Classic Mac OS

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This article is about the classic Mac OS. For the history of Mac OS X, see Mac OS X history.
File:Macos-original-logo.gif
Mac OS System 7, 8, & 9 Logo

On January 24th, 1984 Apple Computer introduced the Apple Macintosh personal computer, with the Macintosh 128K model, which came bundled with the Mac OS operating system, then known as the System Software. The Macintosh is widely regarded as, and credited for, popularizing the graphical user interface. The Mac OS has been pre-installed on almost every Macintosh computer ever sold. The operating system is also sold separately to the computer. The original Mac OS was heavily based on the Lisa OS, previously released by Apple for the Lisa computer in 1983, and also used concepts licensed from the Xerox PARC Xerox Alto which Steve Jobs and several other Macintosh team members had been previewed in December, 1979.

Also in 1984, Apple partnered with Microsoft, in an agreement where Microsoft would create versions of Word and Multiplan (Predecessor to Excel) for the Mac OS. For the majority of the 1980s, the Mac OS lacked a serious amount of software compatible with it. With the introduction of System 7 more software began to become available for the platform. System 6 was the first major change of the operating system, although the Mac OS kernel was kept the same from the System 7 revision until the last revision of the OS, Mac OS 9.

Early history

Development

The Macintosh project started in early 1979 with Jef Raskin, who envisioned an easy-to-use, low-cost computer for the average consumer. In September 1979, Raskin was given permission to start hiring for the project and was, in particular, looking for an engineer that could put together a prototype. Bill Atkinson, a member of the Lisa team, introduced him to Burrell Smith, a service technician who had been hired earlier that year.

In January 1981, Steve Jobs completely took over the Macintosh project. Jobs and a number of Apple engineers visited Xerox PARC in December 1979, three months after the Lisa and Macintosh projects had begun. After hearing about the pioneering GUI technology being developed at Xerox PARC from former Xerox employees such as Jef Raskin, Steve Jobs negotiated a visit to see the Xerox Alto computer and Smalltalk development tools in exchange for Apple stock options. The final Lisa and Macintosh operating systems most used concepts from the Xerox Alto, but many elements of the graphical user interface were created by Apple including the menubar and pop-up menus, the click-and-drag theory was developed by Jef Raskin.

Unlike the IBM PC, which used 8 kB of system ROM for power-on self-test (POST) and basic input/output chores (BIOS), the Mac ROM was significantly larger (64 kB) and held key OS code. Much of the original Mac ROM was coded by Andy Hertzfeld, a member of the original Macintosh team. He was able to conserve some of the precious ROM space by interleaving some of the assembly language code. In addition to coding the ROM, he also coded the kernel, the Macintosh Toolbox and some of the desktop accessories (DAs) as well. The icons of the operating system, which represented folders and application software were designed by Susan Kare, who later designed the icons for Microsoft Windows 3.0. Steve Capps wrote the Macintosh Finder and Macintosh system utilities.

Release

Original 1984 Mac OS desktop

The first version of the Mac OS, then known as the System Software, or more simply the System, was System version 1.0. It is easily distinguished between other operating systems from the same period because it does not use a command line interface; it was one of the first operating systems to use an entirely graphical user interface. It bundled with the original Macintosh 128K in 1984 up until May 1984 when it was updated to version 1.1, including only minor changes. Additional to the system kernel is the Finder, an application used for file management, which also displays the Desktop.

These releases could only run one application at a time, though special application shells such as Switcher (discussed under MultiFinder) could work around this to some extent. Systems 1.0, 1.1, and 2.0 used a flat file system with only one kludged level of folders, called Macintosh File System (MFS); its support for folders (subdirectories) was incomplete. System 2.1 (Finder 5.0) introduced the HFS (Hierarchical File System) which had real directories. System 3.0 was introduced with the Mac Plus, adding support for several new technologies including SCSI and AppleTalk, and introducing Trash "bulging", i.e., when the Trash contained files, it would gain a bulged appearance. System 4.0 came with the Mac SE and Macintosh II.

Changes in early Macintosh operating systems are best reflected in the version number of the Finder, where major leaps are found between 1.x, 4.x, 5.x, and 6.x.

  • System 1.0, Finder 1.0 (January 1984)
  • System 1.1, Finder 1.1g (May 1984)
  • System 2.0, Finder 4.1 (April 1985)
  • System 2.1, Finder 5.0 (September 1985)
  • System 3.0, Finder 5.1 (January 1986)
  • System 3.2, Finder 5.3 (June 1986)
  • System 4.0, Finder 5.4 (January 1987)
  • System 4.1, Finder 5.5 (April 1987)

System 5

System 5 added MultiFinder, an add-on replacement for the Finder which could run several programs at once. Time was given to the background applications only when the foreground (or "running") applications gave it up (co-operative multitasking), but in fact most of them did via a clever change in the OS's event handling. The other significant change that System 5 brought to the Mac was Color QuickDraw, which debuted with the Macintosh II. This significantly altered the extent and design of the underlying graphics architecture (and its APIs), but it is a credit to Apple that most users, and perhaps more importantly existing code, were largely unaware of this.

System 5 was also the first Macintosh operating system to be given a unified "Macintosh System Software" version number, as opposed to the numbers used for the System and Finder files.

  • System Software 5.0 (System 4.2, Finder 6.0, MultiFinder 1.0)
  • System Software 5.1 (System 4.3, Finder 6.0, MultiFinder 1.0)

System 5 was available for a very short time and only in some countries, including the United States.

System 6

File:Sys6screenshotbusy.png
System 6 running two applications and a desktop accessory.

System 6 was the first major upgrade of the Mac OS. It consolidated the previous releases into a much more complete and stable operating system. It also moved the Mac to true 32-bit memory addressing, necessary for the ever increasing amounts of RAM available. Earlier systems used the lower 24-bits for addressing, and the upper 8-bits for flags. This was an effective solution for earlier Macintosh models with very limited amounts of RAM, but it became a liability later. Apple termed code that assumed the 24 + 8 bit addressing "not 32-bit clean", and developers were required to excise such assumptions from their code.

  • System Software 6.0 (System 4.4, Finder 6.1, MultiFinder 1.1 -- the version numbers of the System and MultiFinder files were changed to 6.0 just before the public release)
  • System Software 6.0.1
  • System Software 6.0.2
  • System Software 6.0.3
  • System Software 6.0.4
  • System Software 6.0.5
  • System Software 6.0.6, never released
  • System Software 6.0.7
  • System Software 6.0.8 (identical to System 6.0.7, but configured with System 7.0 printing software for printer sharing with System 7, last version that could run on the original Mac 128K)
  • System Software 6.0.8L (only for Macintosh Classic, Classic II, PowerBook 100, Macintosh LC, LC II)

System 7

File:System7screenshot.gif
Screenshot of System 7.5.3 Revision 2

On May 13, 1991 System 7 was released. It was the first considerably major upgrade to the Mac OS, adding a significant user interface overhaul, new applications, stability improvements and many new features.

The most visible change was a new full-color user interface. Although this feature made for a visually appealing interface, it was optional. On machines not capable of displaying color, or those with their display preferences set to monochrome, the interface defaulted back to the black-and-white of previous versions. Only some interface elements were colorized, scrollbars had a new look, but push buttons remained in black-and-white.

The most notable of all the features added in System 7 includes the built-in co-operative multitasking. In System 6, this function was optional through the MultiFinder. System 7 also introduced aliases, similar to shortcuts that were introduced in later versions of Microsoft Windows. System extensions were enhanced, by being moved to their own subfolder; a subfolder in the System Folder was also created for the control panels. Later versions of System 7 offered a feature called "Extensions Manager" which simplified the process of enabling and disabling extensions.

The Apple menu, in System 6 home only to desktop accessories, was made user-editable: the user could now place aliases to often used folders and applications in the menu, by placing them in an "Apple Menu Items" subfolder in the System Folder. AppleScript, a scripting language for automating tasks was also introduced with System 7. 32-bit QuickDraw, supporting so-called "true color" imaging was also included as standard; it was previously available as a system extension. QuickDraw was used in Mac OS for fast on-screen drawing. TrueType, an outline font standard also included in Microsoft Windows 3.1, was integrated into the operating system.

The Trash, under System 6 and earlier, would empty itself automatically when one quit or, if MultiFinder were not running, when one launched an application. System 7 reimplemented the Trash as a special instance of a regular folder, allowing files to remain in it across reboots until the user performed an "Empty Trash" command.

Systems 7.1 and 7.5 introduced a large number of "high level" additions, considered by some to be less well thought out than they could have been. Some of the most confusing were the reliance on countless System Enablers to support new hardware and various System update extensions with inconsistent version numbering schemes. Overall stability and performance also gradually worsened during this period which introduced PowerPC support and 68K emulation.

Stability returned with Mac OS 7.6, which dropped the "System" moniker as a growing market of third-party manufacturers licensed the software from Apple for Macintosh clones which competed directly against Apple's own hardware.

Although the version number was subsequently changed to 8.x and 9.x, the internal core of the OS remained basically the same.

  • System 7.0 (released in late 1991; integrated MultiFinder into the OS as default)
  • System 7.0.1 (introduced with LC II and Quadra series)
  • System 7 Tuner (update for both 7.0 and 7.0.1)
  • System 7.1
  • System 7.1 Pro (version 7.1.1, combined with PowerTalk, Speech Manager & Macintalk, Thread Manager)
  • System 7.1.2 (first version for Macs equipped with a PowerPC processor)
  • System 7.1.2P (only for Performa/LC/Quadra 630 series, very quickly replaced by 7.5)
  • System 7.5
  • System 7.5.1 (System 7.5 Update 1.0 -- the first Macintosh operating system to call itself "Mac OS")
  • System 7.5.2 (first version for PowerMacs that use PCI expansion cards, usable only on these Power Macs and PowerBooks 5300 and Duo 2300)
  • System 7.5.3 (System 7.5 Update 2.0)
  • System 7.5.3L (only for Mac clones)
  • System 7.5.3 Revision 2
  • System 7.5.3 Revision 2.1 (only for Performa 6400/180 and 6400/120)
  • System 7.5.5
  • Mac OS 7.6 (name formally changed because of the experimental clone program, although System 7.5.1 and later used the "Mac OS" name on the splash screen)
  • Mac OS 7.6.1

Macintosh Performa computers used to have their own, exclusive operating system before they were merged into System 7.5.

  • System 7.0.1P
  • System 7.1P1
  • System 7.1P2
  • System 7.1P3 (last release with new features)
  • System 7.1P4
  • System 7.1P5
  • System 7.1P6

Mac OS 8

Mac OS 8.1 desktop

Mac OS 8 was released on July 26, 1997, shortly after Steve Jobs returned to the company. It was mainly released to keep the Mac OS moving forward during a difficult time for Apple. Initially planned as Mac OS 7.7, it was renumbered "8" to exploit a legal loophole to accomplish Jobs' goal of terminating third-party manufacturers' licenses to System 7 and shutting down the Macintosh clone market. 8.0 added a number of features from the stillborn Copland project, while leaving the underlying operating system unchanged. A multi-threaded Finder was included, enabling for better multi-tasking. The GUI was changed in appearance to a new shaded greyscale look called Platinum, and the ability to change the appearance themes (also known as skins) was added with a new control panel. This capability was provided by a new "appearance" API layer within the OS, one of the few significant changes.

Apple sold 1.2 million copies of Mac OS 8 in its first two weeks of availability and 3 million within six months. Mac OS 8.1 saw the introduction of an updated version of the HFS and HFS+ file systems, which fixed many of the limitations of the earlier system (HFS+ continues to be used in Mac OS X). There were some other interface changes such as separating network features from printing (the venerable, and rather odd Chooser was at last headed for retirement), and some improvements to application switching. However, in underlying technical respects, Mac OS 8 was not very different from System 7.

Mac OS 9

File:Mac OS 9 screenshot 2.jpg
Mac OS 9

Mac OS 9 was released on October 23, 1999. It was generally a steady evolution from Mac OS 8. In fact the only reason that the version was increased from 8 to 9 was to pave the way for the upcoming Mac OS X, rather than leave a gap in the version numbers which might have discouraged some to make the eventual transition from classic Mac OS to Mac OS X. Mac OS 9 was originally planned to be named Mac OS 8.7.

OS 9 also added some transitional technologies to help application developers adopt some OS X features before the introduction of the new OS to the public, again easing the transition. These included new APIs for the file system, and the bundling of the Carbon library that apps could link against instead of the traditional API libraries — apps that were adapted to do this can be run natively on OS X as well. Other changes were made in OS 9 to allow it to be booted in the "classic environment" within OS X. This is a compatibility layer in OS X (in fact an OS X application, known in developer circles as "the blue box") that runs a complete Mac OS 9 operating system, so allowing applications that have not been ported to Carbon to run on Mac OS X. This is reasonably seamless, though "classic" applications retain their original OS 8/9 appearance and do not gain the OS X "Aqua" appearance.

  • Mac OS 9.0
  • Mac OS 9.0.2
  • Mac OS 9.0.3
  • Mac OS 9.0.4
  • Mac OS 9.1
  • Mac OS 9.2
  • Mac OS 9.2.1
  • Mac OS 9.2.2

Mac OS X

Main article: Mac OS X history

While it technically retains the same name as its predecessors, Mac OS X is largely independent. It is primarily based on a UNIX core known as Darwin, while older versions are based on a proprietary core (the same basic core was in use from System 1 up to Mac OS 9).

Other

See also

References

  • Linzmayer, Owen (2004), pages 284-288, Apple Confidential 2.0, No Starch Press ISBN 1593270100
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