It is the heart of the Nintendo64[?] next to the MIPS 4300i . It was developed by SGI specially for Nintendo, and little is known about it, and the way it works.
The RCP features a vector processor that can perform over 500,000,000 arithmetic operations[?] per second, making it a very powerfull chip compared even to Intel's processors (in raw power)
It handles the audio and video of the Nintendo64 and can perform very well in operations such as: real-time edge anti-aliasing, high frame-rate on complex images, automatic load-management, advanced texture mapping, real-time depth buffering[?], etc.
In general, what made the Nintendo64 more advanced than other consoles of its time, was mainly the RCP.
wikipedia.org dumped 2003-03-17 with terodump