IN al,61h
   PUSH ax

   MOV dx,0Bh

Main:

   MOV bx,477     ; 1,193,180 / 2500 (assume this is timing to frequency)
   CALL WarbCom
   MOV cx, 2600h

Delay1:

   LOOP Delay1
   MOV bx, 36         1; 1,193,180 / 32767
   CALL WarbCom
   MOV cx,1300h

Delay2:

   LOOP Delay2
   DEC dx
   JNZ Main

   POP ax
   OUT 61h,al

--------------O/----------
                  O\

WarbCom:

   MOV al,10110110b
   OUT 43h,al
   MOV ax,bx
   OUT 42h,al
   MOV al,ah
   OUT 42h,al
   IN al, 61h
   OR al,00000011b
   OUT 61h,al

   RET

    

   This example, which shows how you can control the speaker directly, uses both 8253 timer and the 8255 PPI. The Warble subroutine (the one I typed in first) provides good sound for error routines. BOOP (one I didn't type in) provides a gentle sound when the wrong key is pressed.    

Syntax

BOOL WINAPI Beep(
__in DWORD dwFreq,
__in DWORD dwDuration
);

Parameters

dwFreq [in]

The frequency of the sound, in hertz. This parameter must be in the range 37 through 32,767 (0x25 through 0x7FFF).
dwDuration [in]

The duration of the sound, in milliseconds.

I don't know what OS you use but if it is windows, why not use better the beep function ?

A long time ago, all PC computers shared a common 8254 programable interval timer chip for the generation of primitive sounds. The Beep function was written specifically to emit a beep on that piece of hardware.

On these older systems, muting and volume controls have no effect on Beep; you would still hear the tone. To silence the tone, you used the following commands:

net stop beep

sc config beep start= disabled

Since then, sound cards have become standard equipment on almost all PC computers. As sound cards became more common, manufacturers began to remove the old timer chip from computers. The chips were also excluded from the design of server computers. The result is that Beep did not work on all computers without the chip. This was okay because most developers had moved on to calling the MessageBeep function that uses whatever is the default sound device instead of the 8254 chip.

Eventually because of the lack of hardware to communicate with, support for Beep was dropped in Windows Vista and Windows XP 64-Bit Edition.

In Windows 7, Beep was rewritten to pass the beep to the default sound device for the session. This is normally the sound card, except when run under Terminal Services, in which case the beep is rendered on the client.

Windows 95:

The Beep function ignores the dwFreq and dwDuration parameters. On computers with a sound card, the function plays the default sound event. On computers without a sound card, the function plays the standard system beep.

        invoke  Beep,500,400
        invoke  Beep,1000,200
        invoke  Beep,2000,100
        invoke  Beep,4000,50
        invoke  MessageBeep,MB_ICONEXCLAMATION
    

Code:

.lutin   dd music,0,@f-$-4 \
         ,.B,.4th ,.Dd,.4th ,.Gd,.4th ,.Dd,.8th ,.Gd,.8th \
         ,.B,.4th ,.E,.4th ,.Gd,.4th ,.E,.8th ,.Gd,.8th \
         ,.B,.4th ,.Dd,.4th ,.Gd,.4th ,.Dd,.8th ,.Gd,.8th \
         ,.Ad,.4th ,.Dd,.4th ,.G,.4th ,.Dd,.8th ,.Gd,.8th \
         ,.B,.4th ,.E,.4th ,.Gd,.4th ,.E,.8th ,.Gd,.8th \
         ,.Dd shl 1,.4th ,.Gd,.4th ,.B,.4th ,.E,.8th ,.Gd,.8th \
         ,.Cd shl 1,.4th ,.G,.4th ,.Ad,.4th ,.Dd,.8th ,.Gd,.8th \
         ,.Dd shl 1,.4th ,.Fd,.4th ,.B,.4th ,.E,.8th ,.Gd,.8th
         @@:
.C = 261
.Cd= 277
.D = 293
.Dd= 311
.E = 329
.F = 349
.Fd= 370
.G = 392
.Gd= 415
.A = 440
.Ad= 466
.B = 493

.0    dd .C/8,.Cd/8,.D/8,.Dd/8,.E/8,.F/8,.Fd/8,.G/8,.Gd/8,.A/8,.Ad/8,.B/8
.1    dd .C/4,.Cd/4,.D/4,.Dd/4,.E/4,.F/4,.Fd/4,.G/4,.Gd/4,.A/4,.Ad/4,.B/4
.2    dd .C/2,.Cd/2,.D/2,.Dd/2,.E/2,.F/2,.Fd/2,.G/2,.Gd/2,.A/2,.Ad/2,.B/2
.3    dd .C*1,.Cd*1,.D*1,.Dd*1,.E*1,.F*1,.Fd*1,.G*1,.Gd*1,.A*1,.Ad*1,.B*1
.4    dd .C*2,.Cd*2,.D*2,.Dd*2,.E*2,.F*2,.Fd*2,.G*2,.Gd*2,.A*2,.Ad*2,.B*2
.5    dd .C*4,.Cd*4,.D*4,.Dd*4,.E*4,.F*4,.Fd*4,.G*4,.Gd*4,.A*4,.Ad*4,.B*4
.6    dd .C*8,.Cd*8,.D*8,.Dd*8,.E*8,.F*8,.Fd*8,.G*8,.Gd*8,.A*8,.Ad*8,.B*8
.7    dd .C*16,.Cd*16,.D*16,.Dd*16,.E*16,.F*16,.Fd*16,.G*16,.Gd*16,.A*16,.Ad*16,.B*16
.8    dd .C*32,.Cd*32,.D*32,.Dd*32,.E*32,.F*32,.Fd*32,.G*32,.Gd*32,.A*32,.Ad*32,.B*32
.9    dd .C*64,.Cd*64,.D*64,.Dd*64,.E*64,.F*64,.Fd*64,.G*64,.Gd*64,.A*64,.Ad*64,.B*64
.10   dd .C*128,.Cd*128,.D*128,.Dd*128,.E*128,.F*128,.Fd*128,.G*128,.Gd*128,.A*128,.Ad*128,.B*128


.bpm=250
.4th = (60*int8.freq)/.bpm
.8th = .4th/2
.keyboard:
Null

;.do   dd 261.6
;.dod  dd 277.2
;.re   dd 293.7
;.red  dd 311.1
;.mi   dd 329.7
;.fa   dd 349.2
;.fad  dd 370.0
;.sol  dd 392.0
;.sold dd 415.3
;.la   dd 440.0
;.lad  dd 466.2
;.si   dd 493.9
beeper:
        dd beep,100,100

music:  dd speaker.loop,0
.call=0
.current=4
.size=8
.data=12
.freq=0
.time=4

melody: dd speaker.seq,0
.call=0
.current=4
.size=8
.data=12
.freq=0
.time=4

beep:   dd speaker.event,0
.call=0
.freq=4
.time=8

speaker:
.loop:
        cmp [.time],0
        jg .noloop
        mov eax,[esi+melody.current]
        add eax,8
        cmp eax,[esi+melody.size]
        jl @f
        mov eax,0
@@:
        mov [esi+melody.current],eax
        mov ebx,[esi+eax+melody.data+melody.freq]
        mov [.freq],ebx
        mov ebx,[esi+eax+melody.data+melody.time]
        mov [.time],ebx
        mov [.cnt],0
.noloop:
        call .tone
        ret

.seq:
        cmp [.time],0
        jg .noseq
        mov eax,[esi+melody.current]
        add eax,8
        cmp eax,[esi+melody.size]
        jge .endseq
        mov [esi+melody.current],eax
        mov ebx,[esi+eax+melody.data+melody.freq]
        mov [.freq],ebx
        mov ebx,[esi+eax+melody.data+melody.time]
        mov [.time],ebx
        mov [.cnt],0
.noseq:
        call .tone
        ret
.endseq:
        call .off
        ret

.event:
        cmp [.cnt],0
        jne @f
        mov eax,[esi+beep.freq]
        mov [.freq],eax
        mov eax,[esi+beep.time]
        mov [.time],eax
@@:
        call .tone
        ret
.tone:
        cmp [.time],0
        jle .stop
        mov eax,[int8.inc]
        sub [.time],eax
        jl .stop
        cmp [.cnt],0
        jne .end
        call .set
        inc [.cnt]
.end:
        ret
.stop:
        call .off
        ret
.set:
        push eax ebx edx
        mov ebx,[.freq] ; RETURNS:  AX,BX,DX = undefined
        mov edx,[.clk+2]
        mov eax,[.clk] ; ;mov ax,0x34DC ; which is more accurate?
        div bx
        mov bl,al
        mov al,0b6h
        out 43h,al
        mov al,bl
        out 42h,al
        mov al,ah
        out 42h,al
        call .on
        pop edx ebx eax
        ret
.on:
        in al,0x61
        or al,3
        out 0x61,al
        ret
.off:
        in al,0x61
        and al,not 3
        out 0x61,al
        ret
.clk    dd 1193180
.time dd 0
.cnt  dd 0
.freq dd ?



.do   dd 261.6
.dod  dd 277.2
.re   dd 293.7
.red  dd 311.1
.mi   dd 329.7
.fa   dd 349.2
.fad  dd 370.0
.sol  dd 392.0
.sold dd 415.3
.la   dd 440.0
.lad  dd 466.2
.si   dd 493.9

    

; AX - Note frequency

speaker_tone:
        pusha

        mov cx, ax                      ; Store note value for now

        mov al, 182
        out 43h, al
        mov ax, cx                      ; Set up frequency
        out 42h, al
        mov al, ah
        out 42h, al

        in al, 61h                      ; Switch PC speaker on
        or al, 03h
        out 61h, al

        popa
        ret


speaker_off:
        pusha

        in al, 61h
        and al, 0FCh
        out 61h, al

        popa
        ret
    

org 0x100
use16
start:
CBA1:
      MOV      CX,10
      MOV      [W],10
CBA2: 
      PUSH     CX
TT4:
      ADD      [W],1000
      MOV      AX,[W]
      SAR      AX,3
      MOV      BX,40
      MUL      BX
      MOV      BX,10000
      MUL      BX
      MOV      [Hz],DX
      CALL     Sound
;      MOV      [ms1],1
;      CALL     DeLay
      MOV      [ms1],11
      CALL     DeLay
      POP      CX
      LOOP     CBA2

      CALL     NoSound
      XOR      AH,AH
      INT      16h
      
      CALL     NoSound
      IN       AL,60H
      CMP      AL,1
      JNE      CBA1

      INT      20h

                                                       
 ;----------------------------------------------------;
 ; Sound                                              ;
 ;----------------------------------------------------;
Sound:
        mov   bx,[Hz]
        mov   ax,0x34dd
        mov   dx,0x0012
        cmp   dx,bx
        jnc   Done1
        div   bx
        mov   bx,ax
        in    al,0x61
        test  al,3
        jnz   A99
        or    al,3
        out   0x61,al
        mov   al,0xb6
        out   0x43,al
A99:
        mov   al,bl
        out   0x42,al
        mov   al,bh
        out   0x42,al
Done1:
        ret

 ;----------------------------------------------------;
 ; NoSound                                            ;
 ;----------------------------------------------------;
NoSound:
        in    al,0x61
        and   al,11111100b
        out   0x61,al
        ret

 ;----------------------------------------------------;
 ; DeLay                                              ;
 ;----------------------------------------------------;
DeLay:                   
        mov   cx,[ms1]
        jcxz  A2                
A1:
        call  DeLaYoneMS
        loop  A1                
A2:
        ret   
 ;----------------------------------------------------;
 ; DeLaYoneMS                                         ;
 ;----------------------------------------------------;
DeLaYoneMS:            
        push  ecx                                    
        mov   cx,[OneMS]                
B1:
        loop  B1               
        pop   ecx                
        ret
                                   
OneMS    dw      40000
Hz       dw      0
ms1      dw      20
W        dw      0