4 Sep
2007
4 Sep
'07
3:33 p.m.
On Tuesday 04 September 2007, Liam Proven wrote:
The POWER4 is dual core, the original G5 is single core. The newest G5
is dual core. IBM didn't make ANY quad-core processors until the
POWER5+.
I wasn't say it was without *any* cache. It just has a lot less than
POWER4. No one builds modern processors without ANY cache, that'd just
be silly.
Why should I read those? That was the exact point I was trying to make.
POWER5 and POWER6 have evolved quite a bit from where POWER4 was. IBM
made a lot more money selling POWER processors, systems, and consulting
to go with it, than they ever did with selling PPC chips to apple. IBM
was dragging their feet with PPC features on the G5 (and whatever would
have been G6), which is why Apple abandoned them; if IBM was making
enough money from Apple on their G5s, I'm sure that they would have
payed more attention to what Apple wanted (like low-power noteboot
CPUs).
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.
Whether or not you need Flash is a matter of debate... but a lot of that
can be handled by firefox, IBM's PPC JREs, and mplayer/xine. Who needs
three separate media players, when you can use one of two OSS players,
and play almost anything. I hear that the OSS flash player is even
very close to being able to play youtube/google flash videos. But,
alas, this still doesn't make a platform intersting to me.
Who said personal/professional use? I though that people collected
computers because they were "interesting", not just because they were
useful.
Pat
--
Purdue University ITAP/RCAC --- http://www.rcac.purdue.edu
The Computer Refuge --- http://computer-refuge.org
On 04/09/07, Patrick Finnegan <pat at
computer-refuge.org> wrote:
I don't feel like looking this up. Go look at SPECfp numbers for PPC
and POWER chips of the same era, for a starting point. There's also a
number of POWER architecture descriptions floating around the internet
which detail differences.
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. On 03/09/07, William Donzelli <wdonzelli at
gmail.com> wrote:
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.
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 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.
The POWER chips have a bunch of hypervisor goo, and many, many MBs of L3
cache on the multicore versions.
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.
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." 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.
Depends on what you mean by "affordable". Easily more affordable than
an inflation-adjusted IBM 5150 or similar.
[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.