unit UPCSpeaker;

interface

procedure Sound(Frequency: word);
procedure NoSound;

implementation

procedure Sound; assembler;
asm
  mov al,  0b6H
  out 43H, al
  mov ax, Frequency
  out 42h,al
  ror ax,8
  out 42h,al
  in  al,  61H
  or  al,  03H
  out 61H, al
end;

procedure NoSound; assembler;
asm
  in    al,  61H
  and   al,  0fcH
  out   61H, al
end;

end.