PSP Media Engine Reload.

Hi!

We all know the PSP has a second CPU and this since its release. This CPU is part of a specialized unit called the Media Engine, which we've never really been able to exploit to its full potential.

This second CPU is a MIPS Allegrex running at 333MHz just like the main one, close to an R4000 arch with its CP0 and an FPU as CP1. But there's also a DSP alongside it! With few dedicated opcodes.

On this specialized unit, PSP 1000 has 2MB of local eDRAM, and newer ones have 4MB. And this unit also has access to the main RAM.

There are also ping pong buffers linked to the main local DMA. These are 24bit buffers with a size of around 64KB segmented in 8KB.

In mid 2005, a homebrewer called crazyc has done crucial work, which included getting code running over there.

After him, the scene more or less settled on using the Media Engine, mainly its CPU, by relying on the reverse engineering of the code that gives the main system access to that specialized unit.

In my opinion this limited the flexibility of integrating the Media Engine into homebrews and made the sync system between CPUs quite constrained by this 'factory' configuration. On the other hand, we still know very little about the DSP that comes with it.

I'm working on this project to dig deeper and see how far we can go with this hardware.

Feel free to share, or participate if you think you have something valuable to add, and if you wish, you can join us on discord