5-4.asm

TCP_USB试验平台下的几个常见的实验的相应要求与代码

DATA  SEGMENTDAP  EQU 2A0H
DATA  ENDS

CODE  SEGMENT
MAIN  PROC  FAR
ASSUME CS:CODE,DS:DATA
START:
      XOR  AX,AX
      MOV  AX,DATA
      MOV  DS,AX

      MOV  DX,DAP
 L0:  MOV  AL,00H
 F1:  OUT  DX,AL
        ;------------延时-----------
      MOV  CX,100D     ;延时计数次数
 FD1: DEC  CX
      CMP  CX,0
      JNZ  FD1
        ;---------------------------
      ADD  AL,8
      CMP  AL,80H
      JZ   S1
      JMP  F1

 S1:  MOV  SI,16
 S2:  DEC  SI
      OUT  DX,AL
        ;------------延时-----------
      MOV  CX,100D     ;延时计数次数
 FD2: DEC  CX
      CMP  CX,0
      JNZ  FD2
        ;---------------------------
      CMP  SI,0H
      JZ   p1
      JMP  S2

  p1: OUT  DX,AL
        ;------------延时-----------
      MOV  CX,100D     ;延时计数次数
 FD3: DEC  CX
      CMP  CX,0
      JNZ  FD3
       ;---------------------------

      SUB  AL,8
      CMP  AL,0H
      JZ   L0
      JMP  p1

      MOV  AH,4CH
      INT  21H
MAIN  ENDP
CODE  ENDS
END   START