A Technical History of Apple's Operating Systems - Mac OS X Internals

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108 Chapter 1 A Technical History of Apple’s Operating Systems Although the marriage of Mach, BSD, and Macintosh in Mach Ten sounds similar to the latter-day Mac OS X, there is a critical difference in design and philosophy. Mac OS X was a continuation of NEXTSTEP technology in several ways. Apple provided legacy compatibility and ease of transition at two primary levels: through APIs such as Carbon, and through the Classic virtualizer. In contrast, Mach Ten was a logical opposite: MacOS remained the first class citizen, whereas Unix ran in a virtual machine (UVM) that was implemented within a standard Macintosh application. The UVM provided a preemptive multitasking execution environment with a set of Unix APIs (such as PO- SIX, including the standard C library and POSIX threads), a BSD-style networking stack, file systems such as UFS and FFS, RPC, NFS, and so on. Mach Ten also included an implementation of the X Window System. Although confined within a single application, Mach Ten consisted of various subsystems similar to a full-fledged operating system. At the logically lowest level, an interface layer talked to MacOS. The Mach kernel resided above this layer, providing serv- ices such as memory management, interprocess communication, tasks, and threads. Other Mach Ten subsystems that directly talked to the MacOS interface layer included the window manager and the networking stack’s ARP layer. 1.8.5. Musical Names Apple’s operating system strategy after acquiring NeXT was two-pronged: it would keep improving Mac OS for the consumer desktop market, and would create a high- end operating system based on NeXT technology. The new system, called Rhap- sody, would mainly be targeted towards the server and enterprise markets. In contrast to the chromatic aberrations such as Pink and Red, Apple also had a string of musically inspired code names for its operating system projects. Copland
Mac OS X Internals (www.osxbook.com) 109 and Gershwin were named after Aaron Copland and George Gershwin, 58 both American composers. Rhapsody in Blue is a famous work of Gershwin. 1.9. STRATEGIES The first release of an Apple operating system after NeXT’s purchase was in late 1996 with version 7.6. This release represented the initial stage of Apple’s new operating system roadmap. It was the first system to be called Mac OS. Apple’s plan was to release full standalone installations once a year, with updates in between. Many Power Macintosh and PowerBook models that were not supported by Mac OS 7.6 were supported by the 7.6.1 incremental update. The system originally slated to be version 7.7 would eventually become Mac OS 8. Mac OS 7.6 required a compatible computer that was 32-bit clean, with at least a 68030 processor. It offered performance enhancements in several areas such as virtual memory, memory management, PowerPC Resource Manager routines, system startup, and the File Manager’s caching scheme. It also integrated key Apple technologies such as Cyberdog, OpenDoc, Open Transport, and QuickTime. Two phenomena were sweeping the computer world at that time: the Internet and Microsoft Windows 95. Apple emphasized compatibility of Mac OS 7.6 with Windows 95 and highlighted the system’s Internet prowess. Mac OS 7.6 included built-in support for TCP/IP, PPP, and Apple Remote Access (ARA). Its integrated Cyberdog technology could be used to incorporate Internet features into documents that used “Live Objects.” For example, live web links and email addresses could reside on the Desktop, and could be activated from the Finder. 58 George Gershwin’s brother Ira actually came up with the title Rhapsody in Blue.
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A Technical History of Apple’s Op
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Dear Reader This is a supplementary
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About Mac OS X Internals Mac OS X w
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A Technical History of Apple’s Op
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Mac OS X Internals (www.osxbook.com
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C H A P T E R 1 A Technical History
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A Technical History of Apple's Operating Systems - Mac OS X Internals

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