Hi all --
Making some progress with the "fire sale" PDP-11/70. Over the past month
I've rebuilt the power supplies and burned them in on the bench, and I've
gotten things cleaned up and reassembled. I'm still waiting on some new
chassis fans but my curiosity overwhelmed my caution and I decided to power
it up for a short time (like 30 seconds) just to see what happens. Good
news: no smoke or fire. Voltages look good (need a tiny bit of adjustment
yet) and AC LO and DC LO looked good everywhere I tested them. Bad news:
processor is almost entirely unresponsive; comes up with the RUN and MASTER
lights on, toggling Halt, and hitting Start causes the RUN light to go out,
but that's the only response I get from the console.
I got out the KM11 boardset and with that installed I can step through
microinstructions and it's definitely executing them, and seems to be
following the flow diagrams in the engineering drawings. Left to its own
devices, however, the processor doesn't seem to be executing
microinstructions at all, it's stuck at uAddress 200.
In the troubleshooting section of the 11/70 service docs (diagram on p.
5-16) it states:
IF LOAD ADRS DOES NOT WORK AND:
- RUN, MASTER & ALL DATA INDICATORS ARE ON
- uADRS = 200 (ZAP)
THEN MEMORY HAS LOST POWER
Which seems to adequately describe the symptoms I'm seeing, but as far as I
can tell the AC and DC LO signals are all fine. (This system has a Setasi
PEP70/Hypercache installed, so there's no separate memory chassis to worry
about.) I'm going to go back and re-check everything, but I was curious if
anyone knows whether loss of AC or DC would prevent the processor from
executing microcode -- from everything I understand it should cause a trap,
and I don't see anything in the docs about inhibiting microcode execution.
But perhaps if this happens at power-up things behave differently? And the
fact that the troubleshooting flowchart calls out these exact symptoms
would seem to indicate that this is expected. But I'm curious why the KM11
can step the processor, in this case.
I'm going to wait until the new fans arrive (hopefully tomorrow or tuesday)
before I poke at this again, just looking for advice here on the off chance
anyone's seen this behavior before.
Thanks as always!
- Josh
Recently acquired an ASR33 with an old EIA (RS-232) Interface convertor
module. ? It came with a two page spec and cable pinout sheet that is
more hole than it is paper. Manufacturer is United Data Services (UDS)
in Phoenix.? Model seems to be 312 A 0568? (might be 0563)? Google
hasn't been much help and Bitsavers is silent as well..? Herb Johnson of
Retrocomputing.com has 312 A 0567 which appears similar but not close
enough to be useful.
Anyone familiar with this unit who could share docs??? (willing to scan
and share if desired)
Steve
Looking at the DEC Pro documentation there's some ambiguity I'm trying to figure out.
The hard drive documentation talks about the "reduced write current" signal. In one place it's explicitly described as relevant to the RD50 only. But later on in the RD50/RD51 chapter the signal is described generally, without any indication that RD51 ignores it.
Does anyone know which is correct? If RD51 also uses it, how does the right value get set? What IS the right value, anyway?
paul
Thanks!??
The radio site aside? from? using low bit rate scan also I think compresses the pdf files.
Ed#
On Wednesday, February 3, 2021 J. David Bryan via cctech <jdbryan at acm.org; cctech at classiccmp.org> wrote:
On Wednesday, February 3, 2021 at 9:25, ED SHARPE via cctech wrote:
> Indeed this site is great for reference but alas are too lo-res for good
> museum display images.
They appear to be scanned at 150 dpi.
The ones here are scanned at 300 dpi:
? http://hparchive.com/hp_journals
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? -- Dave
>
>
> Date: Tue, 2 Feb 2021 09:19:08 -0800
> From: Al Kossow <aek at bitsavers.org>
> Subject: Flip-Chip selloff
>
> I don't have any equipment that uses them any more, so I'll be ebaying off
> my
> A-W series flip chips over the next few days. The W's and PT08 boards are
> up now
>
> https://www.ebay.com/itm/184647476832
> https://www.ebay.com/itm/184647420812
>
I am still maintaining a PDP-8/I & TC01, PDP-8/L, PDP-8/S, PDP-9 & TC02,
and PDP-12 for the Rhode Island Computer Museum.
The RICM would happily accept any donated FlipChips, especially the go-fast
B versions and anything else for the PDP-9. You can even get a charitable
tax deduction for the donation.
--
Michael Thompson
At 08:32 AM 2/2/2021, geneb via cctalk wrote:
>On Mon, 1 Feb 2021, Al Kossow via cctalk wrote:
>>and it is the software and the knowledge of what you need to do when
>>recovering media in volume these guys have no clue about
>
>How about helping out instead of bitching from the sidelines?
I was quite eager to hear Kossow's insights. Any engineer or programmer
(or both) worth their salt eagerly seeks and accepts the "but it would be really
handy if it did X, Y and Z" insights, especially if they're coming from
someone with decades of experience in the field in question.
How else will products improve?
- John
Indeed this site is great for reference but alas are too lo-res for good museum display images.
I do use this as a reference source? but need paper copies sometimes? to hi res scan some times!
Ed#
On Tuesday, February 2, 2021 Richard Milward via cctalk <rsmilward at frontier.com; cctalk at classiccmp.org> wrote:
You can find HP Journal issues at
https://worldradiohistory.com/HP-Journal.htm
<https://worldradiohistory.com/HP-Journal.htm>
The World Radio History site is a fantastic resource in general, I use
it regularly.
**Richard
Adam, I have a VAXstation sitting about three metres from me. As is
usually the case, "it worked when I turned it off 20 years ago" I don't
remember how many years ago I turned it off. I think it is a model 30
but casually looking at the box does not show me what model it is. I
pulled out the nicad battery pack many years ago and it is sitting by
my left hand and it does not leak.
I have the system box, the expansion box with its little SCSI disk drive,
the RRD40 and its wierd disc caddies, and the VR--- monochrome monitor,
and probably the keyboard and mouse and documentation if I look around
for half an hour.
I have no idea where you are but I can send it to you for the price of
shipping which would be astronomical I expect. I hesitate to ship the
monitor - that would be had work - but the other components can be managed.
--
Richard Loken VE6BSV : "...underneath those tuques we wear,
Athabasca, Alberta Canada : our heads are naked!"
** rlloken at telus.net ** : - Arthur Black
As long as we?re talking about divesting: if anyone has a VaxStation that they?d sell me for substantially less than eBay prices, I?d be interested. I have a 3100M38, but it doesn?t POST; indeed, a replacement mainboard would be a place I could start. (I did try burning new ROMs and replacing them, but that wasn?t the problem). I?d even consider swapping an 11/730 in unknown condition (this is from the Kaur collection) for a working VaxStation, on two conditions: you have to pick it up, and you have to take an RM80 drive with it and dump it far enough away from my house that no one thinks it was me what done it.
Adam
I have received a few of the above-mentioned DC300-sized QIC carts for
recovery. The usual stuff about tension bands applies, but I'm a bit
stymied.
The official specs for these tapes say that they're SLR 3. I've tried
Tandberg SLR 3, 4 and 5 drives (any of which should be able to read
these) with no luck. I've even tried an SLR2 QIC525, though why someone
would pay for more tape than they need is a mystery.
These would be ca. 1990 and most likely on a Mac, although the latter is
pure conjecture.
Before I unspool some of this tape and have a look with developer, am I
missing something?
--Chuck
