Jon Elson's take hits home. A 780 was delivered and VMS was running. We
installed 4.1BSD and it ran fine until it crashed. Field service insisted
we needed a full set of RS-232 wires in our cable. Still crashed
(surprise!). Switched to VMS, still crashed after a while. Local field
service couldn't find it. The big guns flew in from Maynard. First day:
Couldn't find it. Second day: "What, what's that wire doing there? Have a
wire-wrap tool?". Removed wire from backplane. Boots, runs. Engineer
flies home.
Side tracking slightly from the "VAX 86x0 schematics" discussion into changing field service procedures over the years: I remember some fairly hairy cases in the 1970, when FS engineers had to be way more capable than board swappers.
1. DEC RS64 fixed head disk was behaving badly, making more noise than expected. Machine was not under contract. FS tech took it apart, diagnosed bad bearing. To save the customer (college physics department) a pile of money, he took it to Appleton Electric Motor Co., where they found a suitable bearing, pulled off the bad one, pressed a replacement on. Jim reinstalled the motor into the drive, worked great.
2. Same college, different machine: RF11 drive was showing "clock track failure". Diagnosis: drive is not spinning. Same tech. Jim took the drive apart on a desk in the computer center, noticed a head had crashed and melted, hot-glueing itself to the platter so the motor was blocked. This machine was under warranty, so he ordered a pile of parts: full set of heads, motor, platter, plus tools. Replaced the motor, replaced all the heads and aligned them, replaced the platter, and formatted the timing track. The manual for that formatter was not exactly intellegible...
3. Different university, CDC 6500 mainframe, occasional data corruption in one of the mass memory transfer paths. After lots of test code added to the application (PLATO system), the tech concluded he knew the answer. Opened up one of the cabinets, lifted up a massive bundle of wire to reach a spot where one of those wires was "punched in" to a module connector, and re-punched the pins of that wire. Repeat at the other end of that wire. Run tests, problem fixed.
In that machine, there were a dozen or so chassis, with up to 750 or so modules, each with 28 signal pins, most of them interconnected to elsewhere with twisted pair wires terminated in tapered pins that were pressed into place. It was a surprisingly reliable system but we learned it wasn't 100%, and it took quite some skill and perseverance to find which of those tens of thousands of wire connections was the failed one.
paul
Hi Paul
I see that you are clearing out QBUS board. I've been looking for a
"DIGITAL Q BUS music board" for a while. It is a board without M-number
as it was never sold. It is a simple dual board with two AY-3-8192 chips
on. There are pictures available, if you want I can send them to you.
I live in Sweden, I hope we can work out shipping if you have the board.
Regards,
Pontus.
I was digging through DEC compatible boards for someone and realized I
should have posted them.
I have over 100 dual, quad, hex and VAX boards from the usual suspects-
ABLE, CMD, DIGITAL PATHWAYS, DILOG, EMULEX, MT, PLESSEY, REMEX (paper tape
interfaces for 8s and 11s).
Included are core memory boards for 8s and 11s.
A small data book library at my work is going to be cleaned out soon. It is
mostly common stuff from 1995 and older. I don't believe there is anything
unique.
You can see a some pictures of the shelves here:
https://photos.app.goo.gl/jdJnUdRPvzvRzeTp6
I can't sell them and I won't ship them.
If you see anything that should be saved I will squirrel it away with the
intention of scanning and getting it online someday.
-chuck
Front panels: I have both 8-A, KY11-LA and -LB for 11/04, /34, one each
11/70 RDC remote diag con, corporate (blue/blue), and regular. I think
there is an 11/40 with a 11/35 silkscreen. I have to go through the 8-E, F,
and Ms.
The last dual extender is on hold, one quad is left, a few hex, a comet
(730 or 750 I think), and a 780.
Also a few 11/04 and 34 in BA11-L, maybe a -K, and a few 11/83s. I think
most of these are systems, not just boxes.
The printers include LA12, LA34, LA36, and LA120 and parts for most.
There are several hundred non-DEC boards, and a lot of core memory.
I'm still looking for the rest of the simms.
At some point, I'll be cutting the fingers off of boards no one wants. If
you are interested in any qbus or unibus boards for chips, let me know.
I can bring items to VCFMW to drop off there. There are a lot of people who
drive in from different parts of the country who might be willing to work
something out for some gas money.
Thanks, Paul
Paul Anderson <useddec(a)gmail.com> wrote:
> If you have an original 11/03, I have a dozen or so H780 power supplies,
> which are very hard to find. They are also used in the Vax 11/780 front
> end, the RKV11-D and possibly a few other items.
Wow, someone who actually knows about the RKV11-D!!! I've had DEC
people visit my place, see the RKV11-D, and proclaim that "DEC never
made that!". Since you know what it is, can you tell us anything about
how it came to be, and why it is so little-known?
I bought mine back in 1978 or so from Newman Computer Exchange for
my 11/03. I later added the missing wires (and chip) to enable 18-bit
addressing when I got an 11/73. I haven't used it since I moved to
Oregon six years ago, but it would take just a few hours to remove
the RK05 head locks and plug things in, assuming that all the
capacitors are still good.
It came in handy to prove to the RSX development group that RSX-11M
version 2.0 would run on an 11/73. :-)
Alan Frisbie
Now that I have my 18 bit retro computer working, I am thinking of
adding classic IO, like paper tape. Sadly I am a few decades too late.
Is there anything out there to replace a punch/reader used as 70's i/o?
Any good mag tape (cassete tape) replacements? I would love a tiny 9
track mag tape toy sized if they made one, like the wall hanging PDP8's.
On wish list, a flex writer or TTY video display replacement, ie
overstrike and underline in 2/3 size VT100 case.
Ben.
https://www.instructables.com/23-Scale-VT100-Terminal-Reproduction/
