[Coco] Mechanical keyboard upgrades for the CoCo

[Mark J. Blair]

> On Aug 25, 2015, at 22:03 , Dave Philipsen <dave at davebiz.com> wrote:
> 
> Remember that on a PC style keyboard the '2' key IS the '@' key.  Why would the scanning software have to believe that the '@' key was pressed when it KNOWS that only two keys have been pressed. What if you erase the '@' character from the keycap? Does the keyscan still see that the '@' key has been pressed?

I'm not sure what you're getting at there. I was under the impression that the main point of having a CPLD was to allow a PC-like key arrangement to be used on the CoCo. To input a "@" character on the CoCo, the CoCo needs to see the matrix position of the "@" key close, with the shift key's matrix position being open. If you wish to input that character on a smart keyboard with PC-style keycap markings, then the CPLD needs to produce that condition when the user enters a shifted "2" key. The CPLD might suppress sending the CoCo a shift closure until it sees what key the user presses next, since it doesn't yet know whether the following matrix closure should include a shift closure or not yet. That will break any software which is polling for shift key press. Or maybe the CPLD sends the shift closure, then opens the shift back up when it determines that it needs to send an unshifted "@" closure. That, conversely, makes the CoCo see spurious shift closures and opens that it wouldn't have seen with an original CoCo keyboard.

That might only break some small percentage of unusual programs, if anything, and the breakage can probably be worked around with some sort of kludge. But it's a moot point to me, because that's just not the product I'm interested in designing or having. If you want to make a smarter keyboard that lets you rearrange the punctuation characters, add macros and so forth, then by all means go for it! That's just not what I want to do for my own selfish desires, is all.

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