The ps1 cpu was just a mips. Building a mips cpu with an fpga is a normal required undergrad project for a cs degree or it was a couple decades ago. I was feeling dismissive until I looked at the specs for the gpu and spu... That was some serious work for the ps1. The ps2 had that odd cell processor, or emotion engine whatever you want to call it. Its still basically multiple simplified mips cores but now all the stuff to synchronize them correctly? I'm surprised the ps2 emulators are as close as they are. Doing it all in hdl, and with the upgraded gpu, that is enough work that I wonder if software emulation fidelity wouldn't reach hardware fidelity before the fpga design did.