The problem with that is that the ATmega is still too powerful for my needs.
I guess my question is: Could suggest a microcontroller that isn’t as powerful, but still able to communicate with a computer? All it needs is to be able to read a momentary high-low.
This can still be done using Windows XP as far as I know, but you will need to find a .DLL (INPOUT.DLL ?) file that allows easy hardware port access. It will also probably take ages to get working.
Using the Arduino or a clone , this will take about 5 minutes to get working and cost less than 25 Euros. How valuable is your time? This seems like a bargain to me.
I am missing a serial/game/parallel port on the computer, so the IO programming wouldn’t work out.
At this point you need something USB based.
You can do it easily enough with a USB → Parallel converter, and read your bit directly from the now present Parallel port.
The cost of one of these, is generally the same as the Arduino, which is why you are going to get that back as an answer over and over again.
Besides… With a little time and creativity a single bit can be made fairly illustrious.
Blink an LED with the bit, or Count bits over time and change blinking rate of Pin13 Led in respect to count, mount a servo behind a picture of a speedometer and position from 0 to 100mph based on rate of bit changes… live it up man!
The problem here is that we are all geared up to think Arduino on the forum after all that’s what it is.
I assume your computer has a serial port. If so then just read one of the control lines on the serial port, say the RTS or the DTR. There are windose commands to do that. So no processor needed at all.