CompTIA A+® Certification All-In-One For Dummies®, 2nd Edition

1.5. Understanding the Macintosh OS

The Macintosh OS has gone through some major changes over the last few years. The original version, Mac OS 1.0, remained essentially unchanged up through version 9.0. The last version of the Classic Mac OS was 9.x, which was replaced with a totally different OS, Mac OS X, which was based on the BSD OS.

NOTE

The first nine revisions of the Mac OS were proprietary, built entirely by Apple. Mac OS X and later are based on a BSD Unix core with Apple proprietary enhancements.

1.5.1. Comparing versions of Mac OS

The Mac OS originally hit the scene in 1984, running on a hardware platform that was very different from the hardware that was used by Windows PCs. It was standardized on the Motorola 68000 processor, and PCs were using Intel processors. The Macintosh also used Small Computer System Interface (SCSI) hard drives, and Windows PCs were using Integrated Drive Electronics (IDE) drives.

Through most of the 1990s, Mac OS 7.x was the main Macintosh OS. Shortly after the release of Mac OS 9.1 in 2001, Apple also released Mac OS X, with the goal of allowing capable computers to dual boot these two OSes. Unlike Windows, Apple allowed you to dual boot the old OS to run any applications that did not work with Mac OS X rather than having to support legacy Mac OS 9 applications in Mac OS X. Mac OS X also offered to run old applications in an emulator called the Classic environment, which can be slow and requires that you have a Mac OS 9.1 system folder ...