Question

Write an assembly language program to multiply two 1-byte data stored at memory locations C600 H and C601 H respectively. Store the 16-bit result at locations C602 H and C603 H beginning with lower order byte of the result. 

Answer 1

Label	Mnemonics code	Comments
	LXI H, C600H	; Load HL pair
		; immediately
		; with C600H
	MOV D, M	; Move contents
		; of memory to
		; register D
	INX H	; Go to next memory
	MOV E, M	; Move contents of
		; this memory into
		; register E
	XRA A	; Clear content of
		; Accumulator, (A) = 00H
	MOV B, A	; Copy (A) to (B)
Back:	ADD D	; Process of multiplication begins by
		; Adding 1st data into
		; Accumulator
	JNC skipcy	; Jump if cy - 0
	INR B	; count cy in B
Skip cy	DCR E	; decrement loop
		; counter E, 2nd data
	JNZ back	; IF counter E ≠ 0
		; Jump 'back' to
		; Continue multiplication
	INX H	; Go to next memory
	MOV M, A	; Copy lower data
		; byte of product
	INX H	; Go to next memory
	MOV M, B	; Copy higher data
		; byte of product
	HLT	; Halt all process

Note: Instead of HLT, RST 01 can be used and awarded equal credit.