Comment by ZX8301
17 hours ago
90% of the PS2’s floating point throughput is in the two vector units, not the R5900 conducting them. Concentrating on that, as the article does, seems as futile as focussing on the 68000 rather than the Amiga PAD in a 16-bit context (ignoring the EE’s 16-bit RAMBUS bottleneck).
However that approach will probably suit the least-ambitious PC-ports to PS2 (by studios that didn’t appreciate the difference) - rather as an ST emulator was a short cut to run the simplest Amiga games.
Hey! I can speak here.
Back in the day, I wrote a simulator for the PS2’s vector units because Sony did not furnish any debugger for them. A month after I got it working, a Sony 2nd party studio made their VU debugger available to everyone… Anyway…
The good news is that the VU processors are actually quite simple as far as processors go. Powerful. Complicated to use. But, not complicated to specify.
This is made much simpler by the fact that the only documentation Sony provided was written by the Japanese hardware engineers. It laid out the bit-by-bit details of the instruction set. And, the bitwise inputs, outputs, delays and side effects of each instruction.
No guidance on how to use it. But, awesome docs for writing a simulator (or recompiler).
I think you're actually describing why recompilation is interesting here rather than why it's futile