11 Aug
2013
11 Aug
'13
9:34 a.m.
On Sun, 11 Aug 2013, Chuck Guzis wrote:
On 08/11/2013 07:45 AM, Steven Hirsch wrote:
That makes sense. I assume that once it has located a track the data
stream is somewhat conventional in order for the WD chip to digest it.
It does not seem like I'll be able to find
media for this gadget, so
I've move to Plan B: Reverse engineer the 5 existing diskettes I have.
Since the originals are read with a WD FDC chip, I thought this would be
a matter of letting ImageDisk have at it to determine the format.
Unfortunately, IMD cannot make heads or tails out of what's on the
diskettes. They do seem like they have 80-tracks, probably at 500KB/sec
data rate - at least that's what IMD tends to converge on in between
cascades of low-level data errors. Even at full analysis setting it's
not able to decide what it's looking at.
These diskettes read fine when I connect the unit to an Apple 2, so
whatever is on them is intact. Anyone have an idea how to decipher it?
I have a suspicion that they deliberately offset the tracks from a
"normal" position. At one point there was a special fluid available to
reveal magnetic domains under a magnifier, but this seems exotic and not
something I would know where to obtain.
I've never had to read an Amlyn magazine, but if I read the patent (4453188),
the code (yes, they included 8080 assembly and PL/M source code) states
pretty clearly that servo tracks are used.
So there you go--the drive and its electronics appear to be sui generis. CHM claims to have an OEM manual for the thing.
Yes, unfortunately there is no information on how one gains access to
items in their archives. I've dropped them a note in the hopes that a
scan or copy is available.
Steve
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