23 Jan
2008
23 Jan
'08
9:25 p.m.
Hello!
I have an elderly Mitsubishi MR535R (60Mb-ish RLL) connected to an ST11R
controller. The control and data cables are homebrew although neatly and
tidying put together.
When I power up an old Pentium II - because it's the only box I have with ISA
slots - the ST11R pops up a message on the screen, clunks the drive in an "I'm
accessing you" kinda way, but then reports "No drives found" and continues
merrily on its way.
The cables are straight-through, and I have the drive set to DS1. If I set the
drive to DS2, the BIOS sits there for several seconds but doesn't access the drive.
As my knowledge is a tad rusty, can anyone help identify what the problem here
is? BIOS shadowing is off for the memory locations that are, and could, be
used by the card.
The only thing I can think of is that the ST11R is in fact an ST11M, tries to
read the drive, goes "Uh-oh, don't recognise you" and reports "No drive
found".
Unfortunately I lack an MFM hard drive to test this out with :(
Peter
--
Peter Hicks | e: my.name at poggs.co.uk | g: 0xE7C839F4 | w: www.poggs.com
A: Because it destroys the flow of the conversation
Q: Why is top-posting bad?
23 Jan
23 Jan
9:49 p.m.
On Wed, Jan 23, 2008 at 09:25:16PM +0000, Peter Hicks wrote:
Hello!
I have an elderly Mitsubishi MR535R (60Mb-ish RLL) connected to an ST11R
controller. The control and data cables are homebrew although neatly and
tidying put together.
When I power up an old Pentium II - because it's the only box I have with
ISA slots - the ST11R pops up a message on the screen, clunks the drive in
an "I'm accessing you" kinda way, but then reports "No drives
found" and
continues merrily on its way.
I have never tried an MFM drive on a machine newer than about a 386. No
idea if the Pentium-II chipset or its BIOS could be adding to your troubles
or not.
As my knowledge is a tad rusty, can anyone help
identify what the problem
here is? BIOS shadowing is off for the memory locations that are, and
could, be used by the card.
Good.
The only thing I can think of is that the ST11R is in
fact an ST11M, tries
to read the drive, goes "Uh-oh, don't recognise you" and reports "No
drive
found".
So you are saying that this drive wasn't originally used with this
controller? If that's the case, then you need to ensure that the drive
is formatted for an ST11R. Even if the drive happens to be rated for MFM
vs RLL (an ST-255 vs ST-238R, say), the controller will _try_ to format
the drive. You just might have problems with completing the format with
few enough errored sectors or with long-term use. The controller doesn't
know anything about the drive that you don't tell it during formatting
(well... if you tell it that you have 8 heads, it *will* notice that there
are only, say, 6... but not the other way around).
I don't have access to the 'net at the moment (for another 12 hours), so I
can't look up the ST11R, but if you find docs, there should be formatting
instructions. From memory, a common way to do it was to jump into DEBUG
and call the formatter in ROM with something like 'G C800:5'. Some
controllers did not have ROM formatters - they came on a floppy. The
docs will sort all of that out.
I don't think the BIOS will see an unformatted MFM/RLL drive on the end
of a controller, or at best, you'll get a cryptic numerical error like
"1701 drive error". It all depends on how new the BIOS on the controller
is. Adaptec SCSI cards were, IMO, one of the better products for showing
you meaningful errors and for the quality of their ROM-based formatter.
MFM and RLL controllers were beyond terse.
Unfortunately I lack an MFM hard drive to test this
out with :(
You can format an RLL drive as MFM. Back in the day, it wasn't
commonly done because of the 25%-40% cost differential (RLL drives
were cheaper per byte than MFM, but not all that much). Formatting
an MFM drive as RLL was always a crap shoot, but the controller _will_
give it a shot.
-ethan
--
Ethan Dicks, A-333-S Current South Pole Weather at 23-Jan-2008 at 21:40 Z
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Ethan.Dicks at usap.gov http://penguincentral.com/penguincentral.html
11:25 p.m.
On Wednesday 23 January 2008 16:49, Ethan Dicks wrote:
Yup. Back in those days there were always folks that tried that, and some
got lucky, while others lost everything on the drive. It's my understanding
that the key point there is the frequency limitation on one of the chips
(read amplifier?) being 5 MHz. vs. 7.5 Mhz, or something like that.
Yup.
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin
On Wed, Jan 23, 2008 at 09:25:16PM +0000, Peter Hicks
wrote:
Last time I used any was back in the 286 days...
(Snip)
Hello!
I have an elderly Mitsubishi MR535R (60Mb-ish RLL) connected to an ST11R
controller. The control and data cables are homebrew although neatly and
tidying put together.
When I power up an old Pentium II - because it's the only box I have with
ISA slots - the ST11R pops up a message on the screen, clunks the drive
in an "I'm accessing you" kinda way, but then reports "No drives
found"
and continues merrily on its way.
I have never tried an MFM drive on a machine newer than about a 386. No
idea if the Pentium-II chipset or its BIOS could be adding to your troubles
or not. The only thing
I can think of is that the ST11R is in fact an ST11M,
tries to read the drive, goes "Uh-oh, don't recognise you" and reports
"No drive found".
So you are saying that this drive wasn't originally used with this
controller? If that's the case, then you need to ensure that the drive
is formatted for an ST11R. Even if the drive happens to be rated for MFM
vs RLL (an ST-255 vs ST-238R, say), the controller will _try_ to format
the drive. You just might have problems with completing the format with
few enough errored sectors or with long-term use. The controller doesn't
know anything about the drive that you don't tell it during formatting
(well... if you tell it that you have 8 heads, it *will* notice that there
are only, say, 6... but not the other way around). I don't have access to the 'net at the moment
(for another 12 hours), so I
can't look up the ST11R, but if you find docs, there should be formatting
instructions. From memory, a common way to do it was to jump into DEBUG
and call the formatter in ROM with something like 'G C800:5'. Some
controllers did not have ROM formatters - they came on a floppy. The
docs will sort all of that out.
Since the card appears to be trying to do *something* I'm wondering if it's
the BIOS on the card doing it, or that on the MB?
I don't think the BIOS will see an unformatted
MFM/RLL drive on the end
of a controller, or at best, you'll get a cryptic numerical error like
"1701 drive error". It all depends on how new the BIOS on the controller
is. Adaptec SCSI cards were, IMO, one of the better products for showing
you meaningful errors and for the quality of their ROM-based formatter.
MFM and RLL controllers were beyond terse.
One other possibility for getting some meaningful info that occurs to me is to
get something like TomsRtBt, basically a bootable linux on a single floppy,
and boot that -- then you can poke around and get a pretty good picture of
just what the hardware sees.
Unfortunately
I lack an MFM hard drive to test this out with :(
You can format an RLL drive as MFM. Back in the day, it wasn't
commonly done because of the 25%-40% cost differential (RLL drives
were cheaper per byte than MFM, but not all that much). Formatting
an MFM drive as RLL was always a crap shoot, but the controller _will_
give it a shot.
24 Jan
24 Jan
7:21 a.m.
Hi Roy
Roy J. Tellason wrote:
[ connecting an RLL encoded drive to an MFM controller ]
Yup. Back in those days there were always folks that
tried that, and some
got lucky, while others lost everything on the drive. It's my understanding
that the key point there is the frequency limitation on one of the chips
(read amplifier?) being 5 MHz. vs. 7.5 Mhz, or something like that.
That was an awesome feeling of suddenly being sick that I just had... :)
Here's hoping that since I've not been able to read anything from the disk,
everything's still intact.
Since the card appears to be trying to do *something*
I'm wondering if it's
the BIOS on the card doing it, or that on the MB?
I guess the card BIOS. I've turned off just about everything I can and don't
need on the system BIOS, and the card /is/ doing something - and its behaviour
changes if I plug the drive in the port 1 or port 2. Short of capturing the
output on the control and data cables, I don't think there's any way to prove
this.
One other possibility for getting some meaningful info
that occurs to me is to
get something like TomsRtBt, basically a bootable linux on a single floppy,
and boot that -- then you can poke around and get a pretty good picture of
just what the hardware sees.
Now you're talking. I'm a Linux hacker of eleven years now. The later kernels
(2.6) don't support RLL/MFM controllers, however I'm fairly sure I can compile
a 2.0 kernel and give that a go.
I'll try that at the weekend and report back!
Peter
--
Peter Hicks | e: my.name at poggs.co.uk | g: 0xE7C839F4 | w: www.poggs.com
A: Because it destroys the flow of the conversation
Q: Why is top-posting bad?
7:16 a.m.
Hi Ethan
Ethan Dicks wrote:
I have never tried an MFM drive on a machine newer
than about a 386. No
idea if the Pentium-II chipset or its BIOS could be adding to your troubles
or not.
I knew I should never have thrown out my really old 286 :-)
So you are saying that this drive wasn't
originally used with this
controller?
Correct. It was from an RM Nimbus AX/2, long dead now unfortunately. I may
get lucky and be able to get some hardware specs from RM, although I don't rate
my chances.
If that's the case, then you need to ensure that
the drive
is formatted for an ST11R. Even if the drive happens to be rated for MFM
vs RLL (an ST-255 vs ST-238R, say), the controller will _try_ to format
the drive. You just might have problems with completing the format with
few enough errored sectors or with long-term use. The controller doesn't
know anything about the drive that you don't tell it during formatting
(well... if you tell it that you have 8 heads, it *will* notice that there
are only, say, 6... but not the other way around).
Gotcha. There is data on the drive already, that's the reason I want to try to
read what's on the disk. Even if I pull off a 60Mb binary image and have to do
something else to extract the data - that's fine. It's really a one-off
operation since I believe there's still a copy of the ancient RM Net 3.1
software on the disk.
I don't have access to the 'net at the moment
(for another 12 hours), so I
can't look up the ST11R, but if you find docs, there should be formatting
instructions. From memory, a common way to do it was to jump into DEBUG
and call the formatter in ROM with something like 'G C800:5'.
That brings back the memories. Yes, G=C800:5 invokes the low-level format
routine on the card. The manual with the ST11R describes this in brief.
Peter
--
Peter Hicks | e: my.name at poggs.co.uk | g: 0xE7C839F4 | w: www.poggs.com
A: Because it destroys the flow of the conversation
Q: Why is top-posting bad?
7:38 a.m.
On Thu, Jan 24, 2008 at 07:16:01AM +0000, Peter Hicks wrote:
Hi, Peter,
Ethan Dicks wrote:
Ah... then you will need to find if _any_ PC controller is compatible
with that.
So you are saying that this drive wasn't
originally used with this
controller?
Correct. It was from an RM Nimbus AX/2, long dead now unfortunately. I
may get lucky and be able to get some hardware specs from RM, although I
don't rate my chances. Gotcha. There is data on the drive already,
that's the reason I want to
try to read what's on the disk. Even if I pull off a 60Mb binary image and
have to do something else to extract the data - that's fine. It's really a
one-off operation since I believe there's still a copy of the ancient RM
Net 3.1 software on the disk.
Obviously that makes the attempt more important.
That brings back the memories. Yes, G=C800:5 invokes
the low-level format
routine on the card. The manual with the ST11R describes this in brief.
At this point, you don't want to do that - you'll lose your data.
I am not so familiar with the nuances of cross-controller compatibility to
even begin to recommend how you could attack the problem. One solution
could be this as-yet-un-invented "Catweasel-like hard drive controller" that
folks have been discussing on and off here - take a raw image of the disk,
then parse out the transitions into address marks, sync marks, tracks,
sectors, etc., then turn it into a 60MB mountable disk image.
I don't know anything about the RM Nimbus AX/2, but knowing how it low-level
formats the drive is likely to be an essential part of the puzzle.
One of the big benefits when the PC world switched from analog recording
to IDE was that it became much simpler to move drives from machine to
machine - all you really had to worry about is track/head/sector geometry,
not flux transitions and how they were grouped.
-ethan
--
Ethan Dicks, A-333-S Current South Pole Weather at 24-Jan-2008 at 07:29 Z
South Pole Station
PSC 468 Box 400 Temp -29.7 F (-34.3 C) Windchill -47.9 F (-44.4 C)
APO AP 96598 Wind 5.5 kts Grid 63 Barometer 686.2 mb (10395 ft)
Ethan.Dicks at usap.gov http://penguincentral.com/penguincentral.html
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