On 01/04/2014 03:02 PM, Glen Slick wrote:
On Sat, Jan 4, 2014 at 11:16 AM, emanuel stiebler
<emu at e-bbes.com> wrote:
On 2014-01-04 11:59, Robert Jarratt wrote:
So how does it do this when the disk is yet to be
formatted? In other
words,
when it formats the disk how does it know what size the disk is?
DEC drives have this information in a special area of the drive.
If for exmaple, the MV2000 finds this blocks, it formats to exactly this
specs. You see this, if you go into the MV2000 diagnostics.
All other drives, you have to enter the specs manually ...
How does that match with this information, if it is correct, that the
MicroVAX 2000 disk recognizer works for the set of known disk drives
even if the disk came from a different system and has no DEC specific
information or formatting on it currently?
http://home.iae.nl/users/pb0aia/vax/fmtbob.html
"The standard DEC drives that are supported in the VS2000 and their
industry equivalents are:
RD54 - Maxtor XT-2190
RD53 - Micropolis 1325 or 1335
RD52 is Quantum D540 31Mb
RD51 is St412 10mb
RD50 is SA(ST)506 5mb
RD31 - Seagate ST-225
RD32 - Seagate ST-251-1
keep in mind there were a TON of suppliers making their own that matched
one of those
as the PC market drove that. Many of the older PCs had a list of drives
they new then
there was user (you supply the drive dimensions). The earliest ones had
a very short list
of valid drives and NO user settings.
If you have any of these standard drives you can
simply plug it into
your 2000 and the ROM formatter will automatically recognize the drive
types. I've never seen this fail, even if the drive has never seen a
DEC machine before, or even if the drive was previously formatted in
a PC."
I have. Usually the drive was different from the list above as in
truly odd
or formatted using a RLL controller. The one that comes to mind was
the 20mb 3.5" half height that was fewer heads than RD31 and more
cylinders and was previously formatted using a Micromint SB180 with
SCSI adapter (256bytes sector) via Adaptec SCSI to MFM bridge!
Another was a RD52 that was tossed by field circus in the MIll (ML3-6
specifically)
because the user inverted the connector (hard to do but they did) and
effective
wiped the drive and the field use formatter didn't recognize it, they
deemed it
bad because of it. I still have and use that drive!
For a long time it was used for a S100 system and that had a Teltek
controller
that formatted it in compatable with anything. When I pulled it to use
in a
PDP11 I used a uVAX2000 to get to DEC formatting and it was not recognized
despite being a genuine RD52, I had to hand feed the parameters.
Allison