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MAINDEC-08-D2C

December 1965

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Document:	maindec-08-d2ca-d
Order Number:	MAINDEC-08-D2C
Revision:
Pages:	8
Original Filename:	https://svn.so-much-stuff.com/svn/trunk/pdp8/src/dec/maindec-08-d2c/maindec-08-d2ca-d.pdf

OCR Text

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IDENTIFICATION

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Product Code:

MAINDEC`-08-D2CA-D

Product Name:

PDP-8 Teletype Punch Test

Date Created:

May 5,1965

Maintainer:

Diagnostic Group

Author:

R. Green

Previous Code:

MAINDEC 812

MAINDEC-08-D2CA-D

ABSTRACT

MAINDEC-08-D2CA punches a test tape in a predetermined pattern.

The tape passes directly

from the Teletype punch to the Teletype reader, which checks the pattern for accuracy.

REQUIREMENTS

Storage
MAINDEC-08-D2CA occupies storage location 0020-0111.

0001 for an interrupt return.

In addition, it uses loca+ion

The RIM Loader must be i.n memory in locations 7756-7776.

Equipment

Standard PDP-8 with Telelype Model 33 Keyboard/Printer, including Teletype punch and

reader .

USAGE

3.1

Loacling

The RIM Loader must be in memory.

Set the Teletype to ON LINE and t.urn reader off.

Place MAINDEC-08-D2CA RIM tape

in the Teletype reader.
Set SWITCH REGISTER +o 7756; press LOAD ADDRESS, +hen START.

Turn on reader.

When program has been read in, turn off reader, and remove program tape.

3.2

Switch Settings

swo 3;wn

3.3

Punch leader of 377's .
Punch pattern 0-377.

Start-up and/or Entry
After program hcis been recid in, set SWITCH REGISTER to 0020.
Press LOAD ADDRESS.
Make sure that SWo is dL9}±!p (c)ff).

Press START.

When sufficient leader has been punched, place the free end of the tape i,n the reader
(do nL2± tear it offl ) so that the first chc]rc]cter read wil[ be a 377.

Turn on the reader.

Set SWo up (on').

This will cause the program to punch the test sequence.

MAINDEC-08-D2CA-D

The program will run conlinuously until an error occurs or until the operator stops the computer.

There is no final halt.

3.4

Errors in u§qge
ICauseofEror(1

C(MA)

Error

I nputfromreader.didno+causeaninter upt.Po!sible dif iculties;Incor ectexecutionofION;nosignalfromread6r;troubleinthe

0050005200740077

E1E2E3E3A

interrupt system.

I
1

The interrupt occurred before the instructions foll)owing the ION
was executed. Probable trouble in the interrup+ Pystem.

The character read from tape is not what it should have been.
Ac displays the character read.
I

The

After the previous halt, this halt a[[ows the operqtor to see what

the proper character is.

The correct code is displayed in the AC

I i ght .

There are no other stops in the program.

``-',
3.5

Recovery from such Errors

Recovery Procedure

If either of these errors occurs, perform Instruction Test 2A of MAINDEd to determine the cause of the trouble.
I

Record the c(AC).

Press CONTINUE to reach the next halt.

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the tape itself for the erroneous character.
reacler; remove +he tape.

:: :::ass:°odN°TTN:°::).

The test will begin again, punching leader.
this point.

To restart the test, turn off the

(See paragraph 3.3)

Follow the start-uP procedure from
I

u
2

MAINDEC-08-D2CA-D

DESCRIPTION

4.1

Discussion

Under the control of SWo, MAINDEC-08-D2CA test's the performance of the Teletype punch,
With SWo down, the program punches the code 377.to provide a leader sect.ion consisting of all holes.

As this is being punched, the operator takes the free end of the tape, places it in the Teletype reader,
and turns the reader on.

He then sets SWo up, causing t.he program to punch the code sequence 000-

377, repeating this as long as desired.
As soon as the first nonleader character is read, the program begins checking +he tape for
the accuracy of the punching.

After each line is read, the interrupt is enabled to test its operation.

If this is satisfactory, the character is checked.
the AC and I.he program halts.

If an error occurs, the incorrect code is displayed in

An immediately succeeding halt displays the correct code i.n the AC.

If an incorrec+ charac+er is encountered, the operator must rest.ar+ the program.

A new

leader will be punched.

4.2

Examples and/or Applications

In addition to checking the accuracy of the punch, MAINDEC-08-D2CA can be used to
observe a+her operations of the punch and reader, as explained below.
The tape drive mechanism in the punch can be checked by allowing the p+ogram to punch a
•few feet of leader. Examine the resulting tape for correct spacing between lines. If the tape is not

advancing properly, the spacing will be irregular, or adiacent characters may overlqp, resulting in

extra large or odd shaped holes.
The reader.s ability to scan a tape containing all holes can be observed by placing the
length of leader in the reader.

If it drops a bit in any line, it will aufomatically begin checking the

tape for a pattern; this will show up immediately as an error, and the program will stop at error E3.
Dropped bits will show as O's in the AC,

METHODS

When the program starts, the link is set to 1.

codes, the link remains set.

As long as the reader sees nothing but 377

When the first pattern character appears, the link is cleared, and from

then on the program will check every.character for accuracy.

EXECUTION TIME

The program runs continuously un+il cin error is encountered or until the opera+or s+ops the

computer ,

MAINDEC-08-D2CA-D

PROGRAM LISTING

/MAINDEC-08-D2CA:

PDP-8 TELETYPE PUNCH TEST

*2©
/INITIALIZE
/LEADER

COUNTERS

AN}

SIGNAL

STUFF

(
I

/INITIALIZE

/PUNCH

INTERRUPT

TtsT

FLAG

/READER

/TEST

FLAG

SW(a)

CLA

PUNCH-I

PCT

/IF SW(a)=©,
/OTHERWISE,

PUNCH LEADER
PUNCH PATTERN

pot
PUNCH
PUNCH

8©45

9847

/TEST
/PUTS

®@5©

/ERROR:

INPUT

®051

/WAS

TAD

2j© 52

/ERROR!

NO,

8©55

/YES,

WAS.

©©54

/AND

STORE

@©55

/TEST

FOR

@@46

INTERRUPT
7777 IN AC
DID

NOT

CAUSE

EXECUTED?
IT

WASN'T.

READ

BUFF`ER

CHARACTER

577

CHARACTER,.

®@56

@057

0©60

/IS

©©61

/NO.

CLEAR

577?

@862
0@65

/YES.

WAIT

LEADER

SIGNAL

LEADER?
FOR

NEXT®,

MAINDEC-08-D2CA-D

/COMPARISON

/KEEP

TEST.

8 BITS

/INCREMENT

0F C(RCT)

READER

/COMPLEMENT

READER

CLA
FLAGS

/IS
/YES.

CHARACTER

TEN

/NO,

CHARACTER

COUNT

C(TEN)-C(RCT)=8?

/ERROR:
CMA

COUNT

IS
IS

0K.
WRONG.

CONTAINS

CHAR.

READ

STL

ROT
/AC CONTAINS CORRECT
/FIND OUT WHAT

/TO

CHARACTEFi

DO?

®1®6

/PUNCH

/READ

811©
©111

/INTERRUPT RETURN
/COMPLEMENT OF .577

®112

CTAB

E2
E5
E5A
FLAGS

INIT
PCT
PPAT
PUNCH
PUNI

RCT
READ

R2
R5
TIM

CHARACTER
CHARACTER

-. BIT

MASK

COUNT
COUNT

FOR

TEST.

MAINDEC-08-D2CA-D

DIAGRAM

8.1

Flow chart

\
6

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