9 Sep
2006
9 Sep
'06
4:52 a.m.
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>
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
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