Brasstacks

Hans Hübner has been at it again, and has developed code to allow a  Teensy AVR development board to adapt a Symbolics keyboard to USB . I ordered a Teensy board of my own, and was hoping to develop a small adapter to avoid cutting up my keyboard cable, but Teensy does not work with my old Mac OS X 10.4 system.

I wanted to post a link referring to recent progress on adapting Symbolics keyboards to modern PCs. Hans Hübner announced that the kbdbabel project (apparently based on 8051 microcontrollers) was able to be adapted to support the slim-line (Rev. C) Symbolics keyboard, adapting it to PS/2 protocol . My own work in this area ground to a halt pretty soon after I received the ADB adapter from DKS. I'm happy to see that others have been able to make progress! UPDATE: Rainer Joswig has commented on his experience using the kbdbabel adapter to connect a Symbolics keyboard to a Macbook running Mac OS X . UPDATE 2: Hans has developed a USB adapter solution .

The ADB adapter has fulfilled its main purpose: providing an example of hardware which can speak to my Rev. C Symbolics keyboard. The apparent trick is that the clock pulses must be narrow, without being too rapid (i.e., a relatively low duty cycle.) A 10 microsecond long low pulse on /CLR, followed 30 microseconds after the beginning of that pulse by the clock going low for roughly 9 microseconds, continuing with a clock period of approximately 50 microseconds does the trick. The ADB adapter pauses somewhat between groups of 11 clock pulses, corresponding to the natural "section breaks" of the keyboard mapping; I don't know if that is strictly necessary. My first crude approximation, using bit-bashing for the PIC with timing loops resulted in Caps Lock and Mode Lock that felt a bit sluggish---needing to be held down relatively long to "lock" or "unlock." The overall cycle time may be important in that regard. In any event, I reconstructed the key...