On: Ask HN: Why don't PCs have better entropy sources?

[JohnHaugeland]

As soon as you try to tell us which kind of FSM the CPU is, you'll realize why it isn't any of them

[MichaelBurge → JohnHaugeland]

I used to have a friend who worked at AMD, and he said they simulated one of their in-progress CPUs on five Virtex-5 FPGAs.

Looking here: https://docs.xilinx.com/v/u/en-US/ds100

* I see a lot of LUTs, adders, and common operations(not a theoretical problem).

* There's memory and IO, but that shouldn't matter for defining a single clock tick.

* Thermal/power monitoring - not sure how important that is, but sure that's outside the definition of a FSM.

I have written simple software and FPGA CPU cores, and I would describe all of them as FSMs. It's possible that newer CPUs wouldn't qualify because e.g. they rely on metastable circuits for randomness, power-monitoring, etc. but most of it should be a FSM and the exceptions aren't anything like "infinite execution paths".