On 2002.02.27 19:05 Chuck McManis wrote:

> In my experience with the SII chip you set up a buffer in its shared
> memory 
> with the MSCP "packet" layed out, and the node number of where you
> wanted 
> it to go at the front. Then you write the that address into the
> descriptor 
> register and the SII chip picks it up and drops it off at the drive.
This would mean that the SII implements at least a part of SCA in
hardware. Hmmm. 

> Questions that were unanswered in my mind when I put this down about
> this time last year were:
>          1) maintaining the physical/virtual mapping between the 128KB
>             buffer and main memory.
This seams to be one of the main features of the SHAC chip. It is a
"nexus" device. This means it does all that nifty scatter-gather DMA
stuff and the like on its own. At least this is my understanding that I
got for the term "nexus" device. (Someone may give me more enlightening
about this.)
-- 



tschüß,
         Jochen

Homepage: http://www.unixag-kl.fh-kl.de/~jkunz/