Can MacBook Pro UTILIZE 4 GB of Ram?

Well a question just popped into my head while I was working on my MBP a while back,so I thought why not just ask it.So I have the Penryn refresh MacBook Pro(running Leopard) with 4 GB of Ram. I know that that my MBP can SEE the 4 GB of Ram, but can it UTILIZE all of the 4 GB? I know with Vista service pack 1, PCs(32-bit) can SEE 4 GB of Ram but can utilize 3-3.5 GB because of the 32-bit architecture. Is it the same with macs or can Leopard utilize all of the 4 GB? This is something I am not sure about, so hopefully someone can shed some light on it.

 

Yes, it can . Mac OS X Leopard is 64-bit!

 

Hey thanks Sam.I kind of had a feeling you would answer this one!!

 

Haha, no problems! And you must be psychic!

 

How about Tiger though?

I have 4gb and it shows that I have 4gb, but does it use all of it?

 

yes! how about tiger!?! and what do they mean 32bit and 64bit architecture of tiger and what do they mean by leopard 64bit from top to bottom, what differentiate them?

 

If you have a 64bit capable CPU, then Tiger will be able to address more than 4GB of RAM. The reason why some say that Tiger has a partly 64bit architecture is because there are a number of core libraries under Tiger that are still 32bit at its heart. Those libraries and frameworks are now fully 64bit, which is why Leopard is advertised as a full 64bit OS.

 

Mac OS X has had 64-bit support since Panther. The difference is that in Panther, the 32-bit 4GB limit per application was enforced, but you could have multiple maxed out 32-bit applications, ie. 4GB+4GB, which you can't do in a pure 32-bit environment. In Tiger, 64-bit was opened up a bit so that command-line applications and behind the scene worker threads mostly used for mathematical crunching can be 64-bit and therefore those threads can use more than 4GB of RAM. The problem was that all the higher level APIs that interact directly with the user were not converted to 64-bit, so you couldn't create a full 64-bit application, your display elements would be 32-bit, but you could have 64-bit worker threads to pass them higher precision calculations. The only Tiger 64-bit compatible application I've used is Mathematica whose function fit perfectly into this paradigm. In Leopard everything you need to make a complete application minus things now designated "legacy" have been converted to 64-bit such as Cocoa, Core Audio, Quicktime, etc.

But the OS X kernel is still 32-bit in all versions so as to not break driver compatibility. I'm not exactly sure how this works, but I suppose you don't need to be a 64-bit kernel to manage 64-bit threads if you are more concerned about directing them where to go rather than what their data is.

And technically 32-bit Windows 2000, XP, and Vista can support the full 4GB of RAM, you just need to jump through some hoops with activating PAE, which I believe moves the memory addresses for things like the graphics card from the 3.2GB-4GB region, above 4GB so that the full 4GB can be used by applications. The only problem is that not all devices support doing that which is why it isn't activated for consumer operating systems. 32-bit Windows 2000 Server, 2003 and 2008, have long supported more than 4GB of RAM even though they are only 32-bit OSs because their drivers have been designed to expect PAE remapping.

 

oh man... this is complex. thanks budding and itcommander. so the OSX leopard's kernel is still 32 bit?

 

No, darwin(OS X's kernel) should be fully 64 bit now. Don't quote me on that though

 

No the kernel must remain 32-bit to maintain driver compatibility, which is why OS X makes a smooth transition to 64-bit, unlike Windows x64 which has a 64-bit kernel and requires new drivers.

http://arstechnica.com/reviews/os/mac-os-x-10-5.ars/6

The specific means that this is done is described in Apple's developer documentation:

http://developer.apple.com/document...//apple_ref/doc/uid/TP30000905-CH210-CHDBCBCB

This article generally references Panther's 64-bit support but the release notes said that the article was updated so that it is consistent with Tiger as well. It hasn't been updated for Leopard, but again it should be consistent otherwise completely new 64-bit drivers would be needed like in Windows.

 

its complicated, but when it comes it down to it, you can use 4GB+ with leopard.