Question

Study the following program and answer the questions given below :

Label	Mnemonics /Operand
BACK	MVIC,08H
	LXIH,6000H
	MOVA,M
	RRC
	DCRC
	JNZBACK
	INXH
	MOVM,A
	HLT

i) Write the purpoe of the program.
ii) Write comments for the instructions used in the program.
iii) If the input data at memory location 6000 H is FF H, then write the result along with corresponding memory location.

Answer 1

i) The purpose of the program is to clear the contents of the data (make them zero) of the block starting from COOOH.

ii)

Label	Mnemonics / Operand	Comments
BACK	LXI H, COOO H	; Set HL with COOOH
	MOV C, M	; Copy memory contents to C reg
	INX H	; Increment HL by 1
	MOV A, M	; Copy memory contents to A reg
	XRA A	; Clear accumulator
	MOV M, A	; Copy accumulator contents to M reg
	DCR C	; Decrement C reg by 1
	JNZ BACK	; Repeat if counter ≠ 0
	HLT	; Stop processing

iii)

Memory Location	Before Execution	After Execution
COOO H	05	05
COO 1 H	10	00
COO 2 H	11	00
COO 3 H	12	00
COO 4 H	13	00
COO 5 H	14	00