INTA01 EQU 21H ;8259A的奇地址端口
DATA SEGMENT
MESS DB "THIS IS A 8259A INTERRUPT!",0DH,0AH,'$'
DATA ENDS
CODE SEGMENT
ASSUME CS:CODE,DS:DATA
START: MOV AX,CS ;先让DS指向代码段
MOV DS,AX
MOV DX,OFFSET INT-PROC ;设置0AH号中断向量
MOV AX,250AH
INT 21H
CLI ;关中断
MOV DX,INTA01 ;读出IMR内容
IN AL,DX
AND AL,0FBH ;允许IRQ2中断
OUT DX,AL
MOV BX,10 ;设置中断次数为10
STI ;开中断
LL: JMP LL
INT-PROC PROC
MOV AX,DATA ;中断服务程序
MOV DS,AX ;将DS指向数据段
MOV DX,OFFSET MESS ;显示发生中断的信息
MOV AH,9
INT 21H
MOV DX,INTA00 ;发中断结束命令EOI
MOV AL,20H
OUT DX,AL
SUB BX,1 ;计数器减一
JNZ NEXT ;不为0，转去执行中断返回
MOV DX,INTA01 ;为0，则读出屏蔽字
IN AL,DX
OR AL,4 ;禁止IRQ2中断
OUT DX,AL
STI ;开中断
POP AX ;恢复堆栈指针SP
POP AX
POP AX
MOV AH,4CH ;返回DOS
INT 21H
NEXT: IRET ;中断结束
INT-PROC ENDP
CODE ENDS
END START ；汇编结束
D:\ASM\MASM5>masm
Microsoft (R) Macro Assembler Version 5.00
Copyright (C) Microsoft Corp 1981-1985, 1987. All rights reserved.
Source filename [.ASM]: \asm\ch168
Object filename [ch168.OBJ]:
Source listing [NUL.LST]:
Cross-reference [NUL.CRF]:
\asm\ch168.ASM(10): error A2009: Symbol not defined: INT
\asm\ch168.ASM(21): error A2028: Operator expected
\asm\ch168.ASM(43): error A2009: Symbol not defined: ENDP
49922 + 383790 Bytes symbol space free
0 Warning Errors
3 Severe Errors
