[Coco] MPI

[Chester A Patterson]

I have a Burke & Burke Hard Drive setup (slot 3) and FDC (slot 4) set up
to boot OS9 from the 20MB HD (MPI slot select switch set to slot 3) Upon
booting, never has there been a problem accessing the floppies - even
though the MPI slot select switch allways remained set to slot 3. I also
could set the MPI to slot 4, boot up OS9 from floppy, with the
appropriate B&B driver/descriptor, and access the hard disk, without
switching the MPI. The Floppy controller is a Disto mini.

Seeking modernization and space, recently I made some software (switch
to NOS9) and hardware (C9 SuperIDE/CF) changes. Truly wonderful
products.

Boot up NOS9 (MPI set to slot 3) but no floppy access. Push switch to
slot 4 (while system running) and then floppies OK, as well as IDE
access no problem. I never had seen this behavior before. Have gone back
and forth with it with Mr. Marlette a little bit (I'm no techie, that's
for certain) he explains that the FDC decodes with CTS. This is most
sensible.

So the current behavior with the new hardware makes sense (it just came
as a bit of a surprise) and the behavior I have taken for granted all
these years does NOT now make sense.

So either OS9 or the Burke and Burke software play with the CTS to get
to the appropriate slot as required. Does this make sense? Comments?
Thanks.