non-PC Floppy imaging

Paul Berger phb.hfx at
Fri Jan 5 15:38:51 CST 2018

On 2018-01-05 4:08 PM, Josh Dersch via cctalk wrote:
> On Fri, Jan 5, 2018 at 11:52 AM, Guy Sotomayor via cctalk <
> cctalk at> wrote:
>> Hi,
>> I now have a number of uCode diskettes for my IBM 4331.  I would somehow
>> like to image them so:
>> a) I have backups in case the floppies themselves go bad
>> b) be able to investigate their contents in case I have to “merge” the
>> contents of multiple floppies to
>>       make a single good one
>> These are all 8” diskettes.
>> The complicating factors in all of this are:
>> a) any text (e.g. strings) are going to be in EBCDIC rather than ASCII
>> b) each uCode diskette was presumably serialized to the CPU it was for
>> c) not sure what the “on-disk” structure looks like
>> d) the only 8” diskette drives that I have are in IBM (non-PC) equipment
>> Any ideas/comments would be welcome.
> As far as backing up the floppies, I used ImageDisk with an 8" Shugart 850
> hooked up to a PC to image and duplicate the microcode floppies for the
> 43xx machines we have at the museum.  It works quite well.  Obviously this
> would require you to pick up a "new" 8" drive (I've no experience with IBM
> 8" drives, but I wager they're not going to "just work" with a PC FDC.)
> The IMD tools come with an image viewer that can translate EBCDIC, though
> you'll probably want something more advanced to actually modify/splice
> things.
> - Josh
>> Thanks.
>> TTFN - Guy
the IBM manufactured 8" drives are not going to work on a PC the signals 
on the interfaces are quite different and there is no track zero signal, 
in IBM systems when they initialized they did enough down steps to  
ensure head was at track zero.  Anyone that has heard a 33FD drive seek 
zero will remember the sound that they made when the carriage hammered 
on the down stop, the problem was the stop would break off and the 
carriage would go below track zero.  There where some 8" drive 
assemblies manufactured for AS/400 that do use drives with and "industry 
standard" interface I recently saw an external one for sale on eBay.


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