Allegrex?
- Thread starter remmy
- Start date
You won't find a datasheet because it's not a publicly available chip, it's something Sony and other companies came up with that's specifically licensed for PSP (same as Emotion Engine was for PS2).
It's not actually a MIPS R4000 series CPU, largely because it's not 64bit. It's basically a MIPS32 r2 CPU with single precision only FPU, no TLB (some rudimentary, possibly fixed memory protection is in place), and a VFPU.
On the integer side some things are a little different. There's no mult instruction (variant that stores the result in a GPR in addition to hi/lo, basically has an implicit mflo tacked on it), the encodings for madd/msub are different, and there are extra instructions for bit reversing, min/max, and I think byte swapping, can't exactly remember.
Still, this document will tell you most you need to know: http://www.cs.tau.ac.il/~afek/MipsInstructionSetReference.pdf
It's not actually a MIPS R4000 series CPU, largely because it's not 64bit. It's basically a MIPS32 r2 CPU with single precision only FPU, no TLB (some rudimentary, possibly fixed memory protection is in place), and a VFPU.
On the integer side some things are a little different. There's no mult instruction (variant that stores the result in a GPR in addition to hi/lo, basically has an implicit mflo tacked on it), the encodings for madd/msub are different, and there are extra instructions for bit reversing, min/max, and I think byte swapping, can't exactly remember.
Still, this document will tell you most you need to know: http://www.cs.tau.ac.il/~afek/MipsInstructionSetReference.pdf