As per an earlier post, I’ve got an old PS/2 keyboard which I’ve just taken apart and removed the circuitboard. There’s not a lot to it as you can see below but the interesting bit is the small parallel rows of pots in the bottom right hand corner. Keyboards use a matrix with the rows and columns made up of wires. Each key acts like a switch so that when a key is pressed, a column wire makes contact with a row wire and completes a circuit. The keyboard controller detects this closed circuit and registers it as a key press. You can get a fuller explanation here. So, back to the pots. On the other side of the board is a ribbon cable connector which the matrix connects to and those pots are where the connector connects to the circuit on the board. After connecting it to my mac with the PS/2-USB adaptor and running up TextEdit I generated a key press by shortening-out 2 pots. I also ran it thru’ the hi patch we messed about with the other week and got some figures from it as well. I’ve just bought a tilt switch which, once my soldering iron is recharged (this sounds a bit bloody familar), I’m gonna stick on the end of a coupla wires and have a muck about with.

Photo of a circuitboard from a PS/2 keyboard

Photo of a circuitboard from a PS/2 keyboard connected to a PS/2-USB adaptor

One Comment on “Keyboard”

  1. In case this is the route you want to go down, I have emailed you some flash source for particle collision (not opensource, but you can work back through it to see how it works.) I also have a reference to a good tutorial on the subject here:

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