Re: Overclockers Australia - Two Hours with the Thunder

["Bryan J. Smith" <b.j.smith@xxxxxxxx>]

Richard Zimmerman wrote:
> With all the talk about AMD vs. Intel, etc. and the AMD 760MP chipset, I
> happen to run across a BETA version on an AMD duel processor system!
> http://www.overclockers.com.au/techstuff/a_tyan_thunder/

BTW, I hope everyone knows that dual-Athlon will NOT be cheap.  It
is designed as a high-end solution.

The Athlon CPUs have advanced cache management that lets their CPUs
use their cache more efficiently, both between L2-L1-buffer and
between multiple CPUs.  And the AMD760MP is a cross-bar northbridge,
not an SMP.  As such, the CPU-memory-I/O can have more than one
connection going on simultaneously.

That means you could have one CPU doing I/O while another reads
memory.  I bet that is actually two memory channels as well.  And I
bet there are at least 2 PCI busses, since I've never seen more than
4 64-bit PCI slots on a single bus at 33MHz, let alone 2 64-bit PCI
slots at 66MHz.

http://www.overclockers.com.au/image.php?pic=techstuff/a_tyan_thunder/board.jpg

So, I bet the cross-bar is:

   CPU
   CPU
   Memory
   Memory
   AGP
   PCI1
   PCI2
   Proprietary (for RAID/SCSI?  weird connector there)

That would be an 8-node cross-bar.  Add in 6 more CPUs and another 2
memory busses and that is probably the 16-node, the maximum number
for the Alpha EV6/7 bus, cross-bar that will be used for future
8-way Athlon systems (possibly Sledgehammer as well).

This is _extremely_high_I/O_ compared to Intel's "SMP" bus where
only one "device" can talk to another at the same time (although >2
way systems use some fancy CPU-memory addressing so you can get
"wide bursts" from memory).

-- TheBS

P.S.  I heard a rumor that multiple AMD760MP chipsets are used for
>2-way.  If so, I bet simply adding another is how they get to 16-node.

-- 
Bryan J. Smith, President        mailto:b.j.smith@ieee.org
(407)366-7013 pager:(888)694-5793 chat:thebs413@AOL/MS/Yho
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