Question

Study the following program and answer the questions given below :

Label	Mnemonics /Operand
BACK	LXIH,COOOH
	MOVC,M
	INXH
	MOVA,M
	XRAA
	MOV M,A
	DCR C
	JNZBACK
	HLT

i) Write the purpose of the program.
ii) Write comments for the instructions used in the program.
iii) If the input data at memory location COOO H is 05 H, then write the result along with corresponding memory locations.

Answer 1

(i) The purpose of the program is to rotate the data (8 times) obtained from memory location 6000 H and store the result obtained at next location. i.e. copying same data to another memory location.

(ii)

Label	Mnemonics /Operand	Comments
BACK	MVIC,08H	; Set C reg to 08 H
	LXIH,6000H	; Set HL to 6000 H
	MOVA,M	; get first no in Accumulator
	RRC	; Rotate the contents of accumulator right by 1 bit
	DCRC	; Decrement C reg by 1
	JNZ BACK	; Repeat if c ≠ 0
	INX H	; Increment HL by 1
	MOV M, A	; Store the contents of Accumulator to M reg
	IILT	; Stop processing

(iii)

Memory Location	Before Execution	After Execution
6000	FF	FF
6001	10	FF