On Ebay there is a DEC Digital Equipment PDP-11/R20...I may have missed a
thread about this, but any info on this? I assume it's just a custom
11/20?
Bill
Rob Jarratt [robert.jarratt at ntlworld.com] wrote:
> I am basing this on a reply I once got on a newsgroup. See
> the replies from Ian Miller here:
>
>http://groups.google.com/group/comp.os.vms/browse_thread/thread/3a8893f
7f6c6
>4aab/adb777d3f37ebed?q=jarratt+tk50+tf
That's certainly news to me - I've never heard that before. Doesn't mean
it's
Not got a grain of truth behind it though.
The reason given (internally to DEC, by the group responsible for these
drives)
for not being able to proceed past an inadvertent write (or physical
damage)
is that the drive is kept constantly synchronised by the stream of data
that
it reads. Once it loses that synch it no longer knows where it is and
cannot
recover. The stream of data is then just so much noise. The only
recovery
possible is at the beginning of a new data stream.
Assuming that all of that was true (and, indeed, correctly remembered
...)
then once you hit physical damage, the way the drive works will not let
you recover data past that point. It's a feature. There may or may not
be
special firmware, but I've never heard of any.
So I'd be willing to believe that a TF drive might handle some issues
better
than a TZ drive (although I'd prefer to see some corroborating evidence
before
repeating this meme myself), if you've got a damaged tape I'd be very
surprised
if either drive makes any difference at all.
That's not a reason to avoid a TF85 or TZ85: you never know when you'll
need
one for some other tape you do want to read. Just don't sped too much!
Antonio
Rob Jarratt [robert.jarratt at ntlworld.com] wrote:
>
> If there is anyone near Manchester in the UK with a TF drive
> then let me know. The TF drive itself is not that expensive
> so I may just get it anyway on the off-chance that a cheaper
> FKQSA or DSSI machine turns up.
Is it not the case that the TZ85 (SCSI) and TF85 (DSSI) are the same
drive, jus twith a different interface? So a TZ85 may be as useful to
you in solving your problem.
As for solving your problem, a perennial complaint within DEC was
"I've somehow started scribbling half-way along a DLT tape but I
stopped quickly and I need to get to the half of the data beyond the
scribbling". I never saw anyone admit to having one of these problems
solved: even when there was a paying customer at the end of a
cheque book. The existence of special recovery firmware was firmly
denied - and I never saw even a hint that it might exist.
So I don't have any reason for believing that a TZ85/TF85 might be
any better or worse at reading your data than anything else that
can handle your DLT.
BTW iirc the TZ86 and TZ87 are (iirc) can read tapes from a TZ85. The
TZ87N lost some of the backwards compatibility (to lower costs).
Antonio
On Fri, Oct 30, 2009 at 4:38 PM, Rob Jarratt
<robert.jarratt at ntlworld.com> wrote:
> I was led to believe that a TF series drive might be able to read past a
> problematic part of a tape I have, and a TF85 has come up on eBay. The
> problem is that I do not have any DSSI-capable machine and I am not familiar
> with DSSI. I have a MicroVAX II and it seems I could use a KFQSA, but they
> seem quite expensive. I also have some VAXstation 3100s and MicroVAX 3100s,
> which are SCSI. Do I have any other options for installing the TF85?
>
A KFQSA M7769 isn't very expensive, at least in the US, if you find
one at the right time. For example this one went for $25 with
bulkhead and terminators:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=350264750147
No idea though if that's the best path to start going down in your
ultimate goal of reading a problematic tape.
After a very long time[1], I have gotten very close to having a functioning power supply.
I'm still not quite there by the looks of it. With a dummy load of two automobile
headlamps (four filaments wired in parallel) for each of the 2.5V and 5V supplies, I now
have pretty decent voltages:
2.54v (2.5V supply main output)
5.21v (5V supply main output)
15.31v
-15.18v
5.08v (+5VB)
-4.98v (-5VB)
12.09v (+12VB)
As far as I can tell, after going through the "H7104 Power System Tech Desc" doc,
these voltages are good. Even the slightly high 5V line is within the spec'd range of +/-
5% or 4.75v - 5.25v.
Still, I don't see a green POWER OK indication on either the power controller or the
cabinet's front panel. What I do see on the front panel is a red FAULT and a green
(slightly dimmer) RUN indication, but this is probably because no boards are yet in the
backplane. There are no lit fault indicators on the power controller itself, which
suggests that the voltages are okay.
Another list member who saw similar symptoms on his 11/750 apparently found that it
was loose contact in the Power Control ribbon cable, but that doesn't seem to be the
case here.
To test this further, I toggled the 5V supply's test switch to LO and saw the voltage drop
to 4.97V, but the POWER OK lamp still didn't light up, so I don't think the problem has to
do with the 5V output being too high.
I should put my 'scope on it to see if the output is stable. I'll do that, but I'm guessing that
it's going to be good, and I don't know if the power controller is sensitive to that
anyway. I haven't checked the POWER OK lamps themselves, and I'm guessing that
since there are two lamps, one in the power controller and one in the cabinet front
panel (and that they are not simply wired in parallel or serially) it's something else.
Maybe the bulbs are ganged together, I'd better check the FMPS again.
Before I dig into that aspect further, I wanted to check in with the group and see if
anything stands out that I've overlooked, or if you guys think I should check something
else before the bulbs.
Just want to make sure the PS is in order before loading the boards into the backplane.
Many thanks.
- Jared
[1] Rescued this unit two years ago this month. Turned out to have an empty card
cage, and a fault in the PS. I finally traced the PS trouble to two of the four power
output diodes in the 5V supply (shorted out, replaced all four), and a poorly contacting
connector in the 2.5V supply. Over time I have scrounged up a complete boardset so I
should have a functioning system Real Soon Now.
I was led to believe that a TF series drive might be able to read past a
problematic part of a tape I have, and a TF85 has come up on eBay. The
problem is that I do not have any DSSI-capable machine and I am not familiar
with DSSI. I have a MicroVAX II and it seems I could use a KFQSA, but they
seem quite expensive. I also have some VAXstation 3100s and MicroVAX 3100s,
which are SCSI. Do I have any other options for installing the TF85?
Thanks
Rob
Pontus Pihlgren <pontus at Update.UU.SE> wrote:
>> > Stacken have had to get rid of most of their stuff, I think, but
>> > Peter still has his, and maybe more.
>
> Did that stuff get thrown out or did it end up with other stacken
> members? (Expect for the stuff that went to uppsala this year)
I'm afraid most of Stackens stuff is lost forever. :-( There was a
little stuff saved in a warehouse somewhere still, if you remember...
But we did manage to save a KS-10, and they kept one at KTH. Both should
be functional. That's always something.
>> > I think I've written about this before, but it seems that either is
>> > noone seeing my mails, or noone remembers them, or possible noone
>> > wants to believe them.
>> > Don't know which...
>
> Posting a link to his gallery makes it more believable, but I'm sure
> that the link has been posted before:
>
> http://www.stupi.se/Bilder/pdp-10/index.html
True.
> Ps.
>
> Checking the archives, both you and Peter posted the link :D
>
> http://www.classiccmp.org/mailman/htdig/cctalk/2003-July/025598.html
> http://www.classiccmp.org/mailman/htdig/cctalk/2009-January/267600.html
Ah. That first link was really good. There people can see what Peter
have in storage. Most of it very much possible to get running. So he
have actually four KI10 systems, as well as two KA10, and a bunch of KL
and KS. It was more than I thought.
Looks like a pretty good collection of all 36-bit machines with PDP-10
like architecture. Missing is a PDP-6, as well as a few clones.
The SC30 is actually online on HECnet. :-)
.ncp tell sol sho exec
Node summary as of 28-OCT-09 19:53:09
Executor node = 59.10 (SOL)
Identification = Systems Concepts SF CA USA - SC30M - DN-20 4.0
State = On, Active links = 0
I think his TOAD-1 is also running, but it don't seem to be online on
HECnet right now.
Johnny
--
Johnny Billquist || "I'm on a bus
|| on a psychedelic trip
email: bqt at softjar.se || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol
Hi all, enough lurking and time to ask a question....
The software company I work for is planning an internal classic computer
show as a little light relief near Christmas. We expect a turnout of
around 100 people and so far have the following planned:
1) Show as many vinatage systems as possible, ideally working. "vintage"
in this context means anything pre-90 as best I can tell but modern rare
machine may be shown too. Think ZX81, C64, etc - mostly home machines.
I'm personally plannig to show my Transputer collection, though I expect
very limited interest :)
2) Have a collection of classic software & games running on emulators
"3) retro" music
4) beer and snacks (not vintage)
5) Competitions for high score on classic games and best retro dress!
6) Possibly invite a well known talker or two, depending on how much
interest we expect to generate and/or finance.
Has anyone helped organise something like this before? is there anything
that worked particularly well/failed miserably? This is a small scale
fun event and not on the scale of VCF!
Many thanks for any advice
James
Dwight asks:
> Is there more? I don't see why that would have put them off doing DECnet.
Decnet has some support in some 80's and early 90's era Cisco products...
but it was comparatively poor and incomplete compared to what the
competition (especially 3Com) was doing. In my opinion (entirely
subjective, no real proof), Cisco support for DECNET and related DEC
protocols (e.g. LAT) was purposefully made incomplete or done poorly, so that
you'd struggle against it a lot with the glimmer of hope that you might
figure it out, but you always feel defeated and sore in the end.
3Com's LAT and DECNET terminal servers were really kick-ass, way better
than the overpriced DEC equivalent. LAT really is a pretty spiffy protocol
for terminal servers.
In the end DECNET Phase V (OSI compatibility) was what killed DECNET. Man, what a mess.
I feel sorry for the DEC programmers who labored for what must've been man-millenia
putting in every possible OSI bell and whistle when in the end nobody ever
wanted any of those bells and whistles!
Tim.
Does anyone know how to get this working? Much googling has produced a
reference to a utility called psadmin that's needed to set the initial ip
address for a jetlan card. Vista can't see the printer while snooping the
network. Any ideas?
brian
