This article is about memory chips manufactured by one of the entities – the leader of the electronic industry of the USSR – Angstrem. As you know, the Soviet Union ceased to exist in December 1991. We restrict ourselves to the development period of the considered memory chips produced at Angstrem, the end of 1991. Let’s make an attempt to track how the capacity of memory chips grew, how technologies were improved that allowed the Soviet Union not to let the world leaders in electronics go far from itself at that time. A small example: Angstrem’s Dynamic RAM 4K went into mass production in mid-1975, Intel introduced its own in 1974. Intel launched a 16K DRAM in 1977, and Angstrem released its counterpart in 1978.

Angstrem Headquarters

Angstrem was established in June 1963 in Zelenograd (outside of Moscow) as a pilot plant in conjunction with the Scientific Research Institute of Precision Technology. At Angstrem, new technologies for the production of microelectronics were developed, and pilot batches of new microcircuits were also produced. The debugged production technology was then transferred to other enterprises of the USSR and countries of Eastern Europe.
The development and manufacture of memory chips was one of the main activities of Angstrem. It was on them that new semiconductor structures and production technologies were more effectively worked out, and the stability of obtaining finished products is considered in world electronics as a sign of technology ownership. It’s relatively easy to make a small batch of good chips, it’s hard to make a process whereby a large amount of chips can be made and be reliable. It was the very low chip yield percentage that played a cruel joke on Angstrem when mastering the production process of the DRAM 565RU7 chip.

SRAM

In 1966, Angstrem created the first MOSFET in the USSR, which was the first step towards the strict goal of creating CMOS integrated circuits. The first CMOS microcircuit, created in the Soviet Union in 1971, was the 16-bit Angstrom matrix of memory cells 1YaM881.The supply voltage is 6 volts instead of 5 volts, like the rest of the chips in this series.

1YaM881 – 1972

The next in a series of static RAM chips was the CMOS K561RU2 (K564RU2), released in 1976. 564 series of chips is a “military” analogue of the 561 series. In these series, there are several dozen microcircuits. The chip has an organization of 256 words by 1 bit.

561RU2 die – 16×16 256bit matrix clearly visible – The image is taken from the site https://radiopicture.listbb.ru/ with the permission of the author.

It contains 2067 integral elements. Supply voltage is 3-15 volts. It’s an analogue of CD4061A.  It should be noted that in most cases ‘analogue’ means similar to, not an exact copy or exactly compatible.  The USSR did make some compatible IC’s, but they mostly made stuff that was similar, but built to their own specifications/needs.

K564RU2A -1978

K561RU2 -1979

The package of the K561RU2 chip is wider than the standard packages of this series.

K565RU2 -1979

The K565RU2 static RAM chip was manufactured using NMOS technology. Chip capacity was 1024 bits (1024×1). Contains 7142 integral elements. An analogue of Intel 2102A, developed in 1974. K565RU2 appeared in 1977. It was originally designed to be placed in a ceramic package, but later, in order to reduce the cost of production, the dies began to be packed in plastic packages.

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This is turning into a bit of a series on Soviet processors.  Continuing from our article earlier on the 1801VM2 LSI-11.  The 1801VM3 is the further development of 1801VM1/VM2 and is the highest performance microprocessor in 1801 series. It’s a 16-bit single-chip microprocessor that includes an operating unit, a firmware control unit, an interrupt unit, a memory controller and Q-BUS control unit. A distinctive feature of 1801VM3 is a large amount of addressable memory (4MB vs 64K for the 1801VM1 and 64k+64K for the VM2), high performance and ability to connect a floating-point coprocessor 1801VM4.

1801VM2 die

1801VM3 Die

1801VM3 Specifications

• Number of processor Instruction: 72 Fixed Point and 46 Floating Point (with 1801VM4 FPU)
• Address Space: 4MB
• General Purpose Registers: 8
• Manufacturing process: 4 micron N-channel silicon gate MOS technology (later migrated to 3 micron)
• Die size 6.65 × 8 mm
• Transistor count: 28,900 active transistors, 200,000 integral elements
• Clock rate: 4MHz  (1801VM3V) 5MHz (1801VM3B) 6MHz (1801VM3A, upgraded to 8 in 1991)
• Performance: For register based operations (like addition) up to 1,500,000 instruction/s (1.5 MIPS)
• IRQ Lines: 4
• Supply voltage + 4.75V-5.52V
• Power consumption: 1.7-2 W
• Packages: CDIP64 (KM1801VM3) LQFP64 (KA1801VM3) CQFP64 (KN1801VM3/N1801VM3)

Like the VM2 before it the speeds were denoted by a series of dots on the package (or lack thereof)

KM1801VM3A – 6MHz (no extra dot) CDIP64 package from 9008

KM1801VM3B – 5MHz (one extra dot) CDIP64 package from 9003

KM1801VM3V – 4MHz (two extra dots) CDIP64 package from 9202

KA1801VM3 – 8MHz (no extra dot – post 1991) PQFP64 package from 9108

N1801VM3 – 8MHz (no extra dot – post 1991) CQFP64 package from 9324 – Remarked from a military part (rhombus marking marked over)

The KM1801VM3 appeared as part of the DVK line of computers, starting with the DVK-3M model (PCB ”Electronics МС 1201.03” and “Electronics МС 1201.04”).  Using the same ISA (Instruction Set Architecture) allowed DVK (and others) to rapidly update their computer line when new processors were available, and allow for a wider software base.  This is very much like the original IBM PC using the x86 architecture.  The transition from 8086 to 80286 was relatively easy to design, and nearly seamless for the end user.

DVK PCB Electronics МС 1201.03 board on the top.

Many devices built on the basis of the 1801 series CPU contain other microcircuits of the same series (support circuits).
In addition to microprocessors, this series includes:
– ULA 1801VP1-xxx
– masked ROM 1801REх-xxx
– EEPROM 1801RR1

ULA and EEPROM

The 1801VP1-xxx is a ULA- (Uncommitted Logic Arrays). It’s made using a 3 micron N-channel silicon gate MOS technology with one metal layer. First, base silicon wafers are made that contain transistors. These are doped regions of silicon and a separate oxide-insulated layer of polysilicon gates. Then all this is covered with an oxide layer. Base wafers are ready.

In this form, the wafers can be stored for a long time or transferred to another fab. All 1801VP1-xxx chips, regardless of number, have the same structure and arrangement of transistors. And they are made on the same base wafers.

KR1801VP1-22 die

Differences between the chips appear only at the last stage of manufacturing. In the upper oxide layer, the die is etched by photolithography to access the required transistors. And then form a metallic pattern from aluminum. This pattern defines the electrical circuit. The number in the marking identifies the purpose of the chip. For example, 1801VP1-033 is an external device controller.  This is similar to how a MaskROM is made but instead of only memory elements, it contains logic elements allowing for a custom IC to be made (like a mask programmable PAL/GAL)

KR1801VP1-119

The 1801VP1-119 is a companion chip for 1801VM3. It can be said to be the “north bridge“.
The 1801VP1-119 performs the following functions:
-forms control signals for DRAM;
-forms control signals for system SRAM;
-generates signals to select system ROM;
-generates control signals for detection and correction of memory errors (EDC) using Hamming code (555VGH1). Error correction circuits reduced performance by 10-15%. Therefore in some computers, there were jumpers to enable/disable the EDC
-buffer data register control;
-generate other signals

This was the beginning of what would be come chipsets, replacing loads of TTL with custom circuits.  The exact same evolution was occurring in the west with the PC environment, until nearly all the support circuits were integrated into just a couple large ASICs.   Its interesting to see the development paths of the Soviet computers and the West.  While they were entirely different instruction sets, they evolved in very much the same way.  East or West, LSI-11 or x86, at the end of the day, a computer is a computer and will evolve in similar fashion.

The Soviet-made 1801VM2 CPU (a binary-compatible implementation of the PDP11 instruction set and QBUS interface) was developed in 1982. The 1801VM2 is a further development of the earlier 1801VM1 doubling the original 5MHz clock speed. From a constructive standpoint this CPU is a completely independent development.

1801VM2 die – 1983 dated

1801VM2 Specifications

• Number of processor Instruction: 72
• Manufacturing process: 4 micron N-channel silicon gate MOS technology
• Die size 5.3 × 5.35 mm
• Transistor count: 18,500 active transistors, 120,000 integral elements
• Clock rate: Up to 10 MHz
• Performance: For register based operations (like addition) up to 1,000,000 instruction/s (1 MIPS) – for operations like multiplication, up to 100,000 instructions/s
• Supply voltage + 5V
• Power consumption: up to 1.7 W
• The case is 40-lead, ceramic DIP (KM1801VM2) or plastic DIP (KR1801VM2). (a surface mount version was also made)

To increase noise immunity in comparison with 1801VM1, additional ground contacts were made for the address / data bus.
The 1801VM2 was manufactured at two factories: Angstrem and Solnechnogorsk Electromechanical Plant (SEMZ).  As was typical of the time speed grading was done by adding extra marking to the chips post-testing.  Its very easy to miss these, if a chip was tested at 10MHz and passed it received no extra marking and was considered an 1801VM’A.’  If the device failed at 10MHz but ran at 8MHz a small dot was added to the package (and was considered a grade ‘B’ device).  This dot was not to be confused with the dot for the pin one marker, though often placed…next to it.

Ceramic DIP 1801VM2A Angstrem – 1989 No extra dot

Ceramic DIP 1801VM2B Angstrem – 1987 – Note the extra dot in this case by the date code

Plastic DIP 1801VM2A Angstrem – 1990

KN1801VM2- Angstrem 1985 CQFP Surface mount version (image Baator)

Ceramic DIP 1801VM2 Solnechnogorsk Electromechanical Plant – 1990 – Extra dot by pin 1 marker

In comparison with 1801VM1, expanded arithmetic instructions (MUL, DIV, ASH, ASHC – part of a the set of PDP-11 EIS), and also operations from the floating point instruction set (FIS) were added. The FIS instructions (FADD, FSUB, FMUL, FDIV) are realized through subroutines – when performing these instructions there is a special type of interrupt and the program handler in memory (“shadow” system ROM K1801RE2) of the console mode is executed, a ‘firmware’ style of FIS implementation, as its not truly hardware (the ROMs break down the FIS instructions into something the 1801VM2 can execute)
During the design of the microprocessor, a microcode error was made, leading to a malfunction of the processor when reading with addressing method 17 ( MOV (PC), R0).

DVK-1 Computer

The 1801VM2 was the heart of a number models of DVK computer. DVK was developed at the Research Institute of Precision Technology , Zelenograd (just outside of Moscow). The first model DVK-1 was developed in 1981, and released in 1983. Architecturally DVK copies mini-computers from DEC PDC-11 and PDP-11. By 1990, 200,000 DVK computers of the nine different models were produced.

Romashka Word Processor

Use of the processor continued well into the 1990’s. The “Romashka” belonged to the latest generation of electronic typewriters, which in their functionality were close to computer text editors. This typewriter made it possible to automatically format text (set alignment, change the spacing between characters and between lines, use bold and underlined fonts, etc.) and had an electronic memory of at least one page (3800 bytes).  In the West these half typewriter half computer were called Word Processors, and were quite popular through the 1980’s.   The machine’s control unit was a microcomputer based on the KM1801VM2 processor.
“Romashka” was produced by the Kursk PO “Schetmash” in the first half of the 1990s.

“Electronics IM-05 “- Soviet chess computer, contains 1801VM2 inside. It was a continuation of the line of chess computers “Electronics”. Produced by the Svetlana Association, Leningrad.

In 1984, the military-grade microprocessor 1806VM2 was released.
This microprocessor functionally corresponds to the 1801VM2, but is made using CMOS technology.

• Clock rate: up to 5 MHz
• Number of Instructions: 77
• Contains 134,636 integral elements
• Power consumption: up to 0.025W

The 1806VM2 developers fixed the microcode bug present in 1801VM2 (much to the relief, or annoyance of programmers). The 1806VM2 was supplied in a 42-lead dual in-line ceramic package with flat leads, N1806VM2 in a 64-lead CQFP. The rhombus marking on the chips denotes a military-grade device.

1806VM2 – Angstrem 1991 in the nice pink flat pack

N1806VM2 – Angstrem 1999 in a Ceramic quad flat pack

CQFP N1806BM2 on a ceramic substrate forming a military Single Board Computer – circa 1987 (image Baator)

These 1806VM2 are still being made by Angstrem, if you need to build a PDP-11 computer to run Tetris on, or repair a Buran shuttle you may have laying around.

In 1990, a radiation-hardened microprocessor was introduced, compatible with the 1806VM2, known as the 1836VM2/N1836VM2.  Just like in other countries, existing code base and known reliability are more of a driver of what the military/industry uses than having the latest and greatest.  There are still MIL-STD-1750A processors being made and used, rad-hard 8051s and 80186s, and Soviet PDP-11 processors right there with them.

Photos of microprocessors from the collection of Perfiliev Andrey (Andreycpu).
Article written originally by Contributing Author Vladimir Yakovlev (edited by cpushack)

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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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.

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.

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

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.

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

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

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)

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.

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.