[Coco] Mechanical keyboard upgrades for the CoCo

[Dave Philipsen]

Well, look at it this way: The CoCo keyboard is a scanned matrix of rows and columns. Typically, the keyboard scan consists of setting a voltage on one of the rows (or columns) and then scanning the columns (or rows) to see if that voltage follows through which would indicate a switch closure (key pressed).  It doesn't matter what the layout is per se whether a CoCo or a PC style layout; the scanning software can still recognize which key (or keys) are being pressed at any particular time.  If the keyboard has 'smarts' it can emulate the correct row/column scanning for the target so that the CoCo is made to believe exactly what the programmer wants it to believe.  Now, it is true that some games and other programs use key presses that are not necessarily related to the character printed on the key but instead they are related to the key's position on the keyboard but there are also ways around that problem.  The cool thing about a CPLD (or FPGA) is that the keyboard can be created and made to work generally in the intended fashion.  Then, when complaints/suggestions come in the corrections/changes can be made in 'software' (or synthesis). 

Dave Philipsen

> On Aug 25, 2015, at 10:29 PM, Mark J. Blair <nf6x at nf6x.net> wrote:
> 
> 
>> On Aug 25, 2015, at 20:03, Salvador Garcia <ssalvadorgarcia at netscape.net> wrote:
>> 
>> 
>> I am not sure if I am following this thread. If I understood, the CPLD was going to be used t compensate the differences in keyboards of the CoCos 1, 2 and 3, not to map a PC layout to a CoCo layout. Am I misunderstanding something?
> 
> I believe that the CoCos all use the same scanning matrix, with the four additional keys found on the CoCo 3 simply filling the four empty scan matrix that are present in the CoCo 1. Even the original HJL-57 keyboards for the CoCo 1 included the four extra keys. So I don't see any need to perform any different mappings for the CoCo 1/2/3. The CoCo 3 has a slightly different physical arrangement of keys, but they're electrically the same except for the four added keys.
> 
> The CPLD was suggested for mapping from PC-like arrangements, if I'm not mistaken.
> 
> 
> -- 
> Mark J. Blair, NF6X <nf6x at nf6x.net>
> http://www.nf6x.net/
> 
> 
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