View Full Version : Motorola MHz -> Pentium MHz

DJ Hoyt
Jul 24, 2001, 09:23 AM
When in PC and Mac debates with my friends at work and school their main response is "But Pentium has faster speeds for much cheaper" Now I know the benchmark tests that put a dual G4 500MHz up against an AMD 1.5 GHz and the G4 won in Photoshop tests. But I wanted a forumula that would convert Motorola MHz to Pentium MHz. That would be quite cool. If not a formula. A simple explanation. My belief is that a G4 at 350MHz is equal to about 700MHz on a PC, I might be wrong though. Anyways, any ideas would be nice to have.

Lee Duan
Jul 24, 2001, 10:08 AM
The Reason the G4 is so much faster is because they use programs that use the velocity engine. That makes the programs a lot faster. The G4 867MHz is i think about the same speed as the 1.7GHz Pentium4 when not using photoshop or any type of program that takes advantage of the velocity engine

DJ Hoyt
Jul 24, 2001, 10:49 AM
Thanks a lot. The Velocity Engine, of course... lol. That will help. Thanks again :-)

Jul 25, 2001, 04:41 PM
If you don't mind using Apple's benchmarks, then you simply take their claim and do the math. I have actually look into it myself, so I hope this helps. A G4 is roughly 2.2 times as fast as a PIII of equivalent speed. Therefore, a 500 Mhz G4 is roughtly equivalent to a 1.1 Ghz PIII. Now, a P4 1.0 Ghz is roughly equal to an 800 Mhz PIII. Thus, a 500 Mhz G4 is roughly equivalent to a 1.4 Ghz P4 or 1 Mhz in G4 equals 2.8 Mhz in P4. By the way, these numbers come from Apple's site and the New York Times (PIII v. P4 comparison), I think. For mobile machines, the G4 500 beats the pentium 850 by 30%. This means that a G4 500 is roughly equivalent to a 1105 Mhz PIII mobile. Thus, the comparison is about the same. For other information, you can check Apple's Megahertz page or some of their archived Hot news section.
- Andrew

Jul 25, 2001, 05:16 PM
Well guys there is no difference in mhz. an 800 mac is the same as an 800 pentium the difference is how it gets from place to place. In mac the gateway is like this
_ _ in pentiums its like this / \. as you can see mac lets more through at a time so mhz don't really matter. Another thing is that when pentiums start up the dump everything into ram allowing a faster startup than macs butt everything else being much slower. Lastly pentiums send bigger chunks of info through cloging everything up where macs send smaller amounts through at a time making them all around faster.

Jul 25, 2001, 05:50 PM
A Mhz is simply one million cycles per second. The amount of work done per cycle is different though. The G4 is based upon a design philosophy called wide but shallow whereas the P4 is based on a design called narrow and deep. A P4 uses a 20 stage pipeline (incredibly deep) whereas a G4 uses a 7 stage pipeline.

Jul 25, 2001, 08:06 PM
The forumula is about right. Apple always over estimates and uses programs that use the The Velocity Engine. Can you figure the new processors and what they compare to? They also have a new bus speed I think.

Jul 25, 2001, 08:14 PM
watch this video at apple from the macworld expo


it explains in many ways

Jul 25, 2001, 08:17 PM
Apple sometimes streches the truth the way they want it. And my modem will over heat and explode if I did. Sorry.

Jul 25, 2001, 08:38 PM
Sorry, I meant this to be a reply rather than a thread.

Of course they use the Velocity Engine. It is what makes the G4 so different from the field. It is the superscalar component and what allows the G4 to achieve gigaflops. Why not tout that? I agree that it does tend to skew the results, but if you think about the design, you will see that Mhz for Mhz, the G4 is still faster. A PIII or P4 uses a 32 bit path. The Altivec uses a 128 bit path. That means for each and every cycle, the G4 does 4 times the work.

This also neglects how the macintosh is inherently more efficient in processing. Compare RAM usage and understand... A Wintel machine requires so much more ram and processing speed to achieve the same results.

Jul 25, 2001, 08:44 PM
Unless your using Os X. Cause, it eats memory. In most case's your right. Apple machines are memory efficent. I'll see you guys later!

MRmacman23@gayol.com (otherwise know as aol)

[Edited by MrMacman on 07-28-2001 at 10:13 AM]

Jul 26, 2001, 11:04 AM
i dont really understand this ******** from intel about their Itanium chip, they say it processes in 64 bit chunks. Tell me if im wrong but doesnt the G4 process in 128 Bit, i heard it has 128bit pipelines?.... hmm maybe i am wrong.
If that is true though then why arent apple advertising 128bit like intel advetise 64bit arse?
this is all very confusing.

Jul 26, 2001, 01:48 PM
In short, Apple does. Only the velocity engine, aka Altivec, is 128 bit. The rest of the chip is composed of 32 and 64 bit pipelines. This is to be expected as different parts of the chip are used for different things. The new Intel chip is a server chip. It is designed to compete against both Sun and Mips based systems which have been using a 64 bit implementation for years. Additionally, it is important to note that both the Mips and Sun based solutions use a 64 bit operating system where as I am unsure about the Microsoft based solution.
- Andrew

Jul 27, 2001, 04:15 AM
Windows had to be ported to the 64 bit chip. that's what took it so long actually. only linux could run on the itanium when it was finished. so win2K was then ported. crapy port, but it's M$.
and OS X used all the 128 bits when it feels like...but typicaly it uses 64 on a G4.
as for the RAM question, OS X manages RAM more efficiently than ANY system in my house, and we have everything from DOS to Win2K to WinXP to Linux to Be to OS2 to UNIX...as well as 3 MacOS' - X, 9.1, pre-aqua OS X server...


Jul 28, 2001, 09:19 AM
Originally posted by PyroTurtle
Windows had to be ported to the 64 bit chip. that's what took it so long actually. only linux could run on the itanium when it was finished. so win2K was then ported. crapy port, but it's M$.
and OS X used all the 128 bits when it feels like...but typicaly it uses 64 on a G4.
as for the RAM question, OS X manages RAM more efficiently than ANY system in my house, and we have everything from DOS to Win2K to WinXP to Linux to Be to OS2 to UNIX...as well as 3 MacOS' - X, 9.1, pre-aqua OS X server...

That would make how many comps? 12? How many of them do you use? I would burn the Dos to WinXP comps. There probally radiating evil.

Jul 28, 2001, 09:13 PM
he he, yes that does make alot of computers. we also have laptops and many other little goodies including Palms, Newtons, (no winCE), and other stuff. the win machines actually serve the purpose of old games and my parents buisness related stuff.
my mother actually is more at home in DOS and UNIX than anything else, so go fig. mostly we have them because i love learning about and on computers. so needless to say, my room is very very messy and very electronical...


Jul 29, 2001, 09:29 AM
Mind given me a comp? A unix one would be very helpfull! I can do much on a mac if you get my drift...

Jul 29, 2001, 03:08 PM
What a bunch of idiots!

First of all, the G4 is a 32 bit processor. No more, no less. The "velocity engine" is able to group 32 bit data into 128 bit "arrays" that can all be processed with a single instruction. This improves the performance in things like manipulating a bunch of pixels - since it can run the same instruction on 4 32-bit (or 8 16-bit, or 16 8-bit, or 32 4-bit, etc) pixels at a time, it can finish a whole lot faster. But don't fool yourselves. You sound like the PC weenies who were wetting themselves over MMX and SSE. For those of you living in a closet (looks like most of you) those are Intel's version of the "Velocity engine." And while the original MMX implementation left a lot to be desired, because it used the floating point registers for SIMD instructions, the Pentium Pro and it's derivatives don't require the context switch and are much more efficient.
AND the P4 is even better at it because it has dedicated MMX/SSE execution units that are capable of taking over floating point execution from the wimpy x87 FPU. So the "velocity engine", while more efficient than Intel's SIMD, isn't anything new. AND I might add that there are a lot more PC applications that take advantage of MMX/SSE than there are Mac apps optimized for the "velocity engine."
What makes the G4 more efficient is the fact that all instructions are a fixed length, 32 bits, it has a huge number of registers available for data and instructions, and it has a massive number of execution units available. Combined with the best branch prediction logic available, it is simply able to do more at one time than any Intel processor.
Think of it this way: You have one hose that can spray 1000 gallons per second. If you want to move more water, you can increase the speed that the water comes out, or you can add more hoses. The P4 tries to push the water through faster, the G4 adds more hoses. The trade off is that the P4 hose will have higher pressure (Mhz) and the G4 has a larger area to push the water through so the pressure (Mhz) isn't as high.
And just to make sure some of you retards understand: I'm MUCH more impressed by the G4 and the performance it is able to wring from even common, unoptimized, code than I am by Intel's latest attempt at "benchmarketing". The 7450 is an awesome design that is only being held back by Motorola's continued schizophrenia.
If you want a formula that will tell you how to "convert MHz" try this one (it's overly simplified so don't bother nit-picking the details, the idiots wouldn't understand anything more accurate): The P4 has 2 1.8 Ghz pipelines that are 20 stages long, the G4 has 4 867 Mhz pipelines that are 7 stages long. Because of the speed differences, the P4 is able to move the same amount of data through it's very long pipelines at about the same speed that the G4 can move through it's much shorter, slower speed, pipelines. The performance difference is due to the more efficient management of code on the G4. There are less performance robbing "pipeline bubbles" on the G4 and their effect is less pronounced because of the short, fat, pipelines.
So, since it's more efficient, the G4 is effectively twice as fast (mostly because it takes 1/3 the time to recover from a stall, branch misprediction, or context switch).

Jul 30, 2001, 08:19 PM
Thanks for clearing that up, even though I would like to e-mail you if you are the ChipMerchant. Now can you explain why techtv.com reveiwed the P4 1.8 vs the 733 G4 ?? Why not a 866 or a Dual 800? That's now my biggest question.

Jul 31, 2001, 08:24 AM
I dont think the dual 800 is available yet is it?
i dont really understand this shipping in month business. :)
Anywayz im really impressed by the dual 800, huge improvement over the dual 533.

Jul 31, 2001, 08:33 AM
They could of delayed the test so both of the could be compared. I mean that test was Damn biased. A top-of-the-line P4 1.8 vs the LOW END G4 733. Even the 867 would of done better and Wipped the P4 sorry ass.