In the old days of DOS and 16bit Windows, writing to ports (serial, printer, game, video and other ports) in your computer was easy; all you had to do was use the "port[]" command.
Delphi no longer supports the "port[]" command, so you may have to use assembly functions as follows:
function ReadPortB
( wPort : Word ) : Byte;
begin
asm
mov dx, wPort
in al, dx
mov result, al
end;
end;
procedure WritePortB
( wPort : Word; bValue : Byte );
begin
asm
mov dx, wPort
mov al, bValue
out dx, al
end;
end;
NOTE: Some operating systems, such as Windows NT, may not let you access ports directly as demonstrated above. In this case, you may have to depend on a third party library to gain proper access to internal ports.