Hewlett-Packard is closing its facility in Marlborough Massachusetts. It's the old Digital Equipement MRO building, and many of the people here are Digital-vintage employees. In the process of cleaning out offices to prepare for the move, people find stuff they've had for a long time and no longer want. It goes into dumpsters or otherwise set out for others to consider. Most of it is true trash, empty pendaflex folders, boxes of floppies, manuals for products no one even remembers.

But occasionally there's something truly interesting. Here's one I found. I don't know what it is, and am hoping someone has an idea.

It's not large (5.5 inches square), but heavier than you'd expect:

The mystery thing

The connectors on the side seem made for heavy-duty current, but are connected to fine traces in the ribbon material wrapped over the edges. The gold area between the chips is etched with perpendicular lines, but they don't seem like circuitry, just a texture:

Showing more detail

The "chips" seem permanently placed, and eight of them are stamped "Mechanical Sample", with a Motorola logo:

Closer still

Underneath looks like a heat sink, though it isn't aluminum, with a hex nut for each of the nine chips on top:

The underside of the mystery thing

Anyone know what this is? Can you explain its mysteries?

tagged: , » 13 reactions


Jhendler 10:45 AM on 19 Oct 2010

Interesting. Posted at http://news.ycombinator.com/item?id=1807502

Mike Garrity 11:11 AM on 19 Oct 2010

Isn't that the CPU block from a VAX 9000?

Pete Lyons 11:30 AM on 19 Oct 2010

I asked my brother-in-law who was a tech guy at Digital for years and he said this:

"This is from a GS160. What you see here is the Alpha CPU module. The GS160 supported many of the CPUs in 1 system. They also had Memory and IO modules that all looked the same. When VMS was running it would balance application across the CPU, Memory and IO modules. Worked great. It was the last Alpha systems that Digital or Compac produced before HP"

Pete 2:38 PM on 19 Oct 2010

Yep - Alpha CPU. I remember the press conference where these were introduced. The exec held one up and said something to the effect of, "we've put a supercomputer into something the size of a ham sandwich."

Larry Narhi 5:27 PM on 19 Oct 2010

This is NOT an Alpha CPU. The etch board P/N 50-18748-01 indicates an early to mid-1970's assembly which pre-dates the Alpha era. All Alpha CPU's had MASSIVE heat sinks either attached directly or bolted on. Motorola never made Alpha CPU's. DEC Hudson or Samsung fabbed the die while IBM packaged the chips in ceramic packages with much higher pin ccounts and pin densities that these Moto devices have. The connector technology is right out of the 70's or very early 80's as well.

My guess is that this is an experimental mechanical mock-up for maybe PDP10 or ???

I was a DEC hardware designer for many years and I worked in product support for all Alpha systems my lst years at DEC/Compaq/HP.

jason404 1:15 AM on 20 Oct 2010

@Larry Narhi
From looking at pictures of CPUs of history, chips just did not look like that in the early '70s. Maybe the serial number is a red herring? I'm going with the VAX 9000 suggestion.

Lennart Regebro 2:24 AM on 20 Oct 2010

70's or early 80's!? With chips like that? Nonsense. Also, it has a copyright stamp with a year, and I think it says 1989, but Ned will have to confirm that.

The circuits look like texture, because they are not actually doing anything, because the chips are not real. But the Motorola stamp and the heatsink implies that this is a 8xCore CPU. The VAX 9000 did indeed employ such things, and those chips were apparently made by Motorola, and it was presented in 1989, so the idea that this is a mockup for such a multichip unit seems to fit most of the evidence.

So, googling for '"Vax 9000" digital cpu' turn out images like this:


Yeah, it's without a doubt a VAX 9000 CPU mockup.

It's a beautiful thing anyway, and I would love to have it decorate my office. I had a DEC core memory module once, but it got lost. They did many pretty parts, DEC. :-)

Ned Batchelder 6:26 AM on 20 Oct 2010

Wow, Mike Garrity had it right out of the gate, and Lennart wins for finding images to prove it! Those images seem pretty conclusive. Thanks everyone for the detective work.

Jon Homan 12:43 PM on 25 Oct 2010

In the late 1980s when I was with DuPont/Berg Electronics we worked with the DEC team on the flex assemblies that are visible on the four sides of the module. One of my colleagues and I were reminiscing about this just the other day so it was very interesting to see this show up at this time!

Oxymoron 3:55 PM on 17 Dec 2013

from the VAX 9000 manual http://bitsavers.informatik.uni-stuttgart.de/pdf/dec/vax/9000/EK-KA90S-TD-001_VAX_9000_System_Technical_Description_May90.pdf.
Mr Narhi, if you were a DEC design engineer in 70s/early 80s you would have thought that this was alien technology gifted to you. I worked LCG (KA10 to DECsystem20) and knew the ECL technology KL10 intimately and witnessed the demise of Jupiter. I remember when flex bus, ZIF chip socket technology was introduced.

Oxymoron 4:00 PM on 17 Dec 2013

from the VAX 9000 manual http://bitsavers.informatik.uni-stuttgart.de/pdf/dec/vax/9000/EK-KA90S-TD-001_VAX_9000_System_Technical_Description_May90.pdf. page 2-12 Figure 2-9 MCU exploded view

Alberto 2:49 AM on 28 Apr 2014

I personally worked in the R&D group that produced these in the late 80s in Marlboro. Its a MCU as the other person said, and not an part of the Alpha workstation (that came after this). 9 different MCUs made up the core of the VAX9000 system. They ran so hot, we had to torque cooling plates that had refrigerated water cycling thru-literally liquid cooled in the R&D days. Once manufacturing started, they then went to an air cooled plate that had 100s of 1.5 inch pins protruding out (giant heat sink)- which had air blowing directly on it. That should solve the mystery of the bottom photo for you all :-) Each MCU had its own clock chip ( the small chip in the middle). It was a lot of fun working on these. The building in California that was manufacturing this system was just leveled for the new parking garage for the Apple Mothership. A bit ironic, I guess. BTW, the hex nuts on the bottom didn't have anything directly to do with the chips on top, other than a torque point for fastening this giant heat sink. There was a very specific torque spec for each hex nut. If the heat sink wasn't torqued properly the unit would burn up in a couple of minutes.

Alberto 2:58 AM on 28 Apr 2014

The guy who said "The circuits look like texture, because they are not actually doing anything" is incorrect.
These were custom chips developed for this system. I personally part of the team that troubleshot and did infrared heat tests on these units. We had special fixtures made for R&D that had vacuum mounts for our Oscilloscope probes with needle-like heads. We'd vacuum mount the scope prob near where we wanted to connect- then we had knobs that would adjust the x, y, and z axis of the probe to connect it on the chip pin in which we wanted to see the signal. This all had to be done under a microscope. I had a great time working on these and they brought me to CA to train some people, and I never left.

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