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DEC-08-LBAB-D

December 1971

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Document:	dec-08-lbab-d
Order Number:	DEC-08-LBAB-D
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Pages:	14
Original Filename:	https://svn.so-much-stuff.com/svn/trunk/pdp8/src/dec/dec-08-lba/dec-08-lbab-d.pdf

OCR Text

IDENTIFICATION
Product Code:

DEC-08-LBAB-D

Product Name:

Binary Loader

Date Created:

June 4,

Maintainer:

Software Services Group

1971

tsMWir© if,
W

#
PDP-8
LIBRARY

DEC-0 8-LBAB-D

BINARY LOADER
1.1

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

tion contained in binary-coded tapes, using the 33-ASR reader or the
High-Speed Reader.
The Binary Loader accepts tapes prepared with the PAL III, PAL-D,
PAL8, or MACRO-8 assemblers.

Diagnostic messages may be included on

tapes produced when using either PAL or MACRO.

The Binary Loader ignores

all diagnostic messages.
1.2

REQUIREMENTS
This program occupies 94^q

(136g)

core locations.

The Binary Loader can be used with a system consisting of the
PDP-8 and a 33-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 TC01 DECtape Library System.

1. 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 1 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
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.

(7756)

J.3.1

Switch Setting
NOTE:

1.4

Memory Extension users see "Special Requirements"
section.

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
SWITCH REGISTER.

Press LOAD ADDRESS key.

(7777)

in the

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.

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 4 through 11 from,

for example, the 33-ASR Reader buffer.

The sum is accumulated charac¬

ter by character and not word by word.

Overflow (a carry out of the

most-significant bit position of the AC)

is ignored both when calculat¬

ing 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.

Restart
pressing

the

after the

tape has been repositioned by

the CONTINUE key.
l'

1.6

computer

;

DETAILS OF OPERATION AND STORAGE
This

program furnishes

binary-coded tapes

are

the basic means by which the

in outline

The

incoming

eight tape

This

subroutine

character

tested to see

the

case,

all

it is

subsequent information

another rubout is

They are preceded and followed by

Within a diagnostic message,

diagnostic message.
message would,

Next the

character

If none of the
subroutine,

are

"rubout"

coming

any

a single

in contrast
character

that two

(all

from the

followed by

rubout char¬

the

rules

valid except,

concerning
of

course,

conclude the

ignored.

tested to see

it is

leader or

in which they

field setting.

are performed.

indicated have occurred upon exit from the BEGG

character is part of
or is

are

consecutive rubouts within a diagnostic

listed in the order

actions

the

of a data word,
is

Note

in effect,

These tests

1.7.1

detected.

a single rubout character which would prematurely

1.7

which

the mechanism by which assembler diagnostic messages

the balance of the binary tape,

course

(tagged BEGG)

follows:

ignored until

detected.
acter.

a short

channels punched).

this

reader is

loaded into core.

The heart of the program is
operates

contents

a part of the

the origin address,
checksum,

and the

contains part

appropriate

the main routine.

SPECIAL REQUIREMENTS OR FORMATS

External Format
Tapes

to be read by

and have

about

foot of

punched;

preferably code

this program must be

in binary-coded

leader-trailer

(any

200).

code

format

code with channel

The
the

first two

characters

represent the

first command on the next portion of

Successive

commands

the

address

(origin)

into which

tape will be placed.

are placed in memory at addresses:

origin+l,origin+2,...,origin+n.

The
while
has

initial

channel

no punches

character of the origin has no punch
is punched.

The

Trailer tape

8 or

similar to

the origin

2-character group representing

punches present in channels

channel

second character designating

in either channel

A concluding

the

checksum has

leader.
•HI

Reference
routine

tests

a test is made
This

which

to Program Listing
see

the

indicates

character

to determine whether

reference to

characters

the

of the

fact that

that after the BEGG sub¬

just read was

the

character

the

leader/trailer,

assemblers

field setting.

produce

tapes

form

11 XXX 000

indicate

the memory

loaded.

If,

designator

for example

should be

other data,

1.7.2

field into which the
XXX were

101,

all data

loaded into memory

field settings

following data is

following the

field five.

are not included in

to be

the

field

Unlike origins

and

checksum.

Example of Binary Loader Format

Tape Channel
87 654 S 321

Notes

Program
Proper

Channels 8 and
7 Indicate

000

Leader

01
00

000
000

.
.

010
000

Origin

In octal the origin 0200.
Loading will start at 0200.

00
00

111
000

.
.

010
000

Contents

200

Yes

The

command

7200

or CLA.

00
00

Oil
111

.
.

010
110

Contents of

201

Yes

The

command

3276

DCA Z

076.

Example of Binary Loader Format

Channels 8
7 Indicate

Tape Channel
87 654 S 321

Program
Proper

and

Notes

Yes

The

Checksum

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

Trailer

00
00

111
000

•
•

100
010

Contents

00
00

000
010

•
•

100
010

000

•

000

202

The octal checksum in
this is the following
102
000
072
000
032
076
074
002
422

1.7.3

(Cont.)

this
sum:

example

command

0422.

Note

7402

or HLT.

that

Origin
First word
Second word
Third word

Memory Extension Usage
It is

ensures

recommended that the Binary Loader exist in

a permanent program lining

are used for TC01 DECtape.
caution must be
applies only

taken not

The
to use

to DECtape users).

it should be noted that the

around

location

7754

loader can exist in
location
Also,

7754

and

any
7755

when the proper

RIM Loader must already be

Binary Loader Loading Procedure for Extended
tape

field 0.
and

7755 which

field,
in

This

though

field 0

field is
in that

chosen
field.

Memory Users

Place the Binary Loader

Place the proper FIELD in the INSTRUCTION FIELD REGISTER
when putting the starting address of the RIM Loader (7756)
in the SWITCH REGISTER.

Press

in the reader.

Press the START key.

Start the reader.
High-Speed Reader:

the LOAD ADDRESS key.

33-ASR:
press READER CONTROL to start.
should already be ready to start.

(this

Operation and Usage for Extended Memory Users
a.

Place the tape to be loaded (tape must be in binary
format) in the reader.
When using the 33-ASR, make
sure reader is on-line.
When using the High-Speed Reader,
make sure reader is on and tape is positioned with
leader/trailer over read head.

In the DATA FIELD register place the field in which the
program is to be loaded.
In the INSTRUCTION FIELD
register place the field that the Binary Loader is in.

Press LOAD ADDRESS key.
When using the High-Speed Reader, change
REGISTER TO 3777 (bit 0=0).
Omit this
the

the SWITCH
step if using

33-ASR.

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.

1.8

PROGRAM LISTING
/COPtWIGHf 1971
DIGITAL
/.v)ArNA^O> 1*1 AS SACK JSE 1" FS

ElJIrMENr COH^OrtAIION

/BINARY AND DECTAPE LOADERS FOR
/555 CONTROL
0000
0000
0000
0000
0000

*7612
SWITCH,
MEMTEM,
CHAR,
CHKSUM,
ORIGIN,

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

*7626
/EXTRACT ERRORS, FIELD, L/T
0
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

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

TAD CHAR
AND FMASK
TAD CHANGE
DCA MEMTEM
JMP BEGG+2
70
CDF
0
0
KSF
JMP .-1
KRB
DCA CHAR
TAD CHAR
JMP I READ
RSF
JMP .-1
RRB RFC

7612
7613
7614
7615
7616

FMASK,
CHANGE,
READ
LOR,

HIR,

0
0
0
0
0

/SET SWITCH
/GET A CHARACTER
/TEST FOR 377
/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

/WAIT FOR FLAG

JMP LOR+3
300

7673
7674

5265
0300

MASK,

7675
7676
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

/TRAILER CODE SEEN
JMS ASSEMB
BEND,
CIA
TAD CHKSUM
HLT
M376,
KCC
BEGIN,
RFC
RDF
TAD CHANGE
DCA MEMTEM
CLA OSR
SMA CLA
TAD HIRI
TAD LORI
DCA READ+1
JMS BEGG
JMP .-1

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,

GO,

CHEX,

M2 00,

LORI,

DCA CHKSUM
TAD MEMTEM
DCA MEMFLD
TAD CHAR
DCA WORDl
JMS READ
DCA WORD2
JMS BEGG
JMP BEND
JMS ASSEMB
SNL
JMP MEMFLD
DCA ORIGIN
TAD WORDl
TAD WORD2
TAD CHKSUM
JMP GO
0
DCA I ORIGIN
ISZ ORIGIN
7600
JMP CHEX
0
TAD WORDl
CLL RTL
RTL
RTL
TAD WORD2
JMP I ASSEMB
JMP LOR

/SAVE FIELD INSTRUCTION

/IGNORE LEADER

/LOOK AHEAD
/TRAILER, END

7753
7754

0006
0000

7755

0000

7777

5301

ASSEMB
BEGG
BEGIN
BEND
CHANGE
CHAR
CHEX
CHKSUM
FMASK
GO
HIR
HIRI
LOR
LORI
MASK
MEMFLD
MEMTEM
M2 00
M376
ORIGIN
READ
SWITCH
WORDl
WORD 2

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

HIRI,

HIR-LOR

W0RD1=7776
WORD2,

*7777
JMP BEGIN

♦

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1

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