I recently upgraded to Mavericks from Snow Leopard. Does Snow Leopard still exist on my Mac? If so, is it possible to restart under Snow Leopard in order to run PowerPC apps? If not, is there an OS available in 64 bit that supports PowerPC apps? Mav ***.

1. No, unless you specified a separate drive or partition when installing Mavericks.

2. If you did(see #1), select it in the Startup Disk pane of System Preferences.

3. Nothing newer than 10.6.8 does.

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Snow Leopard supports more than 4GB of RAM.

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The only reason I upgraded to Mavericks was because my Snow Leopard OS was 32 bit, which I was told would support only 4GB of RAM.

That wasn't quite right. You can put in as much RAM as your Mac's hardware supports. The division is in the apps themselves. A 32 bit app can't use more than 4 GB or RAM. A 64 bit app can use much more.

For example, as a 32 bit only version, Photoshop CS3 can't use more 4GB of RAM, no matter how much you actually have installed. CS4 or later can use all the RAM you want to throw at it.

You're welcome.

The person at the tech desk may have thought the information they had was correct. It's hard to say. But Snow Leopard itself is a 64 bit OS. That was the main change between it and 10.5.x.

By default, the only thing that loads as 32 bit in Snow Leopard is the mach_kernel. The rest of the OS runs 64 bit. If your Mac's hardware supports it, you can hold down the 6 and 4 keys during startup, and the mach_kernel will also load as 64 bit.