[Coco] [Color Computer] Ebay Auction #5188983755

[Arthur Flexser]

On Fri, 22 Apr 2005, j_e_daggett wrote:
> 
> All the Coco keyboards work  on the same premis. There is no need for
> "Key Mapping" to speak of hardwarewise. It is done in software.
> Depending on the version of RSBASIC, the depression of keys that have
> no scan codes are ignored or generate an error code. 

Actually, that's not quite true.  For example, the ALT key causes an "@" to
appear when you type it, and the F2 key gives "b", or "g", or something like
that.  This happens because in the ROM character lookup table, the 4 extra keys
fall "off the end" of the table, and into a few bytes of ML instructions that
follow it, so the character that appears is the translation of a byte of an
instruction.  I remember in developing ADOS-3 that I wanted to use F2 as a more
convenient exit from edit mode than shift-up arrow, but there was the problem
that F2 generated this spurious character because there was a JSR instruction
at this character's spot in the lookup table.  I was able to solve the problem
easily because, by good luck, the equivalent LBSR instruction, which I patched
in, did not give a printable character.

Art