[Coco] SuperIDE and floppy disk

[Gene Heskett]

On Thursday 09 May 2013 11:59:07 Retro Canada did opine:

> i am using 51 and not $51

Which translates to $33, or slot 4.  Exactly as if you had powered it up 
with the switch set to 4.

The problem with coco3's and MPI's in that the coco3 writes to the GIME's 
memory mapping registers in the $FF90-$FF9F block.  But the address decoder 
in the MPI is as usual for tandy, very very incomplete, and those writes 
also get decoded to the MPI's slot select logic at $FF7F.

The CoCo3 fix kits fix that, so a screen change on the coco3 doesn't muck 
with the MPI's slot select.

> but i have fdc (4), superide (3), orch90(2) and s/sc on (1)

Do you know for a fact that none of the above carts share an I/O address, 
which is normally done in in 4 byte wide pieces, the FDC being addressed 
at, depending on which register in the FDC chip is being addressed, $FF40 
to $FF43, and the drive control logic is at $FF48.  But because of the 
defective address decoding, the FDC registers also appear at $FF50-FF53, 
and the drive control logic at $FF58.  Because of this, no other pack can 
have an address below $FF60.  That leaves IF the packs are fully decoded, 
room for only 7 devices out of the whole menagerie of carts we actually 
have, many of which paid zero attention to staying within a 4 byte block 
for their address usage.  The WP-RS I have, had an unused gate in it that 
can be used to restrict it to one 4 byte wide block, but as OOTB, it uses 
the top two byte of the $FF64 block, and the bottom 2 bytes of the $FF68 
block.

I don't own a superide, or an orch90, and I haven't plugged in my s/sc in 
at least 15 years, so I have no idea where they are physically addressed.

So I think you can see that you are dealing with a minefield, and the first 
thing you'll need to do is make sure that kit is installed in your MPI, and 
then adjust the address decoding, and the driver software both, if there 
are any addressing clashes in your setup.  It sure sounds like there is 
from here.




Cheers, Gene
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
My web page: <http://coyoteden.dyndns-free.com:85/gene> is up!
My views 
<http://www.armchairpatriot.com/What%20Has%20America%20Become.shtml>
"Even more amazing was the realization that God has Internet access.  I
wonder if He has a full newsfeed?"
(By Matt Welsh)
A pen in the hand of this president is far more
dangerous than 200 million guns in the hands of
         law-abiding citizens.