22 Apr
2015
22 Apr
'15
1:54 a.m.
I'm attempting to dump an image of the Ridge 32/330's original SMD drive
(A Fujitsu MK2322) -- I'd been running it off of a spare, because I
didn't want to disturb what was on the original drive until I could back
it up. Now that the spare has died I figured it would be an opportune
time...
The Ridge "DISCUTIL" tool (loaded from QIC) is pretty powerful, and
amongst its weapons is the "DS" command which will dump a sector of the
disk to screen, in ASCII HEX. The Ridge has been running for the past
eight days dumping the entire 168mb disk, in HEX, at 9600 baud. Yes,
I'm insane.
Along the way I discovered that the integrity of the data on the disk is
pretty poor. There are lots of bad sectors. In particular surfaces 2
and 3 are completely unreadable for all 823 cylinders, surfaces 4 and 8
are marginal most of the time. After a lot of retries I've managed to
get most of everything (except for surfaces 2 and 3 which yield no data
at all).
So I figured that heads 2 and 3 are toast -- perhaps bad analog logic,
maybe something in the digital logic that selects the head, maybe even
bad heads, who knows.
DISCUTIL also has a "FORMAT" command that will format individual
cylinders, on a specified surface. So after I'd read out everything
possible to save, I tried it on a cylinder (801) known to have trouble
sectors, that also containing all zeros so I wouldn't wipe out anything
vital. After doing a format on cyl 801, head 2 I could read all sectors
on that cylinder/head without issue. Same with head 3, 4 and 8.
Suspecting a possible addressing fault I tried reading every surface on
cylinder 801 after formatting all surfaces on that cylinder, and they
all read without issue. (I'd expect that if, for example, when I asked
the disk to format surface 2 it actually formatted surface 5, then
reading surface 5 later would fail due to an invalid sector header for
surface 5...)
So, I suppose this is somewhat good news in that I may be able to use
the drive, but I wonder what would cause the data on the disk to fail in
such a manner (and I'm still hesitant to reformat the drive without
recovering stuff off of surfaces 2/3...) Any thoughts?
- Josh
22 Apr
22 Apr
10:31 a.m.
At 12:54 AM 4/22/2015, Josh Dersch wrote:
So I figured that heads 2 and 3 are toast -- perhaps
bad analog logic, maybe something in the digital logic that selects the head, maybe even
bad heads, who knows.
Maybe a drive recovery place will take it on as a charity / learning
opportunity. They probably don't see drives that old that often.
If those two heads are bad, maybe there's a way to swap them with
other heads.
- John
8:04 p.m.
On Tue, Apr 21, 2015 at 10:54:42PM -0700, Josh Dersch wrote:
So, I suppose this is somewhat good news in that I may be able to
use the drive, but I wonder what would cause the data on the disk to
fail in such a manner (and I'm still hesitant to reformat the drive
without recovering stuff off of surfaces 2/3...) Any thoughts?
Head alignment off on those heads. Can the drive microstep or any other
way to change the head alignement? You might be able to recover the
data that way.
I have seen an MFM drive with a few heads so out of alighment that
you got data from track n+1 on one head and n on another. Not sure
how you cause that without more serious damage to the drive. For MFM
drives orientation or finger on the stepper motor helps to recover
data when the heads are off. Probably doesn't work with your drive.
23 Apr
23 Apr
2:09 a.m.
On 4/22/15 5:04 PM, David Gesswein wrote:
On Tue, Apr 21, 2015 at 10:54:42PM -0700, Josh Dersch
wrote:
That makes sense.
So, I suppose this is somewhat good news in that
I may be able to
use the drive, but I wonder what would cause the data on the disk to
fail in such a manner (and I'm still hesitant to reformat the drive
without recovering stuff off of surfaces 2/3...) Any thoughts?
Head alignment off on those heads. Can the drive microstep or any other
way to change the head alignement? You might be able to recover the
data that way.
According to the service manual one of the surfaces contains servo
tracks used to position the heads, and all alignment is based on these
tracks. If some of the heads are now out of alignment with those tracks
I don't think there's anything to be done about it (but I've only
skimmed the manual thus far). There does not appear to be anything I
can do at the interface level, at any rate. I wonder, though, if
perhaps running the drive in a different orientation (it's currently on
its side) might have an effect on the wayward heads. Probably not, but
it's worth a shot. I may try that tomorrow...
I have seen an MFM drive with a few heads so out of alighment that
you got data from track n+1 on one head and n on another. Not sure
how you cause that without more serious damage to the drive.
Yeah, I know nothing
of the history of this machine, it seems to have
been well treated aside from being left in a somewhat damp and
rat-infested environment, no evidence of it being dropped. But then,
the chassis on the Ridge is built like a tank so it might very well have
been dropped a few feet to no obvious effect...
For MFM
drives orientation or finger on the stepper motor helps to recover
data when the heads are off. Probably doesn't work with your drive.
Yeah, there's no stepper to grab onto here. And if there was, it'd
probably take my finger off when it moved, this drive means business :).
Thanks,
Josh
8:25 a.m.
At 01:09 AM 4/23/2015, Josh Dersch wrote:
According to the service manual one of the surfaces
contains servo tracks used to position the heads, and all alignment is based on these
tracks. If some of the heads are now out of alignment with those tracks I don't think
there's anything to be done about it
The other danger would be that if the heads drifted out of
alignment when the drive was in use. realigning the heads to
the original servo track might put them out of alignment with
where the last data was written.
- John
11:05 a.m.
at any rate. I wonder, though, if perhaps running the
drive in a different
orientation (it's currently on its side) might have an effect on the wayward
heads. Probably not, but it's worth a shot. I may try that tomorrow...
On many drives, orientation certainly can have an effect. What
orientation was it previously used in?
Also thermal - have you tried chilling and heating the drive?
4:27 p.m.
On 04/23/2015 08:05 AM, Fred Cisin wrote:
On many drives, orientation certainly can have an
effect. What
orientation was it previously used in?
I'm reminded of the early IMI "shoebox" drives (shoebox, I guess if you
had size 21 feet). I think that they were mostly used by Corvus--clear
tinted plastic top with a voice-coil positioner.
If you lifted the front end of these things about an inch off
horizontal, they'd cease to work--the positioner didn't have the moxie
to overcome the force of gravity and would respond with sort of a
squealing retry as it tried to push the heads uphill.
--Chuck
5:32 p.m.
On Thu, 23 Apr 2015, Chuck Guzis wrote:
On 04/23/2015 08:05 AM, Fred Cisin wrote:
> On many drives, orientation certainly can have an effect. What
> orientation was it previously used in?
I'm reminded of the early IMI "shoebox"
drives (shoebox, I guess if you had
size 21 feet). I think that they were mostly used by Corvus--clear tinted
plastic top with a voice-coil positioner.
I have one of these. It's big, heavy beast.
If you lifted the front end of these things about an
inch off horizontal,
they'd cease to work--the positioner didn't have the moxie to overcome the
force of gravity and would respond with sort of a squealing retry as it tried
to push the heads uphill.
Alas, mine arrived non-functional and has remained that way due to a
serious lack of time to devote to troubleshooting.
--
7:36 p.m.
On Thu, Apr 23, 2015 at 8:05 AM, Fred Cisin <cisin at xenosoft.com> wrote:
at any rate. I wonder, though, if perhaps running the
drive in a
different orientation (it's currently on its
side) might have an effect on
the wayward heads. Probably not, but it's worth a shot. I may try that
tomorrow...
On many drives, orientation certainly can have an
effect. What
orientation was it previously used in?
The drive has always been mounted on its side in the Ridge CPU chassis. I
may try flipping it to the other side and see if it makes any kind of
difference.
Also thermal - have you tried chilling and heating the drive?
I have not, I'd only consider that sort of thing as a last resort. What
kind of temperatures would you recommend?
Thanks,
Josh
10:33 a.m.
On 4/22/15 5:04 PM, David Gesswein wrote:
Head alignment off on those heads. Can the drive
microstep or any other
way to change the head alignement? You might be able to recover the
data that way.
Depending on how much work you wanted to put into it, you could always open the
servo loop and drive the positioner externally with a microcontroller.
7:40 p.m.
On Thu, Apr 23, 2015 at 7:33 AM, Al Kossow <aek at bitsavers.org> wrote:
On 4/22/15 5:04 PM, David Gesswein wrote:
Head alignment off on those heads. Can the drive microstep or any other
dumped data and it's an RX/V 1.1 installation (which you've
already archived) that looks like it was used in the development of Ibuki
Common Lisp (or at least some form of Lisp development -- there are mails
related to lisp discussions as well as Ibuki C/Lisp source code on the
disk). That's moderately interesting but unless anyone out there is
clamoring for this stuff I'm not going to expend too much more effort
trying to recover data...
- Josh
way to change the head alignement? You might be
able to recover the
data that way.
Depending on how much work you wanted to put into it, you could always
open the
servo loop and drive the positioner externally with a microcontroller.
I'm not sure it's worth that much effort. I've been poring over the
5:17 a.m.
On Tue, 21 Apr 2015, Josh Dersch wrote:
Fujitsu MK2322) -- I'd been running it off of a
spare, because I didn't want
[...]
pretty poor. There are lots of bad sectors. In
particular surfaces 2 and 3
are completely unreadable for all 823 cylinders, surfaces 4 and 8 are
marginal most of the time. After a lot of retries I've managed to get most
of everything (except for surfaces 2 and 3 which yield no data at all).
I have several of that exact drive in different machines. They have all
been formatted a long time ago and reveal *many* bad blocks. For
example, one is in a PCD Cadmus (QBus 68020 machine) and one in our Zilog
S8000. Especially the Zilog's drive is valuable as it contains the IMO
only existing copy of the ZEUS operating system for the Model 32 (I'd
*LOVE* to get hold of an image of the tape cartidges).
My experience with reading out the contents of those drive (with my
own-built simple ISA SMD interface) is that one has to do 1. many retries
and 2. use all means that the drive provides to successfully read a track
(i.e. offset+ and offset- commands).
So I figured that heads 2 and 3 are toast -- perhaps
bad analog logic, maybe
something in the digital logic that selects the head, maybe even bad heads,
who knows.
I don't think so. Old drives simply tend to get "weak". I suppose that the
alignment of several heads changes slightly over the years.
Christian
3:18 p.m.
Am 23.04.15 um 11:17 schrieb Christian Corti:
Old drives simply tend to get "weak".
Seconded. Especially those 8" Fujitsus. Once upon a time the Unix-AG had
a Sequent Symetry Ssomething with 8 x 80386DX20 CPUs... It used 8"
Fujitsu SMD disks of 600-something MB capacity. The former operator of
that machine at the local university instructed us to low level format
the disks once every year. They simply loose data over time.
--
tsch??,
Jochen
3378
days inactive
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aek＠bitsavers.org -
cc＠informatik.uni-stuttgart.de -
cclist＠sydex.com -
cisin＠xenosoft.com -
derschjo＠gmail.com -
djg＠pdp8online.com -
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