;gg404.asm
;for 梯形波16次<8086>
;2005-05
;p_Sa/lcy
data	SEGMENT
        PORT EQU	280H
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 BX, 0
     l0:MOV CX, 16
        MOV DX, PORT
        MOV AL, 7FH
     l1:OUT DX, AL
        ADD AL, 08H
        CALL delay
        LOOP l1
        
        MOV CX, 16
 	;MOV AL,0FFH
     l3:OUT DX, AL
        CALL delay
        LOOP l3
        
        MOV CX, 16
     l2:OUT DX, AL
        SUB AL, 08H
        CALL delay
        LOOP l2
        DEC BX
        JNE l0        
;================INT-21H================
        MOV AH, 4ch
        INT 21h
delay PROC
        PUSH CX
        MOV CX, 0ffffh
     ys:NOP
        LOOP ys
        POP CX 
        RET     
delay ENDP
coseg	ENDS
        END	start