"Thorsten Froehlich" <tho### [at] trfde> wrote in message
news:40687543$1@news.povray.org...
> In article <40686cfe$1@news.povray.org> , "Chambers"
> <bdc### [at] yahoocom> wrote:
>
> > Well, it's been a few years, but I used to do quite a bit of graphics
> > programming in assembly.  Did you know that, for instance, the FPU
registers
> > load so fast that games used them to load bitmaps from regular memory to
> > video memory?  It worked about 30% faster than a standard transfer.  In
> > fact, this was the reason MMX used the FPU registers, and so you can't
use
> > FPU and MMX at the same time.
>
> That is nonsense.  They are faster for copies because you execute fewer
> instructions per copy and on a 64 bit bus (since the Pentium, and even
with
> burst transfers on a 486 bus) the maximum bandwidth is used.  Further, MMX
> used FPU registers simply as a kludge so operating systems and many
ancient
> programs would not have to be modified to save additional data when
> switching contexts.  This is why certain versions of Windows needed
patching
> later on when SSE with its additional registers was added.
>
>     Thorsten


Well, I only surmised.  Thank you for correcting me.

It's *still* a neat hack for 486 systems to up the transfer rate :)

-- 
...Chambers
http://www.geocities.com/bdchambers79

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