C=Key testing

From: Jim Brain (brain_at_jbrain.com)
Date: 2004-09-22 08:47:04

Taking a break from the IEC interface, I started on the Commodore 
Keyboard interface again.

Before I put the project on the shelf, the HW would interface a 
Commodroe 64 keyboard to a PS/2 or AT keyboard port, and could be 
configured from the keyboard for either literal or functional mappings 
(functional being used with VICE, for example).  Code cleanup is all 
that remains on that interface path.

However, I wanted to also provide PS/2 keyboard to 64/128 interfacing.  
I started work on that this week.  So far, the PC keyboard protocol is 
done, and works in both directions.

My design goal is to remove the "crosspoint" switch from the project. 

The idea is to watch the ROW and COL pins and when any go low, place the 
corresponding lows on the other half corresponding to which keys are 
pressed at that time.

I've pertially implemented it, and (notwithstanding that the Mapping the 
64 book seems wrong when it states WRITE to PORTA and READ from PORTB), 
it is working...

However, if you hold a key down, the repeat is erratic.  As well, if you 
just press and release a key, often I get doubled or tripled chars.

So, my questions:

Anyone have any experience in keyboard scanning routines on the 64?
Anyone with a DSO or logic analyzer who wants to help test?


Jim Brain, Brain Innovations
brain@jbrain.com                                http://www.jbrain.com
Dabbling in WWW, Embedded Systems, Old CBM computers, and Good Times!

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