CompuPro floppy controller differences

[Allison]

>
>Subject: Re: CompuPro floppy controller differences
>   From: "Dave Dunfield" <dave06a at dunfield.com>
>   Date: Fri, 08 Sep 2006 22:35:38 -0500
>     To: <cctalk at classiccmp.org>
>
>>             Is there any practical difference between the CompuPro Disk 1
>> and Disk 1A that would prevent a 1A disk from working on a 1? I have a line
>> on a Disk 1 controller but only have access to 1A disks from Dave Dunfield.
>
>I have a Disk-1A up and running in my Compupro box - unfortunately I do not
>have a Disk-1 to test with. I do however have manuals for both controllers.
>
>>From what I can tell on a cursory readthrough - the Disk-1 and the Disk-1A
>are very similar, but not identical:
>
> - The Disk-1A appears to have some functions available in the write side
>   of some registers which were read-only on the Disk-1 - these seem to
>   control features that had to be set by switches or board modifications on
>   the Disk-1.
>
>- The Disk-1 has a bit-bang serial port which has been dropped on the 1A.
>
>- The difference is NOT the difference between a 765 and a 765A - both
>  manuals list the 765A as the NEC FDC.
>
>- The 765 and motor control registers appear to be in the same place on
>  both controllers.
>
>I have a set of original Cromemco CP/M diskettes, and the labels do NOT
>mention anything about a specific floppy controller board - my guess is that
>the disks would boot and run on either controller. (But as noted above, I
>cannot confirm this, so it is just a guess).
>
>Dave

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.  



Allison