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DIGITAL-8-11-U

December 1966

8 pages

Original

0.2MB

Document:	digital-8-11-u-d
Order Number:	DIGITAL-8-11-U
Revision:
Pages:	8
Original Filename:	https://svn.so-much-stuff.com/svn/trunk/pdp8/src/dec/digital-8-11-u/digital-8-11-u-d.pdf

OCR Text

IDENTIFICATION

1.1

Digita 1-8-11-U

1.2

Double Precision Binary Coded Decimal to Binary

1.3

March 18, 1966

PDP-B
LIBRARY

Digita 1-8-11-U
Page 1

ABSTRACT
This subroutine converts a 6-digit BCD number to its equivalent binary value in two computer

words.

REQUIREMENTS

3.1

Storage
This subroutine requires 89 (decimal) memory locations.

3.2

Subprograms and/or Subroutines (None)

3.3

Equipment
Standard PDP-8

USAGE

4.1

The subroutine is loaded with the Binary Loader. The symbolic is either assembled with the
user program or separately with the proper origin setting.
4.2

Calling Sequence

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}.

4.3

Switch Settings (None)

RESTRICTIONS (Not Applicable)

DESCRIPTION

6.1

Discussion
Upon entry I the BCD number is in the form:

(each digit is 4 bits, 24 = 16)
Using the single precision BCD to binary subroutine, then is reduced to

Digita 1-8-11-U
Page 2
The high order part of the BCD word is effectively multiplied by 1000 (= 8(128 - 3)) and
the low-order part is added, giving

See Digital-8-1 O-U.
6.2

Examples
GO,

X,
HIGH,
LOW,

JMSIX
HIGH
HLT
DOUBLE
1001
1001

1001
1001

999,999

If this program were started at GO, the C(AC) at the halt would be 03648 and C(LOW}
wou Id be 10778 , i. e " 03641 0778 = 999,999 10 ,
7.

METHOD (Not Applicable)

FORMAT (Not Applicable

EXECUTION TIME

9.1

Minimum
252 flsec

9.2

Maximum
255 flsec

Digital-8-11-U
Page 3
10.

PROGRAM

10.1

Core Map (Not Applicable)

10.2

Dimension List(s) (Not Applicable)

10.3

Macro, Parameter, and Variable Lists (None)

10.4

Program Listing

IDI3ITAL

8-11-U-SIM

IDOUSLE PRECISION SCD TO BINARY CONVERS[ON
ICALLI NG SEQUENCE:
I
J MS DOUBLE
I
ADDRESS OF HI GH ORDER ARGUlY1ENT
C(AC)=HIGH ORDER PART
I
REIURtJ:
C(LOW) = LOW ORDER P~RT
I
IALSO CONTAI NS SI (~GLE PRECISION BCD TO Bl NARY
ICALLING SEQUENCE:
I
C(AC) = 3 BCD CHARACTERS
I
Jf'lS BCDSI N
I R E T UR N:
A tJ SINER INC ( AC )
02100
0201
0202
~203

3204
0205
0206
~2~7
~21 QJ

021 1
0212
~213

21214
3215
2121 6
321 7
0220
3221
3222
D223
;~224

,Z225
3226
0227

02.3 (j
~231

2l0~~

7300
1600
3271
22""
1671
4275
3272
2271
1671
4275
3271
1272
71 12
7~12

7010
3275
1275
0327
3274
1275
HI :z
0325
3273
1272
71 ~ 4

DOUBLE, 0
a.. A CLL
I~D I DOUBLE
I FETCH ADDRESS
OCA LOW 1
I STORE
I I NCRE~lENT RETURN
ISZ DOUBLE
TAD I LOW 1 IFETCH HIGH ORDER
JMS SCDBIN ICONVERT IT
OCA HIGHI
I STORE
IS? LOW 1
I INCREMENT POINTER
TA D I LOW 1 IFETCH LOW OR DER
JMS BCDBIN ICO~, VERT IT
OCA LOW 1
I STJRE IT
T,~D HIGHI
QL RTR
RTR
R!\R
IMULTrPLY HIGH ORDER
OCA BCDBIN IPART BY 128
TAD BCOBIN
~D K 1 77
OCA HIGH
Ttl D BCDBI N
RAR
ftJD K7600
OCA LOW
T~D HIGHI
I MUL II PLY HIGH ORDER
a..L RAL
I BY THREE

Digital-8-11-U
Page 4

0232
:3233
0234
~235

0236
3237
0243
Z241
0242
0243
3244
2245
0246
0247
~250

'3251
0252
0253
0254
0255
0256
0257
<3260
CJ261
0262
0263
3264

21265
J266
0267
0270
0271
2,272
0273
0274

TAD HrGHI

1272
7141
1273
3273
74213
7040
1274
3274
1274
7106
71304
;'326
3274
1273
712)6

aA CLL

T~D

/
/

125*HI GH
NOW ,'lUL II PLY BY 8

MASK 9 BITS

LOW

s-lL
Q'11A

TAD HIGH
OCA HIGH
TAD HIGH
Q..L RTL
RAL
~W K7770
OCA HIGH
T~D LOW
a..L RTL
RAL
OCA LOW
TAD LOW
RAL
~D K7
TAD HI GH
OCA HI GH
TAD LOW
NW K 777IJ
Q..L
T~D l'J W1
OCA LOW
TAD HIGH

70~4

7~el4

0324
12, 74
3274
1273
0326
7100
1271
3273
1274
7430

7~131

lAC
JMP I

56~0

000i!

LOw 1,
HIGH 1 ,
LO \~,

Zl00J

~IGH,

0Z00

FORM 128*HI GH-3*HI GH

OCA LOW

3273
1273

00~J

0
Iii
0
el

/CARRY
DOUBLE

/3 BITS

9 BITS

/
/

!\DD LO\I.} O;:{ DER PART
STORE LOW ORDER PART

Digita 1-8-11-U
Page 5

0275
0276
3277
0300
0301
03132
0303
0304
~305

0306
0307
03U
03 II
a312
0313
0314
0315
0316
0317
0320
0321
0322
~323

:.'1324
7.325
0326
2327
0330

ISINGLE PRECISION CONVE:'1SION
BC DBI N, I2l
OCA HI GH
TAD HI GH

0000
3274
1274
0330
7112
3273
1273
7010
1273
7141
1274
3274
1274
0323
7112
3273
127.3
7010
1273
7041
1274
5675
7760
Pl007
76~€l

7770

21177
74~0

K74~0

Q.L RTR
OCA LOW
TAD LOW
RAR
TAD LOW
ClA
TAD HI GH
OCA HIGH
TAD HIGH
N-JD K7760
QL RTR
OCA LOW
TAD LOW
RAR
TAD LOW
ClA
TAD HIGH
JMP I BCDBr N
K7760,
7760
K7 ,
7
K76eJ0,
7600
K 7770,
7770
K 177,
177
K74eJ~,
7430

BCDBH)
0275
DOUBLE 02eJ~
HI GH
0274
HI GH 1212 72
K177
'0327
K7
0324
K7412liJ
033~
K760:3
0325
K7760
0323
K77712l
0326
LOW
0273
LOWI
0271

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