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)