Check that your computer is compatible with Mountain Lion/Mavericks/Yosemite.
To check the model number hold down the option/alt key, go to the Apple menu and select System Information.
- MacBook (Late 2008 Aluminum, or Early 2009 or newer) model number 5,1 or higher
Your Mac needs:
- OS X v10.6.8 or OS X Lion already installed
- 2 GB or more of memory (More is better - 4 GB minimum seems to be the consensus)
- 8 GB or more of available space
Check to make sure your applications are compatible. PowerPC applications are no longer supported after 10.6.
Application Compatibility
Applications Compatibility (2)
Do a backup before installing.
If your computer isn’t compatible, you might be able to upgrade to Lion or Snow Leopard.
Computer Compatibility - Lion Lion
Snow Leopard Purchase