DATA SEGMENT
COUNT DW 1
MESS DB 'The bell is ring!',0AH,0DH,'$'
DATA ENDS
STACK SEGMENT STACK 'STACK'
DB 100 DUP(?)
STACK ENDS
CODE SEGMENT
MAIN PROC FAR
ASSUME CS:CODE,DS:DATA,ES:DATA,SS:STACK
START:
MOV AX,STACK
MOV SS,AX
PUSH DS
SUB AX,AX
PUSH AX
MOV AX,DATA
MOV DS,AX
MOV AL,1CH
MOV AH,35H
INT 21H
PUSH ES
PUSH BX
PUSH DS
MOV DX,OFFSET RING
MOV AX,SEG RING
MOV DS,AX
MOV AL,1CH
MOV AH,25H
INT 21H
POP DS
IN AL,21H ;只允许定时器中断,其他中断屏蔽
AND AL,0FEH
OUT 21H,AL
STI
MOV DI,2000
DELAY: MOV SI,3000
DELAY1:DEC SI
JNZ DELAY1
DEC DI
JNZ DELAY
POP DX
POP DS
MOV AL,1CH
MOV AH,25H
INT 21H
RET
MAIN ENDP
RING PROC NEAR
PUSH DS
PUSH AX
PUSH CX
PUSH DX
MOV AX,DATA
MOV DS,AX
STI
DEC COUNT
JNZ EXIT
MOV DX,OFFSET MESS
MOV AH,09H
INT 21H
MOV DX,100
IN AL,61H
AND AL,0FCH
SOUND: XOR AL,02H
OUT 61H,AL
MOV CX,140H
WAIT1: LOOP WAIT1
DEC DX
JNE SOUND
MOV COUNT,182
EXIT: CLI
POP DX
POP CX
POP AX
POP DS
IRET
RING ENDP
CODE ENDS
END START