24 Jul
2006
24 Jul
'06
5 p.m.
I've got a rather ancient 8" diskette (hard-sectored; 32 sectors) with the
Harris Lanier brand on it. About all that I know is that it was created
during the 1970's and contains word processing documents.
It looks to be MFM with the usual n, 1.5n and 2n frequency distribution,
but I'm not getting much meaningful from digesting the bitstream.
Does anyone have any clues?
Cheers,
Chuck
25 Jul
25 Jul
2:02 a.m.
From: "Chuck Guzis" <cclist at sydex.com>
I've got a rather ancient 8" diskette
(hard-sectored; 32 sectors) with the
Harris Lanier brand on it.
It looks to be MFM with the usual n, 1.5n and 2n frequency distribution,
but I'm not getting much meaningful from digesting the bitstream.
Could it be a 6 or 7-bit character set ? I've seen some funny things,
especially in word processing. If the high order bit always is ON, you could
try to set it OFF. If you mail me a few K, I could have a look at it
Nico
3:09 a.m.
Nico de Jong wrote:
From: "Chuck Guzis" <cclist at
sydex.com>
I got a 8" disk myself, it's a Verbatim brand, but I don't have a
reader
for it.
--
The real problem with C++ for kernel modules is: the language just sucks.
-- Linus Torvalds
I've got a rather ancient 8" diskette
(hard-sectored; 32 sectors) with the
Harris Lanier brand on it.
It looks to be MFM with the usual n, 1.5n and 2n frequency distribution,
but I'm not getting much meaningful from digesting the bitstream.
Could it be a 6 or 7-bit character set ? I've seen some funny things,
especially in word processing. If the high order bit always is ON, you could
try to set it OFF. If you mail me a few K, I could have a look at it
Nico
3:28 a.m.
On 7/25/2006 at 3:09 AM Segin wrote:
I got a 8" disk myself, it's a Verbatim brand,
but I don't have a reader
for it.
The way I do these is to use a Catweasel and my own code to grab the raw
pulse intervals, then write a decoder for what I see. Unfortunately, while
this looks a lot like MFM, it doesn't really seem to be that. The
histogram of the pulse data doesn't look like GCR either. If you take the
shortest clock period as n, FM usually shows as two peaks spaced at n and
2n; MFM, as 3 peaks spaced n 1.5n and 2n, and GCR several (usually 5) peaks
spaced at n.
Cheers,
Chuck
5:46 a.m.
Chuck Guzis wrote:
On 7/25/2006 at 3:09 AM Segin wrote:
I said reader? I meant drive. Hell, I don't even have a computer for
which a drive was ever made for one of those!
--
The real problem with C++ for kernel modules is: the language just sucks.
-- Linus Torvalds
I got a 8" disk myself, it's a Verbatim
brand, but I don't have a reader
for it.
The way I do these is to use a Catweasel and my own code to grab the raw
pulse intervals, then write a decoder for what I see. Unfortunately, while
this looks a lot like MFM, it doesn't really seem to be that. The
histogram of the pulse data doesn't look like GCR either. If you take the
shortest clock period as n, FM usually shows as two peaks spaced at n and
2n; MFM, as 3 peaks spaced n 1.5n and 2n, and GCR several (usually 5) peaks
spaced at n.
Cheers,
Chuck
2:50 p.m.
On 7/25/2006 at 5:46 AM Segin wrote:
I said reader? I meant drive. Hell, I don't even
have a computer for
which a drive was ever made for one of those!
Fortunately, 8" drives aren't yet hard to come by. And hooking one up to a
PC floppy controller (or a Catweasel) isn't difficult either.
FWIW, if anyone wants to take a stab at solving this puzzle, I've got a
catweasel dump of a representative track that I can make available for
download.
CHeers,
Chuck
6:27 p.m.
> I've got a rather ancient 8" diskette
(hard-sectored; 32 sectors) with the
> Harris Lanier brand on it.
> It looks to be MFM with the usual n, 1.5n and 2n frequency distribution,
> but I'm not getting much meaningful from digesting the bitstream.
On Tue, 25 Jul 2006, Nico de Jong wrote:
Could it be a 6 or 7-bit character set ? I've seen
some funny things,
especially in word processing. If the high order bit always is ON, you could
try to set it OFF. If you mail me a few K, I could have a look at it
. . . or inverted data (ala Superbrain),
or EBCDIC (ala some Seikos),
or compressed or encrypted?
6:41 p.m.
On 7/25/2006 at 3:27 PM Fred Cisin wrote:
. . . or inverted data (ala Superbrain),
or EBCDIC (ala some Seikos),
or compressed or encrypted?
No, on the first two and probably no (given the age of the disk) on the
last. My suspicion is that I'm not recovering the data correctly from the
Catweasel stream. And it's not 6-bit data (a la WPS I) as nearly as I can
tell.
Cheers,
Chuck
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cclist＠sydex.com -
cisin＠xenosoft.com -
nico＠farumdata.dk -
segin2005＠gmail.com