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CharlesM
July 9th, 2017, 03:07 PM
Recently picked up this monster of a keyboard. It's an enhanced version of the standard KB3720 and is XT/AT compatible. Here's the EPROM dump, it's a 27C64 with a label marked "55524".

https://www.dropbox.com/s/ba8grw8bqeuo7jo/55524.zip?dl=0

The 8051 doesn't use any internal ROM and runs from the EPROM exclusively. There's a great page with resources KB3270 Plus owners too:

http://www.seasip.info/VintagePC/kb3270.html

The keyboard uses an Exar 22-00958-000 (40-pin DIP) capacitive sensing chip to determine keypresses. The 8051 reads data from this chip over a serial interface (bit-banged, not UART) before doing the scancode translation and finally outputting data to a XT or AT PC.

The PCB layout has strong similarities to the Apple Lisa keyboard which was also developed by Key Tronic using an earlier implementation of the same technology. Since it's capacitive you can actually type directly on the PCB without the keys present. :) All the parts had 1997 date codes which was surprising given how old this keyboard looks.

modem7
July 12th, 2017, 11:46 PM
Welcome to these forums.


Here's the EPROM dump, it's a 27C64 with a label marked "55524".
Thank you.
I have added the dump to [here (http://minuszerodegrees.net/rom/rom.htm)].