5 Jun
2018
5 Jun
'18
10:08 a.m.
On Mon, Jun 4, 2018 at 5:13 PM, Paul Koning via cctalk
<cctalk at classiccmp.org> wrote:
> On Jun 4, 2018, at 1:17 PM, Robert Armstrong via
cctalk <cctalk at classiccmp.org> wrote:
>
> ... FWIW, I have a 725 complete and working. Well, except for the RC25, which never
worked even when they were new.
I had an 11/725 in the 80s and 90s and never had a problem with the
RC25 but they are legendarily terrible.
Hm. I remember some RC25s on RSTS, and they seemed to
be ok. The fact that they had two drives on one motor made it strange, especially if the
fixed platter was your system device. We had to teach the OS how to deal with SY: going
away temporarily.
Oof, yeah. When I used my 725, I didn't spin the RC25 up and down
except when booting and shutting down. I also had devices like RL02s
for removable storage.
I often wonder how hard it would be to develop some other storage
device for the KELSI but then other projects push to the top of the
stack and I move on.
Mostly, what I need is affordable ($250 or less) Unibus storage with
modern media (Flash or IDE adapter or whatever). I don't really care
what form it takes but Unibus SCSI cards are quite pricey and making a
new controller is even less affordable (I used to make and support
DMA-enabled Unibus communication controllers for a living so I have a
pretty good idea of the amount of effort required).
-ethan
5 Jun
5 Jun
10:34 a.m.
On 06/05/2018 01:08 PM, Ethan Dicks via cctalk wrote:
On Mon, Jun 4, 2018 at 5:13 PM, Paul Koning via
cctalk
<cctalk at classiccmp.org> wrote:
I had one on a PDP-11 and never had a problem right up
until I gave it away.
bill
> On Jun 4, 2018, at 1:17 PM, Robert Armstrong
via cctalk <cctalk at classiccmp.org> wrote:
>
> ... FWIW, I have a 725 complete and working. Well, except for the RC25, which never
worked even when they were new.
I had an 11/725 in the 80s and 90s and never had a
problem with the
RC25 but they are legendarily terrible.
11:53 a.m.
I too have heard that RC25s and PDP-11s were used in nuclear subs for some kind of sonar
thingie. I've no idea how that worked, except that maybe DEC gave all the good drives
to the Navy and the rest of us got the crappy ones.
They worked as long as you didn't spin them down or try to change the removable
pack. The removable part would crash at the drop of a hat and, of course given the clever
shared spindle design, if the removable part wouldn't spin up then neither would the
fixed part.
I have (I think) three drives, or maybe just two. Two are internal drives for the 725
and one is in the table top enclosure. None work. If anybody has any tips for fixing
them, or even just a kludge to spin up the Winchester part without needing the removable
part to work too, I'm all ears.
Ethan Dicks <ethan.dicks at gmail.com> wrote:
I often wonder how hard it would be to develop some other storage
device for the KELSI
AFAIK the LESI ("Low End Storage Interconnect") protocol is not documented
anywhere, unlike SDI or MASSBUS which are. If it is, I've never found it. I have
several UNIBUS KLESI boards and I've often thought the same thing, but I'm not
really interested in trying to reverse engineer the protocol w/o documentation.
Bob
12:15 p.m.
On Tue, Jun 5, 2018 at 2:53 PM, Robert Armstrong <bob at jfcl.com> wrote:
I too have heard that RC25s and PDP-11s were used in
nuclear subs for some kind of sonar thingie. I've no idea how that worked, except
that maybe DEC gave all the good drives to the Navy and the rest of us got the crappy
ones.
Hi, Bob,
Perhaps.
They worked as long as you didn't spin them down
or try to change the removable pack.
Ah... that may be part of it. I never did. I loaded one removable
pack and never swapped it out.
The removable part would crash at the drop of a hat
:-(
and, of course given the clever shared spindle design,
if the removable part wouldn't spin up then neither would the fixed part.
Right.
I have a different 11/725 now (long story but I screwed up and the old
one went away at a friend's company when they were purchased and shut
down)... I've had that replacement 11/725 for 10 years but it didn't
come with a removable pack so I mothballed it out at my farm. I have
only gotten a couple of removable packs in the past year and have not
been able to spend time fiddling with it, but it's going to be a full
cleaning and overhaul (dust, fans, PSU test, TU58 roller...)
I have (I think) three drives, or maybe just two.
Two are internal drives for the 725 and one is in the table top enclosure. None work.
No fun.
If anybody has any tips for fixing them, or even just
a kludge to spin up the Winchester part without needing the removable part to work too,
I'm all ears.
I didn't want to bung up my only drive, but if I had 2, what about
this? Put a foam or rubber wedge between the head arms of the
removable pack (to keep them from thwacking together) and defeat any
sort of interlock or removable cardridge sensor (I think there's a mag
sensor at one corner?) The idea is to make the drive think there's a
pack loaded. It might take doing something with a real pack housing
and removing the platter in case the lower mass screws up the spin
rate.
Of course, if the internal drive electronics lose their mind because
there's no signal coming from the removable pack heads, then it will
likely go into Fault and not work. This is all just speculation on my
part but I can envision ways that it doesn't keep the drive
electronics happy.
AFAIK the LESI ("Low End Storage
Interconnect") protocol is not documented anywhere, unlike SDI or MASSBUS which are.
If it is, I've never found it.
Nor have I.
I have several UNIBUS KLESI boards and I've often
thought the same thing, but I'm not really interested in trying to reverse engineer
the protocol w/o documentation.
Same. That's what really slows me down - not wanting to start without
a single idea of how it works.
And then I think of how much work it would be to convert one of my
COMBOARDs from a 3rd-party comms controller into a 3rd-party disk
controller (I have full schematics and specifications and source for
all the COMBOARDs so that's not starting from zero) but between
designing and writing new firmware and writing drivers for every
possible OS (RT-11 and VMS at the absolute front of the list), before
I even get started, I just find something less insane to do.
-ethan
3:19 p.m.
On 06/05/2018 02:53 PM, Robert Armstrong via cctalk wrote:
bill
I too have heard that RC25s and PDP-11s were used
in nuclear subs for some kind of sonar thingie. I've no idea how that worked, except
that maybe DEC gave all the good drives to the Navy and the rest of us got the crappy
ones.
I used mine for more than 10 years and have no idea how long
or much the previous owners used it.? Never a problem.? I kept
the KLESI module to use with tape drives after I gave the disk
away.? Now that was a truly weird system. same controller but
the cable went one way for a disk and the other way for a tape.
They worked as long as you didn't spin them down or try to change the removable
pack. The removable part would crash at the drop of a hat and, of course given the clever
shared spindle design, if the removable part wouldn't spin up then neither would the
fixed part.
I have (I think) three drives, or maybe just two. Two are internal drives for the 725
and one is in the table top enclosure. None work. If anybody has any tips for fixing
them, or even just a kludge to spin up the Winchester part without needing the removable
part to work too, I'm all ears.
Mine was the tabletop model.
Ethan Dicks <ethan.dicks at gmail.com>
wrote:
I often wonder how hard it would be to develop some other storage
device for the KELSI
AFAIK the LESI ("Low End Storage Interconnect")
protocol is not documented anywhere, unlike SDI or MASSBUS which are. If it is, I've
never found it. I have several UNIBUS KLESI boards and I've often thought the same
thing, but I'm not really interested in trying to reverse engineer the protocol w/o
documentation.
5:59 p.m.
On Tue, Jun 5, 2018 at 12:53 PM, Robert Armstrong via cctalk <
cctalk at classiccmp.org> wrote:
AFAIK the LESI ("Low End Storage
Interconnect") protocol is not
documented anywhere, unlike SDI or MASSBUS which are. If it is, I've never
found it. I have several UNIBUS KLESI boards and I've often thought the
same thing, but I'm not really interested in trying to reverse engineer the
protocol w/o documentation.
There's SDI protocol documentation?
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