;gg201.asm/42.asm
;for 讀A口送B口<芯片8255A：A口接8開關,B口接8個燈，pc7單脈沖>
;2005-05
;lcy/p_Sa
data	SEGMENT
        PA	EQU	280h
        PB	EQU	281h
        PC	EQU	282h
        PCTL EQU	283h
data	ENDS
stack0 SEGMENT para stack
        DW	20h	DUP(0)
stack0 ENDS
        
coseg	SEGMENT
        ASSUME CS:coseg,DS:data,SS:stack0
start:  MOV AX, data
        MOV DS, AX
;================MOV-DS-AX==============  
        MOV AL, 98h	;1-0011-000B:A口方式0輸入，B口方式0輸出
        MOV DX, PCTL
        OUT DX, AL
        MOV CX, 10h
     L1:MOV DX, PC
        IN  AL, DX
        TEST AL, 80h
        JZ  L1		;判斷pc7上升沿
        MOV DX, PA
        IN  AL, DX
        MOV	DX, PB
        OUT DX, AL
        MOV DX, PC
     L2:IN  AL, DX
        TEST AL, 80h
        JNZ  L2		;判斷pc7下降沿
        LOOP L1
;================INT-21H================
        MOV AH, 4ch
        INT 21h
coseg	ENDS
        END	start