Digital PDFs

DIGITAL-8-29-U

December 1966

10 pages

Original

0.4MB

Document:	digital-8-29-u-d
Order Number:	DIGITAL-8-29-U
Revision:
Pages:	10
Original Filename:	https://svn.so-much-stuff.com/svn/trunk/pdp8/src/dec/digital-8-29-u/digital-8-29-u-d.pdf

OCR Text

IDENTIFICATION

Digital-8-29-U-Sym
I .2

Double Precision Decimal-fo-Binory Conversion
and Input (ASR-33)

I .3

(Signed or Unsigned)

Jonuory I4, I966

PUP—8
LIBRARY

Digital-8—29-U—Sym
Page l
2

ABSTRACT

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

The string may contain as legal characters a sign (+, —, or space) and the digits 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 re—enter the value. Any character after the first,

other than another digit or ”back-arrow", causes the conversion to terminate and is found in location
"DIDSAV" within the subroutine.
3.

REQUIREMENTS

3 l

Storage

This subroutine requires llO core locations.

3.2

Subprograms and/or Subroutines (None)

3.3

Equipment
Basic PDP-8 with ASR-33

USAGE

4 l

The symbolic tape provided may be assembled with the user's main program with either
PAL II}r or MACRO-8.

There is neither origin setting nor terminating "$" on the symbolic tape, but a

PAUSE pseudo-instruction is the last line on the tape.
4.2

Calling Sequence

The subroutine is called by an effective JMS to location DDCB. The location immediately
following the JMS instruction contains the address of the location where the high-order portion of the
number is 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 down from the calling JMS with the

AC clear.

4.3

Switch Settings (Not Applicable)

4.4

Start-up and/or Entry (Not Applicable)

4.5

Errors in Usage

If the string of decimal digits is preceded by a sign (+, —, or space), the maximum decimal
number that is correctly accepted is 8388607 (223-4)
The sign, if any, must appear first. If the string
of decimal
is not preceded by a sign, the maximum decimal number that is correctly accepted is
.

digits
-1).

16777215 (22

4.6

Recovery from such Errors
If neither of these maxima is exceeded, the results are unspecified.

Digital-8-29-U-Sym
Page 2
5

RESTRICTIONS (None)

5 .1

Status Active Registers
The status of AC and link is not preserved.

5 .2

5.3

Status Core (Not Applicable)
Status Hardware

This subroutine should not be used with the interrupt on.
5 .4

Miscellaneous
The magnitude restrictions on numbers is described in 4.5

DESCRIPTION

6 .1

Discussion

The discussion, example and scaling of the conversion is given in 6.l and 6.3 of the write-up
Digital-8-28-U. The only difference is that the multiplications by "4" and "2" are performed by the

arithmetic shifts as described in Digital-8-8—U.
METHOD

See Digital-8-l2-U
8

FORMAT

8.l

sign, 0-9,

8 .2

Input Data
The input string may or may not contain a sign (+, —, or space). Any character other than
rubout causes the subroutine to terminate as does a sign in any but the first position.

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.
This is the format compatible with the double-precision, fixed point arithmetic subroutines. The terminating
character is found in location DIDSAV.

8 .3

Output Data

Spacing tabulation, carriage return, etc. are not provided for in this subroutine.
Digital-8-l9—U-Sym which contains short subroutines for the latter purposes.
,

EXECUTION TIME

9.l

Minimum (Not Applicable)

9.2

Maximum (Not Applicable)

See

Digital-8-29—U-Sym
Page 3
9.3

Average
This subroutine is input limited at a maximum of 10 cps.

10.

PROGRAM

10.1

Core Map (None)

10.2

Dimension List(s) (None)

10.3

Macro, Parameter, and Variable Lists (None)

10.4

Program Listing
/DOUBLE

/CALLING

PRECISION

DECIMAL-TO-BINARY
DICONV

JMS

ADDRES

DICONV)

IGNORED

/SUBROUTINE
/ADRESS

2332

@291

7333

CLA

CLL

@202

1324

TAD

DISET1+1

/INITIALIZE

@223

3235

DCA

DICTRL

@204

1324

TAD

DISET1+1

OZOS

3227
1602

DCA
TAD

DIXSWI

8226‘
@297

3351

DCA

DIGET

0210

3352

DCA

DIHIHD

/CLEAR

@211

3353

DCA

DILOHD

/NUMBER

0212

3347

DCA

DINEGI

@213

5275

JMP

DIIN

@214

3352

DCA

DIDSAV

@215

1353

TAD

DIDSAV

@216

1341

TAD

DIRBUT

@217

7452

SNA

@220

5201

JMP

DICONV+1
DIM26O

DICONV

U221

1342

TAD

7512

SPA

@223

5235

JMP

@224

1343

TAD DIM27I

/STORE

CHARACTER

/YES,

SMA

SZA

DICTRL

/YES,

@227

7333

CLA

CLL

/NO,

/CLOSE

1234

TAD

.+4

DCA

0'2

@232

1252

TAD

DINMBR-l

@233

3235

DCA

DICTRL

JMP

DINMBR

@234

5251

@235

7223

@236

1352

TAD

DIDSAV

@237

1344

TAD

DIMSPC

@240

7452

SNA

@241

5324

JMP

DISET1+1

@242

1345

TAD

DIMPLS

CLA

@243

7450

SNA

QQ44

5324

JMP

/IS

LESS

GREATER

SWITCH

/IS

DISET1+1

/YES;
IT

/YES,

26%

HOL-

THAN

271

"SPACE"?

SET

SWITCH

"PLUS"?

SET

SWITCH

(IE.9

WHAT
WAS

CI
D.

"DINMI

TERMINAI

SENSE

CHECKING

"O7

WHAT

SEE

ERI

(IE.

SEE

CHARACTER

SWITCH

/CONTINUE

/IS

THAN

TRANSFER

FIRST

/SET

HI.

A "BACK-ARROW"(IE.
REINITIALIZE

TRANSFER

/YES,

JMP

3227

STORE

SWITCH

7743

@231

ADDRESS

NEGATIVE

5235

@230

SWITCHES

/CLEAR

@226

CLA

PROGRAM

USED

@225

DICTRL:

ADDRESS+1

LOCATIONS

/IS

DICTRL

/PICK

/IS

@222

DIXSWI:

HIGH-ORDER

WORD

‘O

922%

DIPROC:

CALLED
STORE

~ORDER

/LOW

INPUT

AND

CONVERSION

/AC

SEQUENCE:

DETERMI

SENSE

TEE

SENSE

TEI

Digital-8-29-U-Sym
Page 4
0245

1346

TAD

0246‘

7650

SNA

CLA

/IS

"MINUS”?

@247

5323

JMP

DISETI

/YES;SET

NEGATIVE

025W

JMP

DIEND

/NO, IT WAS A TERMINATING CH.
/STORE ASSEMBLED NUMBER TEMP.

D253

5332
1353
3354
1352

@254

3355

@255

433%

JMS

DIDSPL

0256

4330

DIDSPL

@251

@252

DINNER:

DIMMNS

TAD

DILOHD

DCA

DIXTMl

TAD

DIHIHD

DCA

DIXTM2

D257

1353

JMS
TAD

@263

1354

TAD

DIXTMI

@264

3353

DCA

DILOHD

@262

7994

RAL

IMULTIPLY

AND.

SWITCH

CURRENT

"ID"

DILOHD

0263

1352

TAD

DIHIHD

0264

TAD

DIXTM2

@265

1355
3352

DCA

DIHIHD

0266

4339

DIDSPL

@267

1350

JMS
TAD

@270
@271
@272
@273
0274

@343

AND

DIXMSK

/PICK
/MASK
/ADD

CURRENT DIGIT
HIGH-ORDER BITS
REMAINDER TO CURRENT

/DID

DIDSAV

1353

TAD

DILOHD

3353

DCA

DILOHD

743%

SZL

2352

ISZ
/INPUT

OVERFLOW?
CORRECT HIGH-ORDER

6031

5275

JMP

@277
0300

6036

KRB

6046

TLS

0391

5214

JMP DIPROC
ITERMINATING ROUTINE

@392

7200

DIEND:

@393

TAD

DINEGl

/PICK

CLL

RAR

/PUT

@305

1347
7110
1352

TAD

DIHIHD

/PICK

@303

7430

SZL

/IS

@307

CMA

/YES:

0311

7040
3751
1353

@312

7430

@313

DIIN:

0‘1

CLA

LINK

"1"?

CLL

CMA

0316

7141
7430
2751
7000

D317

2351

ISZ

@323

3751

DCA

0321

2200

ISZ

DICONV

@322

5600

JMP

0323

2347

ISZ 'DINEGl

/SET

@324

7300

CLA

CLL

ICLOSE

0325

1250

TAD

DINMBR-l

@326

3235

DCA

DICTRL

@327

5275

JMP

DIIN

ISZ

@093

@331

1353
7164
3353

0332
@333

/15
I

DISETl:

DIGET

DIDSPL:

DIGET

TAD

DILOHD

CLL

RAL

DCA

DILOHD

COMPL.

PORTION

"1"?

TWO'S

LINK

COMPolT.

OVER.

"1"?
PRTION

/INDEX

HIGH-ORDER

/TAKES

CARE

/INDEX

POINTER FOR

ISTORE

LOW-ORDER

WHEN

HIGH-ORDER

LOW-ORDER.
POTION OF N.

CORRECT

RETURN

/RETURN

/JUMP
LEFT

LOW-ORDER

/INDEX FOR

DICONV

PRECISION

LINK

/YES;

NOP

/DOUBLE
D333

IAC

SZL

PORTION

IT
UP

/PICK

("1"

ORDER

NEGATIVE.

NUMBER

DILOHD

NUMBER

LINK.

HIGH

TAD
SZL

/IS

INTO

/STORE

DIGET

NEGATIVE

0315

WORD

KSF

DCA

0314

NUB

ROUTINE

@276

0310

OFF

/YES;

DIHIHD

@275

@304

SHIFT

(X2)

NEGATIVE

SWITCH

WAIT

SWITCH

FOR

TRANSFER TO.

CHARAI

Digital-8—"29-U-Sym
Page 5
@334

1352

TAD

@335

7@@4

RAL

@336

3352

DCA

DIHIHD

@337

573@

JMP

/CON5TANTS

AND

DIHIHD

DIDSPL

VARIABLES

@34@

9917

DIKMSK:

/MASK

FOR

LAST

@341

7441

DIRBUT:

-337

/CODE

FOR

ERASE

@342

9957

DIM26Q:

/NUMBER

USED

GENERATE

CODI

@343

7767

DIM271:

-ll

/NUMBER

USED

GENERATE

COD!

@344

75413

DIMSPC’

-24@

ICODE

@345

7765

DIMPLS:

-13

FOR SPACE
/NUMBER USED TO

GENERATE

@346

DIMMNS:

“2

/NUMBER

GENERATE

CODI
CODI

@347

7776
9999

@35@

9999

DIDSAV)

@351

9999

DIGET:

@352

9999

DIHIHD:

@353

9999

DILOHD:

@354

9999

DIXTMI:

@355

9999

DINEGI:

DIXTMZ:
PAUSE

DICONV

@2@@

DICTRL
DIDSAV i
DIDSPL

@235

DIEND

@3@2

DIGET

@351

@35@
@33@

DIHIHD

@352

DIIN

@275

DILOHD

@353

DIMMNS

@346

DIMPLS

@345

DIMSPC

@344

DIM26@

@342

DIM271

@343

DINEGI

@347

DINMBR

@251

DIPROC

@214

DIRBUT

@341

DISETI

@323

DIXMSK

@34@

DIASNI

@227

DIXTMI

@354

DIXTMZ

@355

/STORAGE

GGGG

USED

FOUR

LOCATIONS

BITS

DIgi’roI-8—29- U-Sym
Page 6
II.

DIAGRAMS

1].]

Flow Chart

ENTRY

INITIALIZE PROGRAM
SWITCHES AND ZERO
LOCATIONS FOR HOLDING

FIRST CHARACTER
IS A TERMINATING
CHARACTER

PARTIALLY-ASSEMBLED.
DOUBLE-PRECISION N0.

I
PICK UP ADDRESS FROM

CALLING SEQUENCE FOR
STORING DOUBLE
PRECISION NUMBER
'-

S
EGATIVE SWITCH
SET
7

COMPLEMENT THE
DOUBLE-PRECISION

ERROR MADE
OPERATOR WISHES TO
ERASE NUMBER
WAIT FOR CHARACTER

FROM KEYBOARD
0R READER

NUMBER

I
THIS IS A
TERMINATING

STORE RESULT IN

ADDRESS SPECIFIED BY
THE CALLING SEQUENCE

CHARACTER

FIRST CHARACTER
wAS A DECIMAL DIGIT

SAVE INCOMING
CHARACTERIN
DI

SET SWITCH J'I

DSAu"

I
SET

YES

CONTROL
SWITCH

BACK—

ARROW

T
PICK UP PARTIALLY-

ASSEMBLED. DOUBLEPRECISION NUMBER

YES

IS
CONTROL SWITC

LESS
THAN 260

S T

MULTIPLY BY FOUR
(IE DOUBLE SHIFT

LEFT TWICE)
NO

PICK UP INCOMING

ADD THE PARTIALLY

CHARACTER

GREATER
THAN 27|
7

—

ASSEMBLED. DOUBLE—
PRECISION NUMBER

MULTIPLY BY TWO

(IE DOUBLE SHIFT
LEFT ONCEI

SWITCH

SET

I
ADD THE INCOMING

YES

DECIMAL

DIGIT

TO THE RESULT

[SET

NEGATIVE SWITCH

SET

CONTROL

STORE SUM AS THE NEW

SWITCH

PARTIALLY-ASSEMBLED.

DOUBLE-PRECISION

NO.

Digital-8—29-U-Sym
Page 7
REFERENCES

12.]

Other Library Programs

Digital-8—8-U-Sym
DigifoI-8-19-U-Sym
Digital-8-28-U-Sym