G4 Processors

Discussion in 'MacBook Pro' started by danielhayter, Aug 24, 2007.

  1. danielhayter macrumors member

    danielhayter

    Joined:
    Apr 6, 2007
    Location:
    Paris
    #1
    Hello,

    Could any of the old wizzes here explain what the advantages were of the old G4 processors used in iBooks like mine, against the competition? What are the G4's strong / weak points? What is it better / worse at doing? As a non IT head please go easy on the technical jargon.

    Thanks!
     
  2. galstaph macrumors 6502a

    galstaph

    Joined:
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    The Great White North Eh
    #2
    To the best of my recollection of the differences:
    At the time they were built the G4 had many advantages over the G3 and comparable Pentium processors.
    Aside from clock speed, the G4 tended to have a higher gigaflops rating, meaning it could do more instructions per clock cycle (faster at the given mhz rating than the competition).
    Another advantage was the altivec vector processing, kind of like a built in fancy math co-processor that could computer complex commands quickly, it made for better advantages in certain programs (IIRC this was not passed onto the G5)
    The advantages were soon displaced by the P4's raw speed and SSE2,3 MMX etc. so a top end P4 outpaced a top end G4, but the G4 still paced with the original Pentium M chips as of 2004/5.
    After the release of the G5, which was supposed to be the greatest thing since sliced bread (and dual/quad G5s are still comparable to the low/mid range apple intel offerings) the G4 had only the advantage of being cooler running and altivec, hence why no G5 powerbook. the G4 though has been showing its age for a long time.
    Originally jointly developed by IBM and Motorola, the schedule of upgrading for the speeds was inefficient and often very slow. Motorola sold off its chip division (which was already more interested in embedded ppc applications (ie. routers, cellphones) over desktop/mobile chips) and left IBM to develop the ppc platform for Apple. This led to even slower progress. IBM didn't see the urgency Apple tried to have in the push for new PPC development, insomuch that the long awaited 2 Ghz G4 never emerged off of paper (and it would have been ideal for powerbooks as it was comparable to the G5 but cooler and less power consumption). The G5 was really a derivative of the POWER 5 architecture the IBM uses in its high end server systems and didn't help to pull along development of the G4, which was classed as obsolete essentially.
    Due to these issues with IBMs supply and R&D, Apple decided to go to intel, hence burying the G4 (and PPC) forever as old and obsolete.
    Hope that kind of helps:)

    OR wikipedia is your friend as well G4
     
  3. noodle654 macrumors 68020

    noodle654

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    #3
    Correct. I will also explain.

    At the time the PowerPC G4 Processor was new and fast technology that was better than compition. The one thing that it lacked was a large L2 cache which for your iBook G4 is only 512KB. Compare that today to a 4MB L2 Cache in the MacBook or MacBook Pro. The G4 was a great processor, but with all the updates in software over the past year, the G4 struggles to keep up. In about 2003-2004 IBM/Motorola created the G5 which was dual core, like what you see today in the Intel based Macs. The G5 had flaws, it was very power-demanding and ran at very high temps. So I am sure the question for you is, why didn't it get into the laptops? Well, since it ran too hot, the laptops could not handle the heat and this led to delays in the IBM/Moto creating of G5 Laptop chips. After years of getting nowhere and the G4 basically getting behind in technology, Apple pulled the plug on the AIM pact (Apple, IBM, Motorola).

    But over the past years the PowerPC chip lives on and is used widely today in the Xbox 360, PS3, and other game consoles. I would love to see another PPC based Mac, but that wont ever happen. IBM has created some great chips in the past year and they are up their with Intel for processors.
     
  4. Lord Blackadder macrumors G5

    Lord Blackadder

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    #4
    The G4 was a competitive design, but Intel poured resources into developing the various Pentium architectures, while Apple struggled to convince IBM and Motorola to keep pace. Had they done so, we might still be using G4s in a much more developed form.
     
  5. galstaph macrumors 6502a

    galstaph

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    #5
    Don't forget the Gamecube is a G3 ;)
     
  6. noodle654 macrumors 68020

    noodle654

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    #6
    Since we are on the topic of G5 and heat. There is still a ton of heat in any of there new processors. I mean the Xbox 360 and the PS3 get very hot!! The xbox has I think 2 triple core CPU's running at like 3.2GHz...that is FAST!!!
     
  7. jdechko macrumors 68040

    Joined:
    Jul 1, 2004
    #7
    G3 is marketing nomenclature used by Apple. They could have called the C2D the G6 if they'd really wanted to. The Wii also uses a PPC processor. IBM saw that the potential for game console chips was higher than that for desktop computing, so development for Apple was all but canceled, which led to Apple pulling out altogether. Note, though, that IBM still makes PPC chips for their servers, they're just not into desktop computing anymore (further evidenced by the sell-off to Lenovo).

    Anyway, I think the real nail in the coffin was the switch to dual-core processors. The G4 could have eventually been clocked to 2ghz but it wasn't designed for multi-core computing like the G5 was. And it appears as though there's been a sort-of wall hit as far as clock speeds are concerned, which has brought us to multiple cores.

    Remember that the original 360 SDK was, in fact, a modified Power Mac G5 and early demos were actually running on PMG5s (link).

    But 1) The X360's cores (I think there's only 1 3-core processor) aren't meant for general purpose computing, just like the PS3's cell processor and 2) MS still has/had some major design flaws in that the 360 overheats to the point of dying; proof that it was really too much heat to handle. Then think of a G5 in a notebook enclosure.
     
  8. filmgirl macrumors regular

    filmgirl

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    Seattle, WA
    #8
    Precisely. The biggest reason Apple moved to Intel was because IBM couldn't give them any chips that would be fast enough to compete but wouldn't you know, melt the inside of the computer. IBM makes good processors, but they don't are too hot (and to be specific, too thick) to be used in anything that requires portability or doesn't have GREAT ventilation (see XBox 360 issues -- my first system died because of overheating, and it was on a "stand" of sorts to try to help the airflow).

    Intel chips are hot - but not the same kind of hot. I mean, we aren't talking about searing the inside of the computer and blowing up hot.
     
  9. gnasher729 macrumors P6

    gnasher729

    Joined:
    Nov 25, 2005
    #9
    Motorola was building an extreme low power chip for embedded applications. It came in three versions: Extreme low power, very low power, and low power. The low power chip was what Apple bought; they were the only customer, and that chip wasn't even in Motorola's price list!

    The G4 was cheap, something like $70 instead of >$200 for the cheapest Core Duo chip. For a $70 chip it was excellent. The only problem was, Apple would have loved to buy something three times faster for more money, but Motorola didn't build it :(

    I'd say Intel could probably build a chip with 32 G4 cores running at 2.0GHz in the same size as a quad core Penryn chip, and that would make one hell of a server chip :p
     
  10. noodle654 macrumors 68020

    noodle654

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    #10
    Ok gotcha, thanks, I just learned something new. I love learning from people that are smarter than me :p
     
  11. aliquis- macrumors 6502a

    Joined:
    May 20, 2007
    #11
    G4 = ppc = better arch when x86, altivec = better instructions for media.

    But then, AMD64 instruction set for x86 are better than old x86, and Intel ships got SSE, SSE2 and SSE3 nowadays.

    Your G4 are comparable with a P2/P3 at a little faster MHz, like 1.5 or something, if altivec and all is used.

    Current Core 2 Duos are probably 1.5 times as fast aswell, but then dual core so say 3 times. Atleast.

    So a 2.2 GHz core 2 duo are probably around similair to a 6.5-7GHz P3 and your 1.2 GHz or whatever G4 are probably like a 1.5-2GHz one. So new chips are 3-4 times faster when your G4 uses altivec.

    My description sucks, and i'm drunk.
     

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