How do I choose a default startup drive?

Question

I have two startup drives on my Hard Drive. One is Snow Leopard and the other is Leopard. I need Leopard for some printing issues with Photoshop and Epson. How do I choose a default startup drive? Most of the time I want the Snow Leopard drive at startup but it seems to always start up on Leopard. I need to always hold down the option key at startup. Sometimes I forget.

Answer 1

noondaywitch wrote:
System Preferences > Startup Dive > select the drive with 10.6.x I suspect you may need to do that for both systems. Click the lock to prevent further changes, then do an option-boot and ensure it'll let you start from the other.
Macs store a reference to the default startup drive set in System Preferences > Startup Drive in PRAM, so you don't have to set it individually for each drive or partition -- as long as the selected one is available at startup time, that is the one the Mac will start up from. (Otherwise, it will be the first available one found. If none capable of starting up the Mac are found instead the flashing slashed circle with the question mark in it won't go away, indicating the Mac is still waiting for you to make one available, for instance by powering up an attached external drive or inserting a bootable DVD.)
The option key startup method temporarily overrides this & allows you to choose another drive or partition, but just for that startup -- the next time you start up normally, it will revert to the selected one.
Also, the lock in System Preferences has nothing to do with making preference settings permanent or persistent. It is just a security feature to prevent unauthorized users from making changes from an already logged in user account. For instance, it makes no difference if the lock is closed or open at startup time, because that is before the OS is running or able to check preference file settings stored on disks. During the early stages of the boot process, code resident in firmware checks for depressed keys & buttons before loading the OS from the default source set in PRAM. This is how it decides if it should instead run the Startup Manager (evoked by the option key), first eject a CD or DVD (evoked by the eject key or primary mouse button), or start up from an alternate source like an installer DVD (evoked by the C key).