EXTRN InitKeyDisplay:NEAR, Display8A:NEAR
IO8259_0 EQU 0250H
IO8259_1 EQU 0251H
COM_ADDR EQU 0263H
T2_ADDR EQU 0262H
_STACK SEGMENT STACK
DW 100 DUP(?)
_STACK ENDS
_DATA SEGMENT WORD PUBLIC 'DATA'
BUFFER DB 8 DUP(?)
Counter DB ?
ReDisplayFlag DB 0
_DATA ENDS
CODE SEGMENT
START PROC NEAR
ASSUME CS:CODE, DS:_DATA, SS:_STACK
MOV AX,_DATA
MOV DS,AX
MOV ES,AX
NOP
CALL InitKeyDisplay
CALL Init8259
CALL Init8253
CALL WriIntver
MOV Counter,0 ;中断次数
MOV ReDisplayFlag,1 ;需要显示
STI ;开中断
START1: LEA SI,Buffer
CALL LedDisplay
CALL Display8A
STI
JMP START1
Init8259 PROC NEAR ;8259A 的初始化程序
MOV DX,IO8259_0
MOV AL,13H
OUT DX,AL
MOV DX,IO8259_1
MOV AL,08H
OUT DX,AL
MOV AL,09H
OUT DX,AL
MOV AL,0FEH
OUT DX,AL
RET
Init8259 ENDP
Init8253 PROC NEAR ;编写 8253 的初始化程序
MOV DX,COM_ADDR ;计数器 T2 设置在模式 0 状态,BCD 码计数,初值
MOV AL,91H
OUT DX,AL
MOV DX,T2_ADDR
MOV AL,05H
OUT DX,AL
RET
Init8253 ENDP
WriIntver PROC NEAR
PUSH ES
MOV AX,0
MOV ES,AX
MOV DI,20H
LEA AX,INT_0
STOSW
MOV AX,CS
STOSW
POP ES
RET
WriIntver ENDP
LedDisplay PROC NEAR
MOV AL,Counter
AND AL,0FH
MOV Buffer,AL
MOV Buffer + 1,10H ;高七位不需要显示
MOV Buffer + 2,10H
MOV Buffer + 3,10H
MOV Buffer + 4,10H
MOV Buffer + 5,10H
MOV Buffer + 6,10H
MOV Buffer + 7,10H
RET
LedDisplay ENDP
INT_0: PUSH DX
PUSH AX
MOV AL,Counter
ADD AL,1
DAA
MOV Counter,AL
MOV DX,IO8259_0
MOV AL,20H
OUT DX,AL
MOV DX,T2_ADDR
MOV AL,05H
OUT DX,AL
POP AX
POP DX
IRET
START ENDP
CODE ENDS
END START实验原理图
