[rescue] From Macintouch

Jonathan C. Patschke jp at celestrion.net
Tue Jun 7 14:02:34 CDT 2005

On Tue, 7 Jun 2005, velociraptor wrote:

> For an architecture neophyte, what is the difference b/w the PPC and
> the POWER chips (layman's terms pls :-).

For the modern chips, there isn't a difference.

POWER and PowerPC were originally two separate archtectures, with
PowerPC being a lightweight-but-not-entirely-backwards-compatible
implementation of POWER.  Over the course of POWER2 and POWER3 and
PowerPC 603 and PowerPC 604, they two designed merged.

Nowadays, POWER chips can run PowerPC code.  In fact, the architecture
(even on the big-iron IBM side) is called "PowerPC".  When IBM says
"POWER" they mean "PowerPC with legacy POWER support".  The POWER-
branded chips also tend to be able to do more at once (more integer
units, more FP units, more cache, etc.)

So they used to be two different, but related chips, and now PowerPC is
to POWER what Pentium is to Xeon.

Jonathan Patschke  ) "It's alright for someone to sleep past noon every
Elgin, TX         (   once in a while.  That's what it means to be a
USA                )  free human being."       --Roger Smith, The Big O

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