>>>As retirement approaches and I'm close to 10 years since I started writing some kind of autobiography (in an app I wrote in VFP!), I'm filling some gaps in my archives. Last year I got my hands on one of the last usable 5,25" floppy drives, and I'm lucky to have a rather new motherboard which accepts a floppy. Plugged it in and it works!
>>>
>>>However, it doesn't recognize all formats - only the 1.2M HD and the 360K. Which is about one third of my archive (a full shoebox). The remainder are the HDDD formatted floppies, 720K. It doesn't recognize them at all, says "insert a disk".
>>>
>>>Now theoretically I could lay my hands on some 20 year old box, but then I wonder what my options of bringing the contents from that to my current box would be? The NICs of the time were strictly BNC, the serial connection was pre-USB. Perhaps swapping some old IDE disk would work - may be worth a try.
>>>
>>>I tried doing this from Ubuntu (VM but then it was hosted in W7), from several VMs, including some minimal ones running FreeDos and such, no dice. Perhaps now that I'm running Ubuntu as host (and others as VMs), it may allow it, which I doubt - back then I booted into that from a flash drive, same result. I'd rather like to know if there may be some option to make my current hardware allow for that format, i.e. bypass the current BIOS limitation.
>>
>>Could it be related to a missing media descriptor byte? https://support.microsoft.com/en-us/help/140060/floppy-disk-is-not-accessible,-not-formatted,-or-not-recognized-by-windows
>>If so, then MS-DOS or Win95 may be able to read it. Or, you may be able to write it with a disk tool.
>
>This is even older than that. I've found twenty pages with the lists of media descriptor byte values, and none of them remember this format. It was removed some time later, and if I didn't have these 30-40 disks formatted so, I would have sworn the format never existed :).

Check this: http://thestarman.pcministry.com/asm/mbr/DOS50FDB.htm#BPB
Apparently the media descriptor byte is F9 for both 720K and 1200K (ambiguity which forced the 720K out of standard), but the number of sectors per track is different. I wonder what would happen if you could change both offset 15 (MDB) value to F9, and offset 18-19 (SPT) to 0900. Obviously, if you can't even access the disk, this is a moot point.
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