Question

设8255A的端口A按方式0输出,端口C的高4位输入,端口B按方式1输入,控制字寄存器的地址为63H，试写初始化程序

谢谢~~

Answer 1

控制字为：10001110，即8EH
初始化程序段为：
MOV DX, 63H
MOV AL, 8EH
OUT DX, AL

Answer 2

mov dx,63H;
mov al,8eH;
out dx,al;

Answer 3

MY8255_A EQU 9C60H
MY8255_B EQU 9C61H
MY8255_C EQU 9C62H
MY8255_MODE EQU 9C63H

CODE SEGMENT
ASSUME CS:CODE

START: MOV DX,MY8255_MODE
MOV AL,82H
OUT DX,AL
A1: MOV DX,MY8255_B
IN AL,DX
MOV DX,MY8255_A
OUT DX,AL
CALL BREAK
JMP A1

BREAK PROC NEAR
MOV AH,06H
MOV DL,0FFH
INT 21H
JE RETURN
MOV AX,4C00H
INT 21H
RETURN:RET
BREAK ENDP

CODE ENDS
END START