KayPro II keyboard schematic?

dwight elvey dkelvey at hotmail.com
Fri Dec 14 22:30:36 CST 2007

> From: mcguire at neurotica.com
> On Dec 14, 2007, at 7:09 AM, Allison wrote:
>>> I recently bought a KayPro II keyboard. It contains a nice
>>> Keytronics
>>> mechanical keyboard and really nice case. I'd like to convert it
>>> to a
>>> parallel ASCII keyboard or just reuse its case but was wondering
>>> if anyone
>>> had the schematics?
>>> Please let me know if you have the KapPro II keyboard schematics.
>>> Thanks!
>> It has an 8048 uP if memory serves and the output is TTL level serial
>> ASCII. Making it put out parallel would be a major hackup including
>> reprogramming an 8748.

 I have a parallel keyboard that runs from a 8035 ( romless 8048 ).
It has a clever way of generating the parallel output that would require
little circuit modification. He'd either have to get a 8035 and EPROM or
a 8748 as you suggested.
 What they do is run the wires for the keyboard data as the same
signal lines as used to strobe the keyboard. While scanning the keyboard,
there is junk on the parallel output. Once a key is struck, it outputs
the ascii from a table, along with the parallel strobe.
 This is a clever way to do two different things with the same I/O
 The Keyboard I got was missing a few key codes that I needed for
my computer. Luckily, the ascii lookup tables were easy to spot in
a dump of the ROM. I just modified these and replaced the ROM with
an EPROM and my new tables.

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