Code:

procedure Sound(Freq : Word);

var B : Byte;

begin

if Freq > 18then

begin

Freq := Word(1193181div LongInt(Freq));

B := Byte(GetPort($61));

if (B and3) = 0then

begin

SetPort($61, Word(B or3));

SetPort($43, $B6);

end;

SetPort($42, Freq);

SetPort($42, Freq shr8);

end;

end;

procedure NoSound;

var Value: Word;

begin

Value := GetPort($61) and$FC;

SetPort($61, Value);

end;

procedure SetPort(address, Value:Word);

var bValue: byte;

begin

bValue := trunc(Value and255);

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;