64-Bit
Computing
Leopard now features full 64-bit computing
through out its whole OS architecture. So what does this
mean? In simple terms, your apps will be able to access
more memory and if supported by the application, can do
approx twice the work of a a standard 32-bit application.
Most people however will not see 64-bit as a huge advantage
at all. If you're into dealing with very large photos or
movie files, this is where you'll see some significant
gains in performance. Why is this? Again, 64-bit processing
will allow allocation to more memory to any app that can
take advantage of it. Also, it will allow the processor to
do more work per clock cycle
(think 1's and 0's). When
Apple was building in 64-bit into OS X, they did it in a
way that allows 32-bit backwards compatibility. What does
this mean? This means that you won't have to have to look
specifically for 64-bit applications, printer drivers,
camera drivers, etc. If it needs to use a 32-bit driver, it
will automatically use it on the fly. So everything is
backwards compatible. If it can utilize 64-bit processing
then it will use it, if not, then it will use 32-bit
processing. As the OS and other 3rd party applications get
more and more complex, it will become more and more
important to getting things done more efficiently.
Explaining 64-bit processing in simple terms is very hard
to do. Hopefully this gives you an idea of how it works.
ALL of the major OS X built-in applications are now 64-bit!
Below are just some of the apps:
Finder
iChat
Dictionary
Time Machine
Exposé
Spaces
Mail
Safari
DVD Player
Address Book
Automator
QuickTime
Preview
System Preferences
iCal

Macintosh Computers
that support 64-bit computing:
PowerMac G5 (All
models)
iMac G5 and Intel Core 2 Duo
(excludes G3/G4
models)
MacMini w/Intel Core 2 Duo (excludes G4/Intel Core Duo and Solo
models)
MacBook w/Intel Core 2 Duo
(excludes Intel Core Duo
models)
MacBook Pro w/Intel Core 2
Duo (excludes Intel Core
Duo models)
Mac Pro (All models)
Xserve Xeon Duo and
G5(excludes G4 models)