* Chris Ruprecht <chrup_at_earthlink.net> on Thu, 16 May 2002
| On the subject of IBM: They are now using what they call Power3 and
| Power4 processors in their AIX boxes, any idea where that compares in
| the G3/G4 range? They sound pretty impressive ...
The PowerPC chip is the evolution of IBM's POWER architecture, which has
been the core of IBM's RS/6000 family. Oversimplified, PowerPC is what
happened when Motorola and IBM merged POWER with m68k while retaining full
backwards compatability with both. PowerPC_POWER3 is pretty much identical
to PowerPC G3. I believe that the PowerPC_604 in some RS/6000s were never
used in Macintoshes.
There are two very significant differences and a bunch of minor ones
bewteen Apple's version of PowerPC G4 and IBM's PowerPC_POWER4.
First, POWER4 does not do AltiVec. From IBM's perspective, AltiVec's
features are detrimental in the high-performance server arena. What makes
it good for video and audio processing makes it useless or worse when
logically partitioning a 32-way system like a Regata 690 into hundreds of
logical machines (a feature currently in development that IBM will be
introducing in AIX next year) and such like.
Second, POWER4 is a 64-bit CPU on a 64-bit main boards with 64-bit
components and full 64-bit addressing, and it can be switched at boot time
into 32-bit mode. PowerPC G4 is crippled down to 32-bit all the time.
That may not sound like much, until I say things like 64-bit POWER4 can
address 256GB of physical RAM directly and supports 1TB file size on JFS2
(a JFS2 limitation). It is all about scalability, and POWER4 beats G4 on
that hands down.
Tangental to that, IBM's unified system architecture makes POWER4 and IA64
interchangeable. Can't do that with G4.
--
Rat <ratinox_at_peorth.gweep.net> \ Happy Fun Ball contains a liquid core,
Minion of Nathan - Nathan says Hi! \ which, if exposed due to rupture, should
PGP Key: at a key server near you! \ not be touched, inhaled, or looked at.
That and five bucks will get you a small coffee at Starbucks.
--
Read the List FAQ/Etiquette: http://www.newtontalk.net/faq.html
Read the Newton FAQ: http://www.guns-media.com/mirrors/newton/faq/
This is the NewtonTalk mailing list - http://www.newtontalk.net
This archive was generated by hypermail 2.1.2 : Wed Jun 12 2002 - 20:02:25 EDT