[Coco] Recreating the CoCo keyboard

[Ciaran Anscomb]

Allen Huffman wrote:
> On Oct 21, 2020, at 3:33 AM, Ciaran Anscomb <cocomalt at 6809.org.uk>
> wrote: > > As an example, I think it's nigh on impossible to play
> (unpatched) > Donut Dilemma under emulation on some PC keyboards.
> 
> I wasn’t aware of this. What is the cause?

Just checked...  the key combo to "throw dough" is holding both up and
down, then one of left or right.  PC keyboards can probably quite rightly
assume users won't usually be pressing up and down at the same time.
On this laptop I can throw dough right, but not left :)

> How does the keyboard scan work? Does it allow up to 8 keys if they are
> all on the same column or row?

Yeah that would probably work fine...

Basically if you look at any schematic of the keyboard matrix, if you
hold down keys to form three corners of a rectangle, the other corner
will also be recognised, if scanned for.  Try holding down Shift+/ then
repeatedly hitting Clear.  BASIC will recognise you as pressing ')'
(because shift is down).

And if you want a little Perl tool to verify your selected key
combinations, check out "conflict.pl" linked from here:

http://www.6809.org.uk/dev/dunjunz/#beta-1

..ciaran