On 9/28/23 17:38, Johnny Billquist wrote:
> 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.

Ok. But since there aren't any RM05s around anyway, at least none
that anyone is aware of, it's a non-issue. One of our PDP-11/55s has an
RH11 in it so I mentioned it.

>> 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.

A brief look at the Emulex SC03 manual confirms it.

>>    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.

Yes.

-Dave

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

On 9/28/23 17:34, 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.

I don't know why you're being so argumentative today. I hope
everything is ok.

LSSM is not going to be doing any flux-transition imaging on a 9766.
If that's what the OP wants, he's not going to have an easy time finding
it. We could certainly do it with a lot of time and money, but there
aren't a lot of 9766 packs out there anymore, so it really wouldn't be
worth the investment in time and effort.

But what we DO have, once again, is a CDC 9766 drive, and controllers
for it for a couple of different buses that will read and write 9766
packs in the format used by the DEC RM05. It's much easier to get a
drive running on a computer and do a "dd" like a sane person. If the
goal is to recover the data from intact well-stored disk packs, that's
the best way to do it.

We're not new at this; we do quite a lot of media imaging at LSSM.
We would not approach it any other way.

-Dave

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

On Thursday, September 28, 2023 at 6:55:22 AM UTC-4, Johnny Billquist wrote:
> 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.

A Certain Large Bank paid DEC a lot of money way-back-when to investigate
the issue (it was holding up a mass migration from 11/70 to 11/84 systems).
It turned out that a minor change to the RH11 allowed the RH11/Unibus to
keep up, and the migration proceeded. DEC wasn't interested in publicizing
the change - everyone with RM02 drives on RH11's would be complaining.

> 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.

It might have been so they could have similar rated capacities for 36-bit vs.
16/32-bit hosts. SMD manufacturers generally provided long lists of sector
size select settings and left it up to their customers to select sector sizes
and capacities. You get a fixed number of bits/track, so larger sector sizes
are generally a capacity win due to decreased overhead, except when that
takes you over the bits/track limit and capacity/track drops back in those
tables.

But manufacturers do some weird stuff. MAI Basic Four sold rebadged
Calcomp Trident T-50 drives and rated them for 30MB or something weird
like that.

On Thursday, September 28, 2023 at 8:17:25 AM UTC-4, bill wrote:
> 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.

There's a famous roomful of laughs session from a DECUS Symposium.
For those who don't remember, in the Q&A part you'd step up to the
microphone and state your name, company affiliation, and ask your
question.

Someone steps up and does all of that. The DEC answer was something
along the line of "you should be using X instead because of the power
savings alone". The person says "Perhaps you didn't hear my company
affiliation - Hydro Quebec". Room bursts out in laughter. DEC employee
looks embarrassed.

On Thursday, September 28, 2023 at 5:31:07 PM UTC-4, Johnny Billquist wrote:
> 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.

I assume you mean in the Massbus controller in the bottom of the drive.
The actual drive logic cage has not very many not very big not very bright
cards. As I recall, maybe 5" x 5". I modified a couple sets of drive cards
to change the upper cylinder limit. I was subcontracting data recovery
and they'd send me crashed-but-cleaned packs and tell me "don't go past
cylinder X" when doing the recovery.

I don't know why DEC didn't do Massbus disk strings the way they did
Massbus tape strings - you can't have multiple data transfers going at
the same time on the Massbus anyway, and the Massbus supported
per-drive things like "Seek Complete" already. I guess customers that
cared about over-paying for drives just bought the CDC versions and
3rd-party controllers.

I remember when Emulex came out with a new generation of SMD
controller - UD33, perhaps. I thought the biggest "win" on the new card
was getting rid of the high-speed processor logic in favor of dedicated
gate arrays. I asked my contact at Emulex (I was field testing) what
they thought the most important thing was. They said "controller-
resident diagnostics".

> 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.

Massbus is weird. Somebody saw IBM 360 bus/tag cables and went
"This would be a good idea - how can we make it bizarrely different?"
Trivial example - the RP07 is logically an RM device, not RP. Surprised
a bunch of early customers who tried adding one to a string of RP06
drives.

On Thursday, September 28, 2023 at 7:59:16 PM UTC-7, Dave McGuire wrote:

(snip)

> I don't know why you're being so argumentative today. I hope
> everything is ok.
> LSSM is not going to be doing any flux-transition imaging on a 9766.
> If that's what the OP wants, he's not going to have an easy time finding
> it. We could certainly do it with a lot of time and money, but there
> aren't a lot of 9766 packs out there anymore, so it really wouldn't be
> worth the investment in time and effort.
(snip)

Sorry, that was my suggestion. Not knowing all the details ...
how hard it is to find the appropriate host, controller, drive, and whatever
else might be needed.

It is convenient in that it removes some of the possible problems,
but as you note, creates others.

It seems that the 9766 is SMD, and someone might have done
flux-transition imaging on SMD disks before. (Or maybe not.)

Past that, I don't know that high or low level formatting is the
same for all systems using such drives.

On 2023-09-28, Dave McGuire <mcguire@lssmuseum.org> wrote:
> On 9/28/23 17:34, Johnny Billquist wrote:
>>
>> 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.
>
> I don't know why you're being so argumentative today. I hope
> everything is ok.
>

It's not you - it's Johnny. He's just like that with everyone. :-)

Perhaps life in Zurich doesn't agree with him and he wants to go
back home to Sweden... :-)

Or perhaps he's just a grumpy old sod... :-)

Simon.

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

On 9/29/23 03:25, gah4 wrote:
>> LSSM is not going to be doing any flux-transition imaging on a 9766.
>> If that's what the OP wants, he's not going to have an easy time finding
>> it. We could certainly do it with a lot of time and money, but there
>> aren't a lot of 9766 packs out there anymore, so it really wouldn't be
>> worth the investment in time and effort.
>
> (snip)
>
> Sorry, that was my suggestion. Not knowing all the details ...
> how hard it is to find the appropriate host, controller, drive, and whatever
> else might be needed.

Oh ok, no worries.

> It is convenient in that it removes some of the possible problems,
> but as you note, creates others.
>
> It seems that the 9766 is SMD, and someone might have done
> flux-transition imaging on SMD disks before. (Or maybe not.)

Yes, Chris Fenton did so with a 9762 to recover Cray's COS OS. It's
possible. But frankly if we're going to get the drive running to that
degree anyway, we may as well just connect it to a controller.

> Past that, I don't know that high or low level formatting is the
> same for all systems using such drives.

It's not, but some of the third-party controllers were specifically
designed to be format-compatible with generic (i.e. non-DEC-repackaged)
drives, i.e. an RM02 is a repackaged CDC 9762 SMD drive with a MASSBUS
interface in the bottom, but an Emulex SC03 controller connected to a
CDC 9762's SMD interface will read and write DEC RM02-interchangeable
disk packs. I've done this myself with a different (also Emulex)
controller, at work in the early 1990s on a VAX-11/750.

-Dave

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

On 9/29/23 08:12, Simon Clubley wrote:
>>> 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.
>>
>> I don't know why you're being so argumentative today. I hope
>> everything is ok.
>
> It's not you - it's Johnny. He's just like that with everyone. :-)

Sure, but he's just usually nicer to me on some of the mailing lists.
;) Every highly intelligent person has one "thing" or another.
Johnny's is grumpiness, it's ok. :)

> Perhaps life in Zurich doesn't agree with him and he wants to go
> back home to Sweden... :-)

ROFL

We should import him to the States so he can help us work on machines
at the museum!

> Or perhaps he's just a grumpy old sod... :-)

Perhaps. ;)

-Dave

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

On 9/29/2023 8:12 AM, Simon Clubley wrote:
> On 2023-09-28, Dave McGuire <mcguire@lssmuseum.org> wrote:
>> On 9/28/23 17:34, Johnny Billquist wrote:
>>>
>>> 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.
>>
>> I don't know why you're being so argumentative today. I hope
>> everything is ok.
>>
>
> It's not you - it's Johnny. He's just like that with everyone. :-)
>
> Perhaps life in Zurich doesn't agree with him and he wants to go
> back home to Sweden... :-)
>
> Or perhaps he's just a grumpy old sod... :-)
>
> Simon.
>

Pot, meet kettle ....

:-)

--
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

gah4 <gah4@u.washington.edu> writes:

> 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.

You meant "2020", of course.

> I believe the VAX runs on emulated disk, though.=20

Your belief is irrelevant.

The VAX 11/780-5 ran against an HSJ with a full load of 2GB drives.

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

We had a couple of RM05s, but they were part of a DECSYSTEM-2020 that was kept
unrestored (the late Mark Crispin's Lingling.Panda.com).

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

Preach.

--
Rich Alderson news@alderson.users.panix.com
Audendum est, et veritas investiganda; quam etiamsi non assequamur,
omnino tamen proprius, quam nunc sumus, ad eam perveniemus.
--Galen

Dave McGuire <mcguire@lssmuseum.org> writes:

> On 9/27/23 15:17, gah4 wrote:

>> 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.

We emulated two kinds of drives:

1. Large Massbus drives (RP06 and RP07), because media for either type was
unavaiable. The last disk manufacturer in the US shipped us a batch of
"RP06" packs which were unformattable, because they had changed the
chemistry of the slurry.

2. The CDC drives used by the Xerox Sigma 9, because we had learned our lesson
by then.

>> 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.

We kept RK05, RM02, RM03, and RL01 drives running for smaller DEC equipment, as
well as the drives on the Altos. It's not impossible, but it wasn't our
primary raison d'etre...

NB: I received training from a former DEC FE in how to install and tune heads
in an RP06--without the magic suitcase, just a torque wrench. So don't tell me
what is and isn't doable.

--
Rich Alderson news@alderson.users.panix.com
Audendum est, et veritas investiganda; quam etiamsi non assequamur,
omnino tamen proprius, quam nunc sumus, ad eam perveniemus.
--Galen

On Friday, September 29, 2023 at 3:12:43 PM UTC-7, Rich Alderson wrote:
> gah4 <ga...@u.washington.edu> writes:
> > 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.
> You meant "2020", of course.

Yes, but it makes a better excuse for forgetting which machines are
connected to what.

And it was a while before 2020 when I was last there.
> > I believe the VAX runs on emulated disk, though.=20
> Your belief is irrelevant.
> The VAX 11/780-5 ran against an HSJ with a full load of 2GB drives.

I remember the corner with drives, and remember it being closer
to the PDP-10 than the 11/780-5. The web site doesn't have much
of a map of what is where, and even less, what is connected to what.
> > They do have VAX disk drives, but I don't remember RM05 being one of them.
> We had a couple of RM05s, but they were part of a DECSYSTEM-2020 that was kept
> unrestored (the late Mark Crispin's Lingling.Panda.com).
> > Keeping old disk drives running is much harder than old CPUs.
> Preach.

gah4 <gah4@u.washington.edu> writes:

> On Wednesday, September 27, 2023 at 5:55:54=E2=80=AFPM UTC-7, Dave McGuire wrote:

>> On Wed, 27 Sep 2023 16:04:28 -0700 (PDT), gah4 wrote:=20

>>> 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.

Glen forgets that most of the museum was devoted to small machines, since he is
a mainframer at heart.

And the 4331 was a special case with respect to disk emulation (I forgot about
it, to be honest).

The Massbus Disk Emulator (both generations) was an in-house design whose
backend was a Linux box handling ordinary files using pre-existing tools (FTP!,
nfs).

For the 4331, we licensed/purchased a pair (operating and hot spare) of Flex-ES
servers from Fundamental Software in California. This is a Linux server
running a specific software load, including specialized software for
interacting with the IBM channels, that connects to the 4331 via bus-and-tag.

The two are similar responses to similar needs.

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

There shouldn't have been any stories about that--we never intended to try to
run them. See my earlier answer about learning our lesson WRT the Sigma.

>>> 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.

You've remembered almost everything exactly wrong.

When the School of Engineering at Purdue was finished with the 6500, in 1989,
CDC decommissioned it in order to donate it to the Chippewa Falls Museum of
Industry and Technology, in Seymour Cray's home town. (The local industry as
the Leinenkugel brewery, the technology was Seymour.) It was CDC who cut all
the interior cables off at the bulkheads.

The company which built the original cables is (was) still in business, and
even had the original build specs from when CDC ordered them: 19 coaxes in a
bundle, specs on frequency response and all that.

Back in the early 1960s, when Seymour designed the 6600 and its follow-ons, he
did not like either gold or tin for pins. He specified silver. NB: Not
"silver plated", solid silver.

We needed about 10,000 pins for the new cables. The company which made the
pins could do it, but their minimum order was much larger; we had to provide
enough silver bullion to make 50,000 pins.

The pins are easiy bent, so we probably used 12K-13K putting the system back
together. The late David Cameron nearly went blind (and crazy) getting all
those pins inserted; in the end, we found only two or three that he got wrong.

>> 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.

[ snip ]

> 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.

That would be any RP06, RP07, RA81, RA60, or RM03.

--
Rich Alderson news@alderson.users.panix.com
Audendum est, et veritas investiganda; quam etiamsi non assequamur,
omnino tamen proprius, quam nunc sumus, ad eam perveniemus.
--Galen

"terry-...@glaver.org" <terry-groups@glaver.org> writes:

> On Thursday, September 28, 2023 at 5:31:07=E2=80=AFPM UTC-4, Johnny Billquist wrote:

>> I've been reading the RM02/RM03 manuals, and I can't find any=20
>> 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.

> I assume you mean in the Massbus controller in the bottom of the drive.
> The actual drive logic cage has not very many not very big not very bright
> cards. As I recall, maybe 5" x 5". I modified a couple sets of drive cards
> to change the upper cylinder limit. I was subcontracting data recovery
> and they'd send me crashed-but-cleaned packs and tell me "don't go past
> cylinder X" when doing the recovery.

The DCL ("DEC control logic") on an RP06 is about a dozen hex height boards in
a special card cage on the side. The little 5"x5" cards in the top of the
drive are Memorex (the OEM).

> I don't know why DEC didn't do Massbus disk strings the way they did
> Massbus tape strings - you can't have multiple data transfers going at
> the same time on the Massbus anyway, and the Massbus supported
> per-drive things like "Seek Complete" already. I guess customers that
> cared about over-paying for drives just bought the CDC versions and
> 3rd-party controllers.

I don't understand what you mean here. We had strings of up to 8 RP07 or RP06
drives on our DEC-20s.

> Massbus is weird. Somebody saw IBM 360 bus/tag cables and went
> "This would be a good idea - how can we make it bizarrely different?"
> Trivial example - the RP07 is logically an RM device, not RP. Surprised
> a bunch of early customers who tried adding one to a string of RP06
> drives.

Not sure I ever saw more than one RP06 on a DEC-20 with RP07s, since only one
was needed for the 11/40 front end. It wouldn't make sense to daisychain the
big drives through that any way.

--
Rich Alderson news@alderson.users.panix.com
Audendum est, et veritas investiganda; quam etiamsi non assequamur,
omnino tamen proprius, quam nunc sumus, ad eam perveniemus.
--Galen

On Friday, September 29, 2023 at 3:55:00 PM UTC-7, Rich Alderson wrote:

(snip)

> Glen forgets that most of the museum was devoted to small machines, since he is
> a mainframer at heart.
>
> And the 4331 was a special case with respect to disk emulation (I forgot about
> it, to be honest).

(snip)

> > They had 3350's for the 4331, but never tried running them.
> > There were stories about how hard they were to get running.
> There shouldn't have been any stories about that--we never intended to try to
> run them. See my earlier answer about learning our lesson WRT the Sigma.
The stories were not from LCM, but from outside.
It seems, for reasons I forget, that they are worse than others.

> > 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.
> You've remembered almost everything exactly wrong.
It was some years by now.

I think, though, that I am remembering the explanation given
to tour groups, which didn't have quite as much detail as:

> When the School of Engineering at Purdue was finished with the 6500, in 1989,
> CDC decommissioned it in order to donate it to the Chippewa Falls Museum of
> Industry and Technology, in Seymour Cray's home town. (The local industry as
> the Leinenkugel brewery, the technology was Seymour.) It was CDC who cut all
> the interior cables off at the bulkheads.
But why cut the cables, when they could unplug them?

Reminds me, though, for the 360/20 someone did nicely remove the
cables, and then the museum didn't get them. Might have gone to
metal recycling. There are nice cable clamps that someone screwed back
together after removing them.

And even with cut cables, one could (hopefully) match up the colors.

> The company which built the original cables is (was) still in business, and
> even had the original build specs from when CDC ordered them: 19 coaxes in a
> bundle, specs on frequency response and all that.
> Back in the early 1960s, when Seymour designed the 6600 and its follow-ons, he
> did not like either gold or tin for pins. He specified silver. NB: Not
> "silver plated", solid silver.
> We needed about 10,000 pins for the new cables. The company which made the
> pins could do it, but their minimum order was much larger; we had to provide
> enough silver bullion to make 50,000 pins.
Cray was always hard to figure out. He liked ones' complement for the CDC
machines, though finally two's complement for the Cray-1.

But there was some story, which I forget the details of, that there was a
minimum order, and then they didn't want to make that many.

But I don't remember either of the numbers.

> The pins are easiy bent, so we probably used 12K-13K putting the system back
> together. The late David Cameron nearly went blind (and crazy) getting all
> those pins inserted; in the end, we found only two or three that he got wrong.

I don't think tours got this explanation.

> [ snip ]
> > 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.

> That would be any RP06, RP07, RA81, RA60, or RM03.
So not just a switch or jumper, but needs a whole new controller.

On 9/29/23 18:21, Rich Alderson wrote:
> We emulated two kinds of drives:
>
> 1. Large Massbus drives (RP06 and RP07), because media for either type was
> unavaiable. The last disk manufacturer in the US shipped us a batch of
> "RP06" packs which were unformattable, because they had changed the
> chemistry of the slurry.

I wish you had contacted us; we have some RP06 packs that we'd have
been happy to share with you.

>>> 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.
>
> We kept RK05, RM02, RM03, and RL01 drives running for smaller DEC equipment, as
> well as the drives on the Altos. It's not impossible, but it wasn't our
> primary raison d'etre...
>
> NB: I received training from a former DEC FE in how to install and tune heads
> in an RP06--without the magic suitcase, just a torque wrench. So don't tell me
> what is and isn't doable.

Exactly. Those drives are comparatively easy to maintain, parts are
findable, and the documentation is first-rate.

-Dave

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

On Friday, September 29, 2023 at 7:06:46 PM UTC-4, Rich Alderson wrote:
> "terry-...@glaver.org" <terry-...@glaver.org> writes:
> > I assume you mean in the Massbus controller in the bottom of the drive.
> > The actual drive logic cage has not very many not very big not very bright
> > cards. As I recall, maybe 5" x 5". I modified a couple sets of drive cards
> > to change the upper cylinder limit. I was subcontracting data recovery
> > and they'd send me crashed-but-cleaned packs and tell me "don't go past
> > cylinder X" when doing the recovery.
> The DCL ("DEC control logic") on an RP06 is about a dozen hex height boards in
> a special card cage on the side. The little 5"x5" cards in the top of the
> drive are Memorex (the OEM).

I was talking about RM drives here, specifically the RM05. RP's were a
different kettle of fish..

> > I don't know why DEC didn't do Massbus disk strings the way they did
> > Massbus tape strings - you can't have multiple data transfers going at
> > the same time on the Massbus anyway, and the Massbus supported
> > per-drive things like "Seek Complete" already. I guess customers that
> > cared about over-paying for drives just bought the CDC versions and
> > 3rd-party controllers.
> I don't understand what you mean here. We had strings of up to 8 RP07 or RP06
> drives on our DEC-20s.

I 'm remembering each drive having an unnecessarily-replicated Massbus
controller, while SMD supported 4 drives per controller. So a string of 8
RM05's would occupy 12 cabinets, 8 for drives and 4 for Massbus adapters
(with 2 adapters per cabinet). EK-0RM05-UG-002_Mar82 on Bitsavers
seems to confirm that (for example, on page 1-7).

Massbus tapes like the TU78 could have a drive with a Massbus control-
ler ("primary", to use today's terminology) to which a number of additional
TU78 drives ("secondary") could be attached.

> > Massbus is weird. Somebody saw IBM 360 bus/tag cables and went
> > "This would be a good idea - how can we make it bizarrely different?"
> > Trivial example - the RP07 is logically an RM device, not RP. Surprised
> > a bunch of early customers who tried adding one to a string of RP06
> > drives.
> Not sure I ever saw more than one RP06 on a DEC-20 with RP07s, since only one
> was needed for the 11/40 front end. It wouldn't make sense to daisychain the
> big drives through that any way.

I ran a PDP-11/VAX shop, so I don't know what the DEC-20 and related
hardware did. I did have some friends at other companies who decided
to expand their RP06 storage with an RP07 with other-than-expected
results. I actually ended up with one of those RP07s at SPC because of
this. It died when the local excuse for an electric utility flipped phases
and kicked it into a high-speed reverse. The RP07 logic did have a "phase
error" detector/LED, but at 60 media rotations per single AC cycle, that
didn't prevent the disaster.

On 2023-09-30 01:06, Rich Alderson wrote:
> "terry-...@glaver.org" <terry-groups@glaver.org> writes:
>
>> On Thursday, September 28, 2023 at 5:31:07=E2=80=AFPM UTC-4, Johnny Billquist wrote:
>
>>> I've been reading the RM02/RM03 manuals, and I can't find any=20
>>> 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.
>
>> I assume you mean in the Massbus controller in the bottom of the drive.
>> The actual drive logic cage has not very many not very big not very bright
>> cards. As I recall, maybe 5" x 5". I modified a couple sets of drive cards
>> to change the upper cylinder limit. I was subcontracting data recovery
>> and they'd send me crashed-but-cleaned packs and tell me "don't go past
>> cylinder X" when doing the recovery.
>
> The DCL ("DEC control logic") on an RP06 is about a dozen hex height boards in
> a special card cage on the side. The little 5"x5" cards in the top of the
> drive are Memorex (the OEM).

The RM and RP massbus interfaces are very different. Which, in a sense,
is surprising, since I think they all have SMD in the end.

But for the RM02/03 the massbus adapter sits below the disk in the same
housing as the drive. The RM05 is yet again different and have it sortof
on the side, but you can actually hook up two drives to the same massbus
interface. And the RP04/05/06, as you note, have a side attachment to
the drive, where the massbus interfacing sits. Also with the RP drives,
DEC actually have a modified SMD interface, so no normal SMD drive can
be conntected. And the drive from Memorex (was there some other source
as well?) actually is of a special DEC variation, with a couple of cards
not being the same as when the drive was sold as an SMD drive.

And of course the RP07 (which is an RM drive) have the massbus
interfacing more integrated with the rest of the control logic of the
dive, and I can't remember seeing any separate box with that interface.

>> I don't know why DEC didn't do Massbus disk strings the way they did
>> Massbus tape strings - you can't have multiple data transfers going at
>> the same time on the Massbus anyway, and the Massbus supported
>> per-drive things like "Seek Complete" already. I guess customers that
>> cared about over-paying for drives just bought the CDC versions and
>> 3rd-party controllers.
>
> I don't understand what you mean here. We had strings of up to 8 RP07 or RP06
> drives on our DEC-20s.

Terry talks about tape drives as a comparison. For those, you have the
formatter (usually a TM03) which is what actually sits on the massbus.
One formatted can control up to 8 tape drives, meaning you could have as
many as 64 tape drives on one massbus.

But at the same time, that's the crux of it. For disk drives, there were
never anything equivalent to the tape formatter with subunits.
But it guess in theory it could have been done.

But people usually didn't have that many disk drives anyway, so there
were no real need, I guess.
Not sure if anyone ever really ran with that many tape drives either. I
don't think I've ever seen additional slave drives hooked up to a tape
formatter.

>> Massbus is weird. Somebody saw IBM 360 bus/tag cables and went
>> "This would be a good idea - how can we make it bizarrely different?"
>> Trivial example - the RP07 is logically an RM device, not RP. Surprised
>> a bunch of early customers who tried adding one to a string of RP06
>> drives.
>
> Not sure I ever saw more than one RP06 on a DEC-20 with RP07s, since only one
> was needed for the 11/40 front end. It wouldn't make sense to daisychain the
> big drives through that any way.

At my University we were running a -2060 with three RP06 and one RP07.

The FE have nothing to do with it. The RP06 used for the FE is
dual-ported. The PDP-11 massbus only goes to that drive. The additional
RP06s and RP07 were/are just on the -20.

Johnny

On 2023-09-30 03:07, gah4 wrote:
> On Friday, September 29, 2023 at 3:55:00 PM UTC-7, Rich Alderson wrote:
>

>> [ snip ]
>>> 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.
>
>> That would be any RP06, RP07, RA81, RA60, or RM03.
>
> So not just a switch or jumper, but needs a whole new controller.

Again - no.

If you have a DEC-20 then you are using a RH-20 controller, which via
massbus cables connect to the disk drive. The disk drive itself have no
clue about the format, and you can reformat the disk packs for 18-bit
mode. All in the software.

If you have a PDP-11/70, you are using a RH-70 controller, which via
massbus cables connect to the disk drive. The disk drive is still the
same, and you reformat your pack for 16-bit mode.

If you have a VAX-11/780, you are using a RH-780 controller, which via
massbus cables connect to the disk drive. 16-bit mode. Software.

If we instead talk RA-81, then I'm not sure if the drive could be
reformatted, or if it was actually just a performatted HDA for either
mode. The RA60 I'm pretty sure can be reformatted for 16-bit or 18-bit mode.
But the drives themselves are connected to a controller. For Unibus
machines that would be a UDA-50. As an alternative, they could be
connected to a HSC, which then talks CI. And there was CI-780 and CI-20.
But the HSC is the same independent of machine.

Johnny

On 2023-09-29 04:59, Dave McGuire wrote:
> On 9/28/23 17:34, 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.
>
>   I don't know why you're being so argumentative today.  I hope
> everything is ok.
>
>   LSSM is not going to be doing any flux-transition imaging on a 9766.
> If that's what the OP wants, he's not going to have an easy time finding
> it.  We could certainly do it with a lot of time and money, but there
> aren't a lot of 9766 packs out there anymore, so it really wouldn't be
> worth the investment in time and effort.

I'm not being argumentative, I think. I'm just trying to keep this to
what the OP was writing. You offering something else is fine, but you
need to understand that it was not what was suggested by the OP. And
when I say that what the OP was suggesting is going to be very hard, I
don't appreciate when you disagree with me, when you in the end appear
to understand that what I said is correct - it is going to be very hard.

If anything, I would say you are being argumentative, for no good reason.

Johnny

On 2023-09-29 14:12, Simon Clubley wrote:
> On 2023-09-28, Dave McGuire <mcguire@lssmuseum.org> wrote:
>> On 9/28/23 17:34, Johnny Billquist wrote:
>>>
>>> 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.
>>
>> I don't know why you're being so argumentative today. I hope
>> everything is ok.
>>
>
> It's not you - it's Johnny. He's just like that with everyone. :-)
>
> Perhaps life in Zurich doesn't agree with him and he wants to go
> back home to Sweden... :-)
>
> Or perhaps he's just a grumpy old sod... :-)

Or perhaps I'm right?

Johnny

On 2023-09-29 16:31, Dave McGuire wrote:
> On 9/29/23 08:12, Simon Clubley wrote:
>>>> 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.
>>>
>>>     I don't know why you're being so argumentative today.  I hope
>>> everything is ok.
>>
>> It's not you - it's Johnny. He's just like that with everyone. :-)
>
>   Sure, but he's just usually nicer to me on some of the mailing lists.
> ;)  Every highly intelligent person has one "thing" or another. Johnny's
> is grumpiness, it's ok. :)

I don't think I was unnice here. OP asked for a cryoflux-like solution.
I said that's going to be hard. You disagreed, while not getting what he
asked for. And claiming you can do it. In the end, you also understood
the point and that a cryoflux-like solution is going to be hard.

>> Perhaps life in Zurich doesn't agree with him and he wants to go
>> back home to Sweden... :-)
>
>   ROFL
>
>   We should import him to the States so he can help us work on machines
> at the museum!

In a sense I'd love it. But I also need to earn some money, and I
suspect you don't havae budget for a salary. ;-)

>> Or perhaps he's just a grumpy old sod... :-)
>
>   Perhaps. ;)

I'm definitely that too.

Johnny

On 2023-10-02 12:03, Johnny Billquist wrote:
> On 2023-09-29 16:31, Dave McGuire wrote:
>>    Sure, but he's just usually nicer to me on some of the mailing
>> lists. ;)  Every highly intelligent person has one "thing" or another.
>> Johnny's is grumpiness, it's ok. :)
>
> I don't think I was unnice here. OP asked for a cryoflux-like solution.
> I said that's going to be hard. You disagreed, while not getting what he
> asked for. And claiming you can do it. In the end, you also understood
> the point and that a cryoflux-like solution is going to be hard.

Putthing this another way:

Person A: I would like to do X.
Person B: That would be hard.
Person C: No, it's not hard to do Y at all.
Person B: But that is not what was asked for.

And you claim that person B was then unnice?

Johnny

On Monday, October 2, 2023 at 2:56:55 AM UTC-7, Johnny Billquist wrote:
> On 2023-09-30 03:07, gah4 wrote:

(snip regarding 512 vs 576 byte sectors)

> > So not just a switch or jumper, but needs a whole new controller.
> Again - no.
> If you have a DEC-20 then you are using a RH-20 controller, which via
> massbus cables connect to the disk drive. The disk drive itself have no
> clue about the format, and you can reformat the disk packs for 18-bit
> mode. All in the software.
> If you have a PDP-11/70, you are using a RH-70 controller, which via
> massbus cables connect to the disk drive. The disk drive is still the
> same, and you reformat your pack for 16-bit mode.

The question wasn't (supposed to be) what you could reformat,
but what you could read.

Can you read a 576 byte/sector RP-06 on a VAX?

Can you read a 512 byte/sector RP-06 on a PDP-10?