Mac OS X Snow Leopard (10.6) represents the end of a long-running transition of the Mac operating system from 32-bit to 64-bit support. 64-bit computing offers marginal (but measurable) performance improvements, and more importantly the ability to address more RAM — a lot more RAM, currently more than is even physically available in any shipping consumer computer. By contrast, under the current Mac OS, each 32-bit application can access up to 4GB of RAM. A few tools, like Apple’s EXS24 and Native Instruments’ Kontakt samplers, can address greater memory through the use of virtual memory and memory server schemes. But you don’t get native, 64-bit memory – yet.

That should begin to change. Today, Apple quietly released Logic 9.1 and MainStage 2.1, providing 64-bit support. They should be the first of more tools. MOTU confirms they’re working on a 64-bit version of Digital Performer and their plug-ins. (The free Ardour should work, too, in theory – it’s already 64-bit on Linux; sounds like one obstacle may be its UI toolkit on Mac.) Core Audio and Core MIDI have been rewritten as 64-bit-native Cocoa frameworks, with full 64-bit support, as of Snow Leopard. But prior to Apple’s announcement today, you wouldn’t have noticed, outside things like the developer examples and AU Kit host.

Logic Pro, MainStage get 64-bit support [The Loop, a recent Mac blog with a strong music focus]

Of course, today isn’t exactly the dawn of a brave new 64-bit age on the Mac – more like another (important) step in that direction. You’ll still want plug-ins to run in 64-bit mode, or you don’t get to reap the advantages. 32-bit plug-ins will work via a 32-bit Audio Unit Bridge, but that’s not the same as native 64-bit support, and such bridges are likely to require some testing and refinement before they’re ready for prime time. (On Windows, Cakewalk’s BitBridge technology for doing the same thing has gone through a fair bit of iteration and may as a result be more mature.)

There are some gotchas for some users, as noted by Jim in his story: REX file support, ReWire, AKAI file import (bizarrely), and the Vienna Symphonic Library Tool don’t yet work in the 64-bit version of Logic. In short, 64-bit will be terrific, but most users will want to wait a bit before they switch over.

Of course, this makes the number one question for Mac developers at NAMM, when do you anticipate 64-bit support? (I’m sure they’ll love that.)