Dual boot OSX - 10.9 & 10.6

Install Snow Leopard on a cheap external drive and move your PPC apps to it.

The option key at startup will allow you to choose a boot drive.

3 successive tones, a 5 second pause (repeating): This indicates RAM does not pass a data integrity check.

http://support.apple.com/kb/HT5860?viewlocale=en_US

You can't run two different Mac OS's at the same time so the only time you would boot from the external is when you want to use your older software.

Your internal drive would boot to Mavericks and the external to Snow Leopard. Easier and safer than a partition on just one drive.

I am dual booting Snow and ML from separate partitions on the internal. Not sure why you aren't able to do that. Did you create a second partition from the original? I wonder if there was enough room--contiguous space--to do that? If not, that might explain the problem you're encountering. When I created the second partition for ML, I had plenty of unused space to do that. In any case, to boot to another volume you need to restart while pressing the Option key just at the startup chime.

See

http://pondini.org/OSX/DU3.html

Hrabal wrote:

I formatted the drive, so it's completely clean and partitions are 255Gigs each...

How did you achieved your setup?

That should be working then. I simply added a second partition by clicking the + button, according to Pondini's instructions in that link I gave you.

Are you restarting into the startup manager (boot picker)? Unless it's USB 3.0, a USB external will be extremely slow.

What is Disk Utility showing when you select the partition tab? Do you see both volumes?

To add, I already had ML on an external partition. I simply reverse cloned that ML to the now empty new partition on the internal. Btw, you should always maintain backups with as much redundancy as possible. I have three backups of my ML and two of Snow, all clones, on three external drives. It doesn't sound like you have any.

EDITED: Just re-read your first post more carefully. Do you remember if you ever installed any firmware updates? If so, that may be preventing the 10.6 from booting.

Looks like it.

http://support.apple.com/kb/ht1237

If you have a clone of the 10.6, that might work, if you move it to the !0.6 partition, which you should first erase. Other than that, you could bring it in to an Apple Store and see if they'll put the 10.6 back on for you. I think they are supposed to have a way of overcoming the firmware update issue.

And if the firmware update you applied isn't the problem, then I'm really at a loss to explain why this isn't working.

It shouldn't be an issue, I've used this kind of partitioning numerous times:

You need to resolve that 3 beeps issue, because it's not related to using a multiple partition setup.

I think that all of the retail SL DVDs install 10.6.3. You would then have to run Software Update to get to 10.6.8.

And despite what you've been told, it shouldn't make any difference in what version of SL it is. It could even be Leopard, if the machine was old enough, for that matter.

Important note: According to MacTracker, early 2011 MBPs shipped with either 10.6.6, or 10.6.7, so you would need to use the grey #1 DVD that shipped with your Mac.