An ignorant question: the differences b/w the G3 and the G4

rampancy

Pardon my ignorance (or if I'm beating a dead horse) but...



I'd really like to know what the difference is between the G3 and the G4, asides from the presence of AltiVec. I'm asking because I find myself exceedingly confused by various sources I've read saying that the G4 is simply a G3+AltiVec, while others say that the G4 is more than that.



With the rumour of a AltiVec-ized G3 coming up, how would such a CPU (assuming it existed) differ from a G4?

g-news

That's a long story.

Let's just say the current G4 and the current G3 are a lot more different than the first G4 and the first G3 were. And no, there's more to it than "G3+ Altivec", in fact there was even in the beginning.

Have a look at the tech specs pages from moto (G4) and ibm (G3), you'll already see it there.



G-News

outsider

Off the top of my head,...



G4 can use the MPX bus while the G3 can only use the 60X (less efficient)



G4 has/had wider buses to the cache.



G4 had a double precision FPU while the G3 would have to run the calculation through the FPU twice.

multimedia

iBook will probably go G4 by the end of 2003 so it's not much of an issue for very much longer.

chucker

[quote]Originally posted by Multimedia:

<strong>iBook will probably go G4 by the end of 2003 so it's not much of an issue for very much longer.</strong><hr></blockquote>



iBook won't go G4 until it's necessary. And right now, it isn't. If the "GOBI" rumors are right, there's no reason for an iBook G4 in 2004 either.

stoo

While it may not be necessary for the current iBook to get a G4, it's probably the last Mac to be introduced without Altivec.

stunned

You pay less for a G3.

multimedia

I will be surprised if the iBook isn't a G4 before this time next year.

luca

G4s are great. Altivec really helps because OS X and many iApps are optimized for it. Also, G4s support multiple processors, which really helps with OS X.



However, G3s have advantages too:



1. Cheap

2. Cool and small; perfect for portables

3. Faster at non-Altivec tasks than the G4

4. IBM makes it

5. More L2 cache (although no L3 cache)

luca

Oh, one other thing. It's not a technical dead end. The G3 is older than the G4, but in the hands of IBM, its life is just beginning. The G4 is basically a lame duck. It's reached the end of its usable lifespan and it needs replacement.



The G3, for example, now supports a 200 MHz bus. That's better than the quad-pumped 133 MHz bus on the Pentium 4 and better than the double-pumped 167 MHz bus on Athlons.

rampancy

[quote]Originally posted by Luca Rescigno:

<strong>The G3, for example, now supports a 200 MHz bus. That's better than the quad-pumped 133 MHz bus on the Pentium 4 and better than the double-pumped 167 MHz bus on Athlons.</strong><hr></blockquote>



Sounds interesting. Is there an article on a place like Ars or Tom's Hardware somewhere that would explain this?

zapchud

[quote]Originally posted by Luca Rescigno:

<strong>The G3, for example, now supports a 200 MHz bus. That's better than the quad-pumped 133 MHz bus on the Pentium 4 and better than the double-pumped 167 MHz bus on Athlons.</strong><hr></blockquote>



AFAIK is the 200MHz bus of the IBM G3 only SDR (it may be DDR), which makes it slower than both of the above examples.

It's simple math;

1x200 = 200

2x167 = 333

4x133 = 533



Also, even though a SDR 200MHz bus would be faster than a DDR 100MHz bus (because of the higher address-speed, or more, if anyone would care to elaborate), the SDR one wouldn't beat even a DDR 133Mhz bus, and most certainly not a DDR 167Mhz bus, in most cases.