[Coco] Prototype/Breakout Board

[Darren A]

On Mon, Mar 26, 2012 at 9:17 AM, John W. Linville wrote:
>
> Someone did a project not too long ago that had an external CPU
> (maybe a Propeller?) driving the CoCo's video circuits and such.
> So, It seems like the address lines need to be bidirectional if you
> want something like that to work.
>

Unfortunately, the 6x09's Bus Available signal is not brought out to
the cartridge port.  With the available signals, you should only
change direction of the address lines to input after HALT goes low and
remains low for the number of cycles in the longest instruction (could
be up to 44 cycles when using a 6309).

Probably not worthwhile for a general prototyping board.

Darren