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Apples explanation for not having DDR FSB
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Mac Elite
Join Date: Sep 2001
Location: MA, USA
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Taken from mac central:
"What's different in our architecture from the PC architecture -- which has a higher marketing spec number for the bus -- is that they have every single thing on the system competing for that bus," said Greg Joswiak, senior director of hardware product marketing at Apple. "It has to move quickly because it has a lot of traffic and congestion on the bus. We have each part of the system with its own dedicated bus to the system controller. That means these things don't have a latency or congestion as they wait for other data to migrate through the bus."
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Grizzled Veteran
Join Date: May 2002
Location: On the moon
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huh,
didnt think about that.pretty good explanation.
i always wondered how apple got by with and got such great system performance with slower bus speeds. now i know. :-)
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24" iMac 2.13ghz C2D | 15" MBP 2ghz CD | "Soundwave" 60GB 5G iPod
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Senior User
Join Date: Jan 2001
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I don't think I will take every single word this guy said.
There maybe some truth. But there also lies. Remember this guy is from Apple. He can say whatever he wants but whether people believe him or not is another matter.
If this is spoken by a guy from 3rd party then it will sound more solid
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MacPro 2.66, 5GB RAM, 250GB + 160GB HDs, 23" Cinema Display
MacBook Pro 1.83GHz, 2GB RAM (from work)
MacBook (White) 1.83GHz, 2GB RAM
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Mac Enthusiast
Join Date: Jun 2000
Location: New Jersey, USA
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As smart a guy as Mr. Joswiak may be, notice that the word "marketing" appears in his title. Apply appropriate filter to his comments.
Look, Apple is stuck with a processor that has a slow front-side bus, so they make the best of it by making the rest of the system fast, and keeping data off the FSB as much as possible. Nothing wrong with making the best of a bad situation, but that doesn't mean it isn't a bad situation.
Applications where the CPU is starved from memory will continue to be. Other system functions may be less affected than before. I/O intensive operations may benefit. Overall effect on typical apps? Benchmarks will tell.
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Mac Elite
Join Date: Jun 2000
Location: Pasadena
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a better explaination would be that "Motorola can't give us the MX+ FSB based chips (aka 7470) so we'll have to do with what we got. Also, we are clearing the channels of the 744x-745x chips. Keep in mind the mobo's designed to fully support the next generation chips that CAN use DDR FSB."
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G4/450, T-bird 1.05GHz, iBook 500, iBook 233...4 different machines, 4 different OSes...(9, 2k, X.1, YDL2.2 respectively) PiA to maintain...
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Junior Member
Join Date: Feb 2000
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Okay, so what this guy isn't saying is that both processors are sharing this same bus, effectively making it a 83MHz bus for each one. Also, it's not too challenging for an application to fill a 166MHz bus to capacity.
What can be done if Motorolla cannot and will not supply the goods for the PowerMac line?
That being said, any user will be thrilled with the purchase of the new dual gig system beyond belief. Have you ever met someone who purchased a new powermac that wasn't happy with it? The Mac experience is that good, and only a few gear head techoid geeks could really complain after owning a new one.
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Addicted to MacNN
Join Date: May 2001
Location: Atlanta, GA
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Originally posted by mugwump:
Okay, so what this guy isn't saying is that both processors are sharing this same bus, effectively making it a 83MHz bus for each one. Also, it's not too challenging for an application to fill a 166MHz bus to capacity.
What can be done if Motorolla cannot and will not supply the goods for the PowerMac line?
That being said, any user will be thrilled with the purchase of the new dual gig system beyond belief. Have you ever met someone who purchased a new powermac that wasn't happy with it? The Mac experience is that good, and only a few gear head techoid geeks could really complain after owning a new one.
Applying that logic to the Athlon and Pentium camp puts them in REAL trouble.
Using 266Mhz DDR means that they are on a 133Mhz bus sampled twice. Put the processor, disk controller, USB controller, etc. all on that same bus and the Apple comes out faster.
I guess Apple's explanation is that the processors have their portion of the highway all to themselves. There is some merit in that argument. As to why the marketing person spoke, it's because they don't let us engineering types speak much. <GRIN>
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Mac Elite
Join Date: Apr 2001
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Using 266Mhz DDR means that they are on a 133Mhz bus sampled twice. Put the processor, disk controller, USB controller, etc. all on that same bus and the Apple comes out faster.
Not by a long shot...
With a 266MHz FSB, the Athlon has 2.1Gb/s. The upcoming Athlons with 333FSB will have 3.2Gb/s. With its 533FSB, Intel has 4.2Gb/s. The latest Macs have a 1.3Gb/s FSB.
How much does USB 1.0 consume? A whopping 0.002Gb/s. The disk controller is usually run off the PCI bus, but supposing it too was shared, a typical drive will require less than 0.04Gb/s. 100base ethernet? About 0.0011 Gb/s. Just do the math...and compare that to Apple's 1.3Gb/s FSB. The processor is what requires the vast amount of bandwidth in modern systems; USB, ethernet, disk controllers, etc are only a drop in the bucket.
Apple's processor bus is pathetic. There's just no way around that fact.
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Senior User
Join Date: Mar 2000
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...but I wonder what the intro of these clearly "transitional" models is going to do to the rollout date of the next generation of Power Mac? Summer 2003?
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Fresh-Faced Recruit
Join Date: Aug 2002
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"transitional" is dead right. PM sales fell big time this last quarter and Apple is definately going to make some serious changes in the next year whether its demand related or not.
As for the explanation, I believe him. The problem is that Moto's current processors don't have the bandwith to take advantage of DDR or a faster system bus, Thats why Apple doesn't run a faster 333DDR memory bus or main bus because its a Moto design limitation. They are juggling to do the best they can with what they have.
Things are going to change in the next year. Hopefully.............. 
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Dedicated MacNNer
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Why does anybody listen to what marketing folk say? It's their job to manufacture a positive perception of their product, not provide facts. Users don't have to 'believe' or 'have faith' in what they say, just check out the whitepapers and ignore them.
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Junior Member
Join Date: Sep 2000
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even so you must give some credit to Apple for what they are doing, the architecture is really nice and if they get the 7470 some time soon it won't be to difficult to just stuff it into the XServe architecture. I will be buying the DP876 soon and I think that Apple really made a good machine compared to the low-end PM (should be almost twice as fast as the PM QS 800MHz) and for the same price. So I'm happy and really looking forward to playing with 10.2
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