[spamizbad]

If you're manufacturing chips under sanctions your most difficult finds are going to be the manufacturing equipment, expertise, and raw materials to produce the chips. It's not going to be an ISA - there have been a litany of "open" ISAs and well-documented industry standard ones you're likely going to do unlicensed copies of.

Secondary challenge here, going beyond the ISA, are pre-defined blocks of functionality already implemented (eg: an ethernet controller, internal CPU busses, memory controllers, etc). Even in the RISC-V world many of these are commercial and require a license.

[vbezhenar]

You want to have lots of software for your computer. Like Linux, Chromium, compilers, JIT, etc. It reduces the number of options.

[notsapiensatall]

Most hardware is not field-programmable. You can't update a CPU's DDR3 PHY to DDR4, or switch to DDR3L if your needs change.

The single-purpose nature of ASICs and hardware blocks is what makes them fast and power-efficient.

[nomel]

Yeap! I've worked with analog and digital chip designers, along with some digital designers that now work on fundamental IP for an FPGA company. One thing they all had in common was "we avoid all abstractions". It's all as direct as possible. You don't use extra silicon to appease some tidy block diagram that makes the problem easier to reason about, because the silicon isn't made for humans to reason about, it's made for holes and electrons to do their thing!