[renaudg]

At the end of the day both FPGAs and software emulators are Turing machines that produce a set of outputs given a set of inputs : any logic an FPGA can implement can also be implemented in software, it's computer science 101

FPGAs aren't magically more accurate. That is only up to the programmer and what effort they put in.

The main difference is efficiency and parallelism : it's much easier to reliably produce cycle-accurate parallel outputs in real time with an FPGA, compared to software running on a multi-tasking OS with many layers of abstraction and no deterministic real-time guarantees.

But, as a single-core processor can fake multitasking, by slicing time between processes (preemptive multitasking), software emulation can mimic parallelism if the host is beefy enough compared to the old school system it's emulating. The larger the performance / clock speed gap between the host and target, the more indistinguishable from a truly parallel FPGA an emulator can be.

Software emulation also has practical advantages for developers : while FPGAs force you to painstakingly implement every bit of functionality at the logic gate level, with software you can start off with a much higher level model of the target system that's much easier to implement, and mix & match that with more precise low level simulation where it matters. The time this frees up (+ the availability of various libraries) allows the developer to spend more time researching the original system and adding modern quality of life features that just wouldn't be possible otherwise.

Great article on the topic : https://archive.is/fWosI