ME

Table of Contents Processor Description Differences with the main CPU VME

Processor

Description

The PSP Media Engine very close to PSP's main CPU. It has the same new instructions from Sony, and a FPU, but with no COP2 (VFPU).

Differences with the main CPU

The ME processor has three instructions unused/not available in the main processor:

• DBREAK (debugging break), which exists on other MIPS processors; it's used only once
• MTVME and MFVME.

Those two last instructions actually have the same opcode as LDL and SDL, but the ME CPU is 32-bit: these instructions doesn't really exist, and are always called with $a3 as register containing the memory address.
We actually have:

 ldl $reg, off($a3) <=> mfvme $reg, $off
 sdl $reg, off($a3) <=> mtvme $reg, $off

It's probably used to store and retrieve informations from unknown VME registers.
These instructions seem to be only used for video decoding.

VME

The VME is a still quite obscure part of the Media Engine: it's apparently a reconfigurable DSP.
It can be accessed with the weird mfvme/mtvme instructions, or by storing informations in the memory, from 0x440F8000 to 0x440FFFFF and then calling hardware (to be completed).