[DM-MUG] Leopard and G5s

[Colin Wheeler]

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Im a Mac Developer (using Cocoa) and I can tell you that 64 bit means  
64 bit not x86-64bit (Intel) or powerpc-64bit it's any CPU that's 64  
bit can take advantage of a much larger address space (ie using more  
than 4GB ram.) It's xx-bit dependent not architecture dependent  
thing. That also means all applications can finally deal with more  
than 4GB of data at a time, for those apps that do deal with more  
than 4GB of data (ie iTunes, Aperture, etc) and run on 32bit mode  
that means they are doing their own internal paging of data to and  
from memory which slows it down in 32 bit mode, this will result in a  
big speedup of SOME apps (ie very CPU intensive apps that deal with  
BIG data sets.)

Essentially what Apple said is that if you have a 64 bit chip  
( PowerPC G5, Intel Xeon, Intel Core 2 Duo ( Core Duo is 32 bit  
sorry :(  then the entire software stack will run in 64 bit mode if  
it's available otherwise it'll run the apps that it can't find a 64  
bit executable in 32 bit mode alongside the 64 bit apps. Just the  
same way though that you have to intentionally build a Universal  
application when you compile mac apps you have to specify to build  
for 32 and 64 bit. If you do a universal 32 and 64 bit app your  
building 4 versions of the same app ( x86 32-bit, x86 64-bit, powerpc  
32-bit, powerpc 64-bit ) in 1 executable which people will download/ 
install.

So if you have a G5 relax it will take advantage of the 64 bit  
improvements in 10.5 Leopard :)

Currently 64-bit is only available at the UNIX level in Tiger ( ie  
Darwin ( kernel + apps ) ). Not everybody will really want to take  
advantage of it, if you don't have a big app with a big dataset your  
app could run slower in 64-bit than in 32-bit mode though.

Just for those who want to know or are curious here are the RAM  
limits on each of the bit modes
32-bit : 4GB
64-bit : 16 exabytes or 17,179,869,184 gigabytes

 From Colin Wheeler
http://code.google.com/p/redflag/ The next generation Del.icio.us  
client for Mac OS X

On Jun 11, 2007, at 2:37 PM, Darcy Baston wrote:

> http://en.wikipedia.org/wiki/Mac_OS_X_v10.5
> "Like Mac OS X 10.4, Leopard will be available for both PowerPC and  
> Intel Macs.[29] While it is known that Leopard will support PowerPC  
> G4 and PowerPC G5 processors,"
>
>
> http://forums.macnn.com/90/mac-os-x/304752/leopard-64bit-on-g5-too/
> "Leopard delivers 64-bit power to both Intel- and PowerPC-based  
> Macs, so you don?t have to install separate applications for  
> different machines"
>
>
>
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