Question

Consider a block memory locations from C300 H to C30F H, another block from C400 H to C40F H. Write an assembly language program to exchange contents of these two blocks.

Answer 1

Label	Mnemonics code	Comments
	MVI B, 10 H	; Load block length
		; Immediately into B
	LXI H, C300H	; Initiales addr of 1st
		; block in HL pair
		; data accessible in mem.
	LXI D, C400H	;  Addr of 2nd block is
		; initialized to DE pair.
		; mem (M) not used here
BACK:	MOV C, M	; data from 1st block into C
	LDAX D	; data of 2nd block into A
	MOV MA	; data from A into Mem
	MOV A, C	; data of C into A
	STAX D	; store A into 2nd block
	INX H	; Go to next mem of 1st block
	INX D	; Go to next mem of 2nd block
	DCR B	; decrement length counter
	JNZ Back	; If block length is zero
		; then done. If not, jump
		; back to start of loop
	HLT	; Halt the process
		;
		;