sy7-8255.asm

汇编语言接口技术硬件实验中

        CODE  SEGMENT
              ASSUME    CS:CODE
        MAIN  PROC      FAR
      START:  MOV       AL,89H
              MOV       DX,0C40BH
              OUT       DX,AL

              MOV       AL,10000100B
              MOV       DX,0C408H
              OUT       DX,AL

      LOOP1:  MOV       AL,00100100B
              OUT       DX,AL
              CALL      DELAY

              MOV       CX,8
      LOOP2:  MOV       AL,01000100B
              OUT       DX,AL
              CALL      DELAY
              MOV       AL,00000100B
              OUT       DX,AL
              CALL      DELAY
              LOOP      LOOP2

              MOV       AL,10000001B
              OUT       DX,AL
              CALL      DELAY

              MOV       CX,8
      LOOP3:  MOV       AL,10000010B
              OUT       DX,AL
              CALL      DELAY
              MOV       AL,10000000B
              OUT       DX,AL
              CALL      DELAY
              LOOP      LOOP3

              MOV       AH,0BH
              INT       21H
              CMP       AL,0
              JZ        LOOP1
             ; MOV       AH,4CH
              ;INT       21H

        MAIN  ENDP

       DELAY  PROC      NEAR
              MOV       CX,0FFFFH
      LOOP4:  MOV       DX,0C403H
              MOV       AL,00110000B
              OUT       DX,AL
              MOV       DX,0C400H
              MOV       AL,0
              OUT       DX,AL
              OUT       DX,AL
              LOOP      LOOP4
              RET
       DELAY  ENDP
        CODE  ENDS
              END       MAIN