2 Feb
2001
2 Feb
'01
2:49 p.m.
Hey, Tony!
I've got lots of Shugart doc's, but the 85x are conspicuously missing. If
you have a scan of this document set, I'd certainly like to add it to my
collection. This stuff, once scanned and cleaned up, will be put on a web
site, ostensibly databooks.org, that's still being set up.
Can you help out here?
regards,
Dick
----- Original Message -----
From: "Tony Duell" <ard(a)p850ug1.demon.co.uk>
To: <classiccmp(a)classiccmp.org>
Sent: Friday, February 02, 2001 11:47 AM
Subject: Re: Shugart SA850/851 8" floppy drive
>
> We have a collection of test programs stored on 8" floppies which were
part
of a Fairchild
F70
PCB tester. We're trying to convert them to be read by a PC.
A field Eng. from Schumberger (who took over the Fairchild tester
line) tells me the
8" drive was a Shugart SA850/851.
Well, I have the SA850 service manual somewhere. I could probably even
find it...
We need to know the format information. We have a
couple of old 8"
drives, but can't seem to make out the format. I noticed in one of the
But it's not going to help with the format information. 8" disk drives,
like virtually all floppy drvies have a 'raw' (low level) interface. It's
up to the _controller_ to determine the format.
The disks could be soft-sectored (one hole for the index sensor) or hard
sectored (one hole for the start of each track, evenly spaced, and one
hole midway between 2 of them for the index).
The data could be recorded using FM encoding ('single density'), MFM
encoding ('double density') or a number of other less widely-used methods
(MMFM, GCR, etc).
Even when you've worked out those details, you still have to find the
number of sectors/track, the size of each sector, and other similar
information. If the controller was custom (as opposed to using one of the
standard disk controller chips) then the sector headers could be just
about anything. Heck, I've seen machines using FM encoding for the
headers and MFM encoding for the data...
And after that you've only managed to read raw sectors. You then have to
work out what sectors make up a given file -- things like the directory
format (assuming there is a directory), etc.
The best place to start looking would be in the service manual/schematics
for the instrument itself. You should be able to work out what the very
-tony