Clive: yep, no such thing on this 12+ years pc, has a built in parallel port, windows 7 32 bits, no aero theme or screensaver. I don.t know what are the bios things which I don.t need.

John: ok, got the point a light and a sensor which acts like a switch and this one does not work fast enough. Now changing the drivers (wantai) is not possible, and buying others costs a bit.
Changing or upgrading the optoisolator in drivers or bob is I guess problematic. Like chancing the tiny chip on a pcb, is doable, and I have some tools for that, but not the skills just yet.
I can buy another Bob, if it helps. Should I, and if yes, which one?