17 Jan
2014
17 Jan
'14
6:06 p.m.
On Thu, Jan 16, 2014 at 10:21:04AM -0800, Fred Cisin wrote:
The intended PURPOSE of the archive is critical.
Is the intent storage, with recreation of working diskettes?
or use of the data on other systems?
or analysis and repair of damage?
What I currently plan to support is saving the raw transition data,
decoded sector data, and MFM clock and data bit stream. The first is
because it maintains the most information on the original disk and can be
reprocessed later if decoding has problem. The second is useful for extracting
contents (Linux loopback mounts/emulators that use straight sector data)
though may be limited due to insufficient information on how to interpret
the contents (RD53 thread, one of my drives has two cylinder 152). The last
format is used by the emulator.
If people have an actual use of other formats I can look into supporting them.
Basically, for SOME uses, including copy-protected
disks, it is necessary
to archive every flux transition, since such disks may rely on bits
between the sectors, sector sequence relative to index, and other
weirdnesses. For 5.25" "double density" ("360K" TYPE of
diskettes) that
is 6K - 9K per track
Currently I'm looking at MFM hard drives so the sizes/rates are different
though the issues similar.
The hardware would have no problem with floppies if I put the proper connector
on the PCB. I though that there were sufficient existing floppy projects.
From the discussions I am less clear if that is true.
I don't want to add any floppy support if its just going to split the
users between projects so neither are large enough to stay viable.