If you’re looking for a custom controller for a MAME cabinet build, CNC machine, or just want to control a robot build, you’re going to need to wire up some buttons. You could wire up a bunch of buttons to a microcontroller, but if you use an old computer keyboard the work is already done for you.
[Rupert] sent in a great tutorial on repurposing old keyboards. The build is very, very simple: just take a multimeter to each contact and measure the rows and columns for continuity. Once [Rupert] had the matrix codes for every button on the keyboard, he wired up a length of ribbon cable to the keyboard PCB. From there, a small breakout board provides all the connections that a MAME cabinet would need.
Opposed to a custom keyboard encoder like an I-PAC or a homebrew solution, [Rupert]’s build is very easy and can be built for only the dignity required to dumpster dive for a keyboard.