Most file systems used with DOS, Unix, or other operating systems treat a file as simply a sequence of bytes, requiring an application to know which bytes represented what type of information. By contrast, MFS and HFS gave files two different "forks". The data fork contained the same sort of information as other file systems, such as the text of a document or the bitmaps of an image file. The resource fork contained other structured data such as menu definitions, graphics, sounds, or code segments. A file might consist only of resources with an empty data fork, or only a data fork with no resource fork. A text file could contain its text in the data fork and styling information in the resource fork, so that an application which didn't recognize the styling information could still read the raw text. On the other hand, these forks provided a challenge to interoperability with other operating systems; copying a file from a Mac to a non-Mac system would strip it of its resource fork.
The Classic OS is still supported and Classic Applications Support is shipped in addition to OS X with PowerPC (but not Intel) Macs as late as early 2006.
Mac OS X (2001-present)
-
Mac OS X brought Unix-style memory management and pre-emptive multitasking to the Mac platform. It is based on the Mach kernel and the BSD implementation of UNIX, which were incorporated into NeXTSTEP, the object-oriented operating system developed by Steve Jobs's NeXT company. The new memory management system allowed more programs to run at once and virtually eliminated the possibility of one program crashing another. It is also the second Macintosh operating system to include a command line (the first is the now-discontinued A/UX, which supported classic Mac OS applications on top of a UNIX kernel), although it is never seen unless the user launches a terminal emulator.
However, since these new features put higher demands on system resources, Mac OS X only officially supported the PowerPC G3 and newer processors, and now has even higher requirements (the additional requirement of built-in USB (10.3) and later FireWire (10.4)). Even then, it runs somewhat slowly on older G3 systems for many purposes.
As of 2005, every update to Mac OS X since the original public beta has had the atypical quality of being perceptibly more responsive than the version it replaced, the opposite to the trend of most operating systems. As noted by John Siracusa of Ars Technica:
- "For over three years now, Mac OS X has gotten faster with every release—and not just "faster in the experience of most end users", but faster on the same hardware. This trend is unheard of among contemporary desktop operating systems."[1]
This could, however, be attributed to the relative immaturity of the OS, and the speed gains have diminished as OS X has matured. Some reports regarding Mac OS X 10.4 suggested that it seemed similar to version 10.3 in responsiveness, or even slower at times.
Power PC builds of Mac OS X include a compatibility layer for running older Mac applications, the Classic Environment. This runs a full copy of the older Mac OS, version 9.1 or later, in a Mac OS X process. PowerPC-based Macs ship with OS 9.2 as well as OS X. OS 9.2 must be installed by the user—it is not installed by default on all new hardware revisions released after the release of Mac OS X 10.4. Most well-written "classic" applications function properly under this environment, but compatibility is only assured if the software was written to be unaware of the actual hardware, and to interact solely with the operating system. The Classic Environment does not work in the Intel version of OS X.
Users of the original Mac OS generally upgraded to Mac OS X, but a few criticized it as being more difficult and less user-friendly than the original Mac OS, for the lack of certain features that had not been re-implemented in the new OS, or for being slower on the same hardware (especially older hardware), or other, sometimes serious incompatibilities with the older OS. Because drivers (for printers, scanners, tablets, etc.) written for the older Mac OS are not compatible with Mac OS X, and due to the lack of OS X support for older Apple machines, a significant number of Macintosh users have continued using the older OS. By 2005, it is reported that almost all users of systems capable of running Mac OS X are doing so, with only a small percentage still running the classic Mac OS.
In June 2005, Steve Jobs announced at his Worldwide Developers Conference keynote that Apple computers would be transitioning from PowerPC to Intel processors. At the same conference, Jobs announced Developer Transition Kits that included beta versions of Apple software including Mac OS X that developers could use to test their applications as they ported them to run on Intel-powered Macs. In January 2006, Apple released the first Macintosh computers with Intel processors, an iMac and the MacBook Pro, and in February 2006, Apple released a Mac Mini with an Intel Core Solo and Duo processor. Continuing the trend of switching Apple's entire product line to the Intel chip, Apple released the MacBook on May 16, 2006. To ease the transition for early buyers of the new machines, Intel-based Macs include an emulation technology called Rosetta, which allows them to run (at reduced speed) pre-existing Mac OS X native application software which was compiled only for PowerPC-based Macintoshes.
"Classic" Mac OS technologies
Some features of the "classic" Mac OS are carried forward and implemented natively in Mac OS X, including:
- ColorSync
- ColorSync is a technology for matching colors between the screen and a printer.
- Finder
- The Finder is the interface for browsing the filesystem and launching applications.
- MacRoman
- MacRoman is the character encoding used in classic Macintosh systems. Mac OS X's standard character encoding is Unicode, in its UTF-8 and UTF-16 forms, but HFS volumes using MacRoman encoding are still supported.
- PlainTalk
- PlainTalk is a speech synthesis and speech recognition technology providing Mac OS with a spoken language interface for controlling the computer. The proprietary noise-cancelling microphone interface bearing the same name was phased out with the introduction of the Blue and White Power Macintosh G3s in 1999.
- QuickDraw
- QuickDraw was the first imaging model to provide mass-market WYSIWYG capabilities. Although mostly obsolete on Mac OS X, due to the use of Quartz, QuickDraw still works on Mac OS X 10.4. Apple has deprecated QuickDraw, meaning it may not work in future versions.
- QuickTime
- QuickTime provides support for audio-visual editing and playback, virtual reality motion, and streaming of multimedia content over a network. The Quicktime file format and streaming technology has been adopted in some MPEG 4 standards relating to multimedia content delivery via DVD or by streaming over the Internet to computers and cell phones. The iTunes music store also uses Quicktime.
- TrueType
- TrueType is a very successful scalable font technology which was eventually ported to Microsoft Windows and later integrated into the OpenType font standard.
Obsolete technologies
Many technologies of the "classic" Mac OS are no longer used on OS X, including:
- Chooser
- The Chooser is a tool for enabling AppleTalk, and accessing and selecting network resources such as printers. It was derived from the Choose Printer Desk Accessory found in early versions of the Mac OS.
- Desk Accessories
- Desk Accessories were small "helper" applications that could be run concurrently with other applications, prior to the advent of the multi-tasking MultiFinder and System 7. Mac OS X version 10.4 introduced a similar feature called Dashboard.
- Mac OS memory management
- The Mac OS memory management describes how the Macintosh managed RAM and virtual memory before the switch to the Unix-based Mac OS X. It has been defunct since Mac OS X, but most of the APIs are still available via the Carbon compatibility layer.
- MultiFinder
- MultiFinder was a version of the Finder with support for simultaneous processes. It became a part of the Finder in System 7.
- PowerPC emulation of the Motorola 68000
- The PowerPC emulation of the Motorola 68000 refers to the way in which the Macintosh handled the architectural transition to the PowerPC microprocessor. The emulator could run older software (including parts of the OS) which had not been recompiled to run natively on the PowerPC processor. The 68k emulator remained in Mac OS through version 9, and most old 68k application software still works within the Classic environment of Mac OS X.
- GeoPort
- Geoport Technology allows the Macintosh to run fax, data, and voice telephony services using an interface device called a GeoPort. Unlike true modems, the GeoPort device is merely an interface adapter—the modem is implemented in software, an approach that some say burdens the CPU and slows the computer.
- OpenDoc
- Co-developed with IBM, OpenDoc allowed bits of software, known as "parts" to interact within a framework application known as an "editor." Apple discontinued development on OpenDoc in 1997 in favor of the OpenStep technology now know as Cocoa, acquired in the merger with NeXT Computer.
- QuickDraw GX
- An enhanced printing, screen display and typography system building on the Classic Mac OS QuickDraw system. The technology was introduced with System 7.5, but was initially plagued with bugs and lack of third party support. Though most of the bugs were eventually worked out, it was, like OpenDoc, abandoned in favor of OpenStep technology. The TrueType font engine was isolated and retained, and the rest of Quickdraw GX was removed from Mac OS 8.5 and later OS versions. Mac OS X provides capabilities superior to Quickdraw GX in its PDF-based Quartz graphics engine.
Project Star Trek
-
One interesting historical aspect of the classic Mac OS was a relatively unknown secret prototype Apple started work on in 1992, code-named "Project Star Trek". The goal of this project was to create a version of Mac OS that would run on Intel-compatible x86 personal computers. It was short lived, being cancelled only one year later in 1993 due to political infighting, although its team was able to get the Macintosh Finder and some basic applications, like QuickTime, running smoothly on a PC. It ran on MS-DOS' rival DR-DOS and was generally faster than its 680x0 counterparts.
Fourteen years after project Star Trek, as Apple transitions to the Intel processor, the current version of Mac OS (v10.4) runs smoothly on x86 architecture.
Emulation
Although the Star Trek software was never released, third-party Macintosh emulators, such as vMac, Basilisk II, and Executor, eventually made it possible to run the classic Mac OS on Intel-based PCs. These emulators were restricted to emulating the 68000 series of processors, and as such couldn't run versions of the Mac OS that succeeded 8.1, which required PowerPC processors. Recently, the PearPC emulator has appeared, which is capable of emulating the PowerPC processors required by newer versions of the Mac OS (like Mac OS X). Unfortunately, it is still in the early stages and, like many emulators, tends to run much slower than a native OS would.
Another PowerPC emulator is SheepShaver, which has been around since 1998 for the BeOS platform, but in 2002 was open sourced with porting efforts beginning to get it to run on other platforms. Although it is capable of emulating a PowerPC processor, it can only emulate up to Mac OS 9.0.4 because it does not emulate a memory management unit.
Other examples include ShapeShifter (by the same programmer that conceived SheepShaver), Fusion and iFusion. The latter ran classic Mac OS with a PowerPC "coprocessor" accelerator card. Using this method has been said to equal or better the speed of a Macintosh with the same processor, especially with respect to the m68k series due to real Macs running in MMU trap mode, hampering performance.
Macintosh clones
Several computer manufacturers over the years have made Macintosh clones capable of running Mac OS, notably Power Computing and Umax. These machines normally ran various versions of classic Mac OS. Steve Jobs ended the clone licensing program after returning to Apple in 1997.
A/UX
-
In 1988, Apple released its first UNIX based OS, named A/UX.
This was an operating system that seamlessly integrated the Mac OS look and feel with the power and flexibility of UNIX. Since it was before the advent of PowerPC and therefore had to run on the Motorola 68000 processor, it was not very competitive for its time. A/UX had most of its success in sales to the Federal government of the United States, where UNIX was a requirement that Mac OS could not meet.
Timeline of Apple Macintosh operating systems
See also
External links