Question

Write an Assembly Language Program to count number of times data D9H present in a memory block begins from C400H. The length of the block is stored at C3FFH. Store the result after end of the block.

Answer 1

Label           Mnemonics+ operand                          Comments

START:  LXI H, C3FFH     ; Initialize H-L pair with starting address
        MOV C, M         ; Store count in register C
        MVI B, 00H       ; Initialize occurrence count in register B
        INX H            ; Increment memory location

LOOP:   MOV A, M         ; Get number in accumulator
        CPI D9H          ; Compare with D9H
        JNZ NEXT         ; If not equal, jump to NEXT
        INR B            ; If equal, increment B

NEXT:   INX H            ; Increment H-L pair
        DCR C            ; Decrement count
        JNZ LOOP         ; If count not zero, repeat loop
        INX H            ; Increment memory location
        MOV M, B         ; Store occurrence count in memory

END:    HLT              ; Stop processing