Reverting Back to an Earlier Mac OS X Version

[simonsi]

One of my company's development system has 8 different operating systems on it. Needless to say it uses a big fat hard drive and not an SSD (could you imagine the price!) All booting is done via System Preferences. On Windows there are tools available (the name eludes me now) that allow the system to come up and display which OS to use prior to booting. Too bad the Mac doesn't have something like that. Holding the option key down at boot doesn't count, but it is in some ways similar.

Selecting Startup Drive through System Prefs does just that...

 

[WorkerBee2015]

Selecting Startup Drive through System Prefs does just that...

That's not really what I meant. When the PC boots the boot manager, which I think is called "System Commander" comes up and displays all partitions available. A user can set the timeout value and if an option isn't selected after the timeout, it boots it's assigned default volume. Functionally it's more like holding the "alt" key down at boot time, but you don't have to manually do it. I'm not sure if it's made anymore. It's been nearly 10 years since I did any real PC work.

 

[OldGuyTom]

While we're talking about reverting, has anyone taken a look at how much memory an application uses under an old OS verses a newer version? In El Capitan they seem to be using almost 5 times as much.

 

[simonsi]

While we're talking about reverting, has anyone taken a look at how much memory an application uses under an old OS verses a newer version? In El Capitan they seem to be using almost 5 times as much.

Mine are all similar to before, and overall memory usage is the same (I have 16GB and it typically runs at 11GB in use) so unless you talk specific apps it maybe an issue your installation has...

 

[MacRobert10]

Mine are all similar to before, and overall memory usage is the same (I have 16GB and it typically runs at 11GB in use) so unless you talk specific apps it maybe an issue your installation has...

I'm not "OldGuyTom" but I thought for kicks I'd test this myself. I opened Xcode7 and configured it to be a build that could run on Mountain Lion through El Capitan. All it was was a window that opened up and did nothing. I didn't go back to Snow Leopard because I didn't want to fool with non-ARC apps, this is a simple test.

Result: El Capitan used over twice the memory to launch this do-nothing app than Mountain Lion did, so no, that's not his imagination.