PORTA EQU 02B0H;8255
PORTB EQU 02B2H
PORTC EQU 02B4H
CTRW EQU 02B6H
P8253_0EQU 0290H;8253地址
P8253_1EQU 0292H
P8253_2EQU 0294H
C8253EQU 0296H
DATA SEGMENT
DATA ENDS
CODE SEGMENT
ASSUME CS:CODE,DS:DATA
BEGIN:
START:
MOV DX,CTRW
MOV AL,10000010B
OUT DX,AL;设置8255
MOV CX,0000H
MOV AH,01H
MOV AL,00110110B ;设置8253
MOV DX,C8253
OUT DX,AL
MOV AX,03E8H
MOV DX,P8253_0
OUT DX,AL
MOV AL,AH
OUT DX,AL
ST10: MOV DX,PORTB;读取PB
IN AL,DX
MOV DX,PORTA;输出到PA
OUT DX,AL
JMP ST10
CODE ENDS
END BEGIN