[Coco] Coco ProtoType Board
lamune at doki-doki.net
Sat Sep 2 10:37:33 EDT 2006
> 2) some form of flexible address decoding included along with buffering. It is still
> unclear as to whether just the Coco 3 I/O range be flexible or also the range from
> $C000 to $FFDF also be included.
I think the PLD would be nice, but overkill.
It really depends on how much granularity everyone wants. My guess is
that an 8 or 16 byte block would probably be sufficient. That could be
done with a 74x133, some inverters, and a jumper block to set the X
digit in $FFXY. The 13th input could be the E clock to gate the signal.
If more granularity is needed, a 74x85 or 74x688 could do. It would only
require 2 chips, and if you're going to use SMT they would be extremely
small. (though I'm oldschool and prefer through-hole on this)
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