procedure Sound(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 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 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;