Code:

function HexToBin(Hexadecimal: string): string;

const

BCD: array [0..15] ofstring =

('0000', '0001', '0010', '0011', '0100', '0101', '0110', '0111',

'1000', '1001', '1010', '1011', '1100', '1101', '1110', '1111');

var

i: integer;

begin

for i := Length(Hexadecimal) downto1do

Result := BCD[StrToInt('$' + Hexadecimal[i])] + Result;

end;

procedure TForm1.Button1Click(Sender: TObject);

begin

ShowMessage(HexToBin('FFA1'));

// Returns 1111111110100001

end;