7_1_2.asm

NAME EX7_1_2

DATA SEGMENT
    ADDRESS EQU 0280H
    DAT DB ?
    DAT2 DB ?
DATA ENDS
STACK SEGMENT PARA STACK
      DB 100 DUP(?)
STACK ENDS
CODE SEGMENT
  ASSUME CS:CODE,DS:DATA,ES:DATA,SS:STACK

; delay
DELAY  PROC    FAR
       PUSH    CX
       PUSH    AX
       MOV    AX,02FFH
X1:    MOV    CX,0FFFH
X2:    DEC    CX
       JNE    X2
       DEC    AX
       JNE    X1
       POP    AX
       POP    CX
       RET
DELAY  ENDP  

; main 
START: MOV AX,DATA
       MOV DS,AX
       MOV ES,AX
       
; initialize 8255
    MOV AL,10010000B; method 0£¬A input£¬C output
    MOV DX,ADDRESS+3   
    OUT DX,AL
    
    MOV DAT,01H
    MOV DAT2,00H
LOOPP:  
    MOV AH,1; keyboard read in
    INT 16H
    JNZ READ
      
    MOV DX,ADDRESS
    IN AL,DX
    MOV AH,AL
    AND AH,11000000B
    CMP AH,10000000B
    JE LEFT
    CMP AH,01000000B
    JE RIGHT
    CMP AH,11000000B
    JE SHAN
    MOV AL,0
    MOV DX,ADDRESS+2
    OUT DX,AL
    JMP LOOPP
    
LEFT:
    MOV AL,DAT
    MOV DX,ADDRESS+2
    OUT DX,AL
    CALL DELAY
    ROL DAT,1
    JMP LOOPP
RIGHT:
    MOV AL,DAT
    MOV DX,ADDRESS+2
    OUT DX,AL
    CALL DELAY
    ROR DAT,1
    JMP LOOPP
SHAN:
    MOV AL,DAT2
    MOV DX,ADDRESS+2
    OUT DX,AL
    CALL DELAY
    NOT DAT2
    JMP LOOPP

   
READ:
    MOV AH,0;keyboard read in
    INT 16H
    CMP AL,0EH
    JNE ENDD
    JMP LOOPP
ENDD:  
    MOV AH,4CH
    INT 21H
CODE ENDS
END START