I'd like to control a few input pins (say 5) and a few output pins (at least 2) from a computer. The computer has no parallel port. What is the best way to do this? USB-to-parallel adapter (anybody have one to recommend which works on Linux)? Or perhaps there is some other general purpose USB "control board" where I can use read input from some pins and write output to others? I don't even know what to google for, so any pointers are appreciated!
If you have US$108 to spare, this "Affordable Multifunction DAQ with USB" (http://labjack.com/u3), by LabJack, may solve your problems . Perhaps overkill for what you want (16 I/O pins) but it works with Linux, and it's programmable from all the major languages.
In general, if you search for
linux daq usb you will find plenty of options.
It is very easy to make your own using a microcontroller like an Arduino or mbed. The microcontroller will appear as a virtual serial port when plugged in with USB, and you can send it commands. On the microcontroller side, write a small program that interprets the commands and changes output of the pins or returns an input. This may not provide timing as good as a "real" DAQ box, but if you don't need that kind of quality, it can be an affordable solution.