Question

如何编写程序统计由40000H开始的16K个单元中所存放的字符"A”的个数，并将结果存放在DX中？

Answer 1

DATA SEGMENT
DATA1 DB ‘DFASFAAAFDFAAFFFA'
COUNT EQU
DATA ENDS

STACK SEGMENT
STA DB 100 DUP (?)
TOP EQU LENGTH STA
STACK ENDS

CODE SEGMENT
ASSUME CS:CODE,SS:STACK,DS:DATA
START: MOV AX,DATA
MOV DS,AX
MOV AX,STACK
MOV SS,AX
MOV AX,TOP
MOV SP,AX
MOV CX,COUNT
MOV DX,0
LEA SI,DATA1
MOV BL,'A'
NEXT: CMP [SI],BL
JNZ OTHER
INC DX
OTHER: INC SI
LOOP NEXT
CODE ENDS
END START