> Plenty of technical documentation on the PSP and the main processor is well
> documented (MIPS R4000). I'll see if I can't get an environment going and get
> familiar with the inner workings of the MIPS 4k. I've got a lot of reading to
> do too. We'll see what comes of it.

It doesn't matter much, but it isn't an r4k. The Allegrex (PSP CPU) does borrow some of its features however. Like the r5900 in the PS2, the Allegrex is a custom job - It's more of a (somewhat, anyway) mips32R2 cpu with no mmu.

http://rapidshare.com/files/72446657/MipsInstructionSetReference.pdf.html

might be helpful to have around.