CompuPro floppy controller differences - test-drb@ccmp.vtda.org

9 Sep 2006

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Subject: Re: CompuPro floppy controller differences
   From: "Dave Dunfield" <dave06a at dunfield.com>
   Date: Sat, 09 Sep 2006 08:39:24 -0500
     To: "General Discussion: On-Topic and Off-Topic Posts"	<cctalk at
classiccmp.org>

  You missed one item, different eprom and
contents.  The differences there
 include boot code for 8088 and in very late 1A version 68000. They are 
 essentially the same, though of the two the latter 1a is prefered.   
Yeah, I ment to mention that ... And hand-in-hand with it, the boot option
switch settings on the 1 are different than the 1A (no 8086 modes for
example). 
The 8086 mode is only a preset to a block of eprom for booting, same for 
others.

...
 Q: Are the controllers similar enough that the boot
code from the 1A will
work in the 1 - ie: If Rich wanted to run an 8088/86 CPU could he put
the boot code from the !A into the 1 and boot the system? (He might have
to put in just the mode he wants in an accessable "slot" in the 1A ROM
space) 
Yes, the basic control floppy registers and addresses are identical. 
The DMA also behaves the same.  However it means burning a new eprom 
as the 1A used a larger prom.

NOTE: the caveat is the booter also knows what size floppy is used 
(8 or 5.25) as well as what CPU in the case of the 1A there are 16
different possible S1 settings for booter.  The late 1As could 
boot 8085/88 card,  z80, 8086, 80286, 68000, 32016.

Allison