64-Bit Computing
Mac OS X 10.4 introduced 64-bit computing to the Mac platform. 64-bit computing means that a process can directly address more than the 4 gig address space that 32-bit computing allows. The process might not actually get more than 4 gigs of memory to play with, but it will have the extra address space. That depends on what the user has installed in the machine, per-process limits, different operating system settings, and so on.
How much bigger is the 64-bit address space compared to the 32-bit one? A common analogy is this: if a byte is a dot the size of the period at the end of this sentence, then a 32-bit address space would cover the surface of the Golden Gate Bridge. A 64-bit address space would cover the entire land surface ...
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