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Ars Technica Interviews 970 Designers

11223 writes "John "Hannibal" Stokes has interviewed Pete Sandon, the PowerPC 970's main designer, and David Edelsohn, a compiler writer from IBM, and clarified several points about the 970 regarding group formation, vector issue queues and performance, and more. The interview is a very interesting read for anyone who has been following his earlier articles on the processor that Apple calls the G5."

6 of 225 comments (clear)

  1. Re:Altivec execution by Jon+Abbott · · Score: 5, Informative

    The following was snipped from this message:

    "The AltiVec subunits are more independant than in the 7400, i.e. there isn't just a single vector ALU, instead the vector FPU, vector simple IU, and the vector complex IU can now accept AltiVec instructions concurrently (up to two vector instructions per clock); this means technically, the G4e does have 4 AltiVec units, while the MPC7400 has only two, but in practice the G4e merely relaxes some instruction scheduling restrictions that the 7400 has to adhere to."

  2. Re:Windows based 970? by cant_get_a_good_nick · · Score: 4, Informative

    Windows NT 3.51 and 4.0 supported PowerPC. Was dropped because of bad sales. Solaris had a PowerPC port too if you can believe it. This ws all when PowerPC was shiny and new and PowerPC was going to take over the world, giving a consistent platform free of all that x86 cruft. Problem was NT in that day wasn't compatible yet with loads of software, and Windows 3.1 and 95 were very much x86 only, so the software market never followed to PowerPC. Intel threw enough silicon at the problem to make x86 performance acceptable, and the RISC world withered.

    The most interesting thing for me with all this "cheap PowerPC" stuff is it seems to be the rebirth of CHRP, which Apple kind of scotched becasue they were fearful of clones back then. Maybe they realize they need to kill some of the "hardware premium price" and get costs more in line with Intel boxes.

  3. Re:Improvements to GCC? by Jon+Abbott · · Score: 3, Informative
    This is a fairly big deal as people have pointed out before that GCC on PPC isn't as hot as it should be, but with that kind of muscle and money behind it it should go forwards by leaps and bounds.
    There are some issues with the FSF accepting patches from IBM though, for a number of reasons... This message on the ArsTechnica discussion list explains all of these reasons well, so I won't repeat them here...
  4. Re:Windows based 970? by frankie · · Score: 4, Informative
    What hardware do they make? Last I checked they have gone the commodity PC hardware route

    User-serviceable parts (RAM, HD, AGP, etc) are commodity, but the hard stuff is designed in Cupertino.

  5. Re:Windows based 970? by WNight · · Score: 4, Informative

    What reason is there to expect that EULAs are valid?

    They're post-sale contracts. This sort of thing has never been legit.

    When they show you the license in the store, and you must overtly agree to it to buy the product, then they may be legal. Until then they're lies.

    But, they'll have to be a lot simpler. Judges are already invalidating long small-print contracts for regular consumers. If it takes a law degree to understand, you can't possibly enter into it knowingly. Thus, the company should reasonably know that nobody reads (and hence, nobody agree to) their contracts.

    Further, the concept of post-sale restrictions was decided in the early 1900s, with the First-Sale doctrine. Books were being sold with 'contracts' inside the cover limiting resale rights. It didn't work then, it won't work now, even if the many issues keeping EULAs from being valid contracts were fixed.

    (Such as, they disclaim consumer rights they aren't allowed to disclaim under the Magnuson-Moss warranty act. Many EULAs disclaim all responsibility even if the product doesn't function at all, etc. Not allowed, and in fact, likely criminal to claim.)

    You do everyone a disservice by saying that EULAs might be valid. It's misleading and can be very damaging.

  6. Re:Improvements to GCC? by Halo1 · · Score: 3, Informative

    Apple already has a fork. The gcc that comes with Mac OS X has some 30+ optimizations (both PPC-specific and generic) which aren't in FSF gcc, because FSF refused the patches. Apple does try to keep that kind of stuff at a minimum though, since it means more maintenance work for them as they have to merge those patches with every new gcc version and update them if necessary.

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