Hi, ** Thanks a bunch. This is on a really old 486, so I am going to try and ** make do with the hardware already on the machine. Would I be better ** off using another existing port, such as a mouse port, com port, or ** even keyboard port for the timings? I need just 4 possible wires, ** plus a ground to make this work. You probably could get away with using the PP if you turn off all the buffers and set it in bog-standard bi-directional mode. You might have to manually tinker with the port registers, but that shouldn't be too painful with a datasheet or two. It would _have_ to be IRQ driven though because I assume the events would be triggered as positive pulses and the probability of a process picking one of these up in a loop of checking the PP status would be very low if it's a fast process event. The kernel time overhead might screw this over and you might miss laps :-) Personally, I think DOS might be better for this as once the program is running, the system is all yours. You can still use the DJGPP version of GNU C/C++ to compile any existing code you have. See http://www.delorie.com (I think). It works just as well once you've got past DOS :-) DOS also doesnt have as much overhead. I have done very similar things using embedded systems and operating systems generally just get in the way. IRQs are the key to timing sucess! It's still a pity that PCs don't have a 'geek-port' as standard like the old Acorn BBC computers. HTH Chris. -- To unsubscribe send e-mail to suse-linux-e-unsubscribe@suse.com For additional commands send e-mail to suse-linux-e-help@suse.com Also check the FAQ at http://www.suse.com/Support/Doku/FAQ/