I guess the PowerPC has nothing to offer in the embedded arena that ARM doesn't?
Higher performance at lower clock speeds. But slightly higher power consumption to go with it, unfortunately.
If you consider a 400MHz ARM clocks around 500 MIPS (not including XScale/Wireless MMX etc.) sometimes with a dodgy FPU (and even then most embedded ARM are softfloat), but maybe takes half a watt of power even at full speed, it is a useful chip in any device.
However the current spread of high-end ARM chips (600MHz in the iPhone etc.) are performance comparable and as power hungry as the MPC5200B ever was.
We think the MPC5121E is as relevant in a mobile device as an ARM with the same PowerVR graphics (Freescale even sell one).
So, which market are we going to push for PowerPC? Are we unique in any way at all? Or are all the technology inside PowerPC either copied from ARM or competitors took our ideas and surpassed us?
There isn't much unique except higher performance - PowerPC is generally a little more rounded a design, and has less corners cut. ARM is very quirky sometimes - like MIPS, a lot of the things you take for granted on PowerPC or x86, need to be handled in software like alignment of values in memory.
PowerPC offers a 'thin' instruction set (VLE on the e200) like ARM Thumb, it offers a much better vector unit (AltiVec vs.. Wireless MMX and SSE??) and in general a greater application compatibility across chips. It basically SCALES much better. You do not see ARM-powered servers, or even desktops. Power goes from.. the very lowest to the very best server mainframe. And even some of the very lowest run in the very best supercomputer.
How can you say that Power is not suitable for mobile devices or could not displace ARM? Well, the only problem could possibly come from a vast library of ARM devices and the code associated with them. A lot of effort went into supporting ARM as the defacto small device chipset in routers, mobile phones, PDAs. But when you consider all of these are moving to use Linux, the processor does NOT matter anymore. The same code running on ARM Linux can be recompiled for PowerPC Linux - and it'll run faster.
Matt Sealey, Genesi USA Inc.
Product Development Analyst