Subj : Intel 8085 Multiplication
To   : all
From : Mercyful Fate
Date : Tue Nov 28 2017 19:38:36

Figured i'd post some school fun I'm having with 8085 ASM using j8085
micro-processor emulator.  Of course there is also a second one i think using
Booth's algo, i'll post that one later on .. 


; Intel 8085 ASM Bit Multiplication
; Multiplies bits in B and C Registers  (7 x 3) = 21
;
mvi b, 07        ; Multiplicand (M)
mvi c, 03        ; Multiplier (P)(Q)
mvi d, 00        ; Acculiminator (A)
mvi e, 08        ; Loop Counter

L2:mov a, c      ; Move Multiplier to A
rar              ; Right Shift
jnc L1           ; Not carry, then L1
mov a, d         ; A = A + M
add b            ; Add (M)
mov d, a         ; Copy Result to (A)

L1:mov a, d      ; Move result down (A)
rar              ; Shift Right
mov d, a         ; Move Result Back
mov a, c         ; Move result down (Q)
rar              ; Shift Right
mov c, a         ; Move Result Back
dcr e            ; Decrement loop
jnz L2           ; Counter not zero, continue.

out 00           ; Displays  0001 0101  / 21
hlt

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