32-bit vs 64-bit Mac & Snow Leopard
(Note: This is all based on Developper release 10A432 and is yet to be confirmed in the final release.)
If you’re upgrading your MAC OS to Snow Leopard (only $35 CAD) you should be looking to ensure you’re running the 64-bit version (although Apple claim users won’t notice the difference — and furthermore it would appear that Snow Leopard runs 64-bit applications regardless of how it booted).
Your first step is to determine if your processor is 64-bit capable or not. You must have the 64-bit EFI. Here’s the chart from Apple:
| Processor Name | 32- or 64-bit |
| Intel Core Solo | 32 bit |
| Intel Core Duo | 32 bit |
| Intel Core 2 Duo | 64 bit |
| Intel Quad-Core Xeon | 64 bit |
Once you’ve determined if you’re 64-bit capable, you apparently need to hold down the 6 and the 4 simultaneously on a standard Mac at boot up to force the installation into 64-bit mode, otherwise your Snow Leopard will install in 32-bit mode by default. Also see the com.apple.Boot.plist file for permanent changes.
I’ve searched support on Apple and only confirmed this in Snow Leopard Server.


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