Media Engine

The Media Engine (or shortly ME) — is a second MIPS based CPU core, that was not directly accessible by licensed developers. Instead, Sony runs code on the ME to facilitate decoding audio and video assets, along with the help of more specialized hardware like the Virtual Mobile Engine and "AVC".

Overview

The ME runs at the same clock frequency as the main CPU core. It seems to have the same instruction set.

The ME has two co-processors:

• COP0: general system control
• COP1: 32-bit Floating Point Unit

It has three instructions the main CPU doesn't have (or used):

• DBREAK (also present on other MIPS processors): used only once in the ME firmware
• MTVME
• MFVME

These two last instructions actually have the same opcodes as LDL and SDL, which this CPU doesn't have. The instructions are actually encoded like this:

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

They might be used to store and retrieve information from and to the VME. They seem to be only used for video decoding.

Memory mapping

Start	End	Size	Description
0x00000000	0x001FFFFF	0x00200000 (2MiB)	ME Memory
0x040F8000	0x04100000	0x00008000 (32KiB)	VME Memory (Need confirmation)
0x08000000	0x087FFFFF	0x00800000 (8MiB)	Allegrex Kernel memory (RAM) (ME program is loaded at 0x8300000 - 0x837FFFF)
0x08800000	0x09FFFFFF	0x01800000 (24MiB)	Allegrex User memory (RAM)
0x1C000000	?	?	Hardware Registers
0x1FC00000	0x1FDFFFFF	0x00200000	MIPS Reset Vector