747
4540
7775
4360
7777
6030
7777
7634
7777
7766
7777
7777

SDCONL^

7413
6700
7747
4540
7775
4360
7777
6030
7777
7634
7777
7766
7777
7777

/TABLE OF POWERS OF TEN
/-1^000^000
/-100^000

/-10^000

/-U000
/-100
/- 10

/-I

16-5

Formerly
Digital- 8- 14-U-Sym

CHAPTER 17
BINARY TO BCD CONVERSION
CBinary to Binary Coded Decimal Conversion)

17.1

ABSTRACT

This subroutine provides the basic means of converting binary
data to binary-coded-decimal (BCD) data for printing, magnetic tape

recording, etc.
17.2

REQUIREMENTS
This subroutine uses 33, q

(41g)

storage locations and runs on

any standard PDP-8 family computer with a 33-ASR Teletype console.
The source tape provided is labeled Binary to Binary Coded Decimal

Conversion,

Digital-8-14-U-ASCII
17.3

CALLING SEQUENCE
The subroutine is called by the JMS instruction.

When called, the

binary number to be converted must be in the accumulator

(AC)

The subroutine returns to the instruction immediately following
the calling JMS with the BCD result in the AC.

17.4

DESCRIPTION
Reference to the Flow Chart (Figure 17.1) illustrates this dis-

cussion.
On input the binary number is stored, a pointer is initialized,
the link is cleared, and a counter to control the number of passes

through the computation loop proper is properly set.
The loop is now entered, and is repeated eight times.
The binary equivalents of 800, 400, 200, 100, 80, 40, 20, and 10
are subtracted successively from the original binary number.
17-1

After each subtraction, a test on the link is made.
If the result
of the test shows the link to be 0, the next lower equivalent is

subtracted from the same quantity after the contents of the links
are shifted into the developing BCD number (Location NUMBER)
If the subtraction leaves a negative link,

(0)

the contents of the

accumulator replace the binary representation currently being processed
after the contents of the link (1) have been shifted into the growing
BCD number.
After eight passes through the basic loop, the developed BCD
representation is shifted left four bits and the "residual" least
significant digit is added before exit.
17.5

EXAMPLE

As an example consider the conversion of the binary equivalent
of 512 decimal:

Link

Addition
001 000 000 000
110 Oil 100 000
111 Oil 100 000

-800

001 000 000 000
111 001 110 000
000 001 110 000

-400

000 001 110 000
111 110 001 000
111 111 111 000

200

000 001 110 000
111 110 oil 100
000 000 001 100

-100

Notice that the remainder is the binary representation of 12
decimal. Writing the link bits in the order they are developed gives
0101 the BCD character denoting
17.6

SCALING
The original binary number must be no larger than 999

(decimal)

The binary point is assumed to
which is equivalent to 1747 (octal)
be at the extreme right end of the word (to the right of bit position
.

11)

and the decimal point is also so positioned.
17-2

In other words, this subroutine converts binary integers to BCD

integers.

Note that the subroutine is designed for positive input only

DATA-*. INPUT
(CONTROL)-* POINTER

(COUNT)-* AC

(AC)-*NUMBER
TAD INPUT
POINTER

TAD TABLE

(L) =

(L)=1

(AC)-* INPUT

RETURN

Figure 17.1

FLOW CHART
17-3

FKUbKAM iilb'illNHa

1 / . /

A listing of the program with BCD located in 0200 appears as follows

/BINARY TO BCD CONVERSION 3/6/6 5-HB-DEC
/ENTER WITH BINARY NUMBER C<999(10))
/IN ACCUMULATOR.; EXIT WITH THREE CHARACTER
/BCD NUMBER IN ACCUMULATOR
/AC 0-3J AC 4-7; AC 8-11 WILL CONTAIN
/THE BCD CHARACTER ON EXIT
/WEIGHTING:
AC 0-3
100
AC 4-7
AC 8-11

/
/

/STORAGE
33(10) REGISTERS
/TIME=216 0-235.2 MICRO-SECONDS PDP-8
/IF INPUT >999 (10) RESULT IS UNSPECIFIED
0200
020

0202
0203
0204
020 5
0206

0203
322 6
1225
3210
7 100

0207

1230
322 7
1226

02 10

1231

021

7430
322 6
7200

0212
0213
02 14

122 7

0215
0216

7004
2210
7420
5206
7106
7006
1226
5600

0217

0220
0221

0222
223
022 4
22 5
0226
0227
0230
0231

0232
0233
0234
0235
0236
0237
0240

BCD,

1231

0000
0000
0020
6340
7160
7470
7634
7660
7730
7754
7766

POINTR,

DCA
TAD
DCA
CLL
TAD
DCA
TAD
TAD

INPUT
CONTRL
POINTR

/STORE BINARY
/SET UP TABLE
/POINTERS

COUNT
NUMBER
INPUT
TABLE

/SET BIT 7= l; 8RAL 'S
/WILL PUT IT IN LINK
/OR TABLE+1, TABLE+2, ETC

SZL

/IF C(L)=1, INPUT>-TABLE
/IF SO: INPUT=INPUT+TABLE

DCA INPUT
CLA
TAD NUMBER
RAL
I

CONTRL
INPUT*
NUMBER
COUNT
TABLE,

/PUT THIS BIT IN ANSWER
/UPDATE TABLE POINTER
/IF LINK=1, ALL DONE

SZ POINTR

SNL
JMP
CLL
RTL
TAD
JMP
TAD

POINTR-2
/CONVERTED 2 BCD
/CHARACTERS
/SHIFT LEFT AND Ann
/THE THIRD

RTL

INPUT
BCD
TABLE
I

0020
- 1440
-0620
-0310
-0144
-0120
-0050
-0024
-0012
/EXAMPLE: INPUT 0726
(8)
/
OUTPUT
0100/01

17-4

/-800( 10)
/--400
/-200
/- 100
//--40
/--20
/- 10
-

1/0000

Al(d

(

10)

Formerly
Digital- 8-15-U-Syin

CHAPTER 18
BINARY TO BCD CONVERSION (4-DIGIT)
(Binary to Binary Coded Decimal Conversion, 4-Digit)

ABSTRACT

18.1

This subroutine extends the method used in Chapter 17 so that

binary integers from

to 4095 contained in a single computer word

may be converted to four binary-coded-decimal characters packed in
two computer words

REQUIREMENTS

18.2

This subroutine uses 53^^ ^^^s^ storage locations and runs on any
standard PDP-8 family computer with 33-ASR Teletype Console. The

source tape provided is labeled Binary to Binary-Coded-Decimal Conversion (Four Digit)

Digital- 8-15-U-ASCII

CALLING SEQUENCE

18.3

This subroutine is called by the JMS instruction with the binary

number to be converted in the accumulator (AC)
This subroutine returns to the location immediately following
The format of the result is discussed

that containing the calling JMS.
below.

18.4

DESCRIPTION
This program is essentially Digital-8-14-U-ASCII

(described in

Chapter 17) extended to allow for integers in the range of 1000 to
4095.

18.5

CORE DATA

Results appear in core as:

Word TWO

Word ONE

012. .5678. .11

.5678

10
~BA

RA
18-1

10
BA

The decimal coding for 2048 is illustrated.
18.6

IBM COMPATIBILITY

Note that bits

and 6,

are set so that they can be regarded

as zone B and zone A bits required for IBM BCD mode compatible 6-bit

numerical characters.
In this mode of recording, the character 1010 is used for zero

instead of code 000

which this subroutine produces.

Therefore, to

use this routine in conjunction with IBM-compatible mag tape recording,
it is necessary to write a short auxiliary routine to make this sub-

stitution.
It may also be necessary to generate the even parity required by

such recording if this is not accomplished in the tape control hardware
18.7

PROGRAM LISTING

/CO^YrilGHT 1971
DIGITAL E.2 Jl >^>^ZS^T COr^POxA FI
/MAy,NiA:iJD> >1ASSACHJSErrs
/BINARY TO BCD CONVERSION 3/7/65-HB-DEC
/ENTER WITH BINARY NUMBER IN ACCUMULATOR
/EXIT WITH A SIX-BIT BCD CHARACTERS
/PACKED TWO TO A WORD IN REGISTERS
/ONE AND TWO OR IN A BUFFER.

/USED FOR WRITING MAG-TAPE IN BCD FORMAT
/IN ADDITION TO BCD PARITY
/OUTPUT FORMAT:
/
ONE 0-1
A,B BITS
/
ONE 2-5
1000 DECADE
/
ONE 6-7
A^B BITS
/
ONE 8100 DECADE
/
0TWO
A^B BITS
/
TWO 2-5
10 DECADE
6-7
/
TWO
A^B BITS
/
TWO 8DECADE
-53
/STORAGE
10
lEGl STEPS
/TIME
324.8-350.4 MI CRO- SECONDS PDP-8
1

18-2

0200
0201
0202

0000
3223

20 3
20 4

3240

020 5
20 6
0207
02 10
02
0212

4234
7106
4234

0213

4234
7106
7006
7006

021 4
02 15

0216
0217
0220
0221

0222
0223
0224
0225
0226
0227
0230
0231
0232
0233
023 4

0235
0236
023 7
02 40

0241

0242
024 3

0244
02 4 5

2246
02 4 7
02 50
251

BCD.

DCA
TAD
DCA
TAD
JMS
CLL

122 5

1226

RTL
STEP
TAD BITSl
DCA ONE
TAD C0UNT2
JMS STEP
CLL RTL
RTL
RTL
TAD INPUT
TAD BITS2
DCA TWO
JMP I BCD

3230
1227

1223
1233
3231
5600

1010

0400
0000
0000
0000
0000
0000
7100
3224
1223
1252
7430
3223
7 200
1224
7004
2240
7430
5634
5236

/CONVERT NEXT
/A.B BIT PATTERNS
/OR DCA I AUTO (10-17)
/SET-UP COUNT

jy\s

1232

0000
0000
1252

/STORE BINARY
/SET UP TABLE
/POINTER
/SET COUNT
/CONVERT

INPUT
CONTRL
POINTR
COUNT
STEP

INPUT.
NUMBER,
CONTRL,
COUNT 1.
C0UNT2.

/LEAST SIGNIFICANT BITS
/A.B BIT PATTERMS
/OR DCA I AUTO ( 10- 17)
/EXIT

TAD TABLE
1010
0400

ONE.
TWO.
BITSl.
BITS2.
STEP.

POINTR.

/OR ANY BIT PATTERN
/OR ANY BIT PATTERN
/ACTUAL CONVERSION
/SUBROUTINE
CLL
DCA NUMBER
TAD INPUT
TAD TABLE

/OR TABLE+1. TABLE+2. ETC

SZL

DCA INPUT
CLA
TAD NUMBER

/IF SO:

RAL
ISZ POINTR
SZL
JMP I STEP
JMP POINTR-

18-3

CCL)=U INPUT>-TABLE
INPUT=INPUT+TABLE

/ROTATES WILL BRING
/COUNT BIT INTO LINK
/ctTTP nnMfT

0252
0253
0254
0255
0256
0257
0260
0261
0262
0263
0264

0140
4060
6030
6340
7160
7470
7634
7660
7730
7754
7766

TABLE.

-7640
-3720

/-4000

(

10)

- 1750
- 1440

-0620
-0310
-0144
-0120
-0050
-0024
-0012
/EXAMPLE: INPUT
/
OUTPUT:

ONE

TWO

7777

18-4

(8)

00 0100/
00 1001/ 00 0101

=4095

(

10)

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