[Coco] 6 Chip ^809 Computer -> Kipper SBC

[Gene Heskett]

On Sunday 15 March 2015 01:37:17 RETRO Innovations wrote:
> On 3/14/2015 8:14 AM, Gene Heskett wrote:
> > Jim, this exactly the thinking that resulted in the coco shipping
> > with an address decoder that only decoded in slices $20 wide.  So
> > the on-board I/O used up $40 bytes when in fact it needed $08 bytes
> > to service the two PIA's.
>
> Which is why Tandy put the !SLENB signal on the bus.  By using it and
> a decoder, you can make the onboard PIAs only respond to $08 bytes of
> address space.
>
> Jim

And !SLENB was driven true low by an external decoder? Plz explain 
further as I never did fully understand that, and obviously it was 
poorly understood by everyone, else we would have had a plethora of i/o 
ports that were addressed at $FF04-$FF07 etc. It never happened that I 
am aware of.  If it is in fact that easy, I'd love to build it & play 
with it.

Cheers, Gene Heskett
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