I highly recommend Jimmy Maher’s series, “Tales of the Mirror World,” posted on the Digital Antiquarian blog. (Which anyone who scrolls this far down the page should definitely be reading!)
In particular, part II covers the inflection point, around 1970, when the Soviet Union gave up on designing systems like the BESM mainframe, which was technically on par with Western computers despite not being made from integrated circuits, but which the Soviet Union was unable to produce in quantity. The main problem it had was not in its computer designs, as the Rand Corporation noted at the time, but its ability to produce them. In 1970, the Soviet Union only had approximately five thousand computers.
The article gives as an example:
A popular story that circulated around Western intelligence circles for years involved Viktor Belenko, a Soviet pilot who went rogue, flying his state-of-the-art MIG-25 fighter jet to a Japanese airport and defecting there in 1976. When American engineers examined his MIG-25, they found a plane that was indeed a technological marvel in many respects, able to fly faster and higher than any Western fighter. Yet its electronics used unreliable vacuum tubes rather than transistors, much less integrated circuits — a crippling disadvantage on the field of battle. The contrast with the West, which had left the era of the vacuum tube behind almost two decades ago, was so extreme that there was some discussion of whether Belenko might be a double agent, his whole defection a Soviet plot to convince the West that they were absurdly far behind in terms of electronics technology. Sadly for the Soviets, the vacuum tubes weren’t the result of any elaborate KGB plot, but rather just a backward electronics industry.
The Ryad project that began in 1970 marked a departure from the BESM-6, in that it was a copy of the IBM 360. It would not be the last: Leo D. Bores, an American surgeon who saw the Agat microcomputer called it a copy of the Apple II, and a bad one. DEC was aware that the Eastern Bloc was copying its designs, and began etching messages in pidgin Russian into their CPUs, where they would show up on X-ray scans. One of them was intended to say, “CVAX: When you care enough to steal the very best.” The East German team reverse-engineering the CPU, either unfamiliar with the Hallmark greeting-card slogan the Americans were riffing off of, or wanting to flatter their Russian overlords, told them that it said, “Why steal? You already have the best.” Similarly, the KP580BM80A is, as the name suggests, a copy of the Intel 8080.
Up until the 1970s, the Soviet Union had sometimes been able to buy chip-fabricating equipment from the West, but the Carter and Reagan administrations put export restrictions on American technology that ended those transactions. Starting in 1970, the Soviets began trying to split up the design and manufacturing of different computer components among its Warsaw Pact allies.
There was at least one locally designed computer of the ’80s that deserves mention, however: the Electronica BK-0010. Its CPU was compatible with the instruction set of the American PDP-11, but was an original design, and the machine was a 16-bit personal computer at a time when most American home computers were still 8-bit. It cost one-fifth as much as the Agat, although that meant there was always a long waiting-list to get one, and some people instead tried putting one together from kits. It was created to fulfill a promise by the new Soviet Premier, Mikhail Gorbachev, to put a computer in every classroom.