To download and install either the pay OS X 10.8.5 Mountain Lion or the free mac High Sierra/ macOS Sierra OR OS X 10.11.5 El Capitán you need one of these Macs: This step is really needed in case something goes wrong with the install of the new OS or you simply do not like the new OS, you have a very easy way/procedure to return your Mac to its former working state. Then, use either OS X Time Machine app to backup your entire system to the external drive OR purchase, install and use a data cloning app, like CarbonCop圜loner or SuperDuper, to make an exact and bootable copy (clone) of your entire Mac's internal hard drive. If for some software reason, you need OS X 10.8.5 Mountain Lion, this is a paid upgrade, now.īefore embarking on a major OS upgrade, it would be wise, advisable and very prudent if you have a good, working backup of your current system to an external connected and Mac formatted Flash drive OR externally connected USB, Thunderbolt or FireWire 800, Mac formatted hard drive.
