[Coco] Copying zip file from the sdc card

[Gene Heskett]

On Friday 24 April 2020 18:20:22 L. Curtis Boyle wrote:

> > On Apr 24, 2020, at 4:17 PM, Gene Heskett <gheskett at shentel.net>
> > wrote:
> >
> > But since the sc6551 is AFAIAC a broken chip, we really ought to be
> > designing a better rs232 pack.  Bruce Istead had the right idea with
> > his DACIA, but its a rare bird I've never seen. Could Bruce be
> > talked into another run of those?
>
>    Unfortunately, I think the 6552 chip itself is rare, and not cheap.
> Once we have fully working 16550 drivers, I think that will be the way
> to go.

Unforch the 16550 needs a block of 16 addresses for all its control 
registers. We simply don't have that many free addresses in the coco's 
i/o space. We might be able to multiplex it down to 6 but thats still 
too wide for the conventional 4 byte wide block the coco is designed to 
use. Only if someone rips out the existing decoders and designs a hack 
to make everything from $FF00 to $FF7F into a proper 4 byte wide cs 
scheme, will that ever get fixed. We could then fit 7 more cards into 
the space between the pia's, and another 7 into the space between pia2 
and the floppy at $FF40. But I've been preaching to an empty cornfield 
on that subject for 30+ years now.  Sigh.  And it wasn't the 6552 I was 
thinking of, ISTR there is a candidate in the 68xx area we could use. 

Cheers, Gene Heskett
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