[Coco] Mechanical keyboard upgrades for the CoCo

[Mark J. Blair]

> On Aug 25, 2015, at 15:59 , Brian Blake <random.rodder at gmail.com> wrote:
> 
> And all of the above is why it makes sense to just use off the shelf key
> caps and use a CPLD to remap those keys that need to be done - that removes
> the cost of custom key caps.


I don't like the CPLD approach. I would expect weird things to happen. For example, if one was to perform the following sequence:

1) Press and hold the 2 key.
2) Press a shift key.
3) Release a shift key.
4) Release the 2 key.

On a regular CoCo keyboard, that's the exact sequence that would be seen by any keyboard polling routine. But with a PC layout being translated to the CoCo matrix, the sequence would necessarily look like this (with implementation-specific make/break ordering) as seen by the CoCo:

1) 2 key pressed
2) 2 key released, shift key pressed, @ key pressed
3) @ key released, shift key released, 2 key pressed
4) 2 key released

This might not cause any actual problems with existing software, but it's just not the thing that I want to make. I want a passive matrix, electrically identical to original CoCo keyboards, and using a layout very close to one of the original ones. Just constructed with better keyswitches. Basically, a new implementation of the old HJL-57 keyboard upgrades, since I can't order up a new HJL-57 from an ad in Rainbow Magazine any more.

I may or may not actually build the keyboard that I have in mind, but I certainly won't build a CPLD-based keyboard with PC-style mapping, nor will I build any sort of external keyboard interface (which exists as a product from Cloud 9 anyway, for anybody who wants one). If somebody else would like to build a CPLD-based keyboard, USB keyboard adapter, etc., then I think that's just great! There's plenty of room for folks to build all sorts of cool projects to get exactly what excites them, and I think it's wonderful that the CoCo still has such an involved community after 35 years.

-- 
Mark J. Blair, NF6X <nf6x at nf6x.net>
http://www.nf6x.net/