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 (Bulgaria, Czechoslovakia, East Germany, Hungary, Poland 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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In sports, particularly Baseball, its often said that the longer a record is to say, they less impressive it is.  ‘Most Home Runs Ever’ is much more of an impressive record then ‘Most Home runs in the 7th inning against a left handed pitcher with a runner on 3rd’  Both are of course records, the first, many may even know the answer (Barry Bonds), the second? I’m sure someone can look it up but I have no idea.

So when I got this interesting commemorative AMD Opteron Sample it seems fitting to break down the record engraved on it ‘Shanghai – World’s 1st 45nm Monolithic Quad Core x86 CPU – October, 2008’  That seems impressive, and the reality is that it was (and is) and its a testament to the very hard work the design team, whose names are engraved for perpetuity on the chip, put into it.  The Shanghai was a third gen Opteron that followed the very troubled Barcelona, so it was really a make or break design for AMD.

Intel Core 2 Quad Q9100 QAVK Engineering Sample – Dual 45nm dies – Mid 2008

The most impressive aspect of the record is ‘First monolithic quad core x86 CPU.’  This was putting 4 x86 cores on a single die. Now Shanghai wasn’t the first to do this, as Barcelona had done so previously, thus the addition of ’45nm’ to the record.  Barcelona was made on a 65nm process whereas Shanghai shrank that to 45nm.  At the time Intel had the Quad-Core Clovertown Xeons (65nm) and had (in 2007) just released the Harpertown/Yorkfield Quad-Cores made on a new 45nm process.  All of these used two dual core dies in a single package. Intel was able to catch up later with the Nehalem based processors in 2009.

Was there other single die Quad-cores at the time?  What if we look outside of the realm of x86?  In 2008 IBM released the z10 quadcore processor, it was a single die, running at up to 4.4GHz (!) but it was made on a 65nm process.  Likewise, the UltraSPARC T2 was a 8-core CPU from 2007 but again, only on a 65nm process.  Freescale released the 45nm quadcore, single die P3 series P2040 PowerPC processors, but in 2010.  MIPS had the quadcore 1004K in 2008 but only on 65nm. So it seems AMD may have had a better record then they thought.

What if we stretch what we call a processor? There were at the time some fairly simple large multicores like the Tilera TILE64 (64-basic 32-bit cores) made on 45nm process, but they are less of a general purpose CPU.  Perhaps the closest is the Sony CELL Processor in the Playstation 3, which IBM was moving to 45nm in 2008 and had 1x PowerPC core + 7 SPEs. Perhaps AMD could have made a claim to the first 45nm single die CPU ever, even including non-x86 chips.