[2600]

I heard something similar with Jak and Daxter, where they took advantage of the embedded PS1 hardware on the PS2 to scrape together some extra performance.

I very much enjoyed this video that Ars Technica did with Andy Gavin on the development of Crash Bandicoot: https://www.youtube.com/watch?v=izxXGuVL21o

[midnightclubbed]

Most PS2 games used the PS1 hardware for audio/sfx so you freed the main CPU for rendering/gameplay.

I believe Gran Tourismo 3 used the ps1 hardware for everything except rendering, which was the kind of nuts thing you could do if your games were single platform and with huge budget.