In addition to having a domestic computer design industry (see Pioneers of Soviet Computing [local copy]), the Soviet Union was well-known for copying computer designs from the West. While there were many possible reasons for this, one of the most commonly given ones was the desire to run specific software, also from the West. This could be a particular application program or a whole operating system. Certainly, not having to write software in order to have a deliverable computing product was a huge benefit to the Soviets. While the scale of this cloning program was not entirely understood by the West during the Soviet era (see Total Soviet Computing Power [local copy]) it was well known that a good deal of cloning was going on.

Image courtesy of FSU’s Silicon Zoo
DEC supposedly inscribed the phrase “VAX – When you care enough to steal the very best” on an otherwise-unused area of the die for one of their MicroVAX CPUs. The phrase in the picture reads “СВАКС… Когда вы забатите довольно воровать настоящий лучший” which is horribly mangled Russian, but I think it got the point across.

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The highest-performing PDP-11 CPU DEC built was based on the DCJ11 (or J-11, or Jaws), microprocessor. This CPU was the basis for all subsequent DEC PDP-11 products (PDP-11/53, /73, /83, /84, /93 and /94) up until they sold the product line to Mentec, who continued to use the J-11 on their M70 / M71 / M80 / M90 and M100 CPUs. It was not until nearly 4 years had elapsed after Mentec acquired the DEC PDP-11 line that they introduced a new design, the M11, not based on the J-11. This was probably due to the last J-11 chips being manufactured in early 1998, as production was apparently stopped as soon as Compaq acquired DEC.

The J-11 design was not without its problems. It was a joint manufacturing effort of DEC and Harris Semiconductor (Intersil). DEC had previously used the Harris / Intersil 61×0 chips, which implemented the PDP-8 CPU in a microprocessor. They probably weren’t expecting the issues which plagued the J-11 project. In addition to problems with the CPU itself, there were problems with the optional floating-point accelerator chip (designed and built entirely by DEC) and the support chips needed to make the J-11 function in a system. This led to a number of costly recalls by DEC to fix (or conceal) problems. The original distinction between the various PDP-11 systems based on the J-11 was lost as parts (normally the floating-point accelerator chip) were removed and / or the board swapped for a slower 15MHz one in the field to get the systems working reliably. Eventually the J-11 systems became reliable enough that users could have an 18MHz CPU with working floating point. Earlier J-11 chips had speed restrictions (often 15MHz) and did not work with the floating-point chip. The planned optional Commercial Instruction Set (CIS) option was never produced, although you can see where it would have been placed on the bottom side of the CPU.

Certainly not all of the problems were on the Harris side – I’ve successfully run a J-11 at 24MHz on a 3rd-party board. The DEC support chip set was found to be limited to a bit over 18 MHz, which is why DEC did not press Harris particularly hard to meet the 20MHz design goal (for top-binned parts). The part number DCJ11-AE (the -AE suffix indicated the revision level) was the last version produced, the “good one”. Interestingly, the individual chips on the first DCJ11-AE CPUs were revision 1 on the DC334 chip and revision 11 on the DC335. The newest DCJ11-AE I’ve seen (with a module date code of 9820 and chip date codes of 9819) has a revision 4 DC334 chip and a revision 16 DC335 chip. That DCJ11-AE has the Harris logo stamped on the ceramic carrier as well as the individual chips, while a somewhat earlier sample with a 9711 date code has the same revision 4 and 16 chips, but without Harris markings on the ceramic carrier. 9820 is pretty close to the time DEC was acquired by Compaq, so the J-11 hung on to the bitter end, 4 years after DEC sold the rest of the PDP-11 business to Mentec. Apparently there weren’t user-visible changes which would cause the overall CPU revision to change to a DCJ11-AF. Perhaps the changes were to simplify the manufacturing process.

DEC also “shot themselves in the foot” by having one group think the part was solely for DEC’s use in building systems, while another group was trying to get design wins in 3rd-party products. This led to a bizarre situation where if you tried to purchase a J-11 chip by itself from DEC, you got a call from the J-11 product manager (Cathy Berida) who was forced by upper management to ask you what you planned on doing with it before the order would go through. Needless to say, DEC did not get a lot of OEM design wins due to their inconsistent policies regarding the chip. The result of this is that you can purchase case lots of never-used J-11 chips on places like eBay [local copy] if you happen to need a few hundred of them.

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Image courtesy of ElectronTubeStore

[This and all subsequent images in this post are clickable to show a higher-resolution version.]

This is a DEC M8192 module, used in the PDP-11/73 systems. It has an older J-11 CPU and no floating-point accelerator (FPA) chip (the large empty socket below the white J-11 CPU). A manual for it is available from Bitsavers [local copy]. Note that the manual doesn’t show the socket for the FPA, and the sole mention of the FPA is in the description of the internal J-11 CPU registers.

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Image courtesy of eBay user ru.seller

This is a Soviet M8 CPU board. It looks suspiciously like the DEC M8192 board, doesn’t it? Aside from some component substitutions due to limited availability of things (like PLCC sockets for the support chips and the compact 4-LED display) it is pretty much the same board. Note that this board doesn’t even have a socket for the floating-point accelerator chip. The pads are on the board, but there is no socket. This may indicate that the clone parts were created before DEC got the various design issues ironed out. Additionally, the configuration jumpers are soldered in instead of being removable jumpers as they are on the DEC board. The board in the picture is non-functional as some components (mainly bypass capacitors) have been removed for some reason.

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Image courtesy of eBay user ru.seller

Examining the M8 board in more detail, we can see some very interesting things. At the top center of theis image, you can see two chips with the logo “MHS” and the date code “USA8616”. If you’ve never heard of MHS, I’m not surprised. They were a relatively obscure manufacturer of specialty ICs. MHS stands for “Matra Harris Semiconductor” – yup, the same Harris Semiconductor that was making J-11 parts for DEC. They probably had no idea their parts were ending up in the Soviet Union – often, “front” companies would purchase parts in the West and those parts would eventually make their way into the Soviet Union.

The MHS part is a HM3-65747-5 CMOS 4K x 1 static RAM. The DEC M8192 board, oddly enough, does not use the MHS part. Instead, it uses a National Semiconductor NMC2147HN-3 which appears to be a pin-compatible substitute.

Also in this detail image, you can see 5 parts where the manufacturer and part number information has been ground off and “РУ12” written on on them with a marker pen. There is another of these parts outside the area of this detail. On the DEC M8192, these are Fairchild MB8168-55 NMOS 4K x 4 static RAM. “РУ” was the Soviet type designator for a memory chip. One of the chips on the Soviet board does not have its identifying marks removed, and it appears to be an INMOS IMS1420D-55, also an NMOS 4K x 4 static RAM. The mysterious РУ12 is probably К132РУ12 as this page and this page both show that as an interchange part for the IMS1420-55. They’re almost certainly not Soviet-made parts as there would be no need to grind off the original markings in that case.

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This is the top of a genuine DEC DCJ11-AE. As you can see, there are two large chips mounted to a ceramic carrier. Under the top layer of ceramic you can see some of the leads that connect the two chips to each other and to the pins on the edge of the CPU. There are 4 bypass capacitors for each chip to filter out noise. There is also one SOT-package part (possibly a transistor or 3-terminal regulator) installed, with an unpopulated space for an second one. It possible that the unpopulated space was for a part intended to be used on the underside of the CPU.

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The bottom view of the same part shows the pads which would have held the Commercial Instruction Set if it was ever implemented. You can also see additional leads in an intermediate ceramic layer – the ceramic carrier was a complex, multi-layer affair.

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This angle view shows how the individual chips were soldered to the ceramic carrier.

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Looking at the edge of the CPU, you can get an idea how thick the ceramic actually is on this part.

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Here is where things get interesting. This is a Soviet 1831 clone of the J-11. The logo on the chips indicates that it was made by the NPO Electronics (НПО Электроника) factory (now VZZP) in Voronezh. Instead of the DC334 and DC335 numbering on the DEC chips, the chips on this board are labeled КН1831ВМ1 and КН1831ВУ1. Wikipedia has a detailed article on Soviet integrated circuit numbering, but it breaks down as follows:

• К – Commercial / consumer component
• Н – Ceramic leadless chip carrier (the individual chips on the CPU carrier)
• 1 – Monolithic integrated circuit
• 8 – Microprocessor
• 31 – Number in series
• ВМ – Microprocessor
• ВУ – Microcode
• 1 – Variant

Apparently the two chips had their own code names – Тунгус 1 (Tungus 1) for the КН1831ВУ1 and Теорема 2 (Theorem 2) for the КН1831ВМ1.

You can see the somewhat different method of attaching the pins to the carrier, compared to the DEC CPU. This is due to the thinner carrier as I will discuss below. The same four bypass capacitors are present, but the SOT-package part found on the J-11 is not, although the pads are there. The chips appear to have been hand-soldered onto the carrier. While the carrier in this picture is blue, variants with white and greenish carriers have been photographed. While this part is just labeled M-2-1, other newer samples have been labeled М8К ред4 (M8K red4).

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The bottom of the 1831 shows a much simpler method of construction, compared with the DEC J-11. No additional leads are visible and the only marking is “0133”. It is not known what this means – as the chips on the carrier have 8905 and 8904 date codes, it doesn’t make sense that the CPU would have remained unassembled for twelve years. Perhaps it was the date it was installed into or removed from a system?

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This angle view clearly shows the hand-soldering of the chips to the carrier.

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The edge view shows how much thinner the carrier is compared to the DEC J-11.

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This detail shows the top of an unmounted КН1831ВУ1 chip. It is interesting that while the fabrication method was quite different from the DEC version, they apparently went through a lot of effort to match the packaging exactly. Perhaps they were trying to substitute the КН1831ВУ1 and КН1831ВМ1 chips one at a time onto a DEC package during development? That would not explain why this unusual packaging continued into production, though.

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The bottom of the unmounted КН1831ВУ1 is pretty boring, having only a stamped “35”. This does not match the date code on the top of the chip, 9111, so perhaps it is an inspection mark.

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This is an 1811 (DEC F-11, PDP-11/23 and /24) clone CPU. Unlike the 1831, this assembly is not a drop-in equivalent to any DEC F-11. It contains КН1811ВМ1, КН1811ВУ1, КН1811ВУ2 and КН1811ВУ3 chips. That would be a processor and 3 microcode ROMs. This is equivalent to a DEC F-11 and a DEC KEF11-AA FPU (Floating Point Unit). Oddly, in the DEC implementation the KTF11-AA MMU (Memory Management Unit) is necessary for using the KEF11-AA as the FPU reuses some of the registers in the MMU. This chip is marked МК1 ред1 (MK1 red1). The logos on the chips show that they were fabricated by NPO Electronics, same as the J-11 clone.

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The bottom shows that the CPU is made with a brown ceramic instead of the white ceramic (with blue top coating) used on the 1831. The bottom is marked 8821, which corresponds roughly to the date codes on the individual chips (8808 through 8811). Too faint to be seen clearly is the writing “26-027” across the top of the chip as shown in this picture).

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An angle view, clearly showing the “MK1 red1” marking.

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Here you can see that the carrier is also quite thin, similar to the 1831.

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Image courtesy of Soviet Digital Electronics Museum – Sergei Frolov

This is the CPU board from the Elektronika 89 minicomputer. You can see the 1811 CPU, along with the КР1811ВТ1 MMU chip, in the center of the board.

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I hope you’ve enjoyed this look at a relatively unexplored (in the West) area of computer history. These parts occasionally show up on eBay where they often sell for inflated prices. Not all of the eBay listings have the parts described correctly, so rely on pictures (as long as they’re not “sample image only”) to see what you’re getting.

In the 1980’s and 1990’s, St. Peter’s College* had a number of labs with PCs for student use. Each lab was a separate room equipped with a relatively large number of identical systems. In this particular case the room was full of Northgate Intel® 386™SX systems. These were purchased as complete systems from Northgate, along with their Omnikey keyboards and “Microsoft mice”. These systems had been in use for some years (replacement of expensive working stuff takes a long time at private colleges). We’d learned earlier on that people would steal anything that “wasn’t nailed down”, so the PCs had metal cables wrapped around table legs and locked to the PC case, and the keyboards and mice had their cables tied onto those metal cables near the PC case with plastic cable ties.

The mice were your basic original Microsoft mice, shiny white plastic, 2 buttons, a roller ball and a 9-pin serial connector. None of that ergometric optical PS/2 wheel and 3-or-more buttons stuff.

We should have known that wasn’t sufficent security, as people had popped random keys off the keyboards every now and then. That wasn’t terribly difficult as they just popped off. Northgate even conveniently supplied a keycap removal tool with each keyboard.

Another thing you should know is that having an offbeat sense of humor** was pretty much a requirement for working in the Academic Computer Center at SPC. This was actually pretty common – you can see some other examples of it in The Jargon File and the original BOFH. The protagonist of this story is Joe, a fellow who looked a lot like Radar from the M*A*S*H TV series, who would often wear a hat with what looked like a fish sticking through it. One of Joe’s jobs was to handle minor wear-and-tear items in the computer labs.

One day, Joe comes downstairs to my office and tells me “Somebody took the balls out of all the mice in the Northgate lab!”, to which I replied “You mean someone castrated them?” He asked me what he should do, and I answered “Call Microsoft and order some new ones.” A few hours later he came back into my office and said he couldn’t get anybody on the phone at Microsoft who knew about Microsoft mice (Microsoft’s Hardware Division was apparently a secret at Microsoft, at least to the people who answered the main phone number at Microsoft). I tell him to keep trying and he eventually comes back and tells me he got the phone number of someone who could help him. Very proudly, he dialed the number from my office on speakerphone so I could hear the exchange:

Microsoft: “Microsoft, this is Ms. X at extension xxxx”
Joe: “Is this the group that handles Microsoft Mouse parts?”
Microsoft: “Yes, how can I help you?”
Joe: “Somebody castrated all our mice!”
Microsoft: <Click>
Joe: “Hello? Anyone there? Hello?”

I told him to wait a few hours and call them back from his office and order the darned mouse balls. He came back and said they agreed to the order, at which point we had to do the song-and-dance to get a purchase order issued (a story for another time).

In due time, a box arrived and Joe went to put the new balls into the mice. He comes back down and says “They don’t fit!”. I asked what he meant and he said they didn’t fit into the housing inside the mouse. I told him to call Microsoft back and ask what was going on. Again, he used the speakerphone in my office:

Microsoft: “Microsoft, this is Ms. X at extension xxxx”
Joe: “My balls are too big!”
Microsoft: <Click>
Joe: “Hello? Anyone there? Hello?”

Deja vu all over again. Eventually he gets a hold of someone who asks where he got them, and it turns out that when Microsoft increased the resolution of their mice, they did it simply by changing the size of the ball. They then fobbed their inventory of the older, lower-resolution mice off on their OEM Windows customers who needed cheap mice to sell with their computers.

Eventually, a package arrives from Microsoft with the correct size mouse balls and Joe installs them, much to the relief of the students who have been crowding into the other PC labs when they needed to use Windows software. This package was somewhat oddly-addressed, being sent to “St. Potato’s College”. Apparently someone at Microsoft shared our oddball sense of humor (or had been “infected” with it after the ball-ordering incidents). We decided to use superglue to glue the access covers for the mouse balls onto the mice to prevent this from happening in the future.

While I don’t have the address label from that second mouse ball shipment, Microsoft continued to use “St. Potato’s College” as the official name on our customer account for a number of years:

* The domain name at the time was spc.edu. Later on, they renamed the school to St. Peter’s University. Fortunately, spu.edu (pronounced “spew” or “ess pee-yew”) was already taken by Seattle Pacific University, so they used stpeters.edu. Around the same time, Jersey City State College (jcsc.edu) renamed itself to New Jersey City University. Shouldn’t that be New Jersey Jersey City University, or maybe New Jersey² City University? Anyway, they went with njcu.edu – I don’t even know how to say that – nijj-koo, maybe?

** We actually developed a “litmus test” for co-workers to see if they would fit in. It was pretty simple – we’d ask someone to imagine Elmer Fudd singing the theme from “The Way We Were”. If they broke out laughing or cracked a smile, they’d be a perfect fit. If they looked puzzled because they didn’t get it, they’d need some on-the-job training in our particular sense of humor. If they didn’t like it, chances were close to 90% they wouldn’t fit in and would leave relatively soon. In case you don’t get it… Mem-wees… Misty watta-color mem-wees of da way we wuhhhhhhhhhhh…

While my blog has been silent for over a year, I’ve been inspired to start posting again. This was mostly because I’ve been relating various anecdotes to different people and many of them have said “you should really write a book about your experiences.” I also visted the Computer History Museum in California during the fall of 2016, and the combination of seeing their collection and going “I’ve worked with one of those” and seeing how much history has been lost made me decide to create some content of my own*.

Upcoming posts in the Computer History category will (mostly) detail my personal experiences with computer hardware and software for over forty years (yikes!). These posts will combine items from my personal collection as well as information I know about them. I will be researching these posts and will add links to external reference sites where I can.

The Personal Recollections category will (mostly) be narratives about my experiences working with the people who work with computers. These will be from my memory, to the best of my ability. In cases where I have posted the story to Usenet or a forum (BBS, DECUServe, etc.) site and they differ in a non-minor way from the version I post here, I will try to provide links to my prior posts. Not all of those sites still exist, though. When I name people, they will either be first names only or will have consented to being mentioned (when you read some of these posts, you’ll know why).

As always, all photographs will be by me, unless otherwise credited.

* Both categories will often have footnotes (like this one). Often, some of the funniest bits will be in the footnotes. You can either click the blue asterisk(s) when you come across them in the main article, or just read your way down to the footnote(s) at the end.