1 Chapter 1. Origins of Mac OS X "Most ideas come from previous ideas." Alan Curtis Kay The Mac OS X operating system represents a rather successful coming together of paradigms, ideologies, and technologies that have often resisted each other in the past. A good example is the cordial relationship that exists between the command-line and graphical interfaces in Mac OS X. The system is a result of the trials and tribulations of Apple and NeXT, as well as their user and developer communities. Mac OS X exemplifies how a capable system can result from the direct or indirect efforts of corporations, academic and research communities, the Open Source and Free Software movements, and, of course, individuals. Apple has been around since 1976, and many accounts of its history have been told. If the story of Apple as a company is fascinating, so is the technical history of Apple's operating systems. In this chapter,[1] we will trace the history of Mac OS X, discussing several technologies whose confluence eventually led to the modern-day Apple operating system. [1] This book's accompanying web site (www.osxbook.com) provides a more detailed technical history of all of Apple's operating systems. 1 2 2 1 1.1. Apple's Quest for the[2] Operating System [2] Whereas the word "the" is used here to designate prominence and desirability, it is an interesting coincidence that "THE" was the name of a multiprogramming system described by Edsger W. Dijkstra in a 1968 paper. It was March 1988. The Macintosh had been around for four years. Some Apple engineers and managers had an offsite meeting. As they brainstormed to come up with future operating system strategies, they noted down their ideas on three sets of index cards that were colored blue, pink, and red. Blue would be the project for improving the existing Macintosh operating system. It would eventually form the core of System 7. Pink would soon become a revolutionary operating system project at Apple. The operating system was planned to be object-oriented. It would have full memory protection, multitasking with lightweight threads, a large number of protected address spaces, and several other modern features. After languishing for many years at Apple, Pink would move out to Taligent, a company jointly run by Apple and IBM. Since the color red is "pinker than pink," ideas considered too advanced even for Pink were made part of the Red project. As the 1980s drew to an end, the Macintosh system software was at major version 6. System 7, a result of the Blue project, would be Apple's most significant system yet. However, that would not appear until 1991. Meanwhile, Microsoft had developed its Windows 3.x operating system, which became extremely successful after its release in 1990. Microsoft had also been working on a new operating system codenamed Chicago. Initially slated for release in 1993, Chicago kept slipping. It was eventually released as Windows 95. However, Microsoft did release another Windows operating systemWindows NTin 1993 (Figure 11). NT was an advanced operating system meant for high-end client-server applications. It had various important features such as symmetric multiprocessing support, a preemptive scheduler, integrated networking, subsystems for OS/2 and POSIX, virtual machines for DOS and 16-bit Windows, a new file system called NTFS, and support for the Win32 API. Figure 11. Microsoft Windows NT 3.1 [View full size image] 1 2 Apple needed an answer to Microsoft's onslaught, particularly in the face of the upcoming Windows 95, which was to be an end-user operating system. The Pink and Red projects would turn out to be rather unsuccessful. Apple would continue to attempt to solve the "OS problem" one way or another. 1.1.1. Star Trek Star Trek was a bold project that Apple ran jointly with Novell to port Mac OS to run on the x86 platform. A team consisting of engineers from both Apple and Novell succeeded in creating a very reasonable prototype in an incredibly short amount of time. The project was canceled, however, for various reasons: Apple had already committed to the PowerPC; many within and outside of Apple thought that adding support for the x86 platform would disrupt Apple's existing business model; and vendor feedback was not encouraging. Many years later, Darwinthe core of Apple's far more successful Mac OS Xruns on both the PowerPC and the x86. Whereas the Star Trek prototype showed the "Happy Mac" logo while booting up, Darwin/x86 prints the message "Welcome to Macintosh" during boot. Star Trek was finally vindicated with Apple's mid-2005 announcement of transitioning Mac OS X to the x86 platform. The first x86-based Macintosh computersthe iMac and the MacBook Pro (the successor to the PowerBook)were unveiled at the San Francisco Macworld Conference & Expo in January 2006. 1.1.2. Raptor Raptor was, in many respects, the Red project. It was supposed to provide Apple with a next-generation microkernel that would run on any architecture. As the Star Trek project was being canceled, it was considered for absorption by Raptor, which itself died later due to budgetary limitations and employee attrition, among other reasons. 2 3 1.1.3. NuKernel NuKernel was a kernel project at Apple that was meant to result in a modern operating system kernel on more than one occasion. NuKernel was meant to be an efficient microkernel that would facilitate features such as preemptive multitasking, protected memory, an efficient memory model, a high degree of system extensibility, and most significantly, a hardware abstraction layer (HAL) that was expected to allow any computer vendor to easily design Mac OScompatible systems. 1.1.4. TalOS Apple and IBM formed a company called Taligent in early 1992 to continue work on the Pink project. Pink originally aimed to be an object-oriented operating system but later morphed into an object-oriented environment called CommonPoint that ran on many modern operating systems such as AIX, HP-UX, OS/2, Windows 95, and Windows NT. It was also meant to run on Apple's NuKernel. Taligent Object Services (TalOS) was the name given to a set of lower-level technologies to be built around version 3.0 of the Mach kernel. TalOS was meant to be an extensible and portable operating system, with a small footprint and good performance. TalOS was object-oriented from the kernel up, with even device drivers and network protocols implemented in an object-oriented fashion. Taligent's object-oriented libraries were known as frameworks. There were frameworks for user interfaces, text, documents, graphics, multimedia, fonts, printing, and low-level services such as drivers. These, along with the TalOS development tools, explicitly strived to shift the burden of programming from application developers to application system engineers. Note that even though there existed other commercial systems such as NEXTSTEP that had object-oriented application frameworks, Taligent aimed to build its entire programming model around objects. In NEXTSTEP, the developers who created frameworks had to map object behavior to the underlying libraries, Unix system calls, Display PostScript, and so onall of which had procedural APIs. In contrast, Taligent's CommonPoint applications were not meant to use the host operating system APIs at all. In 1995, Taligent became a wholly owned subsidiary of IBM. The Pink project did not give Apple the next-generation operating system that Apple had been seeking. 1.1.5. Copland Apple made an announcement in early 1994 that it would channel more than a decade of experience into the next major release of the Macintosh operating system: Mac OS 8. The project was codenamed Copland. It was expected that Copland would be Apple's real response to Microsoft Windows. With Copland, Apple hoped to achieve several goals, many of which had been long elusive. • Adopt RISC[3] as a key foundation technology by making the system fully PowerPC-native. [3] Reduced instruction-set computing. • Integrate, improve, and leverage existing Apple technologies such as ColorSync, OpenDoc, PowerShare, PowerTalk, QuickDraw 3D, and QuickDraw GX. • Retain and improve the Mac OS interface's ease of use while making it multiuser and fully customizable. In particular, Copland's implementation of themes allowed customization of most user-interface elements on a per-user basis. • Extend interoperability with DOS and Windows. • Make Mac OS systems the best network clients. • Incorporate active assistance that works across applications and networksthat is, make it very easy to automate a wide variety of tasks. 3 4 • Release Copland as a system that may be openly licensed to foster development of Mac OScompatible clones by third parties. To achieve these goals, Copland was supposed to have a comprehensive set of system-level features, for example: • A hardware abstraction layer that would also help vendors in creating compatible systems • A microkernel (the NuKernel) at its core • Symmetric multiprocessing with preemptive multitasking • Improved virtual memory with memory protection • A flexible and powerful system extension mechanism • Critical subsystems such as I/O, networking, and file systems running as services on top of the kernel • Built-in low-level networking facilities such as X/Open Transport Interface (OTI), System V STREAMS, and Data Link Provider Interface (DLPI) • File searching based on both metadata and content • The ability to perform "live upgrades" on a system without affecting the performance of other running programs Figure 12 shows a conceptual view of Copland. Figure 12. Copland architecture [View full size image] Work on Copland gained momentum during the early 1990s, and by the mid-1990s, Copland was heavily counted on to do wonders for the company. Apple dubbed it as "The Mac OS Foundation for the Next Generation of Personal Computers." However, the project kept slipping.