Hello all.

My name is Ken and I am with the Atari Historical Society (www.atarimuseum.com)

We have about 14 RM05 platters we need to have read and transferred. We would like to have images made of them before any extraction takes place in case of problems.

If you have a working setup of a VAX and a working RM05 drive we would love to hear from you.

I am located in Glenview, Illinois

On 2023-09-26, Ken Van Mersbergen <kvanmersbergen@maine207.org> wrote:
> Hello all.
>
> My name is Ken and I am with the Atari Historical Society (www.atarimuseum.com)
>
> We have about 14 RM05 platters we need to have read and transferred. We would like to have images made of them before any extraction takes place in case of problems.
>
> If you have a working setup of a VAX and a working RM05 drive we would love to hear from you.
>
> I am located in Glenview, Illinois

If you get no joy here, I wonder if an email to Bitsavers might get
you further along ?

They may have contacts they can point you to. See:

http://www.bitsavers.org/

(Email address is at the end of that webpage).

Simon.

--
Simon Clubley, clubley@remove_me.eisner.decus.org-Earth.UFP
Walking destinations on a map are further away than they appear.

On Tuesday, September 26, 2023 at 5:33:28 PM UTC-7, Ken Van Mersbergen wrote:

(snip)

> If you have a working setup of a VAX and a working RM05 drive we would love to hear from you.
> I am located in Glenview, Illinois

Until a few years ago, the best place to find a running VAX was the Living
Computer Museum in Seattle. (That is, a non-micro VAX.)

The museum is still there, but has been closed since early 2000.

I believe the VAX runs on emulated disk, though.

They do have VAX disk drives, but I don't remember RM05 being one of them.

Keeping old disk drives running is much harder than old CPUs.

On 9/26/23 20:33, Ken Van Mersbergen wrote:
> My name is Ken and I am with the Atari Historical Society (www.atarimuseum.com)
>
> We have about 14 RM05 platters we need to have read and transferred. We would like to have images made of them before any extraction takes place in case of problems.
>
> If you have a working setup of a VAX and a working RM05 drive we would love to hear from you.
>
> I am located in Glenview, Illinois

The RM05 is a repackaged CDC 9766. We have a 9766 at LSSM, but it
has not yet been restored. It will probably be a while before we get to
it. We have in-house expertise, but we are short-handed and have a lot
of things ahead of it in the queue. But we do have an inventory of
spare parts for it, service documentation, and packs for testing.

This does not address your requirement right now, but I doubt you'll
find a compatible drive anywhere else.

If a qualified engineer wants to visit LSSM and take on the project
of getting the 9766 running, contact me via email.

-Dave

--
Dave McGuire, President/Curator
Large Scale Systems Museum
New Kensington, PA

On 9/27/23 15:17, gah4 wrote:
>> If you have a working setup of a VAX and a working RM05 drive we would love to hear from you.
>
>> I am located in Glenview, Illinois
>
> Until a few years ago, the best place to find a running VAX was the Living
> Computer Museum in Seattle. (That is, a non-micro VAX.)
>
> The museum is still there, but has been closed since early 2000.
>
> I believe the VAX runs on emulated disk, though.

Most everything there was emulated, it seems.

> Keeping old disk drives running is much harder than old CPUs.

It is, but we do it at LSSM. It's not like it's impossible.

-Dave

--
Dave McGuire, President/Curator
Large Scale Systems Museum
New Kensington, PA

On 2023-09-27 02:33, Ken Van Mersbergen wrote:
> Hello all.
>
> My name is Ken and I am with the Atari Historical Society (www.atarimuseum.com)
>
> We have about 14 RM05 platters we need to have read and transferred. We would like to have images made of them before any extraction takes place in case of problems.
>
> If you have a working setup of a VAX and a working RM05 drive we would love to hear from you.
>
> I am located in Glenview, Illinois

Maybe not helpful, but just wanted to point out that you could dump the
disk if have an RM05 connected to a PDP-11/70 as well.

Johnny

On Wednesday, September 27, 2023 at 1:01:40 PM UTC-7, Dave McGuire wrote:

(snip regarding the Living Computer Museum)

> > I believe the VAX runs on emulated disk, though.

> Most everything there was emulated, it seems.

Last I remember, the Xerox Sigma 9 was running on real disks.

When it was open, the museum computers were running 24/7.
Even when they were new, those drives were never expected
to do that. Systems I remember, had a maintenance time every
morning. And disks were often backed up every day.

As well as I know it, whatever is running now, is running unattended.

At some point, though, it isn't obvious what emulated means.

I a MicroVAX an emulation of the 11/780?

In any case, yes, more is now emulated than when the museum
was open. The Toad2 was designed as competition for DEC,
not as a later day emulator.

Does it matter if it is hardware emulation or software emulation?

I remember knowing about RP07, and not RM05.

> > Keeping old disk drives running is much harder than old CPUs.

> It is, but we do it at LSSM. It's not like it's impossible.
Running continuously for 20 years might be, though.

Oh, one more thing.

One way that LCM does floppy disks, is to make a bit image
backup. That is, not decode the bits, just record where they are.
That works even if it is an unusual low-level format.

That might be the best way to read old RM05 packs, too.

On Wed, 27 Sep 2023 23:41:14 +0200, Johnny Billquist wrote:
> Maybe not helpful, but just wanted to point out that you could dump the
> disk if have an RM05 connected to a PDP-11/70 as well.

Or indeed any Unibus PDP-11. Or any Qbus PDP-11 running directly to SMD
with an SMD controller that's format-compatible, which many are.

-Dave

--
Dave McGuire
Large Scale Systems Museum
Pittsburgh, PA USA

On Wed, 27 Sep 2023 16:04:28 -0700 (PDT), gah4 wrote:
> When it was open, the museum computers were running 24/7.
> Even when they were new, those drives were never expected to do that.
> Systems I remember, had a maintenance time every morning. And disks were
> often backed up every day.

Some of their exhibit machines were running 24/7, but very few...not
all. And those that did (the IBM 4331 comes to mind) ran on emulated
disks and other peripherals.

> At some point, though, it isn't obvious what emulated means.
>
> I a MicroVAX an emulation of the 11/780?

Let's not rehash the old argument of whether, say, a microcoded
implementation is an emulation or not, as fun of a Usenet thread that it
may (yet again) be. In this context we're talking about real hardware
being replaced by, i.e., Raspberry Pis, rather than repairing and
maintaining the real hardware.

Note well that I'm not talking trash about LCM here. I respected the
institution and its staff while they were around. One of their former
staffers works with us now. But their approach was just very different
from ours.

But since you mentioned it, you seem to be the type of person who knows
about the differences between the MicroVAX (pick your flavor) and the
11/780. Which floating point formats are implemented or not (two
different versions of the KD32!) etc etc. ;)

>> > Keeping old disk drives running is much harder than old CPUs.
>
>> It is, but we do it at LSSM. It's not like it's impossible.
>
> Running continuously for 20 years might be, though.

Nobody in their right mind would do that now. Not only is it pointless
(who's going to show up at 3AM to sit in front of a machine?) but there
are power bills to be paid, fire concerns, etc.

> One way that LCM does floppy disks, is to make a bit image backup. That
> is, not decode the bits, just record where they are.
> That works even if it is an unusual low-level format.

It's pretty brute-force, but yes, that's a workable approach. And it
also means people who know nothing about the computers can run the
backups.

> That might be the best way to read old RM05 packs, too.

It may be. Media recovery is mostly a solved problem for more common
formats.

-Dave

--
Dave McGuire
Large Scale Systems Museum
Pittsburgh, PA USA

On Wednesday, September 27, 2023 at 5:55:54 PM UTC-7, Dave McGuire wrote:
> On Wed, 27 Sep 2023 16:04:28 -0700 (PDT), gah4 wrote:
> > When it was open, the museum computers were running 24/7.
> > Even when they were new, those drives were never expected to do that.
> > Systems I remember, had a maintenance time every morning. And disks were
> > often backed up every day.

> Some of their exhibit machines were running 24/7, but very few...not
> all. And those that did (the IBM 4331 comes to mind) ran on emulated
> disks and other peripherals.

They had 3350's for the 4331, but never tried running them.
There were stories about how hard they were to get running.

> > At some point, though, it isn't obvious what emulated means.
> > I a MicroVAX an emulation of the 11/780?

> Let's not rehash the old argument of whether, say, a microcoded
> implementation is an emulation or not, as fun of a Usenet thread that it
> may (yet again) be. In this context we're talking about real hardware
> being replaced by, i.e., Raspberry Pis, rather than repairing and
> maintaining the real hardware.
There are a lot of stories about the CDC 6500, not all of which I remember.
When it was decomissioned, they cut the big cables that connect the
different frames. So they had to rebuild those. They needed the pins
for the connectors. (Since they had connectors, you do wonder why they
had to cut the cables.)

So they asked the company that made the silver plated pins about
buying more. The company said that there was a minimum order.
(I don't remember the number, but it might be 1000.) LCM said yes.

Then the company said that they didn't have that many!
They still got a lot more than needed, though. As far as I
remember the story, the budget for that one was $1 million.

> Note well that I'm not talking trash about LCM here. I respected the
> institution and its staff while they were around. One of their former
> staffers works with us now. But their approach was just very different
> from ours.
> But since you mentioned it, you seem to be the type of person who knows
> about the differences between the MicroVAX (pick your flavor) and the
> 11/780. Which floating point formats are implemented or not (two
> different versions of the KD32!) etc etc. ;)

I remember G_float and D_float. I believe it was a microcode option
which you got on the 780. And also optional H_float.

> >> > Keeping old disk drives running is much harder than old CPUs.
> >> It is, but we do it at LSSM. It's not like it's impossible.
> > Running continuously for 20 years might be, though.

> Nobody in their right mind would do that now. Not only is it pointless
> (who's going to show up at 3AM to sit in front of a machine?) but there
> are power bills to be paid, fire concerns, etc.

Power bills I don't think LCM ever worried about, though maybe they should.

There was one time the power supply on the Unisys machine overheated,
no fire but there was smoke. I got to press the big red button under
that plastic cover. I believe there is a system of smoke detectors
that are supposed to shut things down at night, if needed.

> > One way that LCM does floppy disks, is to make a bit image backup. That
> > is, not decode the bits, just record where they are.
> > That works even if it is an unusual low-level format.

> It's pretty brute-force, but yes, that's a workable approach. And it
> also means people who know nothing about the computers can run the
> backups.

> > That might be the best way to read old RM05 packs, too.

> It may be. Media recovery is mostly a solved problem for more common
> formats.
Reminds me of another DEC disk, which can be used on either PDP-10 or
byte addressed machines. The controllers are different, and can only write
blocks with the appropriate size, which I believe is 576 bytes for the PDP-10,
and 512 otherwise. You can't read disk packs on the other one.

On 2023-09-28 01:04, gah4 wrote:
> On Wednesday, September 27, 2023 at 1:01:40 PM UTC-7, Dave McGuire wrote:
>
> (snip regarding the Living Computer Museum)
>
>>> I believe the VAX runs on emulated disk, though.
>
>> Most everything there was emulated, it seems.
>
> Last I remember, the Xerox Sigma 9 was running on real disks.

Been quite a while since I visited LCM. However, I seem to remember
there were several real disks spinning. But yes, they were also working
on modern replacements. Not sure if I'd call that emulation, though.

Things like modern disks on massbus, made to look like some other disk.

> When it was open, the museum computers were running 24/7.
> Even when they were new, those drives were never expected
> to do that. Systems I remember, had a maintenance time every
> morning. And disks were often backed up every day.

I don't know about Xerox machines... But the DEC machines that LCM had
running were definitely meant to be running 24/7. And they usually were.

And something like backups don't mean the disks are not running. But
yes, having a regular backup schedule was as much a thing back then as
it is today.

Some systems had PM done maybe once per month, which at least brought
the OS down. But it usually didn't mean the system was powered down, but
some diagnostics to check the health of the hardware was run as a part
of the PM. Maybe a short power down if filters needed replacing, or
other physical cleaning was done.

> As well as I know it, whatever is running now, is running unattended.

I think anything larger is not running at LCM at the moment.
Simulations, or possibly some small stuff.

> At some point, though, it isn't obvious what emulated means.

True.

> I a MicroVAX an emulation of the 11/780?

I wouldn't call it that. Just as I don't consider a microcode
implementation in general to be some sort of simulation.
But I do understand that it's a bit fuzzy. You could call any software
that is written to emulate some CPU "microcode" of some sorts.

> In any case, yes, more is now emulated than when the museum
> was open. The Toad2 was designed as competition for DEC,
> not as a later day emulator.

? The Toad2 was designed long after DEC had left the PDP-10 scene. It
was designed because XKL wanted to do a (new) PDP-10, and needed the CPU
small enough to sit inside their network gear. (And it does...)
So it was designed for neither of the two intents you mentioned.

The Toad1 was an attempt at capturing the PDP-10 market that DEC had
left, but it was probably way too late.

> Does it matter if it is hardware emulation or software emulation?

Much of the time, no.

>>> Keeping old disk drives running is much harder than old CPUs.
>
>> It is, but we do it at LSSM. It's not like it's impossible.
>
> Running continuously for 20 years might be, though.

I have disk drives that I've been keeping running way longer than that.
But it very much varies with the disks how feasable it is.

RK05 seem to work forever. RL02 is also very dependable. RA60 I have a
horrible track record with. RA81 had their glue problems already 20
years ago. In general I've had pretty ok experience with RM02, RP06 and
RP07.

But with that said - it's always better if they are kept running. It's
prolonged storage that always cause the biggest problems. Both with
disks and machines in general.

> Oh, one more thing.
>
> One way that LCM does floppy disks, is to make a bit image
> backup. That is, not decode the bits, just record where they are.
> That works even if it is an unusual low-level format.
>
> That might be the best way to read old RM05 packs, too.

Noone really have the hardware to do this with an RM05 pack. LCM can do
it with floppies because someone made the hardware to make it possible.
But it's a nice ability, as such.

Johnny

On 2023-09-28 05:52, gah4 wrote:
> On Wednesday, September 27, 2023 at 5:55:54 PM UTC-7, Dave McGuire wrote:
>> On Wed, 27 Sep 2023 16:04:28 -0700 (PDT), gah4 wrote:
>>>>> Keeping old disk drives running is much harder than old CPUs.
>
>>>> It is, but we do it at LSSM. It's not like it's impossible.
>
>>> Running continuously for 20 years might be, though.
>
>> Nobody in their right mind would do that now. Not only is it pointless
>> (who's going to show up at 3AM to sit in front of a machine?) but there
>> are power bills to be paid, fire concerns, etc.
>
> Power bills I don't think LCM ever worried about, though maybe they should.

I run some small machines, and have had them running for over 20 years
now. Including disks... Hello PDP-11s...

>>> One way that LCM does floppy disks, is to make a bit image backup. That
>>> is, not decode the bits, just record where they are.
>>> That works even if it is an unusual low-level format.
>
>> It's pretty brute-force, but yes, that's a workable approach. And it
>> also means people who know nothing about the computers can run the
>> backups.
>
>>> That might be the best way to read old RM05 packs, too.
>
>> It may be. Media recovery is mostly a solved problem for more common
>> formats.
>
> Reminds me of another DEC disk, which can be used on either PDP-10 or
> byte addressed machines. The controllers are different, and can only write
> blocks with the appropriate size, which I believe is 576 bytes for the PDP-10,
> and 512 otherwise. You can't read disk packs on the other one.

There is the RK05 which is hard sector format and have two different
disk packs. One for 12-bit machines, with 16 sectors per track, and one
for 16-bit machines, which have 12 sectors per track.
I think those are close to impossible to read on the wrong machine.

But apart from that, I think most DEC controllers and disks had special
modes to read the odd stuff, but it wasn't very practical for anything
except possibly recover data on a different system.
But it might also have been that you couldn't read the pack at all. But
you could at least reformat it and use it on either system. (Talking
mostly about -16, -32 and -36 bit systems here.)

Johnny

On 2023-09-28 02:52, Dave McGuire wrote:
> On Wed, 27 Sep 2023 23:41:14 +0200, Johnny Billquist wrote:
>> Maybe not helpful, but just wanted to point out that you could dump the
>> disk if have an RM05 connected to a PDP-11/70 as well.
>
> Or indeed any Unibus PDP-11. Or any Qbus PDP-11 running directly to SMD
> with an SMD controller that's format-compatible, which many are.

Nope. The RM05 supposedly will not work on the RH11. Too slow for the
disk. RH11 only supported RM02, RP04, RP05 and RP06.

The RM02 was a slowed down RM03 for that specific reason.

As for SMD - not sure. DEC certainly used those OEM drives, but for some
reason the capacity was always less than the original drive, which makes
me wonder if DEC did something more funny as well.

Johnny

On 9/28/2023 6:53 AM, Johnny Billquist wrote:
> On 2023-09-28 05:52, gah4 wrote:
>>
>> Power bills I don't think LCM ever worried about, though maybe they
>> should.
>
> I run some small machines, and have had them running for over 20 years
> now. Including disks... Hello PDP-11s...
>

I always smile when I see comments about power usage on old computers.
People used to ask how I could afford to run my 11/24 and RA disks in
my house. Or my Apollo (which made a great room heater in the winter
time). I always pointed out things like when my wife would accidentally
forget to turn off her curling iron and it would run all day while we
were at work. Or even just lights. When the rest of the family would
leave lights on all day. Two 100 watt, eight 40 watt, etc. Add them
up. And then add in the electric clothes dryer, the refrigerator, the
electric water heater and the list goes on and on. Before long the
power consumed by old computers becomes little more than a blip on the
monthly bill. :-)

bill

On 9/28/2023 8:16 AM, bill wrote:
> On 9/28/2023 6:53 AM, Johnny Billquist wrote:
>> On 2023-09-28 05:52, gah4 wrote:
>>>
>>> Power bills I don't think LCM ever worried about, though maybe they should.
>>
>> I run some small machines, and have had them running for over 20 years now.
>> Including disks... Hello PDP-11s...

Since we're throwing around vague terminology, perhaps a definition of "running
for over 20 years now" might be helpful.

Not sure I can make such claims, as there are things like maintenance, cleaning,
power failure, moving, and such. A couple of weeks ago we had a 2-day power
outage. Rare, but it happens.

So, have some of my systems, VAXstation 4000 Model 90A, DEC PC from 1998,
AlphaServer 800 since (can't remember) been running for such extended times, or not?

Note, the itanic is not running, my ear plugs were not adequate ...

--
David Froble Tel: 724-529-0450
Dave Froble Enterprises, Inc. E-Mail: davef@tsoft-inc.com
DFE Ultralights, Inc.
170 Grimplin Road
Vanderbilt, PA 15486

Our goal is to get raw disk images of all of the platters and use emulation to restore the data.

Anything that has a funcional drive that can read these would be good for us.

On 2023-09-28 14:16, bill wrote:
> On 9/28/2023 6:53 AM, Johnny Billquist wrote:
>> On 2023-09-28 05:52, gah4 wrote:
>>>
>>> Power bills I don't think LCM ever worried about, though maybe they
>>> should.
>>
>> I run some small machines, and have had them running for over 20 years
>> now. Including disks... Hello PDP-11s...
>>
>
> I always smile when I see comments about power usage on old computers.
> People used to ask how I could afford to run my 11/24 and RA disks in
> my house.  Or my Apollo (which made a great room heater in the winter
> time). I always pointed out things like when my wife would accidentally
> forget to turn off her curling iron and it would run all day while we
> were at work.  Or even just lights.  When the rest of the family would
> leave lights on all day.  Two 100 watt, eight 40 watt, etc.  Add them
> up.  And then add in the electric clothes dryer, the refrigerator, the
> electric water heater and the list goes on and on.  Before long the
> power consumed by old computers becomes little more than a blip on the
> monthly bill.  :-)

Well. Let's not forget that the power spent there is less power spent
somewhere else, if I need heating. ;-)

It's not like the power disappears into thin air. Energy cannot be
destroyed.

Johnny

On 2023-09-28 15:01, Dave Froble wrote:
> On 9/28/2023 8:16 AM, bill wrote:
>> On 9/28/2023 6:53 AM, Johnny Billquist wrote:
>>> On 2023-09-28 05:52, gah4 wrote:
>>>>
>>>> Power bills I don't think LCM ever worried about, though maybe they
>>>> should.
>>>
>>> I run some small machines, and have had them running for over 20
>>> years now.
>>> Including disks... Hello PDP-11s...
>
> Since we're throwing around vague terminology, perhaps a definition of
> "running for over 20 years now" might be helpful.
>
> Not sure I can make such claims, as there are things like maintenance,
> cleaning, power failure, moving, and such.  A couple of weeks ago we had
> a 2-day power outage.  Rare, but it happens.

Admittedly, power outages have happened, but it was a few years since
last. Uptimes are not that impressive, since I constantly are whacking
at the kernel and networking, which requires me to sometimes reboot.

So - no. It's not been like 20+ years at 100%. But something close to
99.99% for me.

Before then, when I was a student back in the 90s, I lived in a student
apartmen (very small) where I was running my PDP-8 24/7. Sure it made
some noise, but I got used to it.
Besides, a lot of the time I was at the University, hanging in the
computer room next to a DEC-2060, a VAX-8650 and a PDP-11/70. At home
was silent compared to that...

Johnny

On 9/28/23 06:46, Johnny Billquist wrote:
>> That might be the best way to read old RM05 packs, too.
>
> Noone really have the hardware to do this with an RM05 pack.

Once again, we do have a CDC 9766 at LSSM. Someone just needs to
take it on as a project. The problem is manpower, not capability or
inventory.

-Dave

--
Dave McGuire, President/Curator
Large Scale Systems Museum
New Kensington, PA

On 9/28/23 06:55, Johnny Billquist wrote:
>>    Or indeed any Unibus PDP-11.  Or any Qbus PDP-11 running directly
>> to SMD
>> with an SMD controller that's format-compatible, which many are.
>
> Nope. The RM05 supposedly will not work on the RH11. Too slow for the
> disk. RH11 only supported RM02, RP04, RP05 and RP06.

Ahh, I did not know that. Will it actually fail to work, or just not
work very well (overruns/retries)? The distinction matters a lot when
the object is to recover old data from media that nobody else can handle.

> The RM02 was a slowed down RM03 for that specific reason.

Yes.

> As for SMD - not sure. DEC certainly used those OEM drives, but for some
> reason the capacity was always less than the original drive, which makes
> me wonder if DEC did something more funny as well.

We'll check the print sets when/if someone takes on that project.
But my admittedly decades old memory does recall that a CDC 9766 on an
Emulex controller (possibly an SC03) is media compatible with an RM05.

It's definitely the case that an Emulex controller (specifically) for
the VAX-11/750, whose model number I've forgotten, connected to a CDC
9762 is media-compatible with the RM02. I ran such a configuration at
work in the early 1990s and regularly moved packs between the two.

-Dave

--
Dave McGuire, President/Curator
Large Scale Systems Museum
New Kensington, PA

On 9/27/23 23:52, gah4 wrote:
>> Nobody in their right mind would do that now. Not only is it pointless
>> (who's going to show up at 3AM to sit in front of a machine?) but there
>> are power bills to be paid, fire concerns, etc.
>
> Power bills I don't think LCM ever worried about, though maybe they should.

Not anymore.

> Reminds me of another DEC disk, which can be used on either PDP-10 or
> byte addressed machines. The controllers are different, and can only write
> blocks with the appropriate size, which I believe is 576 bytes for the PDP-10,
> and 512 otherwise. You can't read disk packs on the other one.

RM02/RM03. There's a jumper on the backplane.

-Dave

--
Dave McGuire, President/Curator
Large Scale Systems Museum
New Kensington, PA

On Thursday, September 28, 2023 at 5:17:25 AM UTC-7, bill wrote:

(snip)

> I always smile when I see comments about power usage on old computers.
> People used to ask how I could afford to run my 11/24 and RA disks in
> my house. Or my Apollo (which made a great room heater in the winter
> time). I always pointed out things like when my wife would accidentally
> forget to turn off her curling iron and it would run all day while we
> were at work.

Most college dorms don't allow heaters in the room.
But they do allow computers.

Some years ago, someone was suggesting that old Sun workstations
make nice room heaters. That was when they were around, and being
sold for very low prices. By now, the prices are up again.

That was for the desk side VME based models. The desktop
versions might not use enough power to warm a room.

And someone mentioned Itanic. As well as I know, the
power supply for (each) chip is 1 volt at 100 amps,
for 100 watts. Many are dual processor. But they do
tend to have noisy fans.

On 2023-09-28 18:43, Dave McGuire wrote:
> On 9/27/23 23:52, gah4 wrote:
>> Reminds me of another DEC disk, which can be used on either PDP-10 or
>> byte addressed machines. The controllers are different, and can only
>> write
>> blocks with the appropriate size, which I believe is 576 bytes for the
>> PDP-10,
>> and 512 otherwise.  You can't read disk packs on the other one.
>
>   RM02/RM03.  There's a jumper on the backplane.

I've been reading the RM02/RM03 manuals, and I can't find any
documentation on any backplane jumper for such a purpose. There are
jumpers for drive type and serial number, but that's about it as far as
I can find.

By the way, it's kind of strange to talk about different "controllers".
Of course they are different. The PDP-10 have a very different massbus
controller compared to a PDP-11 or a VAX. But they all talk massbus, and
the devices on the massbus itself is sortof agnostic to the machine word
size.

But the disk packs just have a different format depending on what they
are used for, and that formatting can be changed on a per-track basis.
The format is in the header for each sector.

Johnny

On 2023-09-28 18:37, Dave McGuire wrote:
> On 9/28/23 06:46, Johnny Billquist wrote:
>>> That might be the best way to read old RM05 packs, too.
>>
>> Noone really have the hardware to do this with an RM05 pack.
>
>   Once again, we do have a CDC 9766 at LSSM.  Someone just needs to
> take it on as a project.  The problem is manpower, not capability or
> inventory.

Well, the comment was about someone having something equivalent to the
KryoFlux solution for floppies, but addressing the RM05 disk pack.

Do you have the equivalent of a KryoFlox to read that pack? Another disk
drive isn't exactly the same thing, unless you are suggesting to rip out
the electronics, and put in something else/new that will give you the
raw magnetic fluctuations.

Johnny

On 2023-09-28 18:41, Dave McGuire wrote:
> On 9/28/23 06:55, Johnny Billquist wrote:
>>>    Or indeed any Unibus PDP-11.  Or any Qbus PDP-11 running directly
>>> to SMD
>>> with an SMD controller that's format-compatible, which many are.
>>
>> Nope. The RM05 supposedly will not work on the RH11. Too slow for the
>> disk. RH11 only supported RM02, RP04, RP05 and RP06.
>
>   Ahh, I did not know that.  Will it actually fail to work, or just not
> work very well (overruns/retries)?  The distinction matters a lot when
> the object is to recover old data from media that nobody else can handle.

I've never actually tried running en RM05 on an RH11. I've not tried an
RP07 either. But I suspect you might be dropping data on the DMA
transfer, so potentually a non-solvable overrun problem.

I know that I had problems with the RP07 on an RH70. However, tne RP07
can be set in an interleave mode that drops the transfer rate some,
which is enough for the RH70 to keep up.

>> As for SMD - not sure. DEC certainly used those OEM drives, but for
>> some reason the capacity was always less than the original drive,
>> which makes me wonder if DEC did something more funny as well.
>
>   We'll check the print sets when/if someone takes on that project. But
> my admittedly decades old memory does recall that a CDC 9766 on an
> Emulex controller (possibly an SC03) is media compatible with an RM05.

That would be interesting to get confirmed.

>   It's definitely the case that an Emulex controller (specifically) for
> the VAX-11/750, whose model number I've forgotten, connected to a CDC
> 9762 is media-compatible with the RM02.  I ran such a configuration at
> work in the early 1990s and regularly moved packs between the two.

That's interesting, and good to know. The RM02 and RM03 are the same
drive, and packs can be moved freely between them. The RM02 just spins
slower.

Johnny