Re: PC-keyboard but using original C64/C128/CBM-keyboard as base

From: Jim Brain (
Date: 2004-06-29 00:29:44

Baltissen, GJPAA (Ruud) wrote:

>Hallo Jim,
>>My schematic for the atmel is a 1 chip solution.
>Just read in comp.sys.cbm that you already had something running on a
>ATMEGA32. Being so far I'll try to find one for myself as well and see how I
>can help.
No problem.

The work last week was truly a hack, but I cleaned it up a bit over the 

The PS2/AT protocol is nice and clean, uses interrupts to deal with the 
protocol and has a buffer for characters
I am working on the 64 keyboard decoder.  It's mostly working now, but 
got some sort of bug in handling the
shift lock key...  Still tracking down.  The matrix decoder can handle 
keyboard matrices up to 16x8, and signals
key down and key up states for all 128 keys. 

I'm still thinking about how to handle mapping the matrix to PS2 
scancodes, as it's not trivial.  Most are straightforward, most 
unshifted keys, (except +,*,^,@) are easy.  The 4 there need to have 
shift added.  Shifted keys are a bother, as they do not match up all the 
time.  SHIFT DOWN is just a single key on the PC.

I think I'm going to store an array with 2 bytes for each scan code.  
The first byte will tell what meta keys to hold down, if any.  Maybe one 
meta flag will say, this is a sequence of bytes, here is the index...  I 


Jim Brain, Brain Innovations                      
Dabbling in WWW, Embedded Systems, Old CBM computers, and Good Times!

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