globalisateur on 16 January 2014
I think it's because of the very low latency of the 4MB EDRAM of the PS2. Very hard to emulate that via software using regular XDR ram or GDRR5 ram (even DDR3 ram couldn't do it).
That's why only added hardware on the first PS3 models, or partial hardware on later PS3 models, could only perfectly emulate 99% of PS2 games.
The PS2 games on PSN have been reprogrammed, bypassing the very fast EDRAM vram calls.
It would be possible in theory to use the very low latency GPU caches of the PS4 to emulate the 4MB Vram of the PS2, I dunno.
