Actually the last update for Parallels 7 will work with Mountain Lion, if for some reason you have access to upgrading to 7 and prefer to do that. But if you are paying the full upgrade price, go for version 8 anyway.
With the upgrade to Mt. Lion, you will lose Rosetta and its transparent ability to run PowerPC applications (those written for the older PPC CPU platform from the mid 90s until 2006 after Mac's migration to the Intel CPU platform).
The Roaring Apps Compatibility Table will help you determine if you have applications that are affected:
If you run into trouble with older apps, here is a post that I assembled for a similar problem:
Unfortunately you got caught up in the minor miracle of Rosetta. Originally licensed by Apple when it migrated from the PowerPC CPU platform that it had used from the mid-1990's until the Intel CPU platform in 2006, Rosetta allowed Mac users to continue to use their library of PPC software transparently in emulation.
However, Apple's license to continue to use this technology expired with new releases of OS X commencing with Lion (and now Mountain Lion). While educational efforts have been made over the last 6 years, the fact is that Rosetta was SO successful that many users were caught unaware UNTIL they upgraded to Lion or Mountain Lion.
1. If your Mac will support it, restore OS X Snow Leopard;
2. If your Mac will support it, partition your hard drive or add an external hard drive and install Snow Leopard into it and use the "dual-boot" method to choose between your PowerPC software or Lion/Mt. Lion;
3. Upgrade your software to Intel compatible versions, or find alternative software that will open your data files;
3. Install Snow Leopard (with Rosetta) into Parallels:
[click on image to enlarge]
Full Snow Leopard installation instructions here:
NOTE: STEP ONE of the instructions must currently be completed on a Snow Leopard or Lion Mac and the resulting modified Snow Leopard.cdr install file can then be moved over to your Mountain Lion Mac for completion of the remaining steps.
NOTE 2: Computer games with complex, 3D or fast motion graphics make not work well or at all in virtualization.
If I erase, to free up all space, an external hard drive and install Snow Leopard on it will I be able to access the Power PC applications on my laptop which Mountain Lion has made inactive? Those applications are still residing on the MacBook Pro's hard drive. If so, does that mean I must boot up in the external hard drive, thus only running Snow Leopard? Or can I toggle between the drives? If yes what are the steps to select which drive I am booting up in, or to boot both and toggle? Or must I install those Power PC programs on the external drive?
Depending on when your Mac was released and which version of OS X is required to boot it, then yes, you may be able to install Snow Leopard on an external hard drive and use the "dual-boot" method to run it when needed.
Many applications will not require re-installation into the external hard drive, and hence can be run off the internal drive. But some will, depending upon what its Installation procedure installs into the System and Library folders.
This method will not run concurrently with Mt. Lion (like using Bootcamp to run Windows, which will not run concurrently with Mac OS X); hence the term "dual-boot" but it is the most stable and effective method of running applications within Snow Leopard.
You would use System Preferences Startup Disk to select which version of OS X will boot when you restart. And there is a command key available to you that will also direct you to the selection as you startup. I think it is the OPTION key as you startup.
Not that I am aware of other than other threads in this forum and others.
What more do you need to know other than:
1. Install Snow Leopard on external Hard Drive; and
2. Use System Preferences - Startup Disk or the Option key on Startup to choose which version of OS X you boot into.
Which Mac do you have: give us ALL information under the Apple Menu of About This Mac and then More Information and then under Hardware Overview - Model Name and Identifier
If you are going to install Snow Leopard into this external drive you need to use Disk Utility to reformat it (Erase) as:
Mac OS X Extended (Journaled)
Everything will of course be erased.
UPDATE: Oh, it does not show up in Disk Utility. You need to run some diagnostics on this drive. Something is wrong! A "PowerPC" drive will show up as an external drive in Mt. Lion, but it cannot be used as a startup disk.
You may want to start a new thread for help on this subject.
Did you boot (restart holding down the "C" key) from a "retail" Mac OS X Snow Leopard Install DVD, such as that below (and not a restore DVD)? You can purchase one for $19 by calling the Apple Store:
[1-800-MY-APPLE (1-800-692-7753)] or Customer Service and Sales Support at 1-800-676-2775 (ask for a Sales Representative)
You still have not provided the full information about your Mac that I requested, so it is hard to decypher completely your problem...
Oh, the laptop I am working with is a MacBookPro,15-inch, 2.53GHz, Mid 2009 2.53 GHz Intel Core 2 Duo, 4 GB memory, plenty of drive space. I just installed OS X 10.8.2.
Software OS X 10.8.2 (12C60)
Serial Number W89235207XJ
The install disc is Mac OS X Snow Leopard install DVD, Replacement, not for Resale.
I did not reboot as I wanted to install it on the external hard drive, not the laptop.
Much time and effort would have been saved if you just had indicated that you upgraded from Snow Leopard, and hence, your MBP can indeed boot Snow Leopard!
We should cease hijacking this thread (12 posts out of 15), especially if I have to keep repeating myself. So: start a new thread if you need further help; AND BOOT FROM THE SNOW LEOPARD DVD if you want to properly install it to your external hard drive. GOOD LUCK!