In article <alangbaker-29CF31.21145101072004@news.telus.net>,
Alan Baker <alangbaker@telus.net> wrote:

> In article <dd5de929.0407011909.1d95ada6@posting.google.com >,
> imouttahere@mac.com (Heywood Mogroot) wrote:
>
> > "MH" <removemstthiscrow5429spam@earthlink.net> wrote in message
> > news:<UL%Ec.1527$R36.700@newsread2.news.pas.earthl ink.net>...
> > > I'm a PC user considering purchasing a Mac Powerbook G4, and I found the
> > > speed ratings for the system bus and memory at odds with one another.
> > > The
> > > system bus is 167MHz, while the memory is running at 333MHz. More
> > > importantly, the maximum bandwidth a 167MHz 64-bit wide system bus could
> > > reach would be 1.335GBps (167MHz * 8 bytes). The potential data
> > > throughput
> > > of P2700 memory is 2.7GBps. Ergo, the memory is capable of twice the
> > > speeds
> > > of the system bus, but is limited by that very system bus.
> >
> > Yes, I for one believe this is correct. The G4 has suffered from a
> > lame-ass FSB wrt Intel since Intel first started quad-pumping. This
> > exact same issue came up with the 2002 MDD G4'sm which had the same
> > FSB and the same DDR-333 memory. It is also one of the reasons I'm
> > still happy on my 800Mhz PBG4 w/ 133Mhz FSB, I know moving up to a
> > 1.5Ghz G4 isn't going to be that different an experience.
> >
> > > Now, in the PC
> > > world, the system bus and memory bandwidth are equal, or nearly so. For
> > > instance, my AMD Athlon T-Bird has a potential throughput of 2.128GBps
> > > second on its 64-bit wide system bus (266MHz * 8 bytes), and the memory
> > > is
> > > PC2100, so the speeds are nearly matched. Why does Apple use PC2700
> > > memory
> > > in its notebooks if they cannot be properly utilized?
> >
> > It's probably the best match Apple can get. Slower DDR memory isn't
> > going to be any less expensive than PC-2700. Plus with Apple's
> > "Intrepid" memory/IO controller DMA accessess can go directly into
> > memory without CPU intervention. Plus AGP transfers can too.
> >
> > > Wouldn't it make more
> > > sense to use a RAM technology that was a closer match in speed?
> >
> > There is no SDR 167Mhz RAM, so Apple chose to use the next best thing,
> > DDR-333.
>
> You've got it wrong.
>
> 333MHz DDR RAM is supposed to run on a 167MHz front side bus. If you're
> thinking that it's running on a 333MHz bus, consider:

That is absolutely correct. A DDR RAM's bus must run at half the RAMs
clock rate. That's the "double" part in Double Data Rate. The only
problem with Apple's implementation of DDR RAM before the G5 was that
the G4's Front-Side bus architecture didn't directly support it.

--
George Graves
------------------

"This election is shaping up great. Our choices
are a guy who has a lot of second thoughts, or
a guy who has never had a first thought."
-- Jay Leno

Alan Baker <alangbaker@telus.net> wrote in message news:<alangbaker-35EE11.19123901072004@news.telus.net>...
> In article <gmgravesnos-E1FAEB.19015501072004@news.sf.sbcglobal.net>,
> George Graves <gmgravesnos@pacbell.net> wrote:
>
> > In article <alangbaker-4DDA71.18372701072004@news.telus.net>,
> > Alan Baker <alangbaker@telus.net> wrote:
> >
> > > In article <MrNoSpam-065309.09562902072004@news-server.bigpond.net.au>,
> > > Dale Stanbrough <MrNoSpam@bigpoop.net.au> wrote:
> > >
> > > > MH wrote:
> > > >
> > > > A while back (and I've heard nothing new lately that would contradict
> > > > this) the G4 processors were not capable of -really- using the DDR
> > > > RAM, due to Motorola's failure to make a better chip.
> > >
> > > You heard this, huh? Where?
> >
> > I've read this too, Alan. I think he's right.
>
> OK. Where?

See my other post in this thread.

The OP is totally correct about the 167Mhz SDR vs 167MHz DDR (PC-2700)
system bus bandwidth mismatch, though PC-2700 memory is the best
memory to use anyway.

Altivec is in fact horribly starved on the G4 bus, even more so on the
*shared* FSB on dual-proc systems. This is one of the reasons I sold
my dual 1Ghz G4 in the summer of 2002, there just wasn't the
performance delta over my 800Mhz PBG4 to justify the continued
depreciation.

Motorola CPU Division, R.I.H.

George Graves <gmgravesnos@pacbell.net> wrote in message news:<gmgravesnos-EDDD32.00304502072004@news.sf.sbcglobal.net>...
> In article <alangbaker-29CF31.21145101072004@news.telus.net>,
> Alan Baker <alangbaker@telus.net> wrote:
>
> > In article <dd5de929.0407011909.1d95ada6@posting.google.com >,
> > imouttahere@mac.com (Heywood Mogroot) wrote:
> >
> > > "MH" <removemstthiscrow5429spam@earthlink.net> wrote in message
> > > news:<UL%Ec.1527$R36.700@newsread2.news.pas.earthl ink.net>...
> > > > I'm a PC user considering purchasing a Mac Powerbook G4, and I found the
> > > > speed ratings for the system bus and memory at odds with one another.
> > > > The
> > > > system bus is 167MHz, while the memory is running at 333MHz. More
> > > > importantly, the maximum bandwidth a 167MHz 64-bit wide system bus could
> > > > reach would be 1.335GBps (167MHz * 8 bytes). The potential data
> > > > throughput
> > > > of P2700 memory is 2.7GBps. Ergo, the memory is capable of twice the
> > > > speeds
> > > > of the system bus, but is limited by that very system bus.
> > >
> > > Yes, I for one believe this is correct. The G4 has suffered from a
> > > lame-ass FSB wrt Intel since Intel first started quad-pumping. This
> > > exact same issue came up with the 2002 MDD G4'sm which had the same
> > > FSB and the same DDR-333 memory. It is also one of the reasons I'm
> > > still happy on my 800Mhz PBG4 w/ 133Mhz FSB, I know moving up to a
> > > 1.5Ghz G4 isn't going to be that different an experience.
> > >
> > > > Now, in the PC
> > > > world, the system bus and memory bandwidth are equal, or nearly so. For
> > > > instance, my AMD Athlon T-Bird has a potential throughput of 2.128GBps
> > > > second on its 64-bit wide system bus (266MHz * 8 bytes), and the memory
> > > > is
> > > > PC2100, so the speeds are nearly matched. Why does Apple use PC2700
> > > > memory
> > > > in its notebooks if they cannot be properly utilized?
> > >
> > > It's probably the best match Apple can get. Slower DDR memory isn't
> > > going to be any less expensive than PC-2700. Plus with Apple's
> > > "Intrepid" memory/IO controller DMA accessess can go directly into
> > > memory without CPU intervention. Plus AGP transfers can too.
> > >
> > > > Wouldn't it make more
> > > > sense to use a RAM technology that was a closer match in speed?
> > >
> > > There is no SDR 167Mhz RAM, so Apple chose to use the next best thing,
> > > DDR-333.
> >
> > You've got it wrong.
> >
> > 333MHz DDR RAM is supposed to run on a 167MHz front side bus. If you're
> > thinking that it's running on a 333MHz bus, consider:
>
> That is absolutely correct. A DDR RAM's bus must run at half the RAMs
> clock rate. That's the "double" part in Double Data Rate. The only
> problem with Apple's implementation of DDR RAM before the G5 was that
> the G4's Front-Side bus architecture didn't directly support it.

Look, both Maxbus to the memory controller IC and the bus from the
memory controller IC to RAM are 64-bit and 167Mhz. The OP is correct
that using DDR for memory implies a more competitive platform than is
the case, since the DDR ram is sitting around stalled half the time
when the CPU is accessing it.

If Maxbus were double-pumped like the Athlon bus then there wouldn't
be this bandwidth mismatch.

Me & my hardware friends talked about it back in 2002.

Apple *could* use PC-167 SDR RAM and get nearly performance (I don't
think ATA, AGP, and modem DMA is that big a deal). But PC-167 SDR
doesn't exist so the discussion is moot on this point.

> > >I have called Apple Care, and the data
> > > wasn't "available to the public" regarding the Powerbook's
architecture, so
> > > I had to work out the figures from existing knowledge to the best of
my
> > > ability. Thanks for your input.
> >
> >
http://developer.apple.com/documenta...s/Macintosh_CP
> > Us-G4/15inchPowerBookG4/index.html
> >
> > knock yourself out.

Thanks. Although the Apple techs really should know better and not BS their
way through things.

"MH" <removemstthiscrow5429spam@earthlink.net> wrote in message news:<FAQFc.4333$R36.3642@newsread2.news.pas.earth link.net>...
> > > >I have called Apple Care, and the data
> > > > wasn't "available to the public" regarding the Powerbook's
> architecture, so
> > > > I had to work out the figures from existing knowledge to the best of
> my
> > > > ability. Thanks for your input.
> > >
> > >
> http://developer.apple.com/documenta...s/Macintosh_CP
> > > Us-G4/15inchPowerBookG4/index.html
> > >
> > > knock yourself out.
>
> Thanks. Although the Apple techs really should know better and not BS their
> way through things.

They're customer service, not developer support. They were doing their job.

> > Thanks. Although the Apple techs really should know better and not BS
their
> > way through things.
>
> They're customer service, not developer support. They were doing their
job.

If they can't answer customer's questions who have a technical background...

when I have called all of my friends for a solution and cant come up with one, they told me to go to supportrix.com.1.877.787.8749.i got my answers fast.