[Coco] Mechanical keyboard upgrades for the CoCo

[Zippster]

Well, really the behavior could be pretty much whatever you want, especially if you take each switch in
on it’s own IO pin.  There’s more you can work with in a CPLD than strictly a bunch of logic gates.

But absolutely agree that everybody should build what they want to.  There’s not much reason to do it otherwise.

- Ed


> On Aug 25, 2015, at 7:59 PM, Mark J. Blair <nf6x at nf6x.net> wrote:
> 
> 
>> 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/
>