I'd just like to point out that although the G4 had some MHz issues, it's not like the G3 is exactly pushing the 2GHz ceiling either. And G4 has Altivec.
I'm glad some one brought up the change to a seven stage pipe-line. So, if you discount the differences in cache the Current 1 GHz G4 isn't even twice as fast as the 500 MHz model. The megahertz myth isn't a myth if you are talking about the same architecture, especially one that has been dumbed down along the way. I mean the Athlon is setting at 1.8 GHz, were the extra five stages with it... i think so. The P4 has a hefty 20 stages, and even thought one of dose absoutly nothing (seriously it just move the data to the next stage) and 2.5 GHz it's able to beat the Athlon and dual G4 in most benchmarks.
The 745x/744x-series got additional integer unit(s) and I believe (someone, input [HERE]) an AltiVec unit, even though I'm in great doubt about the latter. This means the G4+ scales linearly over the G4 in integer operations (which makes the Ghz*G4+ = 2x0,5Ghz*G4). This is not the case in FP-ops though, and as I said, I'm unsure about Altivec, or even if it is affected by pipeline-stage increases.
Increasing the pipeline increases latency (the amount of time data spends in the chip). Increasing the pipeline can increase what can go wrong.
However, increasing the pipeline DOES NOT reduce a CPUs Input/Output.
A 1GHz G4 can be, and with extra exe units and full speed L2 and L3 cache probably is, twice as fast as a 500MHz G4.
Barto
Edit: The 745x/744x has Float, Complex, Simple and Permute (for a total of 4) vector units, and the 7400/7410 had Arthrimatic Logic and Permute (for a total of 2) units.
Comments
Thanks for the information. I think that what I was saying, though, was that since the MPC 7450 there hasn't been much change, so we agree??
Maybe the design guys have been hard at work on the MPC85XX, but at this point what good is it, will it be the basis for a cpu that Apple can use??
Just thought I'd add that your posts always seem like the voice of reason, I'm just kinda depressed over the whole situation.
[ 08-01-2002: Message edited by: rickag ]</p>
Bad MOT... BAD.
It is seriously time for something else.
The 745x/744x-series got additional integer unit(s) and I believe (someone, input [HERE]) an AltiVec unit, even though I'm in great doubt about the latter. This means the G4+ scales linearly over the G4 in integer operations (which makes the Ghz*G4+ = 2x0,5Ghz*G4). This is not the case in FP-ops though, and as I said, I'm unsure about Altivec, or even if it is affected by pipeline-stage increases.
However, increasing the pipeline DOES NOT reduce a CPUs Input/Output.
A 1GHz G4 can be, and with extra exe units and full speed L2 and L3 cache probably is, twice as fast as a 500MHz G4.
Barto
Edit: The 745x/744x has Float, Complex, Simple and Permute (for a total of 4) vector units, and the 7400/7410 had Arthrimatic Logic and Permute (for a total of 2) units.
[ 08-02-2002: Message edited by: Barto ]</p>