the tenth edition in the series is the Mac OS X Yosemite. Built-to-order options included a 500 GB 7200 RPM hard drive, a 128, 256, or 512 GB solid-state drive, a 1680x1050 glossy or anti-glare display. The Mac OS X series is one of the best line up series of the operating systems. Improvements included faster processors, improved graphics chipsets, and larger hard disks for the low- and mid-range models.