What you're talking about, is writing a device driver of some kind. It
seems like this would be easiest if you worked with a device that people
have written a lot of drivers for, like a mouse. Then you could smash
open the mouse and re-wire it somehow to your electronic wonder-gizmo.
Your program would only be able to use the (X,Y) and pushbutton data of a
"regular mouse," but at least you wouldn't have to write any drivers or
anything.
You could do something similar with a joystick controller.
Or if you want to get into the nitty gritty, you could buy a serial
cable, and get some docs on what the pin-in's and pin-out's mean. The
docs for this sort of thing are freely available on the net, and I'm
sure you could find source code examples for either DOS or Linux. The
Linux OS sources are freely available, and it has an awful lot of
drivers in it. Plus there are FAQ's about this sort of thing in the
various newsgroups. Then you could apply whatever electronics wizardry
you have, to make your own device.
You could use a parallel cable instead, if that's more to your liking.
Or even a SCSI interface, I suppose, if you have one of those.
Unfortunately, all of this is going to take buckets of time if you don't
know what you're doing already. Personally, I'd go with the "rip open
a mouse" approach, because you'd have to invent the least amount of
stuff for it.
If your computer has a Digital Signal Processing chip in it somewhere, then
maybe that's more what you need. But that's a whole 'nother ball 'o' wax
that I know nothing about. Try inquiring in comp.dsp.
You might try looking in the following newsgroups:
comp.robotics
comp.dsp
comp.os.linux.hardware
comp.sys.ibm.pc.hardware.misc
comp.os.msdos.programmer
comp.os.ms-windows.programmer.drivers
comp.sys.mac.programmer.misc
comp.periphs
comp.periphs.scsi
comp.periphs.printers
These were taken from a 6-month old list of newsgroups, so some names may
have changed. You will have to do some digging. :-)
Cheers,
Brandon