pc8253.asm

汇编程序

;FILENAME: PC8253.ASM 
;内容: 定时器/计数器输出控制
TIM_CTL EQU   203H         		;控制口地址
TIMER0   EQU   200H         		;定时器/计数器0地址
TIMER1   EQU   201H         		;定时器/计数器l地址
MODE02   EQU    35H           		;T0模式字，2方式，BCD
MODE13   EQU    77H           		;T1模式字，3方式，BCD
DATA 	SEGMENT
MESS 	DB'8253A TIMERO IN MODE2! COUNT=20',0AH,0DH
       	DB'8253A TIMER1 IN MODE3! COUNT=5000',0AH,0DH,'$'
DATA  	ENDS
STACK 	SEGMENT STACK 'STACK'
       	DB 100 DUP('S')
STACK 	ENDS
CODE   	SEGMENT
MAIN  	PROC FAR
ASSUME  CS:CODE, DS:DATA
START:	PUSH DS
       	MOV AX, 0
       	PUSH AX
       	MOV AX,DATA
       	MOV DS,AX
       	CLI                  		;关中断
       	MOV DX, TIM_CTL
       	MOV AL, MODE02        		;TIMER0.MODE 2, BCD
       	OUT DX, AL
      	MOV DX,TIMER0        		;T0= 20
      	MOV AL, 20H
       	OUT DX, AL
       	MOV AL, 00H
       	OUT DX, AL
       	MOV DX, TIM_CTL        		;TIMER1 ,MODE 3 ,BCD
       	MOV AL, MODE13
       	OUT DX, AL
       	MOV DX, TIMER1          	;T1 =3500
       	MOV AL, 00H
       	OUT DX, AL
       	MOV AL, 50H
       	OUT DX, AL
       	STI                  		;开中断
       	MOV DX,OFFSET MESS
       	MOV AH,09            		;显示信息
       	INT 21H
       	RET
MAIN  	ENDP
CODE  	ENDS
END   	START