[KLUG Hardware] Re: EETimes has more on 64-bit PowerPC -- Power4 ISA (AIX) != PowerPC ISA (MacOS)

[Bryan J. Smith]

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First off, Jack, see my previous PC_Support post (not the original one
you originally responded to, but an earlier one) here: =20
http://www.matrixlist.com/pipermail/pc_support/2002-October/002307.html=20
On Wed, 2002-10-16 at 08:42, Jack Beglinger wrote:
> Power4 are full 32/64 bit processors...

Yes, all Power4 processors have 32-bit instructions.  They are, however,
not fully 32-bit instruction set architecture (ISA) PowerPC compatible
... until now with the PPC970.  It's a combination of memory models and
lack of various 32-bit PowerPC instruction support.

Understand IBM Power4 !=3D Motorola PowerPC.  Yes, Power4 uses a PowerPC
ISA and design, but it is not 100% compatible with 32-bit Motorola
PowerPCs.

IBM attempted to create a 64-bit PowerPC 620 chip with full PowerPC
compatibility a long time ago, but ended up running into design
failures.  They ripped out full 32-bit PowerPC compatibility to move on
with their Power4 series.

Since then, Macs have stuck with only Motorola PowerPC processors.=20
Apple has now stated they will move back to IBM with the PowerPC 970,
which is based on a Power4 core.

> else they would not support the pure 32 bit AIX.

IBM AIX runs on the _Power_ ISA, not the PowerPC ISA like MacOS.  The
IBM/Motorola PowerPC was _designed_ with Power ISA compatibility in
mind.  I followed the creation of the Alpha and PowerPC with great
interest back in the early '90s.  ;-P

Same deal with the Intel IA-64 Itanium.  It sports both Intel x86 and HP
PA-RISC ISA compatibility -- although x86 compatibility is far from
"native" and the PA-RISC compatibility is slightly incomplete (but
easily accommodated in software).

> Power4 come in single and dual core, with a max of 16 Power4 making up=20
> the machine... so 16 way or 32 way are possible with the rest of the moth=
er=20
> board reminding the same.

Correct.  If the design has two cores, it will support upto 32-way.  The
PPC970 will only be produced in a single core.  I think it has to do
with supporting some of the 32-bit PowerPC models -- cache coherency
issues, etc...  Stuff IBM didn't want to tackle.  But I'm only
speculating on why -- just know that that's the deal with the 970.

> Power4 current max speed 1.3G. The roadmap that seams to have 1.6G in=20
> spring, 1.8G in the fall. =20

Correct.  The initial PowerPC 970 will be offered upto 1.8GHz.

> IBM announced a "standard" board (know not the right word but it is close=
)=20
> for Power4, so Power4 could be used from desktop to cluster servers. =20

The "open" Power4 board they are discussing may or may not be with the
970, I don't know.  I'm sure it will depend, as you were=20

> So with all of this, Apple has 9 months to gear up their manufacturing an=
d=20
> OS changes it any.  They could start testing immediately with 1.3G and th=
en=20
> place 1.6 and 1.8 as they come available.

No.  The current Power4 parts are _not_ fully 32-bit PowerPC ISA
compatible.  Only the PowerPC 670 runs 32-bit MacOS without
modification.

But they are sampling the PPC970 chip, so I'm sure Apple is already
working on it.  I'm interested in how much "porting" is required for it,
because the FreeBSD kernel, which Darwin shares a common codebase with
(along with NeXT) is already available for the 64-bit Alpha (and they
were working on a 64-bit Power4 port at one time I believe).

> Now IBM and Sony were looking to the a Power4 core with a video core=20
> added so a "single" chip to run PS... but I have not seen anything new on=
=20
> this for awhile.

IBM's PowerPC line is one heck of an embedded chip for consumer
electronics.  So are many of the MIPS flavors from NEC among others.

--=20
Bryan J. Smith, E.I.            Contact Info:  http://thebs.org
A+/i-Net+/Linux+/Network+/Server+ CCNA CIWA CNA SCSA/SCWSE/SCNA
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           limit      guilt   =3D     { psychopath,
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