[Lester]

Hola, también puedes echarle un vistazo al siguiente código que hace sonar la bocina de la PC...

Código Delphi [-]
procedure SetPort(address, Value: Word) ;
var
   bValue: Byte;
begin
   bValue := trunc(Value and 255) ;
   asm
     mov dx, address
     mov al, bValue
     out dx, al
   end;
end;
function GetPort(address: Word): Word;
var
   bValue: Byte;
begin
   asm
     mov dx, address
     in al, dx
     mov bValue, al
   end;
   GetPort := bValue;
end;
procedure Sound(aFreq, aDelay: Integer) ;
   procedure DoSound(Freq: Word) ;
   var
     B: Byte;
   begin
     if Freq > 18 then
     begin
       Freq := Word(1193181 div Longint(Freq)) ;
       B := Byte(GetPort($61)) ;
       if (B and 3) = 0 then
       begin
         SetPort($61, Word(B or 3)) ;
         SetPort($43, $B6) ;
       end;
       SetPort($42, Freq) ;
       SetPort($42, Freq shr 8) ;
     end;
   end;
   procedure Delay(MSecs: Integer) ;
   var
     FirstTickCount: LongInt;
   begin
     FirstTickCount := GetTickCount;
     repeat
       Sleep(1) ;
       //or use Application.ProcessMessages instead of Sleep
     until ((GetTickCount - FirstTickCount) >= Longint(MSecs)) ;
   end;
begin
   if Win32Platform = VER_PLATFORM_WIN32_NT then
   begin
     Windows.Beep(aFreq, aDelay) ;
   end
   else
   begin
     DoSound(aFreq) ;
     Delay(aDelay) ;
   end;
end;
procedure NoSound;
var
   Value: Word;
begin
   if not (Win32Platform = VER_PLATFORM_WIN32_NT) then
   begin
     Value := GetPort($61) and $FC;
     SetPort($61, Value) ;
   end;
end;

Y bastaría jugar con el procedimiento SOUND(FREQ, ESPERA)

Código Delphi [-]
procedure TForm1.Button1Click(Sender: TObject);
begin
   Sound(500, 1000) ;
   Sound(700, 1000) ;
   Sound(900, 1000) ;
   NoSound;
end;

Salu2,