Disc Imaging / Kryoflux - Acorn ADFS 800KB

Austin Pass austinpass at gmail.com
Sat Jul 2 13:50:16 CDT 2016

Thanks for the feedback Fred.

The Kryoflux Forums are admin-approval-only and I've been waiting a couple
of days for that to happen.

To the best of my own knowledge it's a pretty standard MFM, as the
computers featured the Western Digital 1770 and 1772 controllers.

The specific discs I'm trying to image are 800KB "double density" designed
for the 32 bit ARM based computers.  I can't find any 720KB PC floppies,
but I'll follow the methodology with 1.44MB HD ones to see where it takes


On Sat, Jul 2, 2016 at 3:31 AM, Fred Cisin <cisin at xenosoft.com> wrote:

> On Fri, 1 Jul 2016, Austin Pass wrote:
>> I'm trying to preserve my Acorn ADFS 3.5" discs. To this end, I've
>> purchased a KryoFlux "Pro" board and a new-old-stock ALPS floppy drive.
>> I've hooked it all up to a Windows 8.1 VM and everything *seems* to be
>> working.  However, the .adl images I create are all 0KB in size.
>> I've created a profile to match the discs I'm reading (256byte sector
>> size, tracks 0-79, MFM encoding, interleaved sides).
>> Recording the flux transitions captures data, but when I run the
>> resultant data back through DTC I get the same.
>> Any ideas?
> "everything *seems* to be working"
> Have you tried using the drive without the Kryoflex?
> Have you confirmed that your kryoflex setup is working with anything that
> it is KNOWN to work with?
> I think that Acorn is a "normal" IBM/WD style MFM, but I'm not sure.
> So, the first step is to determine whether the Kryoflex is not working
> right, or whether it is a problem with Acorn format.
> Therefore, make some .adl files from 720K PC-DOS floppies.
> If THAT process fails, then go to the Kryoflex forums with THAT problem,
> since it removes all variable other than your computer, your drive, and
> your Kryoflex.
> If that works, then lets look at other potential problems with the Acorn
> compatability with it.
> For example, if the Acorn was using a WD controller chip, there is a
> possibility that it started writing soon enough after index that the system
> isn't ready.
> Do you know the physical format that your Acorn disks are using?
> Can you read sectors from them with stock PC hardware? (INT13h; if sector
> size other than 512 bytes, then INT1Eh also)
> What capacity are they?
> Do you know for sure that the recording on these disks are intact?
> --
> Grumpy Ol' Fred                 cisin at xenosoft.com

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