[Mplayer-users] risc cpu of the ps2

Kjetil Torgrim Homme kjetilho at linpro.no
Tue Oct 2 02:08:46 CEST 2001

> > No, it's slow. R5900 @ 294mhz, it's pretty much same CPU as MIPS
> > R4400.  If you've ever used R4400 machine (eg some old SGI Indigo)
> > you know it's slow. Maybe these machines were "fast" in
> > 1995... :-)

MIPS gave quite good bang per MHz, roughly twice that of Intel.  This
could be down to superiour memory subsystem in SGI machines, though.

Arpi <arpi at thot.banki.hu> writes:
> yes... i've used r4400-180mhz in sgi a lot. it was comparable to my
> non-mmx p166.

Clearly you didn't do any floating point at all back then :-)

> i think, the same is done in ps2: slow cpu and very powerfull 2d/3d
> GPU.

The GPU is very simple.  All the geometry and logic happens in the
CPU, the Emotion Engine, which includes

 * MIPS III core, but with 128-bit registers rather than 64-bit.
 * IPU, contains the MPEG2 acceleration bits (IDCT, YUV)
 * VPU0, vector processor 0, VLIW, SIMD, can do four 32-bit FP
   mul-adds every clock, and one FDIV every 7 clocks
 * VPU0, vector processor 0, VLIW, SIMD, as VPU0, but also four
   min/max every cycle and one inverse sqrt ever 13 clocks.

All these run in parallel with their own scratchpad RAM and direct
access to the RDRAM.

In addition to the Emotion Engine, there are

 * Graphics Synthesizer (GPU), sporting 48 GiB/s internal bandwidth
 * I/O Processor (IOP), a MIPS R3000 very similar to the one in PSX.
   This chip takes care of the DVD-ROM drive, FireWire, USB etc.
 * Sound Processor (SPU).

All these have their own memory, as well.

It's a very complex machine in that you absolutely _have_ to
parallelise and compartmentalise your tasks to take advantage of it,
but that's a good idea anyway.  It's hard to do a quick port, though.

Kjetil T.

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