3.5" Altair CP/M - test-drb@ccmp.vtda.org

16 May 2007

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Subject: Re: 3.5" Altair CP/M
   From: Grant Stockly <grant at stockly.com>
   Date: Tue, 15 May 2007 17:09:37 -0800
     To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at
classiccmp.org>

At 04:45 PM 5/15/2007, you wrote:
 On 5/15/07, Grant Stockly <grant at
stockly.com> wrote:
 I have a tarbell floppy controller card that has
been rewired to access
3.5" disks using a standard PC 3.5" disk drive.  I have 3 disks that the
Altair can boot off of and read, but my windows computer can't do anything
with them.  I've tried rawread.exe and diskinfo.exe and they both choke on
the disk.  I assumed that if a disk could be written with the standard 3.5"
disk drive on the tarbell card then it should also be read on the same
drive connected to a modern IBM compatible. 
Are you using a 1771 based SD Tarbell card, or a 1791/1793 based DD
Tarbell card?  That might make a difference. 
Its an MDL-1011D with an FD1771-B01.

What's the deal with this chip?  Is it formatting the the disk as 360k? 
the 1771 is single density only and yes.

Also if the format program used didn't fully format the disk with all 
the marks (often done with 1771s) then it will be harder to read with a PC.

Allison