;FILENAME: PCINT.ASM
;內(nèi)容:系統(tǒng)硬件中斷
INTA00  EQU  20H                  	;8259A偶地址
INTA01  EQU 21H                     	;8259A奇地址
DATA 	SEGMENT
MESS   	DB 'THIS A 8259A INTERRUPT!' ,0DH,0AH,'$'
DATA  	ENDS
STACK  SEGMENT STACK 'STACK'
       	DB 100 DUP('S')
STACK 	ENDS
CODE  	SEGMENT
       	ASSUME CS: CODE, DS : DATA
START:	MOV AX, CS           		;設(shè)置DS，指向代碼
       	MOV DS, AX
       	MOV DX,OFFSET INT_PROC
       	MOV AX,250AH        		;裝載中斷服務(wù)程序
       	INT 21H
       	CLI
       	MOV DX,INTA01
   		IN AL ,DX
      	AND AL, 0FBH
       	OUT DX,AL            		;開放IRQ2
       	MOV BX,10           		;設(shè)置計(jì)數(shù)值1
       	STI
LL:   	JMP LL
INT_PROC: MOV AX, DATA
       	MOV DS, AX
       	MOV DX,OFFSET MESS
       	MOV AH, 09
       	INT 21H              		;顯示信息
       	MOV AL, 20H
       	OUT INTA00,AL         		;發(fā)EOI命令
       	SUB BX, 1
       	JNZ NEXT
       	IN AL,INTA01
       	OR AL, 04H
       	OUT DX,AL           		;屏蔽IRQ2
       	STI
       	MOV AH, 4CH
       	INT 21H
NEXT: 	IRET
CODE  	ENDS
       	END START