iMac G5 64bit: True or false?

Hello,

The PowerPC G5 is a 64-BIT processor.

The G4 and previous processors were 32-BIT (or less for the the older processors).

And, OS 10.4 for the PowerPC did have 64-BIT features when run on a G5.

But, the Intel systems released by Apple were initially 32-BIT processors. And, now with the Core2Duo (when implemented) and Xeon are finally 64-BIT processors.

So, Leopard should be 64-BIT enabled when run on either the G5 or Intel Core2Duo or Xeon.

But, naturally, it remains to be seen whether the implementation will favor the Intel processor, or if it will be equally effective when run on a G5. We won't know for sure until Apple releases more information.

I hope this helps.

It should.

I have never read anything that said you had to have 4 GB of RAM to process 64-BIT instructions.

There are those who claim that you need a 64-BIT processor to access more than 2 GB of RAM. But, even that is not true.

You do not need a certain amount of memory to have a 64-BIT processor. Even the new Mac Pro systems are only shipping with 1 GB of RAM. So, that further illustrates the fact.

You do need enough memory to hold all the information and data that you are working with. So, complex 64-BIT programs may need more memory space to perform at a decent level / speed. But, having less memory will not turn your 64-BIT processor into a 32-BIT processor.

Here's a little explanation that may help to clear-up the confusion:

64-BIT processors can move larger chunks of data at a time. Basically, more data paths.

If you look at it as a highway, you might get a clearer picture.

Think of the older 8-bit systems. They could move 8 BIT's at a time (one down each channel or pipeline). An 8-Lane road.

Then, we had 16-BIT systems, which were then able to move 16 BIT's of information at a time.

Then 32, and now 64 (for the G5's).

So, essentially, a 64-BIT system can move more data simultaneously than a 32-BIT system (assuming each channel is used to it's potential).

So, you could theoretically, move more data in the same amount of time with a 64-BIT CPU than a 32-BIT CPU.

Think of it like a highway with 1-lane compared to a highway with 2-lanes. The highway with 2 lanes could potentially move more cars at a time simultaneously than a 1-lane highway. All the cars would be in their own lane moving as fast as they could.

If the same traffic was routed through a single lane, then the cars would be lined-up further back, and waiting longer to get through.

The efficiency improves again when you move to 4 lanes, then 8, etc.

So, carry that theory over to CPU's which now have either 32-lanes or 64-lanes, and you can kind of understand how the difference could be important if you push your system hard, and have software that can use it to it's potential.

But, in a computer, there are also other factors. In PC's for example, you might have a 32-BIT processor, with a 32-BIT path to memory (depending on the system and it's age). Then, it would drop down to 16-BIT's to talk to some of the controller cards and certain I/O devices, and then maybe even 8-BIT's to talk to some of the other cards and devices.

Not everything in the system runs at the same speed or has the same number of BIT's in it's data-path.

For example (again with PC's), you might have a 2 GHz processor, with an 800 MHz data path to it's logic board, and 400 MHz to it's RAM, 66 MHz to it's AGP port (or 66MHz x 4 in a AGPx4 slot), and 33 MHz path to it's PCI cards, and on down the line. So, there are other potential bottlenecks in the system.

Note that it has been a while since I tinkered with PCI and all the other components, but while the numbers are not necessary exact, the point is to illustrate that each component may operate at a different speed and therefore affect overall performance.


I hope this helps.

I think your current G5/OS combination is already using 64-bit coding, but only for UNIX system tasks and probably not even all of them. The change announced for Leopard is that the expanded capability will now migrate across the OS and be made available everywhere, all the time.

The boilerplate you're quoting only proves that Apple claimed that the G5 is a 64-bit processor, which it is. You'll have to provide more than that, e.g., how and where Apple made specific claims that being 64-bit would have specific benefits to the end users.

There are a few urban myths about how the number of bits that a processor can handle relates to the effects on your everyday computer usage.

These myths started out thanks to the videogame console manufacturers and the hype usually surrounding them.

In "console-land" the number of bits the processor could handle was often used by the marketing departments to show how "amazing" the console was going to be. Point in fact: SEGA's Genesis/Megadrive boasted "16-bit" in large shiny letters on its casing. Nintendo even named one of their systems after its processor's bandwith (the '64' in Nintendo64).

Now, in real life, it doesn't really matter what the bandwith of your processor is. A lot of other things matter much more to the home user. Did you know that the Super Nintendo only has an 8-bit processor? Yet it competed against and outperfomed SEGA's Genesis/Megadrive. This was because the SuperNES had better graphics and audio processors.

Sony's first Playstation was 32-bit. I think we can all agree that the first XBOX beats that Playstation model hands down in the graphics and speed departments. Yet they are both 32-bit. Again, a better graphics subsystem and, in this case, a higher clockspeed and busspeed were the deciding factors.

Now back to the Mac side of things. Core Duo-based Macs are generally faster than G5-based machines. Yet the G5 is 64-bit and the Core Duo is 32-bit. The Core Duo has access to faster memory, has a larger cache and, most importantly, there are usually two of them working in tandem (note that 2 times 32-bit does not equal 64-bit).

In short, for home users your graphics card, harddisk transfer speed and amount of RAM are far more influencial to your experience than the bandwith of your Mac's processor is.

64-bit processors are useful for applications that move around large amounts of data (such as Photoshop or Final Cut Pro, server applications etcetera) and even then only when the processor has enough RAM to its disposal to prevent temporarily storing bits of data on the harddrive ("swapping" or "caching") to clear the RAM. So there is some truth to what you've heard, but not in the way you suspected it to be.

short answer - yes

Miriam

If you read the above replies carefully, you will see that there will be some benefits, particularly if you do a lot of video/music editing.

Miriam


P.S., if you'd like, go ahead and click the "Helpful" or "Solved" buttons on any of the posts / replies above if you feel they were helpful or adequately answered your question.

Surley the question is:

Will they release a version on 10.5 that will be PPC compatable?

10.4 for an intel chip wont work with a PPC chip, even though they are both 32 bit chips?

Given the huge number of PPC machines out there, one would hope that 10.5 will be compatible, I can't imagine that Apple would cut us off this quickly. Perhaps 10.6 will be solely intel, but from what I have read, Leopard will be universal.

Miriam

Hello,

So I will get some benefits from Leopard's 64bit
support? Even with my 1.5GB?

Yes. You do not need more memory to benefit from 64-BIT processing. People seem to get stuck on that for some reason. More memory is always better. But, it is not a requirement for you to manipulate 64-BIT instructions.

Your processor will still be a 64-BIT processor regardless of how much memory is installed. And, when presented with a 64-BIT instruction to complete, it will do it. So, yes, you will benefit from running 64-BIT programs on your 64-BIT processor.


I hope this helps.

Let us know if you have other questions.


P.S., if you'd like, go ahead and click the "Helpful" or "Solved" buttons on any of the posts / replies above if you feel they were helpful or adequately answered your question.

Hello,

Will they release a version on 10.5 that will be PPC
compatable?

Yes. The current beta versions support PowerPC G4 and G5 processors (no G3 support).

10.4 for an intel chip wont work with a PPC chip,
even though they are both 32 bit chips?

That is because the PowerPC and Intel Chips are completely different. The only similarity is that they are microprocessors.

Apple could produce a Universal version of 10.4. But, there is no need. All Intel Macs come with 10.4.x installed (the Intel version). So, there is no need to provide a retail package that supports the Intel processor. All the Intel-based Macs already have the latest OS installed.

Now, with 10.5, they will be selling the same box to both PowerPC and Intel users as an upgrade. So, Universal support in the retail package will be important.

Taging for future references.

I am not certain of this, but I seem to recall reading a while back that to get the maximum benefit from a 64 bit processor one should have a matched pair of identical RAM chips.