;mm403.asm
;for 5.8253產生1ms延時：實現三角波（16次×2）<8086>
;2005-05
;p_Sa/lcy
data	SEGMENT
        PA	EQU	280h
        PB	EQU	281h
        PC	EQU	282h
        PCTL	EQU	283h
        
        T0	EQU	288H
        T1	EQU	289H
        T2	EQU	28aH
        TCTL	EQU	28bH
        
        PORT	EQU	290H
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 DX, TCTL
        MOV AL, 25h	;00-10-010-1B:0通道，高8位，方式（頻率發生器），BCD記數
        OUT DX, AL
        MOV DX, T0
        MOV AL, 10h	;1us=>1ms頻率
        OUT DX, AL
        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 SI, 0
     l0:MOV CX, 16
        MOV BL,7FH
     l1:MOV DX, PC
     p1:IN  AL, DX
        TEST AL, 80h
        JE  p1        
        MOV DX, PORT
        MOV AL, BL
        OUT DX, AL
        ADD BL, 08h
        MOV DX, PC
     p2:IN  AL, DX
        TEST AL, 80h;
        JNE p2
        LOOP l1		;l1循環實現三角的/
        
        MOV CX, 16
     l2:MOV DX, PC
     p3:IN  AL, DX
        TEST AL, 80h;
        JE p3
        MOV DX, PORT       
        SUB BL, 08h
        MOV AL, BL
        OUT DX, AL
        MOV DX, PC
     p4:IN  AL, DX
        TEST AL, 80h;
        JNE p4
        LOOP l2		;l2循環實現三角的\

        DEC SI
        JNE l0        
         
;================INT-21H================
        MOV AH, 4ch
        INT 21h
coseg	ENDS
        END	start