# 64 bit LEopard



## artov (Oct 16, 2007)

I am thinking on buying MacBook Pro, once Leopard is available. MBP comes with 2GB memory, but it is upgradeable to 4GB. On 32 bit OS not the whole 4GB is usable, since devices use part of the memory space. But with 64 bit OS, devices can be mapped after the 4GB of memory, so one can access the whole memory.

So my question is: If I start with 2GB, there is no reason to run Leopard in 64 bit. But if I  put the extra 2GB, can I just boot Leopard in 64 bit mode, or do I have to reinstall everything?


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## chevy (Oct 16, 2007)

I don't think there are 32 and 64 bits modes in Leopard. The OS is 64 bits and will exploit it if your CPU is 64 bits compatible.


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## fryke (Oct 16, 2007)

Yup. You can't actually choose anything. It'll run 64bit code if the machine can.


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## Captain Code (Oct 16, 2007)

Leopard is Automagic.


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## ElDiabloConCaca (Oct 22, 2007)

artov said:


> I am thinking on buying MacBook Pro, once Leopard is available. MBP comes with 2GB memory, but it is upgradeable to 4GB. On 32 bit OS not the whole 4GB is usable, since devices use part of the memory space. But with 64 bit OS, devices can be mapped after the 4GB of memory, so one can access the whole memory.



Since your MacBook Pro will have a maximum of 4GB of memory, then this really doesn't affect anything, does it?  You won't have any space "after the 4GB", so the devices will still need to be mapped within the 4GB space whether you're using 32 bits or 64 bits.

Maybe I'm missing something here...


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## fryke (Oct 22, 2007)

I've asked a similar question before in a VMware vs. Parallels thread. I think the answer's a bit elusive. But either way: Since Apple doesn't make us choose what to run, we'll simply get the faster version automagically.


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## artov (Oct 22, 2007)

Check http://en.wikipedia.org, the figure on chapter "Virtual address space details". I guess devices will be mapped to the lower half, and user programs above them. Kernel etc. will be on top of the address space.


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## Veljo (Oct 22, 2007)

You'll have to purchase the 32-bit of Leopard, mail the disc to Apple along with a small fee, and then wait for them to mail you back a 64-bit disc.

...oh wait, that's Vista.


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## ex2bot (Oct 24, 2007)

You can address the entire 4 gb in OS X, whether you have a 32 bit or 64 bit processor in both Tiger and Leopard.

Doug


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## DisabledTrucker (Oct 27, 2007)

artov said:


> I am thinking on buying MacBook Pro, once Leopard is available. MBP comes with 2GB memory, but it is upgradeable to 4GB. On 32 bit OS not the whole 4GB is usable, since devices use part of the memory space. But with 64 bit OS, devices can be mapped after the 4GB of memory, so one can access the whole memory.
> 
> So my question is: If I start with 2GB, there is no reason to run Leopard in 64 bit. But if I  put the extra 2GB, can I just boot Leopard in 64 bit mode, or do I have to reinstall everything?



You must have Mac OS X mixed up with some other crapware, such as Vista.  The Mac's use all the memory available to them and the only limitations in Leopard is the amount of memory the computer can actually hold.  Well until you get well into terabytes or something like that, in other words it will more than likely never happen on one system, unless there are some serious technological advancements in the near future planned that noone is clued in on.  Leopard is only a 64-bit operating system although it will also run 32-bit applications.  You can read more about it here: http://www.apple.com/macosx/technology/64bit.html


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## arninetyes (Nov 4, 2007)

DisabledTrucker said:


> You must have Mac OS X mixed up with some other crapware, such as Vista.


Yeah, it's Microsloth that has all those profit friendly packages of many, many versions of its OS. Buying a copy of Windows reminds of the old joke about buying a car -

"Oh, you want WHEELS with your new car?  That'll be extra."


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