17 Jan
2015
17 Jan
'15
2:11 p.m.
Someone was using my MFM reader to read a Maxtor XT-2190 and was having
problems. From the looks of it the heads are out of alignment. Does
anyone know if this drive has a microstep mode like some Seagates have?
I didn't find any mention in the manuals I could find.
Some heads are mostly unreadable, some heads are mostly ok and some
were unreadable on cylinder 0 and on other cylinders the header says they
are one cylinder less than where it stepped to. Some of the other heads headers
said the cylinder is what was expected.
17 Jan
17 Jan
2:40 p.m.
Sometimes trying different orientations to take up any slack and/or the old
trick of cooling it in the freezer for a little while can make some
unreadable cylinders readable; might be worth a try.
Also, make sure the power supply is up to the task; these things take a lot
of power and I've had intermittent errors when using a slightly inadequate
power supply that cleared up totally with a more substantial one.
Good luck.
m
----- Original Message -----
From: "David Gesswein" <djg at pdp8online.com>
To: <cctech at classiccmp.org>
Sent: Saturday, January 17, 2015 2:11 PM
Subject: Maxtor XT-2190
Someone was using my MFM reader to read a Maxtor
XT-2190 and was having
problems. From the looks of it the heads are out of alignment. Does
anyone know if this drive has a microstep mode like some Seagates have?
I didn't find any mention in the manuals I could find.
Some heads are mostly unreadable, some heads are mostly ok and some
were unreadable on cylinder 0 and on other cylinders the header says they
are one cylinder less than where it stepped to. Some of the other heads
headers
said the cylinder is what was expected.
7:29 p.m.
On Sat, 17 Jan 2015, David Gesswein wrote:
Someone was using my MFM reader to read a Maxtor
XT-2190 and was having
problems. From the looks of it the heads are out of alignment. Does
anyone know if this drive has a microstep mode like some Seagates have?
I didn't find any mention in the manuals I could find.
Hi, David.
That drive has a dedicated servo surface (thus the odd number of heads).
Not sure there's any concept of microstepping in that arrangement.
I'll also second the comment about hefty power requirements. Mine just
about dim the lights in the room on spin-up.
--
18 Jan
18 Jan
1:06 p.m.
On Sat, Jan 17, 2015 at 07:29:10PM -0500, Steven Hirsch wrote:
On Sat, 17 Jan 2015, David Gesswein wrote:
That drive has a dedicated servo surface (thus the odd number of
heads). Not sure there's any concept of microstepping in that
arrangement.
The Seagate ST-4096 is also a servo drive and has the ability to move
the heads a partial track for read error recovery. I assume its adding an
offset into the servo loop to vary the head position.
1:16 p.m.
On 1/18/15 10:06 AM, David Gesswein wrote:
On Sat, Jan 17, 2015 at 07:29:10PM -0500, Steven
Hirsch wrote:
I did some digging and I don't have any schematics scanned for Maxtor.
Are there any patent numbers on the drive? It may be worth digging around
for Maxtor patents from the mid-80's.
On Sat, 17 Jan 2015, David Gesswein wrote:
That drive has a dedicated servo surface (thus the odd number of
heads). Not sure there's any concept of microstepping in that
arrangement.
The Seagate ST-4096 is also a servo drive and has the ability to move
the heads a partial track for read error recovery. I assume its adding an
offset into the servo loop to vary the head position.
1:27 p.m.
On 1/18/15 10:16 AM, Al Kossow wrote:
I did some digging and I don't have any schematics
scanned for Maxtor.
Are there any patent numbers on the drive? It may be worth digging around
for Maxtor patents from the mid-80's.
4937689 is a place to start to see if any of the parts are similar
19 Jan
19 Jan
1:43 p.m.
FWIW, microstepping goes back to at least the CDC SMD of the mid-70s and
even some stepper motor drives were microstepped. So there is no question
the XT2190 can do it.
The XT-2000 OEM spec,
http://bitsavers.trailing-edge.com/pdf/maxtor/1014286A_XT1000_2000_OEM.pdf,
has no mention of microstepping nor does an Mini-Micro Systems article on
the earlier XT-1000.
If you are a tinkerer, u can try injecting an offset voltage into the servo
error amp :-),
Tom
-----Original Message-----
From: David Gesswein [mailto:djg at pdp8online.com]
Sent: Sunday, January 18, 2015 10:06 AM
To: cctech at classiccmp.org
Subject: Re: Maxtor XT-2190
On Sat, Jan 17, 2015 at 07:29:10PM -0500, Steven Hirsch wrote:
On Sat, 17 Jan 2015, David Gesswein wrote:
That drive has a dedicated servo surface (thus the odd number of
heads). Not sure there's any concept of microstepping in that
arrangement.
The Seagate ST-4096 is also a servo drive and has the ability to move the
heads a partial track for read error recovery. I assume its adding an offset
into the servo loop to vary the head position.
20 Jan
20 Jan
12:47 p.m.
On 1/19/15 10:43 AM, Tom Gardner wrote:
FWIW, microstepping goes back to at least the CDC SMD
of the mid-70s and
even some stepper motor drives were microstepped. So there is no question
the XT2190 can do it.
Obviously, though with the limited documentation it would take some reverse
engineering of the Maxtor servo system to do it. There is no way provided to
do it from the 34 pin edge connector that I can see. Know anyone that has
any Maxtor schematics squirreled away?
Someone on Eric's board just asked if ESDI was backwards compatible to ST412
like it incorrectly states on Wikipedia, which got me to re-read the ESDI
spec http://bitsavers.org/pdf/micropolis/ESDI_spec_X3.170-90.pdf and the
good news is there were commands added to microposition the heads there.
Doesn't help with the immediate problem, thought. This is all an interesting
rathole, but I'm down too many others right now.
I looked at an early ESDI spec in the CDC/discs directory, and there was
a step-mode defined which was backwards compatbile, but I have no idea if
any drives actually implemented it, since you still have separate clock and
data on the 20-pin connnector so what's the point?
19 Jan
19 Jan
2:12 p.m.
On 1/17/15 11:11 AM, David Gesswein wrote:
Does
anyone know if this drive has a microstep mode like some Seagates have?
Continuing to dig on this. I don't think you're going to find any embedded servo
drives
capable of doing this from the edge connector. I had never even heard of this mode on
MFM drives before you mentioned it. So far, the only drives that seem to support
microstepping
if you assert pin 16 (recovery mode) on the 34 pin connector and jumper 3-4 is active are
the
ST225 and ST250
I was able to pick up a XT2190 and XT1085 at a surplus place this weekend, and I see that
the
2190 uses a pair of Z8s. It wouldn't surprise me if there is a diagnostic mode buried
inside the
one that controls the servo. It is also curious at the level of interest Russian sites
seem to have
on how disk drives work, and how little of that information exists on the web in the US.
Bill Maddox gave me about a dozen boxes of paper to go through over Christmas, and besides
several
hardware documents for the NGEN, which I did the Snoopy Dance over when I discovered them,
are a bunch
of MFM hard drive schematics from a bunch of vendors. These is as scarce as hen's
teeth, so
I'll try to get those uploaded today. Unfortunately, nothing there from Maxtor.
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aek＠bitsavers.org -
djg＠pdp8online.com -
mhs.stein＠gmail.com -
snhirsch＠gmail.com -
t.gardner＠computer.org