i8080 precise replica in Verilog, based on reverse engineering of real die

There's some pretty famous "signs" that companies would put into their chips to show that it was blatently stolen. Also at some point it became a game:

https://micro.magnet.fsu.edu/creatures/pages/russians.html

What's fascinating is that you can basically run a country with little to no "actual" development of computer hardware, and just have an entire industry around "copying" to keep yourself up to date (or a few years behind at most).

This is pretty evident with China of the past few years in military tech, and now they are starting to leap frog (See engine issues with their new fighter, and how they are almost there but not quite. Russia is unwilling to sell them newer engines for fear of copying essentially)

For the East German Z80 clone U880 there are some wild stories of how the secret service stole blueprints from Zilog, but the more believable version of the story is that some chips were smuggled over the border that had simply been bought in West German electronics stores. The East German Z80 version had definitely been reverse engineered - not simply cloned - because the U880 has a slightly different undocumented behaviour (for instance, the undocumented X and Y flags behave differently than on a real Z80), also apparently the Z80 has various 'trap transistors' which prevent that the mask can simply be cloned, those trap transistors had to be found and fixed (I guess this was the reason why the U880 project was delayed by a year or so).

The much bigger problem than reverse engineering the chips was setting up manufacturing anyway. For East Germany this definitely happened with secret service support. The story goes that a small chip manufacturing company was set up in West Germany, which soon after declared bancrupty with the entire manufacturing equipment sold off to another company somewhere abroad. "Somehow" that equipment disappeared en route and showed up in East Germany a few months later.

https://retrocomputing.stackexchange.com/questions/11143/in-... references "Zilog oral history" and poses the question, but there isn't a strong answer other than the link to the above.

The oral history document referenced is: http://archive.computerhistory.org/resources/access/text/201... . The discussion of traps begins on page 101.

https://emulation.gametechwiki.com/index.php/MiSTer

this might be what is referenced?

I did work as a CPU logic desiger at Amdahl. We had full parity through-checking, so an ALU intermittent logic error would raise a parity exception. Certainly IBM would have had the same, it was standard SOTA reliability logic for the era of mainframes when I was a designer.