Thursday, June 17, 2010

How to convert your old-style Symbolics keyboard to USB

Peter got in touch with me because he tried to follow my instructions how to convert a Symbolics keyboard to USB with his old-style keyboard and he failed. He assumed, and that was what I would have assumed, that the color coding of the internal cabling of the old and new keyboards would match, but they don't. Here is a table that shows the pinout for both keyboard types:

New Style Old Style Function Teensy
Pin# Color Pin# Color
1 blue 8 white GND GND
2 yellow black not connected
3 green 2 red 5V 5V
4 red 3 green DIN D4
5 black 1 yellow CLK D5
6 white 5 blue CLR D6


  1. thanks, works like a charm! i also connected pin 7 to pin 9 (that's what the original connector has).
    do you also have suggestions as to how to setup Xorg/OpenGenera (VLM?) so that the keyboard works well with the emulated lisp machine?
    thanks for publishing this!

  2. I have tried to make the mapping work well with the default mapping of the VLM. The complete mapping can be displayed in Genera with "Show X Keyboard Mapping". It can probably be improved, but I think one needs to modify the mapping code in Genera for that. I left that for someone else to do :)

    Keep us posted if you improve on anything.

  3. Thanks very much for this. (I found out about this from the thread on Deskthority a couple weeks back.)

    I found the firmware didn't work on the Teensy 2.0 I bought, apparently because the chip is not right. I fixed that in the Makefile, and couldn't build because usb_keyboard.c didn't seem to match the headers. But the new version works.

    I need to put some finishing touches on it, but this was great. Thanks for doing this!