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Design Philosophy of the IBM PowerPC 970
D.J. Hodge writes "Ars Technica has a very detailed article on the PowerPC 970 up that places the CPU in relation to other desktop CPU offerings, including the G4 and the P4. I think this gets at what IBM is doing: 'If the P4 takes a narrow and deep approach to performance and the G4e takes a wide and shallow approach, the 970's approach could be characterized as wide and deep. In other words, the 970 wants to have it both ways: an extremely wide execution core and a 16-stage (integer) pipeline that, while not as deep as the P4's, is nonetheless built for speed.'"
Why do you keep claiming its 64 bits?
However, as fast and amazing and AMD crushing as this 970 chip is... it only has a 40 bit data bus.
This means you cannot physically ever attach more than 1024 gigabytes of ram to it EVER.
At least in the 1990's and early 1990's some 64 bit risc chips had 48 bits of addressing, not lame 40 bits.
This is considerred a hack by some engineers.
The Power4 is astounding and amazing and will help apple trounce Intel benchmarks (Pentium4 cannot be multiprocessor only expensive xeon and
itanium) but this chip is only 40 bits! The RC5 key benchmark is already over 4 times faster on a mac than on the fastests Pentium 4, and twices as fast as ADM dual processor. Consult rc5 project site if you doubt this.
True, it the 970 has 64 bit integer instructions that only have value in cryptography, and some relevance in some gaming computation, but the chip is
NOT 64 bits in my mind uless it can physically attach to more than 1024 gigabytes of mapped locations.
Heres another "gocha" Apple, like EVERY OTHER OS KNOWN, will steal a bit or two for dividing pci dma space or dividing kernel space
meaning that this chip will only EVER support 512 gigabytes of RAM, ever. Or even 256 GB if they steal two bits instead of one.
at current prices and projected prices, 512 gigabytes or RAM will barely cost more than a couple of the fastest processors of this type.
In linux you cannot have a single application grab and use over 1 gigabyte of GENUINE held and locked RAM, nor in Win2000 regular, nor
WinMe.... but years ago in 1996 normal mac such as the PowerMac 9500 could actually create and USE over 1 gigabyte of ram dedicated to
a single user task.
In 2002, few unix OSses, not even OS X, allow over 1 gigabyte of ram for a single process.
I want Power4 from Sonnet in my mac, not this 970 inadequacy.
But then again I also need a way to cram in 512 gigabyte of RAM for three-dimensional finite difference time domain 3D FDTD, for studying energy for
optics computation of laser circuitry construction.
FDTD NEEDS RAM!!!! real ram... not emulated virtual ram.
Why do fanboys mod stuff like this down? Its all facts and not expressed elsewhere. I restate this because evidently modding is based on popularity contests and not logic sometimes. My original was slammed at -1 as this one is as well probably, even though it is informative and factual.
Hey, I'll be delighted if it really happens, but that sounds like the usual "BIG NEWS in two weeks" type of stuff from my Amiga days. I can't believe it anymore, and if I tried, I would go insane. Mock my unrealistic fanboy idealism once, shame on you. Mock it twice, shame on me.
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