Programming instructions

APPENDIX 5

Multiply and Divide Subroutines

MULTIPLY SUBROUTINE

/PDP-4 ones complement single precision multiplication subroutine

/calling sequence: /lac multiplier

/jms mult

/lac multiplicand

/return; low order product in AC, high order product in mp5

/time = 2.6 msec. for non-zero cases, approximately 100 microsec. for zero.

mult, 0

dzm mp5

sna

b-w mw

spa + cll - opr

cma + cml - opr

dac mpl

xct i mult

sna

imp mw

spa

cma + cml - opr

dac mp2

lac (360000

ral

dac mpsign

lac (-21

dac mp3

m4,

lac mpl

rar

dac mpl

lac mp5

spl + cll - opr

tad mp2

rar

dac mp5

isz mp3

imp mp4

mpsign, 0

dac mp5

lac mpl

rar

xct mpsign

mpz,

isz mult

jmp i mult

start