Mac OS 9

Mac OS 9, the last major version of classic Mac OS, was introduced by Apple Computer on October 23, 1999. After this operating system was officially deprecated in May 2002, Apple redirected development solely towards Mac OS X for future Macintosh computers.

Advertising
Mac OS 9 was advertised by Apple as "featuring Sherlock 2," which was a definite improvement over the original Sherlock, and having "more than 50 new features and nine internet power tools." Apple also was quick to point out OS 9's 128-bit encryption capabilities.

Features
Apple included a series of bug fixes and new features. Mac OS 9 is, by some, considered the most functional and stable version of the original Mac OS, though OS 9 still does not have some features common to modern operating systems, such as protected memory (which, reportedly was implemented in beta versions of Mac OS 9.1, but pulled at Steve Jobs's command), and pre-emptive multitasking. However, it did ship from Apple with many improvements over earlier versions, such as improved OpenTransport networking, and an upgraded search tool (Sherlock 2), though it did retain the Platinum theme introduced in Mac OS 8. Unlike previous versions, it supports multiple users without third-party additions. Perhaps most importantly, almost all of OS 9 was written in code which was compatible with PowerPC microprocessors. Earlier versions of the Mac OS depended heavily on emulation of the older Motorola 680x0 series of processors. While most of the code was now PPC-only (indeed, Mac OS 9 doesn't run on 680x0 CPUs), there are still many strings in the System suitcase which make references to obsolete 680x0 machinery.

Trivia
Interestingly, when in the "About This Computer" window which shows the amount of memory being used, command-clicking on the Mac OS 9 picture sends you to Apple's page about their OS.

Another feature for laptops was the "Save Memory to Disk" option, found under the Energy Saver Control Panel. It was meant to perform the same function as "hibernate" on PC-compatible laptops. However, it was found to corrupt users' hard drives upon the first use. Apple quickly distributed a patch, in the form of a system extension. It did not fix the problem but merely grayed out the option, so that it could not be selected.

This operating system was codenamed "Sonata" and was originally planned to be debuted as Mac OS 8.7.

Release history

 * Mac OS 9.0   : October 24, 1999
 * Mac OS 9.0.1 : (unreleased)
 * Mac OS 9.0.2 : February 15, 2000
 * Mac OS 9.0.3 : March 2000
 * Mac OS 9.0.4 : April 4, 2000
 * Mac OS 9.1   : January 9, 2001
 * Mac OS 9.2   : June 18, 2001
 * Mac OS 9.2.1 : August 21, 2001
 * Mac OS 9.2.2 : December 5, 2001

Discontinuation
On May 6 at the 2002 Worldwide Developers Conference in San Jose, California, Apple CEO Steve Jobs delivered a mock "funeral" for Mac OS 9 during his keynote address, dressed in black and addressing a coffin containing an orversized retail box. The purpose of the theatrics was to announce that Apple had ended all development of OS 9. Mac OS 9.2.2 was the final version of Mac OS 9, and of the classic Mac OS. Macs that shipped by Apple after that event could no longer boot into any version of classic Mac OS by default.

Despite this, Mac OS 9 continued to live on as the operating system of choice on millions of existing PowerPC-based Macintosh computers, and as of June of 2004, was even still being shipped as a stand-alone operating system (along with OS X) on the Power Macintosh G4, only available directly from Apple as a custom to order (CTO) model (which was eventually discontinued in late 2004). The modernized successor, Mac OS X, provided a compatibility layer called the Classic environment for applications and hardware that needed to run under OS 9, until Mac OS X 10.4.11. Apple also provided Carbon, an API for allowing PowerPC applications that ran natively on OS 9 to also run on versions of OS X, until Mac OS X 10.6.8.

Continued use
Starting in 2014, enthusiasts at Mac OS 9 Lives managed to get a limited number of previously unsupported systems to boot into Mac OS 9.2.2 with reasonable functionality. Mac OS 9 can also be run on more modern systems (including Intel and Apple Silicon) through the use of open source emulators, such as QEMU and SheepShaver.

Articles

 * An OS 9 odyssey: Why these Mac users won’t abandon 16-year-old software by Richard Moss at Ars Technica (2016-09-11)