Re: SX cache

[Bibek Sahu <scorpio dodds net>]

On Wed, 30 Sep 1998, Nils Faerber wrote:

> > The PC on the CPU part number denotes the absence of the L2 cache on the
> > SX cpu...I suspect that an SX is a 21164 on which they disabled the
> > onboard L2 cache cause it failed passing manfacturing tests and stamp it
> > 21164PC and sell it with no L2
> Err ... I do not think so. AFAIK the 21164 is a completely different CPU.
> The PC version also has some "new" instructions which the "pure" 21164 does
> not have. Digital claim those functions to be something MMX equivalent
> able to help encode/decode MPEG1 and things like that.
> But who uses those instructions anyway?

	The instructions are called 'MVI' (Motion Video Instructions, I
think...).  I found the list once, and if I could hunt them down again, I
might try implementing them in mpg123.  Probably build it on a real DU
machine to see what kind of improvements could be had.

	Of course, I have trouble dealing comprehending the transforms
used in mpeg decoding so I may require a fair bit 'o time to build
alpha-optimized assembly... ;-)

- Bob