USSR 1801

1801VM1/2/3/4 is a series of DEC (PDP-11) compatible microprocessors developed in Soviet Union. The first processor from this series 1801VM1 could address 64 KB of memory and executed up to 500,000 register operations per second. Next version of this microprocessor (1801VM2) was twice as fast, and included new instructions: integer multiplication and division, shift right, and 4 basic floating point operations that required external ROM - addition, subtraction, multiplication and division. 1801VM3 microprocessor was enhanced even further. The processor addressed up to 4 MB of memory, was 50% faster than 1801VM2, and supported external co-processor.