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January 26th, 2021 ~ by admin

The Story of the Soviet Z80 Processor

Before we get into the fascinating story of the Soviet (specifically the Angstrem) Z80 clone it’s good to understand a bit about the IC industry in the USSR.  There were many state run institutions within the USSR that were tasked with making IC’s.  These included analogs of various western parts, some with additional enhancements, as well as domestically designed parts.  In some ways these institutions competed, it was a matter of pride, and funding to come out with new and better designs, all within the confines of the Soviet system.  There were also the various Warsaw Pact countries (BulgariaCzechoslovakiaEast GermanyHungaryPoland and Romania), that were aligned with the USSR but not part of it.  These countries had their own IC production, outside of the auspices and direction of the USSR.  They mainly supplied their own local markets (or within other Warsaw Pact countries) but also on occasion provided ICs to the USSR proper, though one would assume an assortment of bureaucratic paperwork was needed for such transfers.

This resulted in some countries developing similar devices, at rather different times, or different countries focusing on different designs.  East Germany was all in on the Z80, Romania, Poland and Czechoslovakia made clones of the 8080, Bulgaria, the 6800 and 6502. They were though, seperate from the USSR’s own institutional system, so while East Germany had a working Z80 in the early 1980’s the USSR did not.  It is this distinction we will focus on today

This article is largely from guest author Vladimir Yakovlev, translated from Russian, and edited/expanded by me.

By the end of the 80s – beginning of the 90s, clones of the British Sinclair ZX Spectrum computer, a simple, cheap computer with a huge library of games originally released in 1982, were being distributed in the USSR. The “strapping” of the central processor instead of the original ULA microcircuit was done on small logic microcircuits of the 555 (74LS) series and the like, but the Z80 itself had to be bought from abroad. Naturally, the thought arose, to start making the processor yourself. After all, the processor itself, developed in 1976 for the microelectronic industry, was not too complicated.

In 1990, the development of an analogue of the Z80 was organized in Zelenograd near Moscow at the Scientific Research Institute of Precise Technology (NIITT) and the “Angstrem” plant. Initially, Zelenograd was conceived as a center of the textile industry, but was later reoriented to the development of electronics and microelectronics by Nikita Kruschev after he visited Silicon Valley (California, USA) in 1959. To this day, Zelenograd has retained the status of a scientific center and the informal name “Russian Silicon Valley”.

The chief designer was appointed Yuri Otrokhov, who had previously led similar developments. Otrokhov, who served as a tanker in his youth (military service being mandatory in the USSR), called the project the T34 microprocessor.

Otrokhov: “T-34VM1 is the internal designation of the KR1858VM1 processor, assigned by me at the stage of development and production in honor of my first tank, on which I learned to drive.”

Here is one of the versions of the creation of the clone, outlined by one of the employees of NIITT at that time, Boris Malashevich [1]:

“Otrokhov, like his colleagues in the department, knew how to develop original microprocessors, but they had not yet had to reproduce analogs. Therefore, the developers included specialists from NIITT divisions who are able to restore the electrical circuit of the IC according to its topology. For 9 months after four iterations, they managed to make an NMOS microprocessor T34VM1 (KM1858VM1, KR1858VM1) – a complete analogue of the Z80A microprocessor, to be made using a 2-micron technology” (The original Zilog version was on a 4 micron process).

While Otrokhov and his team worked at Angstrem to make a NMOS Z80, a similar team was working at ‘Transistor’ in Minsk Belarus to make a CMOS version, later known as the KR1858VM3.

Due to the incredible popularity and demand for the Z80, many analogue manufacturers worked without a license, so in total less than half of all Z-80 produced were licensed products from Zilog or its official partners (SGS, Mostek, etc).

From an interview with the creators of the Z80 [2]:

Faggin: Yes, we were concerned about others copying the Z80. So I was trying to figure what we could
do that that would be effective, and that’s when I came across an idea that if we use the depletion load
the mask that doesn’t leave any trace, then I could create depletion load devices that look like
enhancement mode devices. And by doing that we could trick the customer into believing that a certain
logic was implemented, when it was not. Then I told Shima, “Shima, this is the idea how to implement
traps. Put traps, you know, figure out how to do the worst possible traps that you can imagine,” and then
Shima with his mind, that was steel mind, was able to actually figure out a bunch of traps that he could
talk about.
Shima: I didn’t count [on] talking about that mostly. I placed six traps for stopping the copy of the layout
by the copy maker. And one transistor was added to existing enhancement transistors. And I added a
transistor looks like an enhancement transistor. But if transistors are set to be always on state by the ion
implantations, it has a drastic effect on very much. I heard from NEC later the copy maker delayed the
announcement of Z80 compatible product for about six months. That is what I got from NEC. And finally
a total transistor of Z80 became 8,200 while a total of transistor of 8080 was 4,800.

In the course of the design, due to the fact that the development team had specialists in both the creation of new ICs and the reproduction of analogs, Zilog’s tricks aimed at copy protection were identified and decrypted. For example, the topologist saw the 3-Input-NAND Gate element, but this element worked as 2-Input-NAND Gate. The topology and layout of the resulting clone was different, but the functionality did not differ from the original. At first, it was possible to identify such traps, making sure that the circuit was inoperable, only by examining the circuit elements inside the die using probe analyzers. But, having understood the principle of constructing traps, a mechanism for their detection was also developed. As a result, it was possible to make a full-fledged analog of the Z80, although the electrical circuit and topology of the T34MV1 had some differences.

The German Connection

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CPU of the Day

October 30th, 2016 ~ by admin

East German IC Institutions

MME S555C1 - Hobbyist edition 2708 EPROM - 1983

ZTFM  S555C1 – Hobbyist edition 2708 EPROM – 1983

Thanks to the input of a reader I updated the East German CPU page to be much more accurate as to the various institutions that existed, and their respective logos.  There were institutions in three different cities (Erfurt, Frankfurt, and Dresden), and they had amongst them 7 different names and a variety of logos.

It helps to remember that IC’s were made different in East Germany.  There was not so much corporations as we think of them in the West such as Intel or AMD that made this or that.  In East Germany (and the USSR) IC’s (and most everything else) were made by institutions, that were typically a government organization, or sanctioned by the government to do/make certain things.  These could be changed, consolidated, opened/closed at the whim of the government resulting in a lot of confusion in identity.  Add to that the changes brought with the fall of communism, and these institutions transition to modern corporation and you get some very interesting collecting opportunities.

The updated page should help ID’ing them a bit easier.


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Museum News

March 10th, 2016 ~ by admin

Milandr K1886VE: The PIC That Went to Russia

Milandr K1886VE2U PIC17C756A w/ Flash Memory

Milandr K1886VE2U PIC17C756A w/ Flash Memory

We have previously talked about the Microchip PIC17, and its less then stellar success in the market.  After being introduced in the early 1990’s it was discontinued in the early 2000’s, though Microchip continued to provide support (and some devices) to users for some time after that.

In the early 1990’s a IC company was formed in Zelenograd, Russia (just a short distance to the NW of Moscow), the silicon valley of Russia, home to the Angstrem, and Micron IC design houses.  This company was Milandr, one of the first post-Soviet IC companies, with ambitious plans, and many highly capable engineers from the Soviet times.  They are a fabless company, though with their own packaging/test facilities, specializing in high reliability metal/ceramic packages.

The K1886VE is Milandr’s version of a PIC17C756A, though updated for the 21st century.  While mask-ROM versions are available the VE2 version replaces the ROM with modern FLASH memory.  This is a upgrade that perhaps would have kept the PIC17 alive if Microchip would have done similar.  It is packaged in a 64 pins CQFP white ceramic package with a metal lid and gold leads, not what one is use to seeing a PIC in.  Production of these PICs continues at Milandr (the pictured example is from 2012), as customers still use the parts, mainly in industrial and other places where reliability is key.

The use of a PIC in high reliability applications isn’t something entirely new.  The Microhard MHX-2400 radio system, designed for small satellites such as cubesats, runs on a PIC17C756A, a version flew on NASA’s Genesat-1 in 2006 carrying bacteria samples.  Milandr does offer radiation resistant devices so its likely that some Milandr PIC has flown to space as well.


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CPU of the Day

February 13th, 2016 ~ by admin

RCA CDP1855: A Multiplier for the COSMAC

RCA CDP1855CE - 3.2MHz @ 5V

RCA CDP1855CE – 3.2MHz @ 5V

In the 1970’s MULT/DIV instructions were fairly uncommon to be implemented in hardware on a processor.  They were implemented in software (usually be the compiler, or hand coded) as a series of adds and subtracts/shifts.  In some cases dedicated hardware, usually through a series of bit slice processors, or ‘181s were added to handle MULT/DIV requirements.

In 1978 RCA announced the CDP1855 Programmable Multiplier/Divider for the 1802 COSMAC processor.  Sampling began in 1979, making this one of the earliest ‘math coprocessors’ of the time.  The 1855 was an 8×8 Multiplier/Divider, handling Multiplies with Addition/Shift Right Ops, and Division using Subtractions/Shift Left Ops.  It was, like the COSMAC, made in CMOS, and at 10V ran at 6.4MHz, allowing for a 8×8 MULT to finish in 2.8us.  The CDP1855 was also designed to be cascaded with up to 3 others, providing up to a 32×32 bit multiply, in around 12usec, astonishing speed at the time.  Even the slower CDP1855CE (using a 5V supply and clocked at 3.2usec) could accomplish a full 32×32 MULT in 24usec.  An AMD AM9511 (released a year earlier) can do a 32×32 fixed point multiply in 63usec (@ 3MHz).

Soviet Integral 588VR2A - CDP1855 'Analog' from 1991

Soviet Integral 588VR2A – CDP1855 ‘Analog’ from 1991

The CDP1855 was designed to interface directly with the 1802 processor, but could be used with any other 8-bit processor as well.  It was programmable, so the host processor only needed to load with the data to be multiplied/divided, the control values ot tell it what to do, and then wait for the results.

As was typical, the Soviets made an ‘analog’ of the CDP1855 called the 588VR2 and 588VR2A.  The 588VR2 was packaged in a 24-pin package vs the 28 pins of the CDP1855, so its certainly not directly compatible.  Soviet IC design houses were instructed and paid to design and make copies of Western devices, typically original ideas were discouraged.  This led to a lot of devices being made that were similar, but not the same as their Western counterparts, the design firm could make a somewhat original device, and then simply claim to the bureaucrats that it is an ‘analog’ to a certain Western design.  Thus the 588VR2 is ‘similar’ or an ‘analog’ to the 1855.

The CDP1855 continued to be made, and sold into the late 1990s, much like the 1802 processor it supported.


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CPU of the Day

September 6th, 2015 ~ by admin

The Electronika MK1 red3 PDP-11 Chipset and Tetris

Soviet Electronika MK1red3 - F-11 Clone and implementation of PDP-11

Soviet Electronika MK1red3 – F-11 Clone and implementation of PDP-11

The DEC F-11 ‘Fonz’ implementation of the PDP-11 was released in 1979 and was DEC’s second ‘LSI’ implementation of the PDP.  Like its predecessor it was a multi-chip implementation, consisting at its root of a data chip (DC302) and 1-9 control chips (DC303).  The DC303 control chips were essentially a large ROM/PLA with a few extra features added for interrupts and sequencing.  They formed the microcoded instruction set that drove the 16-bit ALU and registers of the DC302.  This is why more then one were supported.  Expanding the instruction set was as ‘simple’ as adding more DC303 chips with these instructions encoded.  The basic LSI11/23 came with one 303 and one 302.  A second IC could be added to support floating point, which included a pair of DC303 chips implementing the floating point instructions.  A MMU (DC304) was also supported, and required when using the FP option.

DEC 570000101A1 F11 Floating Point Option with 2x 303E Control chips

DEC 570000101A1 F11 Floating Point Option with 2x 303E Control chips

The Soviets also widely adopted the PDP-11 architecture.  Likely because it was designed to be rather hardware independent.  It could be implemented in many different ways, which meant the Soviets could adopt/implement it on their own.  Electronika was part of the Soviet industrial complex in Voronezh, Russia making many different IC’s, but also was tasked with making consumer devices (computers and calculators etc, that were in very short supply.  The Electronika 60 was one of the first PDP-11 computers they made, and it implemented a copy of the DEC Fonz processor.  Electronika combined the standard chipset, and FPU onto a single large MCM with all 4 IC’s (the MMU remained separate) called the MK1 red1 (and later the MK1 red3)

Tetris Electronika 60 - Text Only

Tetris Electronika 60 – Text Only

KH1811VM1 = DC302 – 21-15541 Data Chip (16-bit ALU etc)
KH1811VU1 = DC303 – 23-001C7 standard instruction set
KH1811VU2 = DC303 – 23-002C7 FP instruction set Part 1
KH1811VU3 = DC303 – 23-003C7 FP instruction set Part 2

It was on this chipset, on a Soviet Electronika 60 that Alexey Pajitnov wrote the very first version of the still famous game of Tetris back in 1984.  A game that was very popular, and very widely copied in the West, even to this day.  (the copying of technology most certainly went both ways)

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CPU of the Day

April 22nd, 2014 ~ by admin

Soviet K573RF23 and the Mark of Quality

Soviet Vostok K573RF23 - 2kx4 - 1984

Soviet Vostok K573RF23 – 2kx4 – 1984

This EPROM, made in November of 1984 at the Soviet Vostok factory in Novosibirsk started life as a 2716 2kx8 EPROM.  A Soviet 2716 would be marked as 573RF2, whereas this particular example is marked 573RF23.  The die is a 2716 that was found to be defective, and thus converted to a  2kx4 EPROM, this is denoted by the adding of the 3 to the part number.  This certainly was not an uncommon procedure, even Intel regularly sold 2708 EPROMs as 2704s, whether to use a die with an imperfection, or to simply meet demand.

There are two other interesting markings on this particular EPROM.  First is the CCCP logo, this is the State Quality Mark of the USSR.  This quality mark was used to signify that products met the following conditions:

  • “meets or exceeds the quality of the best international analogs”,
  • parameters of quality are stable,
  • goods fully satisfy Soviet state standards,
  • goods are compatible with international standards,
  • production of goods is economically effective and
  • they satisfy the demands of the state economy and the population.

Meeting these conditions allowed the factory to sell such devices at a 10% premium.  So not only was Vostok able to pass a defective part as a quality part, they were able to do so and make a bit extra revenue.  Thats something Intel would be quite envious of.

Some references show that 573RF23 as being the equivalent of a 2758 EPROM (5V 2708).  This is in fact incorrect.  A 2716 converted to a 2708 is done so simply by removing a single address line (going from 11 to 10)  The 573RF23 retains 11 address lines, but it removes 4 data lines, thus making it 2kx4, same number of address locations, but each locations contains only 4 bits, vs 8 bits.  Rewiring address lines likely did not allow for a working EPROM due to where the defect was, thus cutting the word size down.  The first condition of the State Quality Mark is that said EPROM should meet or exceed the best international analog.  Intel did not make a 2kx4 EPROM, the closest western analog would be the Harris/Intersil IM6657, though it was made in CMOS, vs the 573RF23s NMOS, so one could say that it was easy to beat a analog that did not exist.

The other mark on this EPROM is OTK, which literally means “Technical Control Department,” in others words this part passed the quality control dept, hopefully after it was converted to the lower capacity device, and them marked with the State Quality Mark.  Perhaps it was the best NMOS 2kx4 EPROM the world was to see, certainly it came in a beautiful package.


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EPROM of the Day

February 20th, 2011 ~ by admin

Russian Computers on the Buran Shuttle

In the 1970’s and the 1980’s the Soviets developed and successfully flew their own version of the Space Shuttle.  It was called the Buran.  In many ways it was an enhancements of the US Space Shuttle, based on what the Soviets saw as deficiencies in the US design.  One of the biggest differences was the piloting.  The US STS (Shuttle Transport System) was designed to be a crewed vehicle.  The computers assisted the pilot/co-pilot in launch, orbit, and recovery.  Many of the functions on the STS can be handled by the computers (the Flight Computers were based on the IBM System/4 Pi) but the pilot was needed to handle the rest.  The Soviets, on the other hand, designed the Buran to be able to launch, orbit, and land fully automatically.  This meant the computers has to be very robust, and the programming even more so.  The computers had to respond quickly to chaning inputs, and be able to handle failures gracefully.  While each mission would have a set profile, unknown conditions would cause deviations that the computers must detect, analyse, and properly handle.  Preferably without wrecking the multi-billion ruble space craft.

Buran Computer

The main computer of the Buran is actually 4 independent systems that receive the same inputs.  The clock in generated externally (with 4 backups) so that each computer is in perfect time (the STS uses software to ensure the computers are in time, rather then hardware).  Redundancy is achieved by the voting system. Each computers outputs are compared, if one computers output is different, it is automatically shut down, leaving the 3 remaining computers.  These computers are powered by a clone of the DEC PDP-11.  The Soviet’s ‘acquired’ a few PDP/11 systems and then copied and cloned them into many different systems.  The most common is the 1801 a 5MHz NMOS PDP-11 type device.  The Buran used the 1806, which is the CMOS version.   Here is a general overview of the flight computer.

Angstrem CMOS N1806VM2 - MicroVAX

In addition to the 1806 there were many sub-systems with their own processors.  Details on these are a bit thin, however looking at other Soviet space computer designs it is very likely that many of these used the 134IP3 series of ALUs (a clone of the 54L181 TTL 4-bit ALU).  This chip is also used in the Argon-16 and Argon 16A computers of the Soyuz and Progress spacecraft that are still in use today.  Bit-slice devices were used extensively for many Soviet designs as it gave them a great ability to design custom processors to meet the applications needs.  The Argon-17, which was used for anti-ballistic missile work, was based on the 583 series, an 8-bi slice processor.  The C100 and C101 computers (used as weapons computers on the MiG-29) also use a BSP design.

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October 11th, 2010 ~ by admin

Soviet Beauties: Processors from behind the Iron Curtain

The Soviet Union’s electronic programs were mainly focused on copying and cloning Western devices.  Either by simple theft, or painstaking reverse engineering.  They made clones of devices such as the Intel 8080, and the AMD 2901 as well as simple TTL.  The Soviets also made many single and multi-chip versions of the venerable DEC PDP-11 computer system.  Many of these have no Western analogs, they were pure creations of the Soviet industry.

Soviet Kvantor 580VM80 - Intel 8080 - Milspec

While Western chips rapidly transitioned into mostly black plastic by the 1980s the Soviets did not.  The 8080 above was made in 1991 though looks like something from the 70’s. Black plastic is cheap, and easy to make, but it isn’t great looking. The Soviets on the other hand made some of the best looking (if not always functioning) processors of the time.

Soviet J-11 Missing the chips

Here is just the substrate (its a non finished example) of a Soviet clone of the DEC J-11 CPU. Not often do you see a brilliant blue processor.

Soviet Angstrem K1801VM1

This is a nice pink ceramic Soviet PDP-11 5MHz CPU. Again this was made in 1991.  Its a form of surface mount package that was used extensively for industrial and military designs.  Just as the PDP-11 was used by the American military throughout the 70’s and 80’s. the Soviets used it (and now Russians) in todays times.

Soviet era CPUs are very interesting to collect.  Each state run factory had their own logo which was typically (but not always) put on the chip. Many part numbers were made by more then one factory. Most chips have a western analog, but not all.  Soviet chips also were ever so slightly different sized then Western ones. The Soviets used a pin spacing of 2.5mm where as the West used 0.1″ (2.54″), rather noticeable on a 40 pin DIP. Reading/translating some of the Cyrillic  based characters can be a chore but really when you get to see things like this…

Electronika J-11 - Image courtesy of iguana_kiev

Can you really complain?