17 Jul
2009
17 Jul
'09
3:48 p.m.
On 17 Jul 2009 at 21:56, Tony Duell wrote:
I have a schematics book for it (about the only manual
I do have), but
I think it only covers the 'main' unit. I don't think I have any info
on the disk controller board in the disk drive unit (and from what I
remember when I looked inside, it's not simple, there was certainly a
processor (Z80?) in there).
I can't help you much. About all I recall is that I received a
package of 8" HS diskettes from a defense contractor technical guy
who said he was told that they contained "source code" for some
project he was very interested in. He didn't know what kind of
source code, nor the system involved in producing it--he had only the
project contract information--and he wasn't at liberty to disclose
that.
Fortunately, GCR has a very distinctive pattern when flux changes are
plotted on a histogram. It helped that the disk was hard-sectored,
as I could pretty much depend on some sort of sector ID at the
beginning of each sector, probably also containing a track number.
As this turned out to be a simple 5-to-4 group code, after I'd
figured out what the sector headers were, I had most of the puzzle
and was getting some ASCII data out of the raw bit-crunching.
One of the first strings was "FUTURE DATA" and that rang a distant
bell.
About all I have to add is that the customer was fairly happy with
what he got--however, one disk went missing over the years and the
source code with it, so the project wasn't a complete success. I did
retrieve some Intel-format HEX binaries, so he could at least fill in
the gaps with some reverse assembly and go on to develop whatever new
weapon of mass destruction he was bent on creating.
--Chuck