12 Dec
2004
12 Dec
'04
10:07 p.m.
On Mon, 2004-12-13 at 00:32 -0500, Roger Merchberger wrote:
All this talk about getting older drives to work on
newer hardware got me
thinking about a totally different track on how to get this done (not to
mention the previous subject was referencing a 5 foot, 3 inch floppy
drive... ;-) )
There are VAXen that have SCSI bridgeboards to control 3.5" 1.44Meg floppy
drives via the SCSI bus - how "controllable" are those, WRT different
drives, data rates & low level programmability? I have one, but other than
"it gives my VAX a floppy drive" I know very little about them.
I've been playing around with Torch Manta board which do exactly the
same thing; they'll run up to 4 drives of mixed types (plus I have the
relevant protocol spec). They're also to swap the function of some of
the interface pins around in software too so that they'll work with a
few oddball drives.
They confuse the Linux low-level SCSI drivers a little as they show up
as a fixed device with 4 LUNs, rather than a removeable device and so
Linux expects to be able to read the first block from each LUN at
startup. After all sorts of timeouts it eventually boots though :)
The Mantas at least conform to the CCS; I'd like to get some of the
other bridge boards around to work with Linux (e.g. Adaptec and OMTI
SCSI-ST506) but they predate the CCS and so don't support some of the
basic stuff expected by the Linux drivers (such as inquiry). You may
find the VAX boards are the same. (I've been looking for a non-Adaptec
SCSI HBA for the PC for a while so I can hack the driver to work with
these boards - the Adaptec HBA in my PC also runs all the normal drives,
so I don't fancy messing with it!)
Of course I remember asking on this list as to whether the modulation
used for floppies was a standard, and it appears not - MFM done by one
manufacturer's FDC chip isn't necessarily the same as another's. Which
means such a board *still* won't work with all formats even if the
media's supported and it uses FM or MFM modulation. The only way to cope
with that is to do all the processing in software (hence the reason I
started asking about parallel ports and the like a few months back!)
cheers
Jules