4 Sep
2007
4 Sep
'07
11:43 a.m.
On 04/09/07, Patrick Finnegan <pat at computer-refuge.org> wrote:
Well, of course, but I went on to define what I meant in the same
sentence on the same line. Desktop-relevant stuff that I can actually
use. I'm reading and writing this on a web page; for the 2007 Web, I
need a modern CSS2-capable browser, Flash, Javascript, Java,
RealPlayer, QuickTime and Windows Media support. OS X delivers those;
even PowerPC Linux, probably the most-widely-supported desktop Unix
environment on PPC, does not.
On Monday 03 September 2007 17:41, Liam Proven wrote:
Can you give some supporting evidence for that assertion? I've been
following the development of POWER and PowerPC since their first
announcements, and as far as I can see, the process has been one of
gradual convergence. The PPC601 was a single-chip implementation of
what was still a processor /chipset/ on the IBM side - IIRC, I think
the contemporary IBM processor was spread over 5 chips or something.
Since the PPC601, the PPC has gained more power, more integration,
more cache, better branch prediction, more logic units and so on. The
POWER chipset was shrunk onto a chip, then followed a similar
evolution.
On 03/09/07, William Donzelli <wdonzelli at
gmail.com> wrote:
Arguably, this may be so, but I'd submit two rather important riders
on to that.
[1] Whereas this was the case with the 601/603/604 and so on, I'm not
sure it's really true any more. The "G5" is pretty much a 2-core
POWER4, AIUI
As I've read, the 601 is more POWER than the rest of the PPC chips.
Still much slower and dumbed down than the proper POWER (non-PC)
versions. I have a
number of PowerMacs for that side of things. :?)
The PowerPCs in Macs are the retarded little brothers of the real
POWER processors. And you have that backwards, the G5 is 1/2 of a POWER4
chip.
I have nothing whatsover backwards and kindly don't make assumptions.
I stated that the "G5" - the PPC970 family - is a dual-core POWER4;
given that I was talking to someone who claims good knowledge of the
POWER processors but seems not to be so /au fait/ with PowerPC, I did
not see any necessity to spell out that POWER4 is a quad-core design.
PPC970 also adds Altivec-compatible SIMD instructions to POWER, but is
a highly capable 64-bit implementation of POWER.
I'm not aware of much that modern PPC processers can't do that POWER
can, other than things intended for the support of legacy IBM OSs such
as OS/400 or zOS.
I guess a
dual-core G5 is close to a POWER4, but it's still lacking some things,
like cache.
(?) The 970 has onboard primary and secondary cache. In the first
model, 64KB of direct-mapped L1 instruction cache and 32KB of L1 data
cache, plus 512KB of 2-way associative L2 cache.
And, the G5 has VMX/Altivec, which the POWER4
doesn't.
Mostly, the POWER4 was designed to be a enterprise server grade CPU,
and the G5 is designed to be a consumer-grade CPU. There's a lot of
trade-offs that they made when designing one vs the other.
You might find it instructive to read these articles:
http://www.arstechnica.com/articles/paedia/cpu/ppc970.ars
http://www.arstechnica.com/cpu/03q1/ppc970/ppc970-0.html
They discuss the tradeoffs between POWER4 and PPC970 in some detail.
The PPC is and always has been a desktop processor for the retail
consumer market; its rivals were the Athlon64 and Pentium 4D. As such
it's tuned towards different demands than the POWER4, which is aimed
for expensive, non-cost-sensitive IBM servers, minis and mainframes -
not that there's a lot of difference between those 3 categories today.
To copy the 1st article I link's summary of the differences: "In sum,
the 970 is made to be faster, cheaper, and significantly less reliable
than the Power4."
I guess that a POWER3 is technically also a
"PowerPC 630", but no
resemblance to the PPC60x series of chips.
So PPC 60x is different to PPC63x? No, *really?* :?)
The POWER5 and POWER6 are quite a bit more interesting
than any PowerPC
chip.
Yes, arguably, but now Apple has abandoned the PPC, it's dead in the
water as far as the desktop is concerned, so it won't really evolve
any further. (Which I think is a great shame.)
On the other hand, in the embedded market, there are fascinating chips
like PA Semi's PWRficient line.
http://news.zdnet.com/2100-9584_22-5907281.html
http://www.theregister.co.uk/2005/10/24/pasemi_power/print.html
These will carry the torch forward for PPC, but we won't find them in
any affordable desktop machines.
[2] All the
interesting apps and the desktop-relevant stuff is on
PowerPC. Specifically, on OS X. Even a 10y old G3 Mac with OSX makes
a pleasant and usable machine for the Web today and for day-to-day
use. I can't think of a lot of use for a 10yo RS/6000 except as a
server - as a workstation running Motif or something, it wouldn't be
much use on the desktop today.
Interesting depends on what you mean by it. POWER has AIX and i5/OS / OS/400. by themselves, much
more interesting
to me than anything that runs on MacOSX. Of course, I'm "one of those
people" who runs Linux on their work-provided PowerMac G5. I just
can't seem to get my boss to want to pay $10k for a proper POWER5
workstation from IBM. ;)
A snag!
I find these to be academically interesting OSs, ones I'd like to work
with and know more about, but neither I nor my small-business clients
have any direct personal or professional use or need for them. Unlike
a Mac.
--
Liam Proven ? Profile: http://www.linkedin.com/in/liamproven
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