Beep Sound 1 - Assembly Language - MASM

Program:

GENERATION OF BEEP

.model tiny

.code

.startup

JMP INSTALL

ADD9 DD ?

;ISR to generate beep sound

beepISR PROC FAR

PUSH AX

PUSH BX

PUSH CX

PUSH DX

IN AL,61H

OR AL,03H

OUT 61H,AL ; Turn ON system speaker

MOV AL,0B6H ; program Counter 2

OUT 43H,AL

MOV BX,2000

MOV AX,34DCH

MOV DX,12H

DIV BX

OUT 42H,AL ;set the frequency of counter 2 to 2000Hz

MOV AL,AH

OUT 42H,AL

MOV CX,1FFFH

BACK2:

MOV DX,0FFFFH ; Delay

BACK1:

DEC DX

JNZ BACK1

LOOP BACK2

IN AL,61H

XOR AL,03H ; Turn OFF system speaker

OUT 61H,AL

PUSHF

CALL CS:ADD9 ; Call original ISR9

POP DX

POP CX

POP BX

POP AX

IRET

beepISR ENDP

INSTALL:

MOV AX,CS

MOV DS,AX ; overlap CS and DS

MOV AH,35H

MOV AL,09H

INT 21H

MOV WORD PTR ADD9,BX

MOV WORD PTR ADD9+2,ES ;Get the current vector 9 and save it in ADDR9

MOV AH,25H

MOV AL,09H

MOV DX,OFFSET beepISR ;install beepISR at Vector 9

INT 21H

MOV DX,OFFSET INSTALL

MOV CL,4

SHR DX,CL ; find the paragraph size in Dx

INC DX

MOV AH,31H ; exit to DOS as TSR

MOV AL,00H

INT 21H

end