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A Technical History of Apple`s Operating Systems

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1. The inherent philosophy of the endeavors of Engelbart and his team was boot strapping which they defined as the recursive process of building tools that let you build better tools A successful example of the bootstrapping philosophy is the UNIX operating system Even with such impressive innovations NLS ran into misfortune Several NLS team members went to the then nascent Xerox PARC where they hoped to create a distributed across the network 1ather than time sharing version of NLS Worse still SRI dropped the program leaving no funding for the project Engelbart went to a phone networking company called Zymshare where he sat in a cubicle in an office building in Cupertino very near to the birthplace of the Macintosh 1 2 4 Smalltalk The work done at Xerox PARC would greatly influence the face and surely the interface of computing The 1970s saw the development and maturation at PARC s Computer Science Laboratory CSL of technologies such as high quality graphical user interfaces windowing systems laser printing and networking Smalltalk emerged as both a programming language and a programming environ ment at PARC While a graduate student at the University of Utah in the late 1960s Alan Kay had collaborated with Ed Cheadle on designing a personal computer the FLEX ma chine for those who were not computer professionals The FLEX machine had a pointing and drawing tablet a calligraphic display and a multiwindo
2. Apple had plans to port to Rhapsody most key Mac OS frameworks for ex ample QuickTime QuickDraw 3D QuickDraw GX and ColorSync Rhapsody was also to support numerous file systems such as Apple Filing Protocol AFP FAT HFS HFS Plus S09660 and UFS There were two developer releases of Rhapsody dubbed DR1 and DR2 These were released both for the PowerPC and the x86 platforms 1 9 2 1 Blue Box Shortly after Rhapsody DR1 was released Apple extended the PowerPC version with a Mac OS compatibility environment called the Blue Box Implemented by a Rhapsody application MacOS app Blue Box was a virtual environment that ap peared as a new Macintosh hardware model MacOS app loaded a Macintosh ROM file from disk and created an environment within which Mac OS ran mostly un changed Blue Box initially ran Mac OS 8 x full screen with the ability to switch between Rhapsody and Mac OS using the lt cmd return gt key combination It placed certain restrictions on the applications that ran within it For example an application could neither access the hardware directly nor could use undocumented Mac OS APIs The implementers initial goal was to achieve 90 to 115 of native Mac OS performance Blue Box beta 1 0 used Open Transport rather than BSD sockets for networking Support for newer versions of Mac OS as well as for running the Blue Box windowed was added later The Blue Box environment would be known as the Classic environm
3. ware Figure 1 13 shows a mockup of the STAR user interface Chart Title Scrollbar Document Printer Paginate Button Close Button d Directory Help Button FEI What the world wants is Tort character The world is in P need of those whose life Es ES is one burning love selfless Es ES Awake awake great souls The world is burning in misery Can you sleep EEEEEEEEGEEE Fe ke Audience Ea Folder Frame eb Es Ea Ei Graphic Directory Out Basket In Basket Display Keyboard I I Adjust Mouse Select FIGURE 1 13 The Xerox STAR system The STAR user interface provided the user with an electronic metaphor for the physical office As Figure 1 13 shows there were electronic analogs of common office objects paper folders file cabinets mailboxes calculators printers and so on It would be an understatement to say that the STAR interface greatly influenced many systems that came after it Noteworthy aspects of the STAR user interface included the following e The user s first view of the working environment was the Desktop which displayed icons small pictures of familiar objects such as docu ments folders file drawers in baskets and out baskets Mac OS X Internals www osxbook com 39 e The user could click on an icon
4. 60 Chapter 1 A Technical History of Apple s Operating Systems e Support for larger disk drives e AppleShare client features Figure 1 17 shows a screenshot of System 6 File Edit View Special Control Panel SE Rate of Insertion O 7 43 54PM I OS Point Blinking System 6 0 8 General eis Calculator Desktop Pattern Keyboard Menu Blinking Time D 7 43 55 PM 12hr O 24hr of 12 3 2 23 4 O CH O Gate E q John Steve and Bruce Computer Inc 1983 90 RAM Cache A spd Sporer FIGURE 1 17 Macintosh System 6 An important improvement came when Apple incorporated cooperative multi tasking through the MultiFinder Initially included as a separate piece of software along with the original Finder MultiFinder soon became mandatory It allowed the user to have several programs open simultaneously and to assign specific amounts of RAM to these programs Usability improvements included providing a progress bar with cancel button for copy file and erase disk operations Until this point the Finder did not use color even on color capable systems This was remedied with the introduction of Color QuickDraw Mac OS X Internals www osxbook com 61 1 4 2 What Color is Your System In March 1988 after the Macintosh had been around for four years some Apple engineers and managers had an off site meeting As they brainstormed to come up with future operating system strategies they noted down thei
5. machines were made during the long life span of the Apple line the Apple Ile Ifc le Enhanced e Platinum the 16 bit Gs and the c that was introduced in 1988 as the last Apple model Many of these models had multiple revisions themselves As we will discuss next several operating systems were created for the Apple family 1 1 2 1 Apple DOS Shortly after the release of the Apple in 1977 it was realized that a better storage solution than the existing one which was based on cassette tape was imperative for the computer Wozniak created a brilliant design for a floppy disk drive the Disk and thus there was need for a disk operating system DOS Apple s first ver sion of a DOS was released as Apple DOS 3 1 in July 1978 Apple DOS is unrelated to Microsoft s popular MS DOS During a time when it was a luxury to have disk drives and for an operating system to support them many such disk operating systems had the term DOS in their names The first release of Apple DOS had the version 3 1 as opposed to say 1 0 because one of the implementers Paul Laughton incremented a revision counter of the format x y every time the source code was recompiled The counter started with 8 Chapter 1 A Technical History of Apple s Operating Systems x being 0 and y being 1 Every time y reached 9 x was incremented by 1 Apple DOS was beta tested as version 3 0 Figure 1 3 shows a screenshot from Apple D
6. system 1 3 1 3 Display Lisa had a 12 CRT display with active dimensions of 8 5 x6 Apple referred to it as a half page 3 display given that a Letter sized sheet of paper measures 8 5 x11 The bitmapped display s maximum resolution was 720x364 It allowed for up to 45 lines of 144 characters each The horizontal and vertical pixel densities were not the same being 90 and 60 dots per inch respectively Therefore a mathe matical square did not appear as a square on Lisa s screen Like the Xerox STAR system Lisa strived to present a physical office metaphor It mimicked the appear ance of real life paper by displaying black text on white background Since a white screen flickers more than a black screen Lisa required a higher refresh rate for its display thus adding to its price 1 3 1 4 Storage Each of Lisa s two built in floppy disk drives used special high density double sided 5 25 diskettes with a formatted capacity of 851KB The 5MB Apple ProFile was a Self contained external hard disk drive unit that connected to Lisa s built in 31 You can get a feel for the size of Lisa s display by folding a Letter sized sheet of paper into half Mac OS X Internals www osxbook com 43 parallel port It was possible to connect multiple such disk unit for a maximum of seven units using optional parallel interface cards 1 3 1 5 Expansion Lisa had a built in parallel port two built in se
7. Macintosh Toolbox Drivers Core OS 68k Applications QO Multi Finder Drivers 68k Emulator i Nanokernel PowerPC 3 FIGURE 1 22 Transitioning to the PowerPC 77 Multi Finder Applications Macintosh Toolbox 68k 2 Multi O C Applications Finder Carbon 68k Emulator Nanokernel PowerPC 4 MAE provided an emulated System 7 Depending on the MAE version it sup ported features such as aliases AppleEvents AppleTalk NFS QuickDraw Quick Time and TrueType MAE ran as a user space process called mae along with an auxiliary daemon process called macd which was the Macintosh environment dae mon Multiple copies of MAE could run simultaneously on a workstation within the constraints of available resources 78 Chapter 1 A Technical History of Apple s Operating Systems MAE contained an implementation of the Macintosh Process Manager which was responsible for loading and unloading all Macintosh applications used from within MAE When the mae process started it reserved a memory region for use by the Process Manager and the virtual Macintosh system The default size of this re gion was 16MB although the user could configure it based on resources available on the host the number of MAE instances that could be launched and the amount of physical memory desired in the virtual environment Even though MAE itself ran on a UNIX system applications within MAE ran with c
8. Steve Jobs hoped that the Macintosh would become the second desktop appliance Bill Gates of Microsoft stated To create a new standard takes some thing that s not just a little bit different It takes something that s really new and captures people s imaginations Macintosh meets that standard In 1984 Apple also introduced AppleTalk a self configuring multilayered local area network LAN protocol whose features include dynamic addressing router discovery and name binding 1 4 MANY SYSTEMS FOR MANY APPLES After the Macintosh s release Apple spent the next few years improving the Macin tosh operating system and creating some other noteworthy systems 1 4 1 System Software Releases 2 6 For a long time there were multiple independent versioning schemes in effect for Macintosh system components a System Software Release a System Version a Finder Version a MultiFinder Version a LaserWriter Version and so on Eventually there were attempts to unify these versions Notable improvements made during this time included the following e Continued speed improvements for the Finder including a disk cache and an additional minifinder to make applications launch faster e Commands for common tasks such as shutting down creating new fold ers and ejecting disks e A hierarchical file system HFS that supported true hierarchy allowing folders to be nested without illusory aid e Support for multiple monitors
9. performance of other running programs Work on Copland gained momentum during the early 1990s and by the mid 1990s Copland was heavily counted on to do wonders for Apple Apple dubbed it as The Mac OS Foundation for the Next Generation of Personal Computers However the project kept slipping A few prototypical Driver Development Kit DDK releases went out but a 1996 release as had been planned and hoped did not seem feasible Due to numerous pressures full memory protection had not been included after all Apple s CEO Gil Amelio described the state of Copland as just a collection of separate pieces each being worked on by a different team that were expected to magically come together somehow 88 Chapter 1 A Technical History of Apple s Operating Systems A conceptual view of Copland is shown in Figure 1 24 Preemptive Multitasking with Memory Protection Macintosh Copland aware System 7 x Application Application Macintosh Toolbox Environment OpenDoc QuickDrawGX QuickDraw3D PowerTalk PowerShare Open Component Transport Software Networking Architecture API s Frameworks Libraries Services Architecture File System IO Subystem Networking Subsystem Preemptive Protected System Extension Multitasking Memory Mechanism Hardware Abstraction Copland Microkernel FIGURE 1 24 Copland architecture Apple eventually decided to cancel Copland in May 1996 Amelio announced that Copland s best piece
10. e LisaTerminal asynchronous communications application that supported emulation of teletype TTY VT52 and VT100 terminals e LisaWrite WYSIWYG word processor Lisa applications had consistent user interfaces so that a user was not required to learn every application from scratch It was also possible to transfer data between applications Lisa s competition included the IBM PC XT introduced on March 8 1983 Mac OS X Internals www osxbook com 51 the DEC family of personal computers the Rainbow 100 the DECmate Il and the PC300 line the Corvus Concept Network Workstation which also used the M68000 processor the Fortune 32 16 Hard Disk System the Xerox STAR System and the Xerox 820 II Personal Computer Multiple programming languages were available for Lisa such as Pascal BASIC Plus C and COBOL Lisa s software library many of whose components are shown in Figure 1 14 provided a variety of primitives for building complex applications Pascal language units in the software library included the Alert Man ager the Font Manager the Print Manager QuickDraw and the Window Manager QuickDraw was a high performance bitmap graphics technology that used regions both for clipping and for implementing shapes with efficient use of memory A region was an arbitrary area that could include multiple groups of disjoint areas 1 3 1 7 Lisa WorkShop Lisa WorkShop was Lisa s development environment Strongly influen
11. ronment and the Interface Builder visual tool for creating graphical user interfaces The Windows NT implementation of Yellow Box provided a very similar environ ment through a combination of the following Apple provided Windows system serv ices and applications e The Mach Emulation Daemon the machd service e The Netname Server the nmserver service e The Window Server the WindowServer application e The Pasteboard Server the pbs application Earlier implementations of the OpenStep API for platforms such as Solaris used a similar architecture Yellow Box evolved into the Mac OS X Cocoa APIs 1 10 TOowARDS Mac OS X After Rhapsody s DR2 release Apple would still alter its operating system strategy but would finally be on its way towards achieving its goal of having a new system During the 1998 Worldwide Developer Conference Adobe s Photoshop ran on what would be Mac OS X However the first shipping release of Mac OS X would take another three years Figure 1 33 shows an approximation of the progression from Rhapsody towards Mac OS X 118 Chapter 1 A Technical History of Apple s Operating Systems OPENSTEP 4 4BSD Mac OS FreeBSD Rhapsody DI ae NetBSD oe September 1997 Bi e ln ue BOX Mach 3 0 October 1997 Rhapsody DR2 ee May 1998 D se Mac OS X Server 1 0 Darwin 0 1 March 1999 March 1999 Mac OS X DP1 ae May 1999 ZN P 1 0 1 Mac OS X DP2 November 1999 1 0 2 Mac OS X DP3 x January 2000 GNU Darwin 1
12. 1 26 Chapter 1 A Technical History of Apple s Operating Systems Besides the Smalltalk group at PARC the Pilot Mesa and the Interlisp groups shared credit in developing or refining the concepts of bit mapped graphics windows menus and the mouse 1 2 5 Xerox Alto The personal in PARC s personal computing effort referred to a non shared sys tem containing sufficient processing power storage and I O capability to support the computing needs of a single user The result was the Alto which was originally designed by Charles P Thacker and Edward M McCreight Other contributors to the Alto included Alan Kay Butler Lampson and various members of PARC s Computer Sciences Laboratory and Systems Sciences Laboratory Bob Metcalfe and David Boggs designed the Ethernet an important technology used in the Alto The first Alto was functional in April 1973 It was named Bilbo The very first bitmap picture it displayed was that of the Muppets Cookie Monster Small talk was soon bootstrapped on this machine Alan Kay referred to the Alto as the Interim Dynabook The Alto s key hardware characteristics were the following e It consisted of a 16 bit medium scale integrated MSI micro programmed processor The processor was not single chip It emulated a standard instruction set that was derived from the Data General Nova computer thus aiding in portability The corresponding emulation mi crocode the normal emulator
13. Apple s Operating Systems H overlapping pieces of paper on an electronic desktop with each paper containing an independently running activity e Iconic and textual menus e Scroll bars e The use of the mouse as a single uniform method of selecting cutting and pasting various types of objects e The use of the mouse to perform operations or commands on objects Smalltalk along with its integrated environment facilitated development of useful and interesting tools such as a WYSIWYG editor a music capture and edit ing system and an animation system In turn the availability of such tools was con ducive to writing programs editing text drawing real time animation and music synthesis Smalltalk was meant to be a powerful language that experienced pro grammers could use yet one that could still be easily grasped by children Figure 1 7 shows a rendition of the Smalltalk 80 user interface A modern portable open source implementation of the Smalltalk environment is available as Squeak which was created by Kay Ingalls Kaehler and others in 1995 while these people were employed at Apple Squeak is available for Mac OS X Kay did not achieve all his goals with the FLEX machine In the late 1960s he came up with the idea of a powerful easy to use lap sized personal computer that he called the Dynabook It was so called because Kay envisioned the personal com puter to be a dynamic conglomeration of all other med
14. Application programmers can gain a deeper understanding of how their applications interact with the system System administrators and power users can use the book to harness the power of the rich environment offered by Mac OS X Finally members of the Windows Linux BSD and other Unix communities will find the book valuable in comparing and contrasting Mac OS X with their respective sys tems Please visit the book s web site osxbook com for more information on the book including a detailed Table of Contents and links to reviews A Systems Approach This page intentionally left blank A Technical History of Apple s Operating Systems 1 1 First Bytes into an Apple eeeEEEEEEEEEEEEEREEEERERREEREREEEEEEEEEEEn 6 VA WE ee EE 6 NEE ei E TEE 10 L TEE Ee 11 t122 Apple PASCAL irpini iedh i ae aa a en 12 LE e Apple EE 13 Tel ee EE 14 LS e EE 14 LE 3 2 AD PIC PODOS EE 16 ET E ET 17 Laf M n acta I E TE E EE Edel 18 1 2 2 Sketchpad deiere dee vee ined eddie eed ee 19 1 2 3 NLS The ONLine Gwvstem eect eeeeneeeeeneeeeeeeeeeeeeeteeeeeseaeee 21 1 2 3 1 The First Computer Mouse 21 1 2 3 2 A 5 CHOrd EEN 22 1 2 3 3 Document ProC SSING etiri eea dek eee deena eats 22 1 2 3 4 Hypertext and Image Mans 22 E SCAICHING ss el ng 23 12536 WING ONERE EEE A E crinea decades esieseeetiese 23 123 7 COllaDOlaliON wa tosh Baia eae Sie i ea ie ea eed 23 1 2 3 8 Live Interactive CONADOLAtION cccccccccccccccecccececeeeeeen
15. MICROSOFT amp Microsoft R gt Windows NTC WINDOWS N lt C gt Copyright 1985 1993 Cusersdefault zuer Windows NT Version 3 16 Version 3 1 Program Manager WINNT31 amit Fil Options Window Help J File Manager Control Panel Print Manager ClipBook Command Wim Viewer Prompt q C users default gt FIGURE 1 20 Microsoft Windows NT 3 1 Microsoft s Windows 3 x had been extremely successful since its release in 1990 Microsoft had been working on a new operating system code named Chicago Initially slated for 1993 release Chicago kept slipping It would be eventually be released as Windows 95 Microsoft did however release Windows NT in 1993 NT was an advanced operating system meant for high end client server applications It had various important features such as symmetric multiprocessing support a pre 48 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 84 Chapter 1 A Technical History of Apple s Operating Systems emptive scheduler integrated networking subsystems for OS 2 and POSIX virtual machines for DOS and 16 bit Windows a new file system called NTFS and sup port for the Win32 API Apple needed an answer to Microsoft s onslaught particularly in the face of the upcoming Windows 95 whic
16. Pascal but had language extensions access to up to 256KB of memory a floating point implementation called Standard Apple Numerical Environment SANE and the ability to access SOS from Pascal programs using the SOSIO unit Steve Wozniak once called SOS the finest operating system for a micro computer He lamented however that SOS was closed source In general Apple s attitude with the Apple was that of starkly heightened secrecy as compared to earlier systems 12 Chapter 1 A Technical History of Apple s Operating Systems SOS evolved into Apple ProDOS 1 1 3 2 Apple ProDOS Apple ProDOS was first released as version 1 0 in October 1983 Based on SOS it was Apple s replacement for Apple DOS 3 3 ProDOS provided better facilities for programming in BASIC assembly language and machine language better interrupt handling faster disk I O with direct block access and so on Figure 1 5 shows a screenshot from ProDOS Apple II System Utilities Version 4 Work on Entire Disks Catalog a Disk List Volumes Quplicate a Disk Format a Disk Verify a Disk Work on Probs Disks Only Other Options Create Subdirectory About the System Utilities Set Prefix Quit Rename Volumes i he to select an option s RETURN Pres FIGURE 1 5 Apple ProDOS ProDOS also had a relatively sophisticated hierarchical file system with fea tures such as the following Mac OS X Internals www osxbook com 13 e Mul
17. X Internals www osxbook com 29 The Alto was later reengineered as the Alto II By 1979 over 1500 Altos were in use within and outside of Xerox As the number of Altos increased many of the system aspects were standard ized Several standard facilities were made ROM resident including I O device in terfaces such as display disk Ethernet keyboard and mouse 1 2 5 1 Alto OS The Alto s operating system which was stored in the file Sys boot was imple mented in BCPL Its functionality included the following e Drivers for disk keyboard and display e Management of memory the clock interrupts and other events e The file system e The BCPL environment BCPL was developed as a general purpose recursive programming lan guage with emphasis on systems programming It has similarities to AL GOL It was used on a variety of computer systems such as CTSS at Pro ject MAC PDP 11 GE635 GECOS and Nova The Alto ran its instruction set emulator in a task called Emulator which ran with the lowest priority It also was the 0 task This task was always requesting wake up but could be interrupted by a wake up request from any other task In this sense it ran in the background Other standard tasks included tasks for the follow ing subsystems e Disk Disk Sector Task Disk Word Task e Display Display Word Task Cursor Task Display Horizontal Task Dis play Vertical Task e Memory Memory Refresh Task Pari
18. a few ap plications had been written for it Figure 1 25 shows a screenshot of BeOS BeOS initially ran on Be s own PowerPC based machine called the BeBox It was later ported to the x86 platform 90 Chapter 1 A Technical History of Apple s Operating Systems Be LS LS zeng SampleMedia Welcome to BeOS Thirel Party of Tracker movies D MediaPlayer File Window amp MemorialDayLower avi MemorialDayUpper ay SampleMedia File Window Attributes e desktops 8 images F miai amp movies amp sound FIGURE 1 25 BeOS Gass e and Apple negotiated back and forth over Be s acquisition The total investment in Be at that time was estimated to be about 20 million and Apple val ued Be at 50 million Gass e sought over 500 million being confident that Apple would buy Be Apple negotiated up to 125 million and Be negotiated down to 300 million When things still did not work out Apple offered 200 million and even though it is rumored that Gass e was actually willing to accept this offer it is also said that he came back with a final price of 275 million hoping Apple would bite the bullet The deal did not happen In any case Be had a tough con tender in NeXT a company founded and run by another one time Apple employee Steve Jobs Mac OS X Internals www osxbook com 91 Be would eventually fail as a company its technological assets were acquired by Palm Inc in 20
19. appeal to all operating system enthusiasts and students Amit Singh Sunnyvale California http osxbook com contact This page intentionally left blank About Mac OS X Internals Mac OS X was released in March 2001 but many components such as Mach and BSD are considerably older Understanding the design imple mentation and workings of Mac OS X requires examination of several technologies that differ in their age ori gins philosophies and roles Mac OS X Internals A Systems Ap proach Amazon page is the first book M ac OS x that dissects the internals of the system presenting a detailed picture that grows n te rna ls incrementally as you read For example you will learn the roles of the firm ware the bootloader the Mach and BSD kernel components including the rocess vittual memory IPC and ile system layers the object oriented I O Kit driver framework user librar ies and other core pieces of software You will learn how these pieces connect and work internally where they origi nated and how they evolved The book also covers several key areas of the Intel based Macintosh computers AMIT SINGH Over 1600 pages of the what how and why of Mac OS X A solid understanding of system internals is immensely useful in design development and debugging for programmers of various skill levels Sys tem programmers can use the book as a reference and to construct a better picture of how the core system works
20. beginnings were promising Jobs initially used 7 million of his per sonal money Several larger investments would be made in NeXT such as 20 mil lion from Ross Perot and 100 million from Canon Inc a few years later True to its original goal NeXT strived to create a computer that would be perfect in form and function The result was the NeXT cube The cube s motherboard had a clever visually appealing design Its magne sium case was painted black with a matte finish The monitor stand required an as tonishing amount of engineering for a monitor stand An onboard digital signal processing chip allowed the cube to play stereo quality music The machines were manufactured in NeXT s own state of the art factory 1 7 1 NEXTSTEP Jobs unveiled the NeXT cube on October 12 1988 at the Davies Symphony Hall in San Francisco The computer ran an operating system called NEXTSTEP which used as its kernel a port of CMU Mach 2 0 with a 4 3BSD environment NEXT STEP s window server was based on Display PostScript a marriage of the Post Script page description language and window system technologies In 1986 Sun Microsystems had announced their own Display Postscript Window System called NeWS NEXTSTEP offered both a graphical user interface and a Unix style command line interface The NEXTSTEP graphical user interface had multilevel menus windows whose contents were shown while being dragged and smooth scrolling A dock applicati
21. configurations as well as bundled accessories For example Apple computers with 16KB or more memory came with game paddles and the STARTREK game tape The Apple provided a machine level monitor Depending on the Apple JI model resetting the computer could either leave the user in the monitor or could auto start the ROM dropping the user in BASIC Calling a specific subroutine from BASIC allowed access to the monitor The monitor provided commands for tasks such as the following e Examining changing moving and verifying memory e Performing cassette I O 2 The Apple J s keyboard connector was a 16 pin IC socket at location A7 on the main circuit board whereas a 16 pin game I O connector was located at J14 3 Typing CALL 151 at the BASIC prompt provided access to the monitor Mac OS X Internals www osxbook com 7 e Configuring the video mode e Assembling disassembling running and debugging machine code Upon its release the Apple was the first personal computer to display color graphics Apple provided special software to make use of the Apple s capabilities including its graphical prowess For example the High Resolution Operating Sub routines package provided graphical subroutines usable from both BASIC and ma chine language Using these subroutines the programmer could initialize high resolution mode clear the screen plot a point draw a line and draw or animate predefined shapes Various Apple
22. e Retain and improve the ease of use of the Mac OS interface while mak ing it multiuser and fully customizable In particular Copland s imple mentation of themes allowed customization of most user interface ele ments on a per user basis Mac OS X Internals www osxbook com 87 e Extend interoperability with DOS and Windows e Make Mac OS systems the best network clients e Incorporate active assistance that works across applications and net works that is make it very easy to automate a wide variety of tasks e Release Copland as a system that may be openly licensed to foster de velopment of Mac OS compatible clones by third parties To achieve these goals Copland was supposed to have a comprehensive set of system level features for example e A hardware abstraction layer HAL that would also help vendors in cre ating compatible systems e A microkernel the NuKernel at its core e Symmetric multiprocessing with preemptive multitasking e Improved virtual memory with memory protection e A flexible and powerful system extension mechanism e Critical subsystems such as I O networking and file systems running as services on top of the kernel e Built in low level networking facilities such as X Open Transport Inter face OTI System V STREAMS and Data Link Provider Interface DLPI e File searching based on both metadata and content e The ability to perform live upgrades on a system without affecting the
23. everybody s expectations 1680 pages There fore it was hard to justify the inclusion of this much history even if it is inter esting history I strongly believe that reading this document will help in understanding the evo lution of Mac OS X and to some extent of some aspects of modern day op erating systems An important reality of technology and of computing in par ticular is that many things that we think of as new ideas are not quite new As Alan Kay once said Most ideas come from previous ideas This is also true in the case of Mac OS X As one digs the past of Mac OS X and its predecessors one begins to understand how ancient things influenced not so ancient things and the fact that we owe what we have today to many more people than are usually credited Please note again that this document is vot the same as the books first chapter In particular this document was not copyedited composited or proofread by the publisher I prepared this PDF from my raw manuscript Therefore this document is not an example of the book s final typesetting or other production aspects I hope you enjoy reading this document and the book Just as this document provides a super detailed history of Apple s operating systems the book itself is super detailed on the internals of modern day Mac OS X It is not at all a book about using Mac OS X it is about the system s design and implementation Therefore expect it to
24. for booting to commence This packet the BreathOfLife pack et was a raw Ethernet packet that was sent by a boot server periodically on each directly connected Ethernet The boot microcode enabled the Ethernet receiver to 28 Chapter 1 A Technical History of Apple s Operating Systems accept packets directed to a special host 377B The received packets were copied into memory beginning at location 1 When a packet of type 602B was received without error the Alto began executing instructions at location 3 The loader would establish further communication to continue booting Figure 1 8 shows a rendition of the Alto s interface EE g Ready Es EZ Select file names with the mouse S Start Red Copy Yel Copy Rename Blue Delete S Click Start to execute file name commands Ea ELTE Pages 832 d Pages 0 Files listed 72 i Files listed 0 Files selected 0 Delete 0 Files selected 0 Delete 0 Copy Rename 0 Copy 0 Copy Rename 0 Copy 0 DPO lt SysDir gt No Disk lt SysDir gt gt BEGINNING BattleShip er BattleShip RUN BlackJack RUN Bravo error Bravo messages Bravo run Calculator RUN Chess log Chess RUN Com Cm CRTTEST RU DMT boot empress run Executive run FTP run FTP log Fly run galaxian boot Garbage Mesa Typescript NEPTUNE RUN Rem cm Swatee Sys boot SysDir Sysfont al User cm REENEN EEN FIGURE 1 8 The Xerox Alto system Mac OS
25. for the com mon case e Ports had the semantics of capabilities e Messages could be sent to processes on another machine through an in termediary process thus providing location transparency Memory related API calls in Accent included functions for creating destroying reading and writing memory segments with support for copy on write One may think of Accent as RIG enhanced with virtual memory and network transparent messaging Mac OS X Internals www osxbook com 101 Accent was developed to support two distributed computing projects SPICE distributed personal computing and DSN fault tolerant distributed sensor network Accent was also the name of a food product a spice sold by Accent International Inc The only ingredient of this product was mono sodium glutamate MSG In computing one often abbreviates message as msg Accent ran on PERQ computers which were commercial graphics worksta tions Three Rivers Corporation delivered the first PERQ in 1980 QNIX was a UNIX environment based on AT amp T System V UNIX that ran under Accent on PERQ machines Developed by Spider Systems QNIX used its own microcode but ran in an Accent window managed by Accent s Sapphire window manager with other Accent programs running alongside A LISP machine SPICE LISP was also available for Accent along with other languages such as Ada PERQ Pascal C and Fortran PERQ could interpret bytecode in hardware akin to latt
26. imply fewer instructions RISC architectures are predominantly load store and register centric usually employ fixed format instructions have efficient pipelining require relatively fewer clock cycles per instruction and so on The line between RISC and CISC has been growing fuzzier over the years Mac OS X Internals www osxbook com 71 particularly as focus of microprocessor companies has shifted to micro architecture It is common to see companies attempting to optimize su perscalar out of order execution For example Intel s Pentium Pro 1995 translated complex x86 instructions into RISC like micro operations during instruction decoding A superscalar engine executed these micro operations in a speculative out of order fashion with register renaming Intels P6 ar chitecture had various other RISC like features The 801 Minicomputer Project so called after the name of the building it was housed in started at IBM in 1975 John Cocke who is regarded as the father of RISC architecture and others explored a simplified instruction set along with compiler code generation strategies for improving performance and reducing cost An early RISC tenet was an instruction processing rate of 1 per clock cycle The 801 was able to achieve a clock cycles per instruction CPI ratio of 1 for contrived code but not for general purpose code It had 120 instructions As instruction pipe lining and cache memories evolved and improved it
27. included Insignia Solutions SoftPC 1 7 2 OPENSTEP NeXT partnered with Sun Microsystems to jointly release specifications for Open Step an open platform comprised of several APIs and frameworks that anybody could use to create their own implementation of an object oriented operating sys tem running on any underlying core operating system The OpenStep API was implemented on SunOS HP UX and Windows NT NeXT s own implementa tion essentially an OpenStep compliant version of NEXTSTEP was released as OPENSTEP 4 0 in July 1996 with 4 1 and 4 2 following shortly afterwards The OpenStep API and the OPENSTEP operating system did not seem to turn things around for NeXT even though they caused some excitement in the business enterprise and government markets NeXT started to shift focus to its WebObjects product which was a multiplatform environment for rapidly building and deploying web based applications As we saw earlier NeXT was purchased by Apple in early 1997 Mac OS X would be based on NeXT s technology WebObjects would keep up with advance ments in its domain as exemplified by its support for Web Services and Enterprise Java Apple uses WebObjects for its own web sites such as the Apple Developer Connection ADC site the online Apple Store and the Mac offering Figure 1 28 shows a screenshot of OPENSTEP 98 Chapter 1 A Technical History of Apple s Operating Systems Preferences Info Info Edit i P
28. normally remain hidden and can be summoned by a key press Other important Tiger features include the following e Improved 64 bit support with the ability to compile 64 bit binaries and 64 bit support in the libSystem shared library e Automator a tool for automating common procedures by visually creat ing workflows e Core Image a media technology employing GPU based acceleration for image processing e Core Video a media technology acting as a bridge between QuickTime and the GPU for hardware accelerated video processing e Quartz 2D Extreme a new set of Quartz layer optimizations that use the GPU for the entire drawing path from the application to the frame buffer e Quartz Composer a tool for visually creating compositions using both graphical technologies such as Quartz 2D Core Image OpenGL and QuickTime and non graphical technologies such as MIDI System Serv ices and Rich Site Summary e Support for resolution independent user interface e Improved iChat AV with support for multiple simultaneous audio and video conferences e PDF Kit a Cocoa framework for managing and displaying PDF files from within applications e Improved Universal Access with support for an integrated spoken inter face e Improved Sync Services e An embeddable SQL database engine SQLite allowing applications to use SQL databases without running a separate RDBMS process e Core Data a Cocoa technology that integrates with Cocoa
29. number of Alto computers on a single Ethernet to facilitate a distributed multiplayer game The game s objective was to destroy the enemy and his base without being destroyed and to become the Master of the Universe Each Alto user participating in the game could control one space ship Trek s display consisted of seven distinct areas long range and galaxy scan short range scan acceleration and direction controls energy and velocity indicators damage information fire control and supplies indicators and the communication area Xerox used the Alto s technology to create a system designed for office pro fessionals the STAR System 1 2 6 Xerox STAR System Xerox introduced the 80107 STAR Information System at a Chicago trade show in April 1981 The STAR s hardware was based on the Alto with better components such as more memory bigger disks a higher resolution display and faster Ethernet An important difference from the Alto was that the STAR user interface was explic itly designed before actually building the hardware or software Moreover rather 27 The Xerox STAR 8010 was also nicknamed the Dandelion 28 Even though the overall system was marketed as STAR the name STAR should only apply to the software The computer itself was an 8000 series workstation 38 Chapter 1 A Technical History of Apple s Operating Systems than using an existing computer the hardware was specially designed for the soft
30. resided in ROM The instruction set could be extended through a small amount of microinstruction RAM e It had 64KB of error correcting code ECC 16 bit word semiconductor memory with a cycle time of 850 ns The memory was expandable to 256KB e It had a bitmapped 606x808 point graphical display with a viewing area of 8 5 x11 The display was oriented with the long tube dimension ver 19 MSI refers to the number of electronic components on a chip MSI has evolved to very large and ultra large scale integrated systems VLSI and ULSI respectively Mac OS X Internals www osxbook com 27 tical It was implemented using a standard 875 line raster scanned televi sion monitor with a refresh rate of 60 fields per second or 30 frames per second The on screen contents were refreshed from a bitmap in main memory as bits were serially extracted from words fetched from mem ory resulting in a video signal There was a 16x16 hardware cursor whose bitmap was contained in 16 memory words at a specific address The cursor was merged or composited with the video to present the fi nal image Displaying on the entire screen at full resolution the screen fill operation required about 60 of the processor cycles e The Alto s input devices included a 61 key or 64 key unencoded key board a five finger key set and a three button mouse The key set was programmatically visible as five bits of memory The mouse contained a b
31. subsystem was designed to sup port large sparse virtual address spaces and was integrated with IPC In traditional UNIX contiguous virtual memory space was implied with the heap and the stack growing towards each other In contrast Mach allowed for sparse address spaces Regions of memory could be allocated from anywhere in the address space Mem ory could be shared for reading and writing in a structured manner Copy on write techniques were used both to optimize copy operations and for sharing physical memory between tasks The generalized memory object abstraction allowed for ex 54 Tt is possible to have a Mach task with zero threads although such a task would not be very useful 55 Certain subsequent versions of Mach further subdivided a thread into an activation and a shut tle Mac OS X Internals www osxbook com 105 ternal memory pagers to handle page faults and page out data requests The source or target data could even reside on another machine FreeBSD s virtual memory architecture is based on Mach s As noted earlier Mach was neither meant to provide nor provided any file system networking or I O capabilities It was to be used as a service operating sys tem to create other operating systems from It was hoped that this approach would maintain simplicity and promote portability of operating systems One or more op erating systems could run on top of Mach as user level tasks However real lif
32. 01 1 6 8 Plan A Unlike Be NeXT s operating systems had at least been proven in the market de spite NeXT not having any resounding successes In particular OPENSTEP had been well received in the enterprise market Moreover Steve Jobs pitched NeXT s technology strongly to Apple asserting that OPENSTEP was many years ahead of the market The deal with NeXT did go through Apple acquired NeXT in February 1997 for over 400 million Amelio later quipped We choose plan A instead of Plan Be NeXT s acquisition would prove pivotal to Apple as NeXT s operating system technology would be the basis for what would become Mac OS X Let us now look at the background of NeXT s systems 1 7 THE NEXT CHAPTER All of Steve Jobs operational responsibilities at Apple were taken away on May 31 1985 Around this time Jobs had come up with an idea for a startup for which he pulled in five other Apple employees The idea was to create the perfect research computer for universities colleges and research labs Jobs had even attempted to seek the opinion of Nobel laureate biochemist Paul Berg on using such a computer for simulations Although interested in investing in Jobs startup Apple sued Jobs upon finding out about the Apple employees joining him After some mutual agreements Apple dropped the suit the year after The startup was NeXT Computer Inc ER Chapter 1 A Technical History of Apple s Operating Systems NeXT s
33. 1 Apple The Apple I was based on an 8 bit processor the 6502 which was made by MOS Technology Inc of Norristown Pennsylvania The 6502 was designed by ex Motorola engineers It was similar to the more expensive 6800 from Motorola An other alternative the Intel 8080 was also more expensive than the 6502 The 6502 was chosen primarily because it was cheap it could be had for 25 whereas the 6800 and the 8080 were well over 100 apiece MOS Technology advertised in 1975 that it would sell the 6502 at a dis counted price of 20 at the Wescon electronics show in San Francisco The 6502 s low price and popularity would eventually cause Intel and Motorola to lower the prices of their processors Motorola had also sued MOS Tech nology over the similarity of the 650x processor line to the 6800 The 6501 was consequently withdrawn from the market The 6502 came in a 40 pin package The Apple I used a clock oscillator with a frequency of 1 023 MHz Moreover in the Apple I 4 out of every 65 clock cycles were dedicated to memory refresh Therefore the effective cycle frequency was 0 960 MHz Other key features of the processor included the following Mac OS X Internals www osxbook com 3 e An instruction set consisting of 56 documented instructions e Interrupt capability with support for non maskable interrupts e A 16 bit address bus with an addressable memory range of up to 64KB e Over a dozen addressing modes e An 8 bit acc
34. 2 Mac OS X DP4 May 2000 1 2v3 Mac OS X Public Beta September 13 2000 OpenDarwin org Mac OS X 10 0 March 24 2001 Mac OS X Server 10 0 3 May 21 2001 Mac OS X 10 x y Mac OS X Server 10 x y FIGURE 1 33 An approximation of the Mac OS X timeline Mac OS X Internals www osxbook com 119 1 10 1 Mac OS X Server 1 x As people were expecting a DR3 release of Rhapsody Apple announced Mac OS X Server 1 0 in March 1999 Essentially an improved version of Rhapsody it was bundled with WebObjects the QuickTime streaming server a collection of devel oper tools the Apache web server and facilities for booting or administering over the network Apple also announced an initiative called Darwin a fork of Rhapsody s de veloper release Darwin would become the open source core of Apple s systems Over the next three years as updates would be released for the server product development of the desktop version would continue with the server sharing many of the desktop improvements 1 10 2 Mac OS X Developer Previews There were four Developer Preview releases of Mac OS X named DPI through DP4 Substantial improvements were made during these DP releases 1 10 2 1 DP1 An implementation of the Carbon API was added in DPI Carbon represented an overhaul of the classic Mac OS APIs which were pruned extended and modified to run in the more modern Mac OS X environment Carbon was also meant to help Ma
35. 40 it lacked a floating point unit 76 Chapter 1 A Technical History of Apple s Operating Systems switches between the two types of code Code pieces belonging to the two archi tectures could also call each other The manager was transparent to 68K code but PowerPC code was aware of it The initial PowerPC ports of Mac OS had little native PowerPC code most existing applications device drivers system extensions large parts of the Toolbox and the operating system itself were not PowerPC native In fact even though Ap ple s PowerPC introduction occurred in 1994 most of the operating system was still 68K based in 1996 It would not be until 1998 that Mac OS was mostly PowerPC native Figure 1 22 is a conceptual depiction of part of the transition to PowerPC It was hoped that the nanokernel would form the basis for future Apple sys tems perhaps as a robust microkernel 1 5 4 MAE A Mixed Mode Manager was also used in Apple s Macintosh Application Environ ment MAE product MAE was an X Window application available for Sun and Hewlett Packard workstations It ran on SunOS SPARC and HP UX HP9000 700 providing an emulated Macintosh environment It also contained a 68K emu lator for example MAE 3 had a 68LC040 emulator The Mixed Mode Manager was used to optimize execution by translating 68K code to native instructions if possible Mac OS X Internals www osxbook com Single Single Application Finder
36. 975 20 The Alto s processor did not support virtual memory 21 BIT BLT is pronounced as bit blit The BLT stands for Block Transfer The term is commonly used to refer to an algorithm for moving and modifying rectangular bitmaps from one area of memory to another on a bit mapped device Typically one of the areas resides in main memory and the other resides in display memory Mac OS X Internals www osxbook com 31 CLIPC MOV 3 1 SUBR FOR WINDOW CLIPPING SAVE RETURN BBSTABLE COMES IN AC2 STA 1 TEMP1 2 LDA 0 CHAR 2 LDA 1 SPACE SNE 0 1 JMP SPCIT ISZ TRLCHR 2 INDICATE NON_SPACE CHAR HELP DEAL WITH MULTIPLE SPACES IN JUSTIFICATION NOP SOMETIMES USED AS NIL FLAG ARGHH FIGURE 1 10 Assembly language excerpt from the BIT BLT source for the Alto 1 2 5 2 Alto Executive The program that a user interacted with just after the Alto booted was the Alto Ex ecutive Executive Run a command interpreter akin to the UNIX shell It ran atop the Alto OS and could theoretically be replaced by another program It had built in facilities for executing programs and command files listing on disk files querying file sizes and so on Examples of Executive subroutines that could be in voked from the command line included the following e BootFrom FileName Sys Boot e Chat e Copy DestFileName SourceFileName e Delete FileName e Diagnose e FileStat FileName S Ftp e Logi
37. A Technical History of Apple s Operating Systems Amit Singh A Supplementary Document for Chapter 1 from the book Mac OS X Internals A Systems Approach Copyright Amit Singh All Rights Reserved Portions Copyright Pearson Education Document Version 2 0 1 July 28 2006 Latest version available at http osxbook com book bonus chapter1 This page intentionally left blank This is a supplementary document for Chapter 1 from my book Mac OS X In ternals A Systems Approach A subset about 30 of this document ap pears in the book as the first chapter with the title Origins of Mac OS X This document is titled A Technical History of Apple s Operating Systems Whereas the book s abridged version covers the history of Mac OS X this documents coverage is considerably broader It encompasses not only Mac OS X and its relevant ancestors but the various operating systems that Apple has dabbled with since the company s inception and many other systems that were direct or indirect sources of inspiration This was the first chapter I wrote for the book It was particularly difficult to write in terms of the time and other resources required in researching the mate rial I often had to find and scavenge ancient documentation software and hardware all actual screenshots shown in this document were captured first hand However I couldn t include the chapter in its original form in the book The book SE in size beyond
38. Lisp languages It was originally developed at Apple in collabo 6 Newton devices could exchange information with each other using infrared wireless transmission Mac OS X Internals www osxbook com 135 ration with Carnegie Mellon University and Harlequin Inc One of Dylan s primary de sign goals was to be a suitable language for commercial software development Apple abandoned Dylan in 1995 1 11 3 The iPod s Operating System Apple s successful iPod portable music player runs a proprietary operating system When the first iPod was released in 2001 its software s About section mentioned PortalPlayer a company that offers platform suites to manufacturers developing portable digital entertainment devices A small company called Pixo was also cred ited Pixo s focus was on developing a wireless software platform and services for phone manufacturers The Pixo software platform consisted of components such as the following e Pixo Kernel e Pixo Toolbox e Pixo Application Framework e Pixo User interface Builder e Pixo Platform Applications e Pixo Partner Applications e Pixo Internet Microbrowser Pixo was acquired by Sun Microsystems in 2003 The iPod uses PortalPlayer s Digital Media Platform which is marketed as a turnkey solution consisting of System On Chip integrated circuits ICs a custom izable firmware suite integrated third party services PC software and other com ponents The iPod uses P
39. OS 3 3 ICATALOG ON WI Bi I me CH oT eS m mMm JAANA OCL VOM COHCH ZZZ D CH m Al Kal ONAN EI oz eh a s E Ted ww TT Tun bam 0 re x E x x E E E MEMEO ORR om a weza FIGURE 1 3 Apple DOS 3 3 1 1 2 2 Apple Pascal The p System was a Pascal language and development system that was very popular in the 1970s and the early 1980s It was created at the University of California San Diego UCSD It was a portable operating system essentially a stack based virtual Mac OS X Internals www osxbook com 9 machine running p Code with UCSD Pascal being the most popular programming language for it In 1978 most of Apple s software development was around the BASIC and assembly languages Two Apple employees Bill Atkinson and Jef Raskin were in strumental in introducing the Pascal language at Apple They also licensed the p System from UCSD UCSD students Mark Allen and Richard Gleaves developed a p Code inter preter for the 6502 in the summer of 1978 This interpreter became the basis for the Apple Pascal that was released in 1979 Apple Pascal included a compiler an assembler a filer a modal editor and various utility programs The system was command line driven Pascal code would compile into p Code which would then be interpreted by the 6502 native interpreter It supported program modules called units which coul
40. OS supported segmented virtual memory wherein read only code segments could be swapped in as needed A program had to be accordingly compiled and linked for this to work For example the programmer could divide a program into independent parts with the size of each part being limited to 128KB When an in struction attempted to access code that was not in physical memory a bus error oc curred The consequent system trap was handled by the memory manager which brought the required segment into physical memory and restarted the instruction Examples of Lisa memory management system calls included the following e make_dataseg e kill _dataseg e open _dataseg e close_dataseg e mem_info e info_address File System Lisa OS used a hierarchical file system that incorporated both UNIX like aspects and some hitherto new concepts The mount system call performed a similar func tion as on UNIX it was used to introduce a new object into the file system s name Mac OS X Internals www osxbook com 47 space Besides files and folders the file system name space also contained disk vol umes printer devices and serial devices again like UNIX The system performed T O to these objects uniformly regardless of the underlying device although one could perform device specific control operations on files representing devices The file system stored redundant information for each file to reduce the likeli hood of data loss in a crash T
41. Physical Storage 4X CDROM drive floppy disk drives and disk drives attachable through an expansion bus Support for NTSC PAL S Video and VGA 640x480 up to 16 7 million colors support for 8 bit and 16 bit video Stereo 16 bit 44 kHz sampled input and output Input Devices Support for up to four simultaneous game controllers over the Apple Desktop Bus support for standard ADB key board and mice connected through adapters Mac OS X Internals www osxbook com 131 e Detats o Serial port and telephony support via an optional GeoPort The Pippin also offered a proprietary digital filtering technique for improving text visibility on a standard television screen Planned connectivity features for the Pippin included file sharing and other communication with home computers Inter net connectivity was to be provided using an additional adapter or an external mo dem Apple announced in early 1995 that the Pippin would ship by the end of that year There were no plans to ship an Apple branded Pippin The first third party to license the Pippin was Bandai Digital Entertainment Corporation a Japanese toy manufacturer and CDROM game title publisher Bandai s Pippin based Power Player product was expected to sell for approximately 500 A cheap multimedia computer s cost was over 1000 at that point The Pippin ran a custom version of Mac OS that had various dedicated fea tures Several Macintosh computer speci
42. 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 op erating 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 F
43. Windows 1 Hide h q Quit Compose E ei To Subject ce Ss e Salk Bias SS 4 A Deliver p Service Addresses Re All Forward Info xi a DI Librarian bshif Library Bookshelves ZG n Edie eyed inn par ice Prsisrsnecss ae By Erik Kay and Richard Williamson me Notebook Graphic Design by Jeff Yaksick and Keith Ohifs Copyright 1988 1994 NeXT Computer Release E OPENSTEP 4 2 Inc All rights reserved i In Contents Word e me oe Le E al Janu gt a oer o EN smrwrFrFs pt _J24 Hour 21 35 49 Library Addresses Example addresses AddressBook table Library Bookshelves Librarian bshif 2 Mailboxes Active mboxtable_of_contents a a FIGURE 1 28 OPENSTEP 1 8 THE MACH FACTOR Along with NeXT s operating system came its kernel which became the kernel foundation of Apple s future systems Let us now briefly discuss the origins and evolution of Mach a key component of the NEXTSTEP kernel and in turn of the Mac OS X kernel Mac OS X Internals www osxbook com 99 1 8 1 Rochester s Intelligent Gateway A group of researchers at the University of Rochester New York began develop ment of an intelligent gateway system named RIG Rochester s Intelligent Gate way in 1975 Jerry Feldman who coined the name RIG largely did the system s initial design RIG was meant to provide uniform access s
44. XTSTEP the company had proven to be economically unviable over the years In early 1993 NeXT announced its plans to leave the hardware business but continue development 51 Mac OS X supports fat binaries In particular a fat binary can be used to contain 32 bit and 64 bit versions of a program on Mac OS X 10 4 and later The so called Universal Binaries on the x86 version of Mac OS X are simply fat binaries 96 Chapter 1 A Technical History of Apple s Operating Systems of NEXTSTEP for the x86 platform Figure 1 27 shows the timeline of NeXT s operating systems RIG Mach 0 8 mid 1970s Accent Mach 0 9 circa 1979 Mach 1 0 Project started in 1984 4 3BSD USENIX paper in 1986 Mach 2 0 Bee NeXT additions to Mach Mach2 5 0 gt NEXTSTEP 1 0 September 1989 NEXTSTEP 0 8 October 1988 September 1990 2 1 Mach 2 6 March 1991 September 1992 3 1 May 1993 Mach 3 0 7 OpenStep October 1993 x Specification H 1994 February 1995 a i OPENSTEP 4 0 July 1996 4 1 December 1996 4 2 Apple buys NeXT aAA January 1997 February 4 1997 FIGURE 1 27 The timeline of NeXT s operating systems Mac OS X Internals www osxbook com 97 Canon had a personal workstation the object station 41 which was designed to run NEXTSTEP The system s 100 MHz Intel 486DX4 processor was upgradeable to an Intel Pentium OverDrive processor Besides NEXTSTEP as the operating system the machine
45. Yellow Pages and so on e The Berkeley Fast File System ffs e Multiple Unix command interpreters such as the Bourne Korn and C shells e Acomprehensive set of development tools such as lint lex yacc debug gers adb sdb MacsBug various editors assembler linker C compiler cc FORTRAN compiler 77 make and SCCS e The X Window System e AppleTalk printing and file sharing client services via LocalTalk or Eth erTalk 38 For example A UX ran on a Macintosh SE 30 Mac OS X Internals www osxbook com 65 Besides POSIX compatibility A UX supported the BSD and System V APIs In particular A UX was compliant with the System V Interface Definition SVID and passed the System V Verification Suite SVVS Figure 1 19 shows a screenshot of A UX File Edit H CommandShell i d localhost root uname 0 LES JAZUX localhos 3 0 1 SUR2 mc68a3a d localhost root Is mF Applications Documentation Shared Data 4 System Folder alias Desktop Folder k FILES bin dev etc libs lost found qmac matz newunix nextunix root dshlib tmp unix users usr d localhost root ps PID TTY TIME COMMAND 151 C1 8 43 sh 265 C1 6 61 ps A UH System Console Running on mc68a3a mce68882 Floating Point Coprocessor_ID_1 Onboard SCC serial driver An oleae C 12 40 00 F te Apple 4 About This Macin scen Apple localhost root cat hello c d incl
46. acked up by a computer that was alive for you all day and was instantly responsi ble err responsive how much value could you derive from that Well that basi D cally characterizes what we ve been pursuing for many years 1 2 3 1 The First Computer Mouse Engelbart demonstrated the first computer mouse a three button pointing device with a tracking spot or bug on the screen The mouse s underside had two wheels that could roll or slide on a flat surface Each wheel controlled a potentiome ter As the user moved the mouse the respective rolling and sliding motions of the 13 Online refers to the interactive nature of NLS In the 1960s computing was typically batch oriented which made an interactive system very appealing 14 Quoted from a video recording of Engelbart s demonstration 18 Chapter 1 A Technical History of Apple s Operating Systems two wheels resulted in voltage changes that were translated to relative coordinate changes on the screen 1 2 3 2 A 5 Chord Key Set Another input device Engelbart used in his demonstration was a chord key set a five finger equivalent of a full sized keyboard The key set could be used to input up to 31 different characters 2 minus the one state when no keys are pressed 1 2 3 3 Document Processing Engelbart showed that text could be entered dragged copied pasted formatted scrolled and grouped hierarchically in nested levels Multiple lines o
47. al History of Apple s Operating Systems Gestalt is originally a German word that means wholeness shape or form In one of its connotations it is used to denote a structure or configuration integrated to form a functional unit in such a way that the properties of the whole are not derivable by summation of its parts 1 4 3 GS OS As noted earlier the Apple had a rather long life span After the release of the Macintosh in 1984 the Apple J still existed as a product The Apple cs was intro duced in 1986 almost as a bridge between the old and the new It was the first and only 16 bit Apple and had impressive multimedia abilities the GS stood for graphics and sound Its notable features included the following The Apple Joes had several other additions or improvements over previous A 6502 compatible37 65C816 processor The firmware resident monitor allowed assembling and disassembling instructions for both processors Support for 24 bit addressing which allowed memory expansion up to 8 MB The monitor could handle both 16 bit and 24 bit addresses Two very high resolution graphics modes 320x200 with a 16 color pal ette and 640x200 with a 4 color palette RGB and NTSC video outputs A 32 voice Ensoniq Digital Oscillator chip that could be driven by firm ware to produce up to 15 musical instruments A mouse driven color desktop interface with windows and menus A built in control panel desk accessory allow
48. all as opposed to the wheels in the SRI mouse Rather than numbering the mouse buttons the Alto convention was to name them red yellow and blue even though they were visually not of these colors e The Alto was housed in a small cabinet that contained the processor one or more disks and their power supplies Other larger I O devices could be contained in their own cabinets that could be located away from the Alto which was meant for desktop use It had interfaces for local con nection to printers and plotters and a 2 94 Mbps Ethernet interface via which it could be connected to other Altos and laser printers Note that the Alto s processor controlled the disk the display and the Ethernet The Alto could be booted from either a local disk or the network In the case of a disk boot the user could specify a disk address from where to fetch the 256 word disk bootloader with the default location being disk address 0 The first key board word was read to determine the boot type to perform Pressing the lt BS gt key implied a network boot otherwise the microcode interpreted any reported key presses as a disk address The bootloader loaded a portion of Alto main memory from a boot file eventually jumping to a known fixed location The newly loaded program could then initialize still more of the Alto s state In the case of a network boot a special boot packet containing a 256 word Ethernet bootloader would have to arrive at the Alto
49. allow multiple file systems to coexist GS OS eventually went on to have FSTs for various file systems Macintosh HFS ISO High Sierra Apple Share and native file systems of Apple DOS 3 3 Apple Pascal MS DOS and Pro DOS Since the AppleShare FST allowed GS OS to access an AppleShare file server using AppleTalk networking the GS OS Finder could browse over the net work GS OS could even be network booted 64 Chapter 1 A Technical History of Apple s Operating Systems The graphical control panel in GS OS was a facility for controlling various system settings Third party developers could add their own control panel devices CDEVs thus extending the set of entities that the control panel could access The last version of GS OS 4 02 shipped with Apple cs System 6 0 1 1 4 4 A UX A UX was Apple s own version of POSIX compliant UNIX It was released in late 1988 It only ran on 68K based Apple machines with both a floating point unit FPU and a paged memory management unit PMMU The earliest A UX was based on 4 2BSD and AT amp T UNIX System V Release 2 but it would later derive from 4 3BSD and various subsequent System V releases A UX features included the following e 4 3BSD extensions such as groups signals and job control e System V IPC semaphores messages and System V style signals e Networking AppleTalk STREAMS TCP IP over Ethernet as well as over a serial connection sockets domains subnets NFS with
50. and push the lt OPEN gt key to open the icon which resulted in a window displaying the icon s contents Icons could represent either Data Document Folder or Record File or Func tion The user could copy delete file mail move open close and print data icons Function icons operated on data icons Many of the function icons were analogous to modern day application icons Examples of function icons include File Drawer In and Out Baskets Printer Floppy Disk Drive User User Group Calculator Terminal Emulator and Net work Resource Directory e Windows had title bars displaying the corresponding icon names and a context sensitive command menu Context sensitive help was accessible via the button Horizontal and vertical scroll bars provided page up page down and jump to features However STAR windows could only be tiled and were explicitly designed not to overlap overlapping behav ior was considered a nuisance for the end user in the Alto by STAR s designers e An abstraction called Property Sheets was analogous to today s control or property panels A related abstraction called Option Sheets imple mented a visual interface for providing options arguments to com mands For example the Find option sheet was a powerful tool for searching text in a part or whole of a document or selection Even textual properties such as case face font position and size could be used for searching It also allowed optiona
51. apability pressing the power switch while Lisa was operating sent a reset signal to the CPU The handler routine for this signal caused open documents and the state of the desktop to be saved to disk after which the computer went into a low power state Powering Lisa on would restore the desktop state Other software controls allowed ejecting a diskette and adjusting preferences such as screen brightness key repeat rate and the tone generator volume Lisa also had a hardware serial number that could be used by its software for multiple purposes including a rudimentary form of digital content protection 50 Chapter 1 A Technical History of Apple s Operating Systems he File Print Edit Format Customize Si v EI Calculator Clipboard Diskette Clock v E Diskette Documents Empty Folders Lisa LisaCalc Se LisaDraw gi LisaGraph Sr LisaList alal Lisawrite Preferences E Calculator Trash clipboard FIGURE 1 12 Lisa s graphical user interface Lisa came with a suite of the following GUI based office applications e LisaCalc spreadsheet and financial modeling tool with support for up to a 255x255 worksheet e LisaDraw drawing and illustration application e LisaGraph application for making bar line pie and scatter graphs e LisaList database for creating and maintaining various types of lists e LisaProject visual project management and scheduling application based on Project Evaluation and Review Technique PERT
52. ating Systems The Network Server came with the AIX for Apple Network Servers operating system which was based on IBM s AIX The server did not support Mac OS With AIX Apple had an advanced operating system with features such as the following e Memory protection e Preemptive multitasking e Multithreading e Support for various networking protocols including AppleTalk and AppleTalk services e RAID e Journal File System JFS e Logical Volume Manager LVM which supported multiple file systems up to 256GB in size and could handle files up to 2GB in size The user could work with the command line interface or could have one of the AlXwindows or Common Desktop Environment CDE graphical interfaces The operating system included several applications to ease administrative tasks A menu driven System Management Interface Tool SMIT was used for configura tion installation maintenance and troubleshooting A graphical Visual System Management VSM interface allowed system tasks to be performed by clicking on icons Apple revised the Network Server line shortly after its introduction but dis continued it in 1997 The next serious server offering from Apple would not be until 2002 when the Xserve would be released Mac OS X Internals www osxbook com 83 1 6 QUEST FOR THE OPERATING SYSTEM Settings Help A Fonts International System Date Time Drivers Server Services bal Changes the Windows screen t
53. ation used 4 3BSD as the starting code base Its designers had RIG and Accent as references in the area of message passing kernels DEC s TOPS 20 operating system provided some ideas for Mach s virtual memory sub system As Mach evolved portions of the BSD kernel were replaced by their Mach equivalents and various new components were added When published in 1986 the original Mach paper hailed Mach as A New Kernel Foundation For UNIX Development While not everybody saw or sees it that way Mach went on to become a rather popular system From Apple s stand point the paper s title might as well have been 4 NuKernel Foundation Nomenclature Avadis Tevanian one of the inventors of Mach and Apple s Chief Software Tech nology Officer told me the following history about how Mach was named Tevanian qualified the account as his best memory of an event that occurred two decades ago On a rainy day in Pittsburgh Tevanian and some others were on their daily trek to lunch As they were thinking of names for the yet unnamed Mach kernel Tevanian navigating around one of the numerous mud puddles suggested the name MUCK in jest MUCK was to stand for Multi User Communication Kernel or Multiprocessor Universal Communication Kernel As a joke Richard Rashid passed the name along to a colleague Dario Giuse who was Italian Guise inadvertently pronounced MUCK as Mach and Rashid liked it so much that th
54. ay via terminals to a variety of local and remote computing facilities Local facilities could be locally connected disks magnetic tapes printers plotters batch processing or time sharing computers and so on Remote facilities could be available through a network such as the ARPANET RIG s operating system called A eph tan on a Data General Eclipse minicomputer The Aleph kernel was structured around an interprocess communication IPC facility RIG processes could send messages to each other with a port specifying the destination A port was an in kernel message queue that was globally identified by a dotted pair of integers a process number and a port number A process could have several ports defined within itself each of which could be used to wait for a message to arrive on A process X could shadow or interpose another process Y In the case of shadowing X received a copy of every message sent to Y While inter posing X intercepted all messages sent to or originating from Y This IPC facility based on messages and ports was a basic building block of the operating system RIG was killed a few years later due to several fundamental shortcomings in its design or in the underlying hardware for example e The lack of paged virtual memory e A 2KB limit on the size of a message due to the limited address space provided by the underlying hardware e Inefficient IPC due to limited message size e No protection for ports e No
55. became increasingly possible to meet the goal of having a CPI of 1 IBM s first RISC based product was the IBM Personal Computer RT RISC Technology which was announced in January 1986 It ran an operating system called the Advanced Interactive Executive AIX Further work led to a new design called AMERICA which led to RIOS and eventually the POWER architec ture POWER is a contraction for Performance Optimized With Enhanced RISC It combined the original RISC concepts with some traditional CISC concepts re sulting in a more balanced architecture representing the second generation of IBM s RISC technology The associated product family included the RISC System 6000 RS 6000 along with the AIX 3 operating system The first RS 6000 systems were announced on February 15 1990 The POWER architecture defined 184 instructions which although a few too many from a RISC purist s perspective performed well with the independent execu tion units available in the RS 6000 as multiple instructions could be executed in a 72 Chapter 1 A Technical History of Apple s Operating Systems single cycle As the POWER architecture evolved the earliest version of the archi tecture came to be known as POWER T Even in the POWER1 era there were mul tiple implementations of POWER such as the low end RISC Single Chip RSC the mid end RS 9 and the high end RS 1 0 The RSC had a shared data and in struction cache It wa
56. bindings and allows visual description of an application s data entities whose in stances can persist on a storage medium e An improved Search Kit 6 amp 4 Relational Database Management System Mac OS X Internals www osxbook com 129 e Fast Logout and Autosave for improved user experience e Support for Access Control Lists ACLs e New formalized and stable interfaces particularly for kernel program ming e Improvements to the Web Kit including support for creating and editing content at the DOM level of an HTML document the Safari web browser including RSS support QuickTime including support for the H 264 code and a new QuickTime Kit Cocoa framework the Audio subsystem including support for OpenAL the Open Audio Library the Mac OS X installer application Xcode and so on The first shipping x86 based Macintosh computers used Mac OS X 10 4 4 as the operating system 1 11 OTHERS Besides desktop and server computers Apple has made various other devices run ning operating systems such as the Pippin multimedia device hand held computers the MessagePad and the eMate and the iPod portable music player 1 11 1 Mac OS on the Pippin Apple announced the Pippin platform in Tokyo on December 13 1994 The Pippin was dubbed as a multimedia device a set top box and a network computer It was a multimedia player platform based on Apple s second generation Power Macintosh hardware and software The nomenc
57. bytes e 1 Possible Garbage Byte Pup Checksum FIGURE 1 12 The standard Pup format The Alto made heavy use of networking As we saw earlier it also included capabilities for file transfer and remote interactive access A protocol called Copy Disk which was similar to FTP allowed creation of a disk s bit for bit copy over the network In all such protocols the server listened for connection requests on a well known socket A client initiated a connection to the server using commands sent over an established connection to operate the server 36 Chapter 1 A Technical History of Apple s Operating Systems 1 2 5 7 Worms An interesting investigation involving networked Alto computers was with worm programs In 1975 science fiction writer John Brunner had written about such pro grams in his book The Shockwave Rider PARC researchers John F Shoch and Jon A Hupp experimented with worm programs in the early 1980s The experimental environment consisted of over a hundred Ethernet connected Altos A worm was simply a multimachine computation with each machine holding a segment of the worm Segments on various machines could communicate with each other If a segment was lost say because its machine went down the remaining segments would search for an idle Alto on which to load a new copy self repairing software It is important to note that the idea behind the worm experiments was not that of mischief The researchers inten
58. c OS developers in transitioning to Mac OS X A Classic application would re quire an installation of Mac OS 9 to run under Mac OS X whereas Carbon applica tions could be compiled to run as native applications under both Mac OS 9 and Mac OS X 120 Chapter 1 A Technical History of Apple s Operating Systems 1 10 2 2 DP2 The Yellow Box evolved into Cocoa originally alluding to the fact that besides Objective C the API would be available in Java A version of the Java Develop ment Kit JDK was included along with a just in time JIT compiler The Blue Box environment was provided via Classic app a new version of MacOS app that ran as a process called TruBlueEnvironment The Unix environment was based on 4 4BSD DP2 thus contained a multitude of APIs BSD Carbon Classic Cocoa and Java There was widespread dissatisfaction with the existing user inter face The Aqua user interface had not been introduced yet although there were ru mors that Apple was keeping the real user interface a secret Carbon is sometimes perceived as the old API Although Carbon indeed contains modernized versions of many old APIs it also provides functional ity that may not be available through other APIs Parts of Carbon are com plementary to new APIs such as Cocoa Nevertheless Apple has been adding more functionality to Cocoa so that dependencies on Carbon can be eventually eliminated For example much of the QuickTime functionalit
59. cation user interfaces graphically A number of software kits were provided to aid in application development A soft ware kit was a collection of reusable classes or object templates Examples in clude the Application Kit the Music Kit and the Sound Kit Objective C Objective C is an object oriented compiled programming language invented by Brad Cox and Tom Love in the early 1980s It is an object oriented superset of C with dynamic binding and a messaging syntax inspired by Smalltalk It aims to be a simpler language than C Consequently it does not have many features of C such as multiple inheritance and operator overloading 94 Chapter 1 A Technical History of Apple s Operating Systems Cox and Love founded StepStone Corporation from which NeXT licensed the language and created its own compiler In 1995 NeXT acquired all rights to Step Stone s Objective C related intellectual property Apple s Objective C compiler used in Mac OS X is a modified version of the GNU compiler At the time of the cube s announcement NEXTSTEP was at version 0 8 It would be another year before a 1 0 mature release would be made NEXTSTEP 2 0 was released a year after 1 0 with improvements such as sup port for CD ROMs color monitors NFS on the fly spell checking and dynamically loadable device drivers In the fall of 1990 Timothy John Tim Berners Lee at CERN created the first web browser It offered WYSIWYG br
60. ced by UCSD Pascal it was primarily meant for Pascal based development although it supported other languages such as BASIC Plus C and COBOL 74 It provided a multitude of tools for software development a Pascal compiler a 68K assembler a linker a low level debugger a file comparison utility a mouse based graphical text editor and so on It also provided a command line shell along with subsystems for accessing files on storage devices the File Manager and for accessing low level features of Lisa the System Manager The WorkShop could even copy protect software after which copies of such protected software would only run on one ma chine the first machine on which the copy was made 34 The Pascal Basic Plus and COBOL products could be purchased from Apple at the time of Lisa s introduction at the suggested retail price of 595 295 and 995 respectively 52 Chapter 1 A Technical History of Apple s Operating Systems The WorkShop was extensively used for the development of Macintosh soft ware 1 3 1 8 Lisa s Fate Despite Lisa s technical sophistication and Apple s advertising Lisa was a com mercial failure partly owing to its high cost The addition of more memory and a disk drive pushed Lisa s price well above 10 000 The Macintosh which was un der development was perceived by many as a far more affordable mini Lisa In 1984 Apple released a second version of the computer Lisa 2 at half the price of
61. ch money could buy And when the engineers were finally finished they introduced us to a personal computer so personable it can practically shake hands And so easy to use most people already know how They didnt call it the QZ190 or the Zipchip 5000 They called it Macintosh Later known as the Mac 128K due to the 128KB of built in RAM the Macin tosh debuted at a price of 2 495 It had the following key specifications e 7 83 MHz Motorola MC68000 processor e No memory management unit MMU no floating point unit FPU and no L1 or L2 caches e 32 bit internal data bus e 64KB ROM 56 The Macintosh ran a single user single tasking operating system initially Chapter 1 A Technical History of Apple s Operating Systems 128KB RAM 20 bytes of parameter memory PRAM on a CMOS custom chip with 4 5 V user replaceable backup battery Internal single sided 3 5 floppy disk drive that accepted 400KB hard shell floppy disks An external drive port with a DB 19 connector that allowed attachment of a second drive Mouse port DE 9 connector and a mechanical tracking mouse with optical shaft encoding at 3 54 pulses per mm 90 pulses per inch of travel Synchronous serial keyboard bus with an RJ 11 connector and a software mapped 58 key keyboard Two RS 232 RS 422 serial ports DE 9 connectors for connecting mo dems printers and other peripherals Four voice sound generator with 8 bit digital analog conversion and 22 kHz samp
62. cost of RAM video terminals were designed with shift registers at that time The Apple I s display memory was comprised of seven 1K dynamic shift registers The Apple I also had a keyboard interface and a cassette board meant to work with regular cassette recorders The computer was simply a motherboard see 4 Chapter 1 A Technical History of Apple s Operating Systems Figure 1 1 The user had to provide a case a display device an ASCII encoded keyboard and two AC power sources The Apple I was introduced at a price of 666 66 It came with 4KB of RAM and a tape of Apple BASIC FIGURE 1 1 The Apple computer board The Apple I incorporated a firmware resident system monitor sometimes called the Hex Monitor It was an extremely simple program that could be thought of as its operating system The program was 256 bytes in size residing between lo cations 0xFF00 and OxFFFF in the PROM It made use of the keyboard and the display to present the user with a command line for viewing memory contents typ ing programs executing programs and so on Certain RAM locations were used for designated purposes by the monitor and therefore were unavailable to the user for other purposes Programmable Read Only Memory Mac OS X Internals www osxbook com 5 Figure 1 2 shows a test program entered at the monitor s backslash prompt The first line of hexadecimal numbers is the program itself Its purpose is to pri
63. ctivity and security features to Mac OS X besides providing general performance and usability improvements Notable 10 3 features included the following An enhanced Finder with a sidebar and support for labels Audio and video conferencing through the iChat AV application Expos a user interface feature that can live shrink each on screen window such that no windows overlap allowing the user to find a win dow visually after which each window is restored to its original size and location FileVault encryption of a user s home directory Secure deletion of files in a user s trash can via a multipass overwriting algorithm Fast user switching Built in faxing Improved Windows compatibility courtesy of better support for SMB shares and Microsoft Exchange Support for HFSX a case sensitive version of the HFS Plus file system The BSD component in Panther was based on FreeBSD 5 1 10 4 5 Mac OS X 10 4 Besides providing typical evolutionary improvements Tiger introduced several new technologies such as Spotlight and Dashboard Spotlight is a search technology consisting of an extensible set of metadata importer plug ins and a query API for 127 128 Chapter 1 A Technical History of Apple s Operating Systems searching files based on their metadata even immediately after new files are cre ated Dashboard is an environment for creating and running lightweight desktop utilities called widgets which
64. d as a low cost secondary component in the BBC microcomputer It is noteworthy that ARM eschewed some key features of the prevailing Berkeley RISC architecture delayed branching register windows and requiring all instructions to execute in a single cycle each Even before the AIM alliance was formed Apple had teamed with Acorn to fund a new company called Advanced RISC Machines ARM Limited The com pany s goal was to create a new RISC microprocessor standard VLSI Technology was an investor and technology partner in this endeavor It was also ARM s first licensee ARM Limited s first processor was an embeddable RISC core called the ARM6 Based on version 3 of the ARM processor architecture ARMv3 the ARM6 had full 32 bit code and data addressing An ARM6 processor a 20 MHz 42 VMX is the same as AltiVec which is a Motorola trademark 43 One of Acorn s best known computers was the BBC micro which at its launch in 1981 was based on a 2 MHz 6502 processor Mac OS X Internals www osxbook com 75 610 was used in Apple s MessagePad hand held that ran the Newton operating system 1 5 3 Mac OS for PowerPC System 7 1 2 was the first Apple operating system to run on the PowerPC even though much of the code was not PowerPC native Given Apple s roadmap porting all components of the operating system to a new architecture would have taken pro hibitively long Moreover it was extremely important for Apple to provi
65. d be segmented and therefore were typically memory resident only when needed Apple Pascal s memory usage was limited to 64KB Apple Pascal lived as a product for five years with the Pascal support in the Macintosh Programmer s Workshop MPW eventually replacing it 1 1 2 3 Apple CP M Microsoft introduced a coprocessor card a circuit board named SoftCard in 1980 It was originally called the Microsoft Z 80 SoftCard but Microsoft had to rename it to avoid a lawsuit from Zilog the makers of the Z 80 processor The SoftCard plugged into a slot and added a Z 80 processor essentially converting an Apple into two computers An Apple with a SoftCard could run Z 80 programs based on 4 p Code was akin to what is now commonly known as bytecode 5 Apple s Pascal system for the Apple 1 was derived from a specific implementation of the p Code architecture UCSD Pascal II 1 10 Chapter 1 A Technical History of Apple s Operating Systems the popular CP M operating system which had a rich software library of programs such as dBase and WordStar Programming languages such as Microsoft ANSI Standard COBOL and FORTRAN could also be used on the Apple JI Besides SoftCard there existed other coprocessor cards for the Z 80 and for other processors such as the Motorola 6809 For example the Stellation Mill 6809 card allowed the OS 9 real time operating system to run on compatible Apple ma chines 1 1 3 Apple The A
66. de a way so that 68K based applications would continue to run even on the PowerPC platform The system architecture devised to address these issues included a hardware ab straction layer HAL and a 68K emulator A nanokernel was used to drive the PowerPC Executing in supervisor mode the nanokernel acted as the HAL It exported low level interfaces for inter rupt management exception handling memory management and so on Only the system software and possibly debuggers could use the nanokernel API The 68K emulator was initialized by the nanokernel during boot time It only emulated a 68LC040 user mode instruction set without emulating the paged MMU PMMU or the FPU Exception stack frames were created as per a slightly older processor the 68020 for better compatibility There were other caveats and limitations as compared to a real 68LC040 In particular since A UX used the PMMU directly it did not run on this emulator Since two instruction set architectures were simultaneously in effect a system level component called the Mixed Mode Manager was used to handle context 44 Keywords often associated with ARM processors include embedded high performance low 99 66 cost power efficient and RISC Such features are especially appealing for low power devices 45 A term sometimes used to refer to a kernel that is even smaller than a microkernel 46 The 68LC040 was a low cost version of the 680
67. ded a preemption safe memory allocator The multiprocessor MP API library could now run with virtual memory enabled although virtual memory was still optional When Mac OS 9 was released in 1999 it was hailed by Apple as the best Internet operating system ever It was the first Mac OS version that could be up dated over the Internet It could also use the AppleTalk protocol over TCP IP Its useful security features included file encryption and the Keychain mechanism for storing passwords securely An important component of Mac OS 9 was a mature installation of the Carbon APIs which at the time represented about 70 of the legacy Mac OS APIs Carbon provided compatibility with Mac OS 8 1 and later Mac OS X Internals www osxbook com 113 The last release of Mac OS 9 was released in late 2001 as version 9 2 2 With the advent of Mac OS X this old Mac OS would eventually be referred to as Classic Figure 1 30 shows a screenshot of Mac OS 9 y E File Edit Video Controls Window Help 11 47 PM Apple DVD Player E Sherlock 2 S AQHAOOL 5 a llliliit S wy a ba About This Computer fhe INTAR E MacOS 9 2 Yersion Mac059 2 2 Built in Memory 256 MB irtual Memory 257 MB used on Mac 05 Largest Unused Block 184 7 MB amp Apple Computer Inc 1983 2001 e to QuickTime Apple DYD Player 13 2 MB Ea AppleCD Audio Player 924k EI E Gra
68. ded to create useful programs that would utilize oth erwise idle machines essentially a form of distributed computing Nevertheless the aberrant potential of worms was clearly identified although worms were still not perceived as a real security risk Comparatively viruses and self replicating Trojan horse programs were considered bigger threats to security Examples of ap plications that used such worms include the following e The Existential worm was a null worm that only contained logic for its own survival e The Billboard worm could distribute graphics images to multiple ma chines e The Alarm Clock worm was a distributed fault tolerant computer based alarm clock that could call a user on the telephone at a designated time e The Multimachine Animation worm was part of a distributed real time animation mechanism involving multiple compute nodes and a single master node 26 The Alto worms were conceptually similar in some aspects to the controller and agent programs in a modern day grid computing environment such as Apple s Xgrid Mac OS X Internals www osxbook com 37 e The Ethernet Diagnostic worm conducted network tests to locate errone ous Ethernet interfaces It reported the findings to a control host Other useful things that the worms were meant to do included reclaiming file space shutting down idle workstations and delivering mail A popular application for the Alto was the game Trek which used a
69. dynamically switch between them Mac OS X Internals www osxbook com 73 e It had a cleaner and simplified superscalar design e It had a cleaner separation between architecture and implementation The resulting architecture was flexible enough to permit a broad range of im plementations e It supported symmetric multiprocessor SMP systems CHRP was also aimed at companies other than Apple so that they could sell PowerPC based systems Microsoft Windows NT 3 51 and 4 0 ran on PowerPC Reference Platform PReP compliant systems until Microsoft announced in early 1997 that it would phase out NT development on the PowerPC architecture A version of Solaris 2 5 1 was also released as Solaris PowerPC Edition The first PowerPC processor was the 601 It was jointly developed by the AIM companies at the Somerset Design Center in the Northwest Hills of Austin Texas When introduced in September 1993 the 601 ran at 66 MHz It implemented the 32 bit subset of the PowerPC Architecture but without the full PowerPC instruction set It was regarded as a bridge that would allow vendors to transition to PowerPC IBM s RS 6000 Model 250 Workstation was the first PowerPC based system to ship From PowerPC to x86 After Apple adopted the PowerPC it remained the mainstay of Apple hardware for over a decade until the year 2005 specifically Steve Jobs announced in his Worldwide Developer Conference 2005 keynote that Apple had decided to trans
70. e Macintosh Finder the MultiFinder specifically still supported only cooperative multitasking When 32 bit addressing was in effect the startmac application was responsible for creating the Macintosh environment under A UX The startmac24 variant was used with 24 bit addressing Many aspects of this environment were customizable including which application to run as the Finder Macintosh style menu driven login logout system startup and shutdown procedures were sup ported A conceptual diagram of the A UX architecture is shown in Figure 1 20 Many proponents of A UX regarded it as the holy grail of Unix systems Given compatible hardware the A UX installation procedure was incredibly simple for a Unix system being essentially one click From trivialities such as similar commands such as appleping to the more elaborate marriage of the Unix and Macintosh environments vestiges of insights gained through A UX can be seen in Mac OS X Examples include the following e A UX used mac lt host gt Desktop Folder and mac lt host gt Trash as the Unix pathnames for directories containing items visible on the Macintosh Desktop and in the trash can respectively e Unix uses the character to separate path components whereas Macin tosh file systems use Invisible translation was done while accessing or moving files from one environment to the other e Home directories for user accounts were located in users 39 R
71. e file and print server It was also intended to run relational database RDBMS products such as Oracle7 Cooperative Server Mac OS X Internals www osxbook com 81 e WGS 9650 233 MHz PowerPC 604e ran Mac OS 7 6 1 The 60 80 and 95 were introduced in 1993 whereas the 9650 was introduced in 1997 1 5 6 NetWare for PowerPC Apple partnered with Novell in the mid 1990s to port NetWare to the PowerPC The jointly funded port was designed to be much easier to configure than NetWare for x86 It was intended to run on an Apple designed server called Shiner Although the port was more or less completed the project was killed before it ever shipped Shiner would lead to the Apple Network Server which ran AIX 1 5 7 AIX for PowerPC A few years later in 1996 Apple had a short lived product called Apple Network Server The PowerPC based server had hardware features such as the following e Processor resident on a daughterboard for easy upgradeability e An easy to replace logic board e Up to 1MB of L2 cache e Up to 512MB of parity RAM e A 4MB ROM and an 8KB NVRAM e Multiple hot swappable and RAID capable drive bays for a total ap proximate disk capacity of 340GB e Hot swappable power supplies and fans e Provisions for adding several SCSI devices and PCI cards e An external LCD display for system diagnostics and status messages e Several physical security features 82 Chapter 1 A Technical History of Apple s Oper
72. e implementations deviated from this concept Release 2 0 of Mach as well as the rather successful Release 2 5 had monolithic implementations in that Mach and BSD resided in the same address space One of CMU s important decisions was to provide all Mach software with un restrictive licensing free of distribution fees or royalties The Open Software Foundation OSF used Release 2 5 of Mach for providing many of the kernel services in the OSF 1 operating system Mach 2 x was also used in Mt Xinu Multimax Encore Omron LUNA 88k NEXTSTEP and OPENSTEP The Mach 3 project was started at CMU and continued by OSF Mach 3 was the first true microkernel version BSD ran as a user space Mach task with only fundamental features being provided by the Mach kernel Other changes and im provements in Mach 3 included the following e Kernel preemption and a real time scheduling framework to provide real time support 56 Implies external to the kernel that is in user space 57 The OSF was formed in May 1988 to develop core software technologies and supply them to the entire industry on fair and reasonable terms It went on to have several hundred members from among commercial end users software companies computer manufacturers universities research laborato ries and so on The OSF later became the Open Group and then became Silicomp 106 Chapter 1 A Technical History of Apple s Operating Systems e Low level device support w
73. e Graphics Processing Unit GPU on supported graphics cards e iChat an AOL Instant Messaging AIM compatible IM client e An enhanced mail application Mail app with built in adaptive spam filtering e Anew Address Book application with support for vCards Bluetooth and iSync synchronization with Mac servers PDAs certain cell phones and other Mac OS X computers the Address Book s information was acces sible to other applications e QuickTime 6 with support for MPEG 4 e An improved Finder with quick file searching from the toolbar and sup port for spring loaded folders e Inkwell a handwriting recognition technology integrated with the text system allowing text input using a graphics tablet e Rendezvous which was Apple s implementation of ZeroConf a zero configuration networking technology allowing enabled devices to find one another on the network e Better compatibility with Windows networks e Version 3 of the Sherlock Internet services tool 63 Rendezvous was later renamed Bonjour Mac OS X Internals www osxbook com Hereafter Apple introduced new applications and incorporated technologies in Mac OS X at a bewildering pace Other notable additions to Mac OS X after the release of Jaguar included the iPhoto digital photo management application the Safari web browser and an optimized implementation of the X Window system 1 10 4 4 Mac OS X 10 3 Panther added several produ
74. e name stuck Initially the Mach designers presented four basic abstractions in the kernel 5 TOPS 20 was a descendant of the TENEX operating system 104 Chapter 1 A Technical History of Apple s Operating Systems A task is a container for the resources of one or more threads 4 Examples of resources include virtual memory ports processors and so on A thread is a basic unit of execution in a task The task provides an execution environment for its threads whereas the threads actually run The various threads of a task share its resources although each has its own execution state which includes the program counter and various other registers Thus unlike a process in Accent a Mach process is divided gt into a task and multiple threads A port is similar to an Accent port it is an in kernel message queue with ca pabilities Ports form the basis for Mach s interprocess communication facilities Mach implements ports as simple integral values A message is a collection of data that threads in different tasks or in the same task can send to each other using ports Another basic Mach abstraction is that of a memory object which could be thought of as a container for data including file data mapped into a task s address space Mach requires a paged memory management unit PMMU Through its pmap physical map layer Mach provides an excellent interface to the machine dependent MMU facilities Mach s virtual memory
75. e on microfilm A variety of content ranging from books to daily newspapers could be trivially inserted into the memex e The memex would have photocopying abilities so that users could con veniently add their own content to the machine s data store e A lever would allow a user to flip forward and backward through pages of information with the browsing speed dependent on how far the lever was moved A shortcut would warp to the first page of the index e The user would be able to arbitrarily annotate preexisting information in the memex e The memex would not only index its content normally but would allow the user to build trails of information connecting one piece to another to build associations between related bodies of knowledge Thus Bush 10 As We May Think by Vannevar Bush Atlantic Monthly 176 1 July 1945 pp 101 108 Mac OS X Internals www osxbook com 15 described the core idea behind the web the hyperlink almost half a century before the first web browser was created Bush made numerous uncanny predictions He suggested that some day an entire encyclopedia would be available on a storage medium the size of a matchbox He envisioned that people from all walks of life chemists historians lawyers pat ent attorneys physicians and so on would use the memex to perform hitherto im possible or inordinately difficult tasks The modern day Internet the development and proliferation of high densi
76. ease 1 10 4 1 Mac OS X 10 0 Apple dubbed Cheetah as the world s most advanced operating system Finally Apple had shipped an operating system with features that it had long sought How ever it was clear that Apple had a long way to go in terms of performance and sta bility Key features of 10 0 included the following e The Aqua user interface with the Dock and the Finder as the primary user facing tools e The PDF based Quartz 2D graphics engine e OpenGL for 3D graphics e QuickTime for streaming audio and video shipping for the first time as an integrated feature e Java 2 Standard Edition J2SE e Integrated Kerberos Mac OS X Internals www osxbook com 125 e Mac OS X versions of the three most popular Apple applications avail able as free downloads iMovie 2 iTunes and a preview version of Ap pleWorks e Free IMAP service for Mac email accounts When Mac OS X 10 0 was released there were approximately 350 applica tions available for it 1 10 4 2 Mac OS X 10 1 Puma was a free update released six months after 10 0 s release It offered sig nificant performance enhancements as indicated by Apple s following claims e Up to 3x improvement in application launch speed e Up to 5x improvement in menu performance e Up to 3x improvement in window resizing e Up to 2x improvement in file copying There were substantial performance boosts in other areas such as system startup use
77. echnical History of Apple s Operating Systems have 32 bit support and a larger virtual memory capability through a 32 bit system enabler program called MODE32 on System 7 The standard ROMs of these machines were not 32 bit clean and therefore were only compatible with 24 bit addressing MODE32 allowed selecting and chang ing between 24 bit and 32 bit addressing modes With 32 bit addressing it was possible to use more than 8 MB of contiguous physical memory With virtual memory it was possible to use hard disk space as swap space to run programs Even with the aforementioned improvements System 7 only performed coop erative multitasking and lacked memory protection Around this time Apple formed an alliance with IBM and Motorola a move that put the PowerPC on Apple s hardware roadmap The advent of the PowerPC required fundamental changes in the design of the Macintosh operating system 1 5 2 AIM for POWER The emphasis on making the semantics of computer architecture close to those of higher level programming environments had led to very complex processors How ever people like Seymour Cray understood the benefits of simplicity in computer architecture design even in the early 1960s Cray s CDC 6600 supercomputer and the CRAY 1 computer were both RISC machines although the term RISC had not been coined yet 1 5 2 1 A RISCy Look Back RISC stands for Reduced Instruction Set Computer although it does not only
78. ed the user to set machine pa rameters for display disk drives processor speed serial ports and so on Two standard serial ports that could be used with AppleTalk Apple machines Apple ProDOS was forked into 8 and 16 bit versions to accommodate the Apple Joes After using ProDOS 16 as the computer s operating system for a short 37 The user could select either the 1 MHz processor clock speed of the 6502 or a faster 2 8 MHz Mac OS X Internals www osxbook com 63 time Apple replaced it with GS OS a new 16 bit native mode system that signifi cantly improved performance on many fronts such as boot time disk access time and program launch time Figure 1 18 shows a screenshot of GS OS e File Edit Windows View Disk Special Colors Extras ee O O HRH el ES Di ProD0S System BASIC System I System Software 6 0 1 Copyright Apple Computer Inc 1983 93 Total Memory 3776K Available 2987K Finder 315K Desk accessories 51K System 345K Setup files 76K MMMM FIGURE 1 18 GS OS GS OS had several modern features It had the concept of file system transla tors FSTs a generic file interface that allowed different file systems to be read from and written to The concept was along similar lines as AT amp T s file system switch Sun Microsystems vnode vfs and DEC s gnode that were being introduced in the mid 1980s to
79. eel still in spin And theres no tellin who That it s namin For the loser now Will be later to win For the times they are a changin Mac OS X Internals www osxbook com 55 Besides being a vehicle of Lisa s technology of windows icons pull down menus mouse commands and software integration the Macintosh was a compel ling execution of marketing wizardry Apple hailed it as the computer for the rest of us After demonstrating the Macintosh s capabilities Jobs said We ve done a lot of talking about Macintosh recently but today for the first time ever I d like the Macintosh to speak for itself A program running on the Macintosh spoke an introductory message Hello I am Macintosh It sure is great to get out of that bag Unaccustomed as I am to public speaking I d like to share with you a maxim I thought of the first time I met with an IBM mainframe NEVER TRUST A COMPUTER YOU CAN T LIFT Obviously I can talk but right now I d like to sit back and listen So it is with considerable pride that I introduce a man who been like a father to me STEVE JOBS An early Macintosh sales brochure had the following blurb For the first time in recorded computer history hardware engineers actually talked to software engineers in moderate tones of voice and both were united by a common goal to build the most powerful most transportable most flexible most versatile computer not very mu
80. el extensible communi 68 The eMate 300 measured 289 6x305 0x53 3 mm and weighed 4 2 Ibs 134 Chapter 1 A Technical History of Apple s Operating Systems cations subsystem managed serial hardware infrared and AppleTalk networking This subsystem was extensible in that new protocols could be dynamically added and removed 1 11 2 2 System Services Many system services ran atop the operating system such as Book Reader End point Communications Filing Find Imaging and Printing Intelligent Assistant Object Storage System Routing and Transport Stationery Text Input and Recogni tion and View System 1 11 2 3 Application Components These included the NewtonScript Application Program and the user interface that ran atop System Services Newton applications both built in and third party ran in a single operating system task Newton used a sophisticated modeless input recognition system that could recognize text shapes and gestures The text recognizer could handle printed cur sive or mixed handwriting The shape recognizer could recognize both simple and complex geometric shapes A descendant of this recognition technology exists as Inkwell in Mac OS X A programming language called Dylan was considered as a candidate for being the primary language for developing Newton applications Dylan is an object oriented Lisp like dynamic language that combines the features of static such as C and C and dynamic such as
81. elated information 1 2 3 5 Searching NLS provided powerful search facilities keywords could be weighted and search results were ordered accordingly Results could also be presented as hyperlinks 1 2 3 6 Windows The computer screen could be split into a frozen display and a scanning window While you were reading a manual for example and you needed to look up a term you could split the screen and view the term s definition in the dynamically chang ing scanning window similar to latter day frames in web pages 1 2 3 7 Collaboration The system also kept track of who you were and what you were doing People could work collaboratively on files annotate each other s text and leave notes for each other akin to modern day document versioning systems It was also possible to leave messages for one or more specific people A special language essentially a programmable filter would allow a test to be associated with pieces of text There after readers could only view what they were allowed to as determined by the re sult of the context sensitive test 20 Chapter 1 A Technical History of Apple s Operating Systems 1 2 3 8 Live Interactive Collaboration The SRI team demonstrated live audio video conferencing The communicating parties could even have collaborative screen sharing with each party having inde pendent capabilities For example two people could look at the same display but one of them would have read o
82. en s barrel could be rotated to vary the distance between the photodiode and the lens at the pen s tip thus adjusting the field of view s size As the user drew directly on the screen using the light pen Sketchpad inter preted the drawing Using straight line segments and circle arcs as basic drawable shapes the user could draw more complex shapes The system treated on screen shapes as objects that could be operated upon For example transforms such as rotation scaling and translation could be applied to existing drawings Once drawn shapes could be saved and reused as primitive units The light pen was used in conjunction with push button controls For example the draw control created a new line segment or arc with the drawn shape s end point remaining attached to the pen Other examples of controls included circle center move delete and instance Sketchpad was demonstrated by creating electrical mathematical mechanical scientific and even artistic drawings Moreover arbitrary mathematical conditions which could be the result of complex computations could be applied to drawings Sketchpad would automatically satisfy the conditions and alter the drawings to pic torially display the results It had various other mathematical abilities that made it a powerful graphical input program for example it allowed sub pictures within pic tures with no intrinsic limit on the nesting level Sketchpad drawings or rather their
83. en the multiple disks of a single computer e FTP was a file transfer program 1 2 5 4 Programming Facilities Many programming languages were available on the Alto including BCPL LISP Smalltalk Mesa and Poplar The system s debugger was called Swat It saved machine state in a file named Swatee You could stop a running program and get back to the Executive by hold ing down the left lt SHIFT gt key and hitting the lt SWAT gt key 23 Mesa was a Pascal like strongly typed system programming language 24 Poplar was a simple interactive text oriented programming language 34 Chapter 1 A Technical History of Apple s Operating Systems 1 2 5 5 Applications The Alto began with several productivity applications and went on to have many more Examples of sophisticated Alto applications include the following e Bravo was a feature rich multiwindowed text processing application e Draw was an interactive illustrator program for creating pictures com posed of lines curves and text captions It divided the screen into multi ple areas brush menu command menu font menu picture area caption area and a message area for displaying information error or prompting messages e Laurel was a display oriented mail messaging system that provided fa cilities to display forward classify file and print mail messages It stored messages on the local Alto disk e Markup was a document illustration applicati
84. ent in Mac OS X provided by an applica tion named Classic Startup app The Blue Box environment is a virtualization layer and not an emulation layer Harmless instructions execute natively on the processor whereas harmful instructions such as those that can affect the hardware are trapped and handled appropriately 6 The application was called Classic app in earlier versions of Mac OS X 116 Chapter 1 A Technical History of Apple s Operating Systems 1 9 2 2 Yellow Box Rhapsody s development platform was called the Yellow Box Besides being hosted on the Power Macintosh and x86 versions of Rhapsody it was also available inde pendently for Microsoft Windows Figure 1 32 shows a screenshot of Yellow Box running under Windows XP UNTITLEDO eomedeld C Documents and Settings Admin 7a previewSplashScreen bmp C App O X hicrosoft Internet Explorer vi e E http w ael Blylolalol e z Ki Bi sel a SC JN YELLOW BOX FOR WINDOWS Gat hun Cp Bz Forums Ey Humor f i ee Eon Epa Preview store iPod iTunes Stored Pi ch WI 8 Ap In Hot News Switch Hardware Software Made4M 20 Feb 2004 Browse Extras Settings Backlight ER 0 31 NSCell html nstext Box 0 30 NSNotification htm nstext Button 0 29 NSCStringText htm nstext a Field1 F Switch ot Wem H e Reminder to self This is a e SS Searc
85. er day mechanisms for Java Within a few years the future of Accent did not look promising as well It needed a new hardware base support for multiprocessors and portability to other kinds of hardware Accent also had difficulty supporting UNIX software The Matchmaker project was started in 1981 as part of the SPICE project Matchmaker was an interface specification language intended for use with existing programming languages Using the Matchmaker language object oriented remote procedure call RPC interfaces could be specified The specification would be con verted into interface code by a multitarget compiler Matchmaker is readily comparable to the rpcgen protocol compiler and its language The Mach Interface Generator MIG program which is also used in Mac OS X was derived from Matchmaker 52 The PERQ had soft microcode allowing its instruction set to be extended 102 Chapter 1 A Technical History of Apple s Operating Systems 1 8 3 Mach The sequel to Accent was called Mach which was conceived as a UNIX compatible Accent inspired system In retrospect with respect to the first version 1 0 of Mach one could consider Accent and RIG to be Mach versions 0 9 and 0 8 respec tively When Mach was developed UNIX had been around for over fifteen years Although the designers of Mach subscribed to the importance and usefulness of UNIX they noted that UNIX was no longer as simple or as easy to modify as it once had been R
86. er itself a CRT screen two floppy disk drives and the power supply e A one button mouse e A keyboard with a numeric keypad e AnApple ProFile hard disk drive unit Various peripherals such as mouse keyboard hard disk drives printers and serial devices could be plugged into the main unit Moreover it was possible to dis assemble the unit without tools 1 3 1 2 Processor and Memory Lisa had a 5 MHz Motorola MC68000 processor which had a 16 bit external data path with a 32 bit internal architecture The system had a memory management unit MMU but no floating point unit FPU Lisa initially included 1MB of RAM but could support up to 2MB However the processor was capable of handling a 16MB address space and supported multiple memory addressing modes A physical ad dress could lie in one of following three address spaces 30 When introduced the Lisa project had consumed about 200 man years and 50 million dollars 42 Chapter 1 A Technical History of Apple s Operating Systems e The main memory RAM where Lisa programs and data were stored e The I O address space which was used for accessing peripheral control lers status registers and control registers e The special I O address space which was used for accessing the boot ROM and internal MMU registers Lisa s MMU provided four numbered 0 through 3 logical address space con texts for programs to run of which context 0 was reserved for use by the operating
87. f text could be collapsed into a single line The text so created could be saved in files with provi sion for storing metadata such as the file s owner and time of creation The use of a mouse made these operations easier Engelbart referred to the overall mechanism as view control The system was useful while editing code as well blocks of code could be expanded and collapsed and even auto completion was supported Furthermore documents could contain embedded statements for markup which allowed formatting of documents for specific purposes such as printing 1 2 3 4 Hypertext and Image Maps Using hypertext or text with hyperlinks Engelbart could jump from one location to another Hyperlinks could be used to facilitate access to search results or could be explicitly used as visible or invisible live links to information The system also had picture drawing capabilities Even pictures could have live hyperlinks like latter day image maps in web pages Mac OS X Internals www osxbook com 19 Origins of Hypertext Theodor Holm Nelson came up with the term hypertext whereas the concept itself is ascribed to Vannevar Bush who described it in the context of the memex ma chine as we saw earlier in this chapter Nelson is noted for his Xanadu project which was to be a worldwide electronic publishing system He coined the term hyper text in 1965 to refer to a flexible generalized non linear presentation of r
88. fic features had been removed to minimize memory footprint However highly used or otherwise necessary features were in cluded for example the Macintosh Toolbox a built in 680x0 emulator integrated QuickTime and an integrated PowerPC native version of QuickDraw Since the Pippin did not include a disk drive by default it typically booted from system soft ware residing on the same disc as a Pippin title Developers could create their own system software bundle by choosing the appropriate system version and configura tion The Pippin s intended software library was to include games and software for reference learning and interactive music It was believed that the Pippin would 65 Apple eventually provided a Pippin Developer SDK in early 1996 66 Bandai s product line included the Power Rangers action figures 132 Chapter 1 A Technical History of Apple s Operating Systems even run simple versions of financial software spreadsheets and word processors In fact Apple expected many Macintosh applications to run unchanged on the Pip pin with the only requirement being a remastering step to include system software on application discs Conversely Pippin titles were expected to work on the Macin tosh too The Pippin met with a positive reception from the media An October 1996 article in a Microsoft developer column called Pippin A Real Network Computer The article pointed out that the Pippin s appeal was that
89. for the price of a high end VCR it delivered an almost complete low end Macintosh Apple s licensing plans were also praised Apple s go it alone attitude has achieved legendary status Thats why its amazing that the company that once vowed never to license their crown jewels is neither manufacturing nor marketing the Pippin itself The Network Computer may be a joke so far but Pippin clearly is not BYTE magazine proclaimed Bandai Digitals WORLD Web browsing system may one day be the Mac network com puter for corporations However the Pippin was a failed product it did not reach most of its in tended markets Bandai sold some systems marketing them as ATMARK in Japan and WORLD in USA The WORLD system came with a slightly modified ver sion of the Spyglass Internet browser A few other variants of Pippin existed as samples or prototypes Some Pippins had a PowerPC sticker and another stating Advanced Technology By Apple Computer Apple also had a set top box product the Apple Interactive TV Box It sup ported the MPEG 2 video decompression standard and a variety of input and output ports such as ADB dual 21 pin EURO SCART RF IN and RF OUT either NTSC or PAL RJ 45 connector for either E1 or T1 data streams Apple System Peripheral 8 Cable serial S Video output RCA 67 Nevertheless the Pippin was a fundamentally more limited runtime environment as compared to a Macintosh Mac OS X Internals www osxbo
90. ght under contention when Apple tried to trademark it but Apple eventually managed to buy the trademark During the legal battle Apple considered acronyms such as MAC for Mouse Acti vated Computer There were alleged jokes within Apple that MAC actually was an acronym for Meaningless Acronym Computer For a short while there were even efforts to change the project s name to Bicycle which al luded to a quote from Steve Jobs about personal computers being bicycles for the mind Jef Raskin had written The Book of Macintosh an Apple internal document on personal computing that described a cheap user friendly computer designed for the Person In The Street PITS Some of the desirable features of the computer were the following e The computer system must not consist of myriad external components It must be all in one with components such as the display the keyboard disks and others all integrated into one package Moreover the package must be portable with a handle and must not weigh more than 20 lbs e The computer s internals should not be visible e The PITS should never be required to open the computer nor even see its interior The only reason to open the computer should be for repair e The PITS should not be required to deal with components in sockets whether inside or outside of the computer Any additional boards RAMs ROMs or other accessories should be allowed only if they exist as standalone app
91. h for MSIE Windows computer Score Document gt 1 00 NSText htm e eou 8 0 87 NSText html 0 51 NSTextview html a 0 51 PB_index sl 0 40 NSTextFieldCell html d 0 35 NSTextFieldCell ntml Van i 0 33 NSCell html nstext 0 32 NSControl htm nstext Ted Message Text informational Text 0 28 NSChangeSpelling html nstext 0 28 IntroAppKit html nstext Radio An MET a Aint e SE C Radio Hot News Headlines Newest Switchers Scien Fielde Annla Ctara NN millian Status Found 40 items FIGURE 1 32 Yellow Box Yellow Box included most of OPENSTEP s integrated frameworks which were implemented as shared object libraries These were augmented by a runtime and development environment There were three core object frameworks whose APIs were available in Objective C and Java e Foundation was a collection of base classes with APIs for allocating deallocating examining storing notifying and distributing objects Mac OS X Internals www osxbook com 117 e Application Kit was a set of APIs for creating user interfaces managing and processing events and using services such as color and font man agement printing cut and paste and text manipulation e Display PostScript was a set of APIs for drawing in PostScript compo siting images and performing other visual operations It could be con sidered as a subset of Application Kit Yellow Box included NeXT s Project Builder integrated development envi
92. h was to be an end user operating system The Pink and the Red projects would turn out to be rather unsuccessful Apple would continue to make attempts to solve the OS problem one way or another 1 6 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 No vell actually succeeded in creating a very reasonable prototype in an incredibly short amount of time The project was cancelled however for various reasons Ap ple had already committed to the PowerPC many within and outside of Apple thought that doing so would disrupt Apple s existing business model and vendor feedback was not encouraging Many years later Darwin the core of Apple s far more successful Mac OS X would run 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 tran sitioning Mac OS X to the x86 platform The first x86 based Macintosh comput ers the iMac and the MacBook Pro the successor to the PowerBook were un veiled at the San Francisco Macworld Conference amp Expo in January 2006 Mac OS X Internals www osxbook com 85 1 6 2 Raptor Raptor was in many respects the Red project It was supposed to provide Apple with a
93. he host platform supported copy on write substantial portions of MAE could be shared between its multiple instances MAE made heavy use of processor caches performing best on machines with large caches It cached both instructions and data Examples of instruction cache use by MAE included the following e Native code to support the 680x0 glue and dynamic compilation e Native code to emulate instructions e Dynamically compiled code to emulate instructions Examples of data cache use by MAE included the following e Native data to support the 680x0 glue and dynamic compilation e Dispatch table for mapping 680x0 opcodes to native emulation code e 680x0 instructions emulated by MAE e 680x0 data for Mac OS system code and the Toolbox e Graphics framebuffer MAE was discontinued on May 14 1998 Apple had announced another emulation based Mac on Unix solution called Macintosh Application Services MAS Unlike MAE MAS supported both 680x0 based and PowerPC based Macintosh software on PowerPC based Unix systems such as AIX 47 The dispatch table was indexed by the 16 bit 680x0 opcode It was perhaps the most aggressive cache user among all of MAE s components 80 Chapter 1 A Technical History of Apple s Operating Systems Meanwhile Apple continued to develop System 7 adding features and im proving existing features The Internet was burgeoning rapidly making networking capabilities an essential component of even end user ope
94. he right side for the trash can files fold ers and minimized windows Other notable components of DP4 included an inte grated development environment and OpenGL The Dock s visual indication of a running application underwent several changes In DP3 an application s Dock icon had a few pixels high bottom edge that was color coded to indicate whether the application was running This was replaced by an ellipsis in DP4 and was followed by a triangle in subsequent Mac OS X versions DP4 also introduced the smoke cloud animation that ensues after an item is dragged off the Dock 1 10 3 Mac OS X Public Beta Apple released a beta version of Mac OS X at the Apple Expo in Paris on Septem ber 13 2000 Essentially a publicly available preview release for evaluation and development purposes the Mac OS X Public Beta was sold for 29 95 at the Ap ple Store It was available in English French and German The software s packag ing contained a message from Apple to the beta testers You are holding the future 122 Chapter 1 A Technical History of Apple s Operating Systems of the Macintosh in your hands Apple also created a Mac OS X tab on its web site that would contain information on Mac OS X including updates on third party ap plications tips and tricks and technical support Figure 1 34 shows a screenshot of Mac OS X Public Beta Grab File Edit Window Help Library Sherloc
95. he volume format had a central disk catalog that con tained critical information about each file This information was replicated in a spe cial block belonging to the file Moreover each used block on disk was tagged con taining information indicating that block s logical position in the contents of the file that it belonged to Thus critical redundant information was distributed throughout the volume making it possible to recover or reconstruct information after a system crash in many cases The standard file system repair program was called the scavenger The Lisa file system supported per file attributes System generated metadata such as a file s size and creation date were stored as attributes There were APIs using which applications could define create and access their own attributes which were stored in a per file abe an early form of the resource fork in the latter day Macintosh Hierarchical File System HFS It was also possible for a program to preallocate contiguous file system space Examples of Lisa file system calls included the following e open e make_pipe e read_data e flush e lookup e allocate e truncate 32 Recall that the Alto s file system repair program was also called scavenger 48 tem configuration The system call Pascal interface was implemented in the Lisa Chapter 1 A Technical History of Apple s Operating Systems e read_label e get_working dir e device control Other set
96. herein devices were presented as ports to which data or control messages could be sent with support for both syn chronous and asynchronous I O e Acompletely rewritten IPC implementation e System call redirection that allowed a set of system calls to be handled by user space code running within the calling task e Use of continuations a kernel facility that gives a thread the option to block by specifying a function the continuation function that is called when the thread runs again Historically arguments in favor of true microkernels have emphasized a greater degree of system structure and modularity improved software engineering ease of debugging robustness software malleability for example the ability to run multiple operating system personalities and so on The intended benefits of microkernel based operating systems such as Mach 3 were offset by the significant real life performance problems that occurred due to reasons such as the following e The cost of maintaining separate protection domains including the cost of context switching from one domain to another often simple opera tions resulted in many software or hardware layers to be crossed e The cost of kernel entry and exit code e Data copies in MIG generated stub routines e The use of semantically powerful but implementation heavy IPC mechanisms even for same machine RPC Many operating systems were ported to the conceptual virtual machine pro vided b
97. ia animation audio graph ics text and so on Key described the Dynabook as a personal computer for chil dren of all ages Kay s work and ideas inspired an effort to create a personal computer at PARC in 1972 one that would be known as the Alto 8 Kay would later become an Apple fellow 25 Mac OS X Internals www osxbook com uo ng LeM JOSUsS JNA LOS ID W404 ad4n0S e BuL 1 1ed9e4 104 aupu e adi ysanba yue1g yLlurll d UJN 4 aBelLssed BurdA 10 Ydadde puewwod nuaw SuLsooyd Aq azeuLwsal yULOd NO 34ayM MOUS 11LM MALA BY UDS ay UO aJaYyMaWIOS UOJING Pas YIL1I 0 NOA 104 SzLeM a1 dwex z 1dwex gt 2uezsut sues 92 414 7U1 W 1lt4 99 41 UI a 1dwexa LAURLTGAYLUT11LL4 88ngaqg adeysaquy MB HSL 0 UCT GayLUT11L4Joedsuy a2ej 4aqUuT T o1dwexa juoljesus sue SUL jaSMO1G 99e449 UT DAUCTGSYULUTT1LIYND 4aSmMOig wazsks Mau U d Nd uagrdLg 3e 1e 11eU sasueyjingaltls 3S Sasueyd pawenetlLy weasise Ll saZueyu PLP is augNailtl powena lly wess3s91L4 saBueujInoatlLs 3S Sasueyd pawenaltlLy weas3sa tL UTALLS is sa upun pawenalLjp1o wees3seall4 Sat adedsy4om Ww S S adedsysom Waliss ddtudsues w S S dedsyIoM 4JasmMoig SL1 arts 2 o0u4d yoefoud LX Ke dsip 10 S 4 ALERT LewWS ut yDefo4ud aydwes e st styl ddtadsuesl Ww S S terface In tegrated user i In 80 i 7 The Smalltalk FIGURE
98. ichard Rashid called the UNIX kernel a dumping ground for vir tually every new feature or facility Mach s design goals were partially a response to the inexorably increasing complexity of UNIX The Mach project started in 1984 with an overall goal of creating a microker nel that would be the operating system foundation for other operating systems The project s specific goals included the following e Provide full support for multiprocessing e Exploit other features of modern hardware architectures that were emerg ing at that time Mach aimed to support diverse architectures including shared memory access schemes such as Non Uniform Memory Access NUMA and No Remote Memory Access NORMA e Support transparent and seamless distributed operation e Reduce the number of features in the kernel to make it less complex while giving the programmer a very small number of abstractions to work with Nevertheless the abstractions would be general enough to allow several operating systems to be implemented on top of Mach e Provide compatibility with UNIX e Address shortcomings of previous systems such as Accent Mach was intended to primarily implement processor and memory manage ment but no file system networking or I O The real operating system was to run Mac OS X Internals www osxbook com 103 as a user level Mach task Written in C the Mach kernel was also meant to be highly portable Mach s implement
99. ided 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 also in cluded an implementation of the X Window System Although confined within a single application Machen consisted of various sub systems similar to a full fledged operating system At the logically lowest level an inter face layer talked to MacOS The Mach kernel resided above this layer providing serv ices such as memory management interprocess communication tasks and threads Other Machen 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 both American composers Rhapsody in Blue is a famous work of Gershwin 1 9
100. inder 58 George Gershwin s brother Ira actually came up with the title Rhapsody in Blue 110 Chapter 1 A Technical History of Apple s Operating Systems OpenDoc was a cross platform component software architecture for Mac OS OS 2 Windows and UNIX It started as collaboration between several companies including Apple IBM and WordPerfect An independent association called Component Integration Laboratories CI Labs was founded to act as a forum for the open evolu tion of OpenDoc OpenDoc was implemented as a set of shared libraries that allowed construction and sharing of compound documents An OpenDoc document was composed of build ing blocks of content called components which could be interactively edited A compo nent was a relatively small software unit containing a well defined focused functionality OpenDoc aimed to replace large monolithic applications with applications constructed by mixing and matching various components Examples of OpenDoc component types include graphics Internet spreadsheet text and video components OpenDoc s im plementation of such functionality which was identified as hitherto being redundant across complex applications yielded reusable building blocks that could be embedded into OpenDoc aware documents A document could have features such as editable portions live data feed from an Internet source user interface elements that linked one part of the document to another and hot areas
101. ith Darwin Apple would continually leverage a substantial amount of exist ing open source software by using it for and often integrating it with Mac OS X Apple and Internet Systems Consortium Inc ISC jointly founded the OpenDar win project in April 2002 for fostering cooperative open source development of Darwin GNU Darwin is an open source Darwin based operating system The New Kernel Darwin s kernel is called xnu It is unofficially an acronym for X is Not Unix It is also a coincidental tribute to the fact that it is indeed the NuKernel for Mac OS X xnu is largely based on Mach and FreeBSD but includes code and concepts from various sources such as the formerly Apple supported MkLinux project the work done on Mach at the University of Utah NetBSD and OpenBSD 1 10 4 Mac OS X 10 x The first version of Mac OS X was released on March 24 2001 as Mac OS X 10 0 Cheetah Soon afterwards the versioning scheme of the server product was re vised to synchronize it with that of the desktop system Since then the trend has 124 Chapter 1 A Technical History of Apple s Operating Systems been that a new version of the desktop is released first soon followed by the equivalent server revision The first few major Mac OS X releases are listed in Table 1 1 Note that the code names are all taken from felid taxonomy TABLE 1 1 Mac OS X Versions Let us look at some notable aspects of each major Mac OS X rel
102. ition from PowerPC to the x86 platform within the next two years Apple also announced its partnership with Intel to facilitate the transition Mac OS X was demonstrated to be already running on x86 hardware during the keynote Apple has used many PowerPC generations over the years Until Apple intro duced the Power Macintosh G5 in June 2003 all PowerPC processors used by 74 Chapter 1 A Technical History of Apple s Operating Systems Apple had been 32 bit implementations The first 64 bit G5 chips namely the PowerPC 970 and 970FX are very similar to the POWER4 chips since the G5 is based on the POWER4 architecture A key difference is that the G5 contains the VMX vector processing unit VPU Moreover a single POWER4 chip has two processor cores whereas the 970 and the 970FX only have one each Apple added the dual core 970MP processor to its PowerPC offerings in the second half of 2005 1 5 2 3 Apple Likes RISC ARM As Apple was turning to RISC computing in the early 1990s it collaborated with other partners besides IBM In the mid 1980s the Cambridge based British com pany Acorn Computer Group had developed the world s first commercial RISC processor At that time ARM stood for Acorn RISC Machine The first version of the ARM architecture ARMv1 had 26 bit addressing with no onboard multiplier or coprocessor The first ARMv1 processor the ARM1 saw limited use in proto types of the Archimedes workstation an
103. k A o G if istom About This Mac bin Mac 0S 9 cores p Mac 0S X Install CD dev Gei Ad localhost amit ls sbin 3 F A SystemStarter fsck qutodiskmount fsck_hfs es ternet People oppir halt ifconfig Q init ipfw kext load File Names Co dynamic_pager kextunload fastboot kmodload Preheat Nene alindex Star el fasthalt kmodunload f T localhost amit ls l machi L amit No Index END wheel 4259 W i MacOSX Not index RER v Mac OS X InstallC Not index System Users bin cores Untitled 1 00 00 00 FIGURE 1 34 Mac OS X Public Beta Although the beta release was missing important features and ostensibly lacked in stability and performance it demonstrated several important Apple tech nologies at work particularly to those who had not been following the DP releases The beta s key features were the following Mac OS X Internals www osxbook com 123 e The Darwin core with its xnu kernel that offered true memory protec tion preemptive multitasking and symmetric multiprocessing e The PDF based Quartz 2D drawing engine e OpenGL support e The Aqua interface and the Dock e Apple s new mail client with support for IMAP and POP e Anew version of the QuickTime player e The Music Player application for playing MP3s and audio CDs e Anew version of the Sherlock Internet searching tool e A beta version of Microsoft Internet Explorer W
104. lature has fruity connotations and connections Pippin is also a vari ety of apples the fruit Pippin apples are smaller than the McIntosh variety of apples The Pippin was meant for activities such as playing back CDs surfing the Internet reading email and playing games but not for full fledged computing Its primary display was meant to be a television screen It was therefore positioned as a 130 Chapter 1 A Technical History of Apple s Operating Systems device that was more than a video game console but less than a personal com puter Apple s plan was to license the Pippin platform to third parties allowing manufacturers to build and sell their own versions The license terms were to in clude a per title royalty The Pippin s technical specifications are shown in Table 1 2 Note that of the 6MB RAM approximately 2MB was used for system software and video and the rest was available for use by titles Memory could be added via expansion cards in increments of 2MB 4MB or 8MB The few devices actually made also had 128KB of built in NVRAM of which the system software used 8KB The NVRAM was represented as a small HFS volume TABLE 1 2 The Pippin s technical specifications Processor 66 MHz PowerPC 603e processor with 3 instructions per clock cycle 8KB data cache 8KB instruction cache and IEEE standard compliant single double precision floating point unit Memory 6MB total RAM and 64KB SRAM
105. lesser extent by the Xerox STAR System Apple was made privy to many details of PARC s technologies thanks to a deal in which Xerox received Apple stock in re turn for allowing Apple to visit Xerox to observe and understand some of Xerox s work The marketing requirements for the Lisa project which was already under way when Apple visited PARC for the first time included heavy incorporation of Smalltalk concepts Apple also adopted the STAR system s Desktop metaphor along with STAR s use of icons Apple would refine and augment these concepts and use them to create a pragmatic and efficient user interface for Lisa Apple released Lisa at an annual shareholder meeting on January 19 1983 a year before the Macintosh was introduced Lisa s price was 9995 making it five Mac OS X Internals www osxbook com 41 times more expensive than the originally planned price of 2000 Apple pro claimed that Lisa would revolutionize the way work was done in office environ ments Apple also emphasized Lisa s small learning curve by claiming that a first time user could do productive work with Lisa in less than 30 minutes Apple had earlier estimated that existing computers required twenty to thirty hours of training and practice before a user could start being productive 1 3 1 1 Packaging The first Lisa system consisted of the following discrete parts e A patented compact desktop unit weighing 48 lbs it housed the com put
106. liances that can be trivially connected to the computer 36 Jef Raskin was Apple employee number 31 54 Chapter 1 A Technical History of Apple s Operating Systems e There should be no external cables besides a power cord In the ideal world there would not even be a power cord e If there are multiple models of a computer system the models should not have differences that require documentation in a user s manual e There should not be too many keys on the keyboard e There should be as few manuals as possible and even those should be small The manuals should not use computer jargon e The end user should be able to purchase the computer for no more than 500 Besides documenting his vision for an affordable appliance like computer Jef Raskin also put together a capable initial team in late 1979 to pursue his Macintosh project However Raskin left the project and some time later the company be fore Macintosh could become substantial Steve Jobs who took over would be the driving force behind the Macintosh product Steve Jobs unveiled the Macintosh on January 24 1984 at the Flint Center in De Anza College Cupertino The occasion was Apple s annual shareholders meet ing Jobs opened the meeting by reciting lines from Bob Dylan s song The Times They Are A Changin Come writers and critics Who prophesize with your pen And keep your eyes wide The chance wont come again And dont speak too soon For the wh
107. ling rate 512x342 pixel bit mapped black and white display on a 9 inch diagonal CRT screen Physical dimensions of 13 6 x9 6 x10 9 with a weight of 16 lb 8 oz 7 5 kg and a logic board area of 80 square inches No internal fan known as Mac System Software which resided on a single 400KB floppy disk Many Macintosh programs were either conversions of or influenced by Lisa pro grams Examples include MacPaint MacProject and MacWrite Unlike Lisa the Macintosh was not designed to run multiple operating sys tems The Macintosh ROM contained both low level and high level code The low level code was for hardware initialization diagnostics drivers and so on The higher level Toolbox was a collection of software routines meant for use by applica tions quite like a shared library Toolbox functionality included the following Management of dialog boxes fonts icons pull down menus scroll bars and windows Event handling Mac OS X Internals www osxbook com 57 e Text entry and editing e Arithmetic and logical operations The Lisa derived QuickDraw portion of the Toolbox contained highly opti mized primitives for drawing shapes and user interface elements The use of com mon system provided user interface routines ensured a consistent and standard user interface With time the Toolbox would have an incredible amount of functionality and associated APIs packed into it obstructing Apple s attempts to crea
108. lists program source files and library catalogs could be effectively searched through this subsystem 1 2 5 3 NetExec There also was a networked version of the Executive the NetExec that loaded programs from a boot server available via the Ethernet rather than from the local Mac OS X Internals www osxbook com 33 disk One could query available facilities by typing lt gt Examples of utilities typi cally available through the NetExec included the following e Scavenger was a program that rebuilt the file structure but not the con tent of an Alto disk It was analogous to the UNIX fsck program It checked disk packs while attempting to correct erroneous header blocks checksum errors and other problems It prompted the user for confirma tion in most cases It could discover all well formed files and all free pages verify that the serial numbers of all well formed files were dis tinct and link all irrecoverably bad pages together as part of the file Garbage Scavenger was available from the NetExec as an emer gency remedial measure in case the local disk was rendered unbootable e Chat was a subsystem that allowed teletype like interactive access to a remote computer on the network It included an extension to support text display control and graphics similar to the latter day telnet pro gram e CopyDisk was a standalone program used to transfer the entire contents of a disk either between computers or betwe
109. lly user confirmed replacement of the found text and its properties The STAR system was rather expensive with a base configuration initially costing 16 500 1 3 THE GRAPHICAL AGE AT APPLE Apple was instrumental in making personal computing affordable for the masses with the Apple However even after the Apple s success computers were diffi cult to learn for most people a fact that was perceived by Apple and many others as a large impediment to computer use The Lisa Local Integrated Software Archi 29 Window overlapping was allowed and in fact was turned on by default in STAR s successor View Point A0 Chapter 1 A Technical History of Apple s Operating Systems tecture project began at Apple in 1979 to create an integrated stand alone single user and easy to use microcomputer 1 3 1 Lisa Lisa s goals included the following e Be intuitive e Be consistent e Provide an integrated environment that was in line with people s day to day work e Provide sufficient performance without being overly complex or exorbi tantly priced e Provide an open architecture to make it easy for Apple and third parties to develop additional hardware and software e Be reliable e Be aesthetically appealing and not out of place in a typical work envi ronment As we noted at the beginning of Section 1 2 Lisa was greatly inspired by the work done at Xerox PARC especially by the Smalltalk environment and to a
110. n e NetExec 22 The character which was used for identifying Executive commands was illegal in a filename 32 Chapter 1 A Technical History of Apple s Operating Systems e Quit e Rename OldFileName NewFileName e Scavenger e SetTime e Type FileName The Executive supported powerful command line editing and filename expan sion The user could refer to a set of files by specifying patterns containing special characters such as and which the Executive expanded The Executive displayed a digital clock and other useful status information such as the versions of the oper ating system and the Executive itself the owner s name the disk s name the Ether net address of the Alto and the number of free pages on the disk When a user called another program from the Executive the display was erased and replaced by that of the called program The operating system invoked the Executive whenever a program finished running or specifically whenever the BCPL operator finish or equivalent was executed Figure 1 11 shows an example of the Executive s prompt XEROX Alto Executive 11 May 18 1981 786 Pages OS Version 18 16 Alto 0 377 gt eventBooted gt FIGURE 1 11 The Alto Executive s prompt The Alto s Find subsystem allowed fast pattern based file searches Special purpose files such as address or telephone
111. next generation microkernel that would run on any architecture As the Star Trek project was being cancelled it was considered for absorption by Raptor which itself would die due to budgetary limitations and employee attrition among other reasons 1 6 3 NuKernel NuKernel was a kernel project at Apple that was meant to result in a modern operat ing system kernel on more than one occasion 1 6 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 Serv ices TalOS was the name given to a set of lower level technologies that were to be built around Mach 3 0 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 in terfaces text documents graphics multimedia fonts printing and low level serv ices such as drivers These along with the TalOS development tools explicitly 86 Chapter 1 A Technical Hi
112. nly privileges whereas the other would be able to modify the display 1 2 3 9 The Result Engelbart stated that NLS was a vehicle to allow humans to operate compose study and modify within the domain of complex information structures where content represents concepts NLS was meant to be a tool to navigate complex struc tures something linear text could not do well Perhaps no discussion of individual components of NLS can convey how awe inspiring the overall system that resulted from the integration of these parts was NLS is best understood and appreciated by watching a record Ing of the NLS demonstration Engelbart was also involved in the creation of the ARPANET the precursor to the Internet His team planned to create a special ARPANET service that would provide relevant network information For example the service would answer ques tions such as the following Who is providing what services What protocol do I use to get there Who is down in the networking sense today and who is up ID Recordings of the NLS demonstration are available online at a Stanford University web site http sloan stanford edu mousesite 1968Demo htm1 16 The ARPANET began life in the late 1960s as a network consisting of only four computers or net work nodes It was started by the U S Department of Defense Advanced Research Projects Agency DARPA SRI hosted one of the network nodes Mac OS X Internals www osxbook com 21
113. nt a continuous stream of ASCII characters on the display Typing 0 A prints a listing of the program and typing R runs the program FIGURE 1 2 The Apple Te firmware resident system monitor Compared to the UNIX general purpose time sharing system which was in its Sixth Edition then the Apple I s operating environment was decidedly puny How ever a contemporary computer system running UNIX would have cost many thou sands of dollars The Apple I was an attempt to make computing affordable for hob byists and as those behind it hoped for the masses Within the first nine months of the Apple I s introduction all but a few of the two hundred or so units manufactured had been sold 6 Chapter 1 A Technical History of Apple s Operating Systems 1 1 2 Apple 1 The Apple I had a life span of less than a year but its successor would live much longer Wozniak soon began work on the Apple J Although based on the 6502 processor as well the Apple was introduced as an integrated computer it came completely assembled in a beige plastic case The contents of the original Apple package included the following e An Apple J P C Printed Circuit Board complete with specified RAM memory e AD C power connector with cable e A 2 speaker with cable e A Preliminary manual e Two demonstration cassette tapes e Two 16 pin headers plugged into locations A7 and J14 on the Apple JI board Latter models varied in their
114. ocess management system calls included the following e make_process e kill_ process e activate process e suspend_process e info process e setpriority process e yield_process e sched class System level exceptions resulted in the termination of a process a side effect of the execution of default exception handlers Processes could install custom ex ception handlers which were invoked with detailed exception context Examples of Lisa exception management system calls included the following e enable excep e disable excep e declare excep bal e Signal excep Interprocess Communication By default a process was not allowed to access the logical address space of another process Interprocess communication was possible through multiple mechanisms such as events shared files and shared memory Events were structured messages consisting of a system attached header and a sender provided data block transmit ted between processes over named channels A process could listen on a channel waiting for messages to arrive Alternatively a process could register an exception handler and arrange for an exception to be generated upon message arrival 46 Chapter 1 A Technical History of Apple s Operating Systems Examples of Lisa event channel management system calls included the fol lowing e make_event_chn e kill event ehn e open event cChn e Close event chn e Walt event hn e Send event chn Memory Management Lisa
115. ok com 133 composite video output RCA stereo audio output and SCSI HDI 30 1 11 2 Newton OS Newton was a software and hardware technology that Apple created for a family of PDAs and PDA like products Apple s line of hand held computing devices such as models of the MessagePad and the eMate 300 ran the Newton operating system Newton also ran on clone devices The MessagePad was physically similar to a latter day Personal Digital Assis tant PDA with an active LCD screen for on screen tapping writing and drawing The original model was introduced in 1993 with Newton OS 1 0 It had a 20 MHz ARM 610 processor 640KB RAM and 4MB ROM The last model the MP2100 was introduced in late 1997 It had a 161 9 MHz StrongARM processor 8MB RAM and 8MB ROM It ran Newton OS 2 1 The eMate was a portable computer with a 480x320 pixel active LCD screen and a keyboard Its screen had a 0 30 mm dot pitch supported 16 levels of gray and had a yellow green luminescent backlight The Newton System Software was logically divided into three parts Newton OS at the lowest level System Services and Application Components 1 11 2 1 Newton OS The operating system was preemptive and multitasking It could be considered as a modular set of tasks each dedicated to specific functionality such as scheduling task management inter task communications memory management power man agement and various interactions with hardware A low lev
116. on e Neptune was a utility program for managing files and directories e Officetalk was an experimental forms processing system that inspired the Xerox STAR system Alto used file extensions to conventionally indicate file content types A file extension was a filename s trailing portion following a period It could be null Examples of such extensions include log program action history mail Laurel mail file run BCPL program executable et Smalltalk source file and syms BCPL symbol table file Alto filenames could be at most 39 characters in length 1 2 5 6 Networking The development of inter network communication facilities at PARC led to a packet format called PARC Universal Packet or Pup Besides the name of the abstract de sign of the packet format Pup also represented the corresponding inter network architecture which included a hierarchy of protocols The standard Pup format is shown in Figure 1 12 Pup influenced the creation of the TCP IP protocol suite 25 A subsequent mail program for an Alto successor machine was called Hardy Mac OS X Internals www osxbook com 35 gt 1 byte 1 byte Pup Length Transport Control Pup Type Pup Identifier Destination Network Destination Host i f Pup Header 20 bytes Destination Port Destination Socket D Source Network Source Host R Source Port Source Socket t H Packet Contents Conterits 0 532
117. on always stayed on top and held frequently used applica tions Other NEXTSTEP features included the following e The ability to hide applications instead of quitting them 50 The Mach implementation in NEXTSTEP included NeXT specific features as well as some features from later versions of CMU Mach Mac OS X Internals www osxbook com 93 CD quality sound A versatile mail application that supported voice annotation of messages inline graphics and dynamic lookup of email addresses over the network Drag and drop of complex objects between applications A services menu that could be accessed from various applications to pro vide services such as dictionary and thesaurus A Digital Librarian application that could build searchable indexes of content dragged to it A file viewer that extended across the network An object oriented device driver framework called the Driver Kit NEXTSTEP used drag and drop as a fundamental powerful operation It was possible to drag an image from say the mail application to a document editing ap plication such as WordPerfect Conversely you could drag a spreadsheet to the mail application to attach it with a message Since the file viewer was network capable a remote directory could be dragged as a short cut on the user s desktop specifically on the shelf NEXTSTEP used Objective C as its native programming language It included Interface Builder a tool for designing appli
118. ood 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 NeXT as well as their user and devel oper 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 This chapter discusses operating systems that Apple has created in the past those that it attempted to create and some that influenced or in spired Apple In this discussion we will come across several technologies whose confluence eventually led to Mac OS X 2 Chapter 1 A Technical History of Apple s Operating Systems 1 1 FIRST BYTES INTO AN APPLE As 1975 came to an end Steve Wozniak had finished his prototype of a home brew computer built using inexpensive components Hewlett Packard Wozniak s em ployer at that time was not interested in his creation Wozniak requested and was soon granted a release of the technology On April first 1976 Steve Jobs Steve Wozniak and an Atari engineer named Ronald Wayne founded Apple The com pany s first product was Wozniak s computer the Apple I 1 1
119. ooperative multitask ing as they would on a real Macintosh Moreover there was no memory protec tion MAE had several behavioral similarities to A UX It made UNIX file systems visible as Mac OS volumes UNIX symbolic links were represented as aliases A MAE user could launch UNIX commands from the Finder Since MAE had neither a real Macintosh compatible graphics card nor a real monitor its graphics component had to provide an illusion to the Macintosh soft ware running within it It implemented a virtual Macintosh monitor as a frame buffer which was updated as a result of applications making QuickDraw calls with QuickDraw in turn notifying MAE of the parts of the bitmap that had changed In early versions of MAE the entire framebuffer was passed to the X Window system In version 3 0 of MAE updates to the framebuffer were translated to Xlib calls that were sent to the X server MAE included the following primary components e The main executable apple bin mae the auxiliary daemon other native UNIX code and related data e The MAE engine apple lib engine which included code for the Mac OS ROM Toolbox 680x0 glue code and related data e Mac OS system code application code and data e The MAE X Window graphics buffer Mac OS X Internals www osxbook com 79 The glue code mapped Mac OS operations to UNIX system calls The MAE engine and associated data were mapped into memory using the mmap system call If t
120. ortalPlayer s PP50xx chip which contains two ARM7T DMI processor cores Its embedded operating system along with its encoding and decoding components also come from PortalPlayer 136 Chapter 1 A Technical History of Apple s Operating Systems Pixo s software particularly the Toolbox provided the foundation on which the iPod s user interface was originally designed and implemented by Apple The Pixo Toolbox provided modules for memory management low level graphics such as bitmaps boxes lines and text Unicode collection classes resource database and standard libraries Pixo s range of applications included Address Book Calcula tor Calendar Email Graphical World Clock Memo Maker Todo List and PC Syn chronization
121. ouncement in November 1983 Microsoft s selling point was that Windows provided a new software development and runtime environment that used bitmap displays and mice thus freeing the user from the MS DOS method of typing commands at the C prompt C 14 Chapter 1 A Technical History of Apple s Operating Systems 1 2 1 Memex Vannevar Bush published an article titled As We May Think in the July 1945 edition of The Atlantic Monthly Bush was then the Director of the Office of Scientific Research and Development in the United States His article described among sev eral incredible visionary insights and observations a hypothetical device Bush had conceived many years earlier the memex The memex was a mechanized private file and library a supplement to hu man memory It would store a vast amount of information and allow for rapid searching of its contents Bush envisioned that a user could store books letters re cords and any other arbitrary information on the memex whose storage capacity would be large enough The information could be textual or graphic Other features of the memex included the following e It would be incorporated into an ordinary looking desk thus fitting in the user s normal work environment Its user interface would consist of a keyboard buttons levers and translucent projection screens e Its primary storage medium would be microfilm e New material would be primarily available for purchas
122. owsing and authoring The browser was developed on a NeXT computer Tim s collaborator Robert Cailliau later said that Tims prototype implementation on NEXTSTEP is made in the space of a few months thanks to the qualities of the NEXT STEP software development system At the 1992 NeXTWORLD Expo NEXTSTEP 486 a 995 version for the x86 was announced The last version of NEXTSTEP 3 3 was released in February 1995 By that time NEXTSTEP had very powerful application development facilities courtesy of tools such as the Project Builder and the Interface Builder There existed an exten sive collection of libraries for user interfaces databases distributed objects multi media networking and so on NEXTSTEP s object oriented device driver toolkit was especially helpful in driver development Figure 1 26 shows a screenshot of NEXTSTEP Mac OS X Internals www osxbook com 95 RenderManager o 38 ftp CIA E ftp gt o sunsite unc edul H N lt v thought th ti think ing D C SS a SS Servers CDPlayer app localhost NextDeveloper Ken FIGURE 1 26 NEXTSTEP NEXTSTEP ran on the 68K x86 PA RISC and SPARC platforms It was possible to create a single version of an application containing binaries for all sup ported architectures Such multiple architecture binaries are known as fat binari esl Despite the elegance of NeXT s hardware and the virtues of NE
123. phing Calculator 3 MB D EI Mac os 13 M em em Track Elapsed Time me mmm n SES ES ee GERD ONC OSOEDES DER EERE SED SD ESEUEB FIGURE 1 30 Mac OS 9 1 9 2 Rhapsody We saw that after acquiring NeXT Apple based its next generation operating sys tem called Rhapsody on NeXT s OPENSTEP Rhapsody was first demonstrated at the 1997 World Wide Developers Conference WWDC Figure 1 31 shows a screenshot of Rhapsody 114 Chapter 1 A Technical History of Apple s Operating Systems AAA Virtual PC Rhapsody File Edit view Tools Window Services Help 6 31PM A D Workspace Mana es v A European Keys iCKi rnapsody ca deer ZE Canna Japanese input hidden RHAPSODY INSTALL etc profile Syster lib 1 Local bin mach Net cores mach_kernel Network dey private L zhapsody ls las ach_kernel See Demos System Administration Applications Demos Developer Documentation Library Apple Computer Inc DEVELOPED WITH YELLOW BOX FIGURE 1 31 Rhapsody Rhapsody consisted of the following primary components The kernel and related subsystems that were based on Mach and BSD A Mac OS compatibility subsystem the Blue Box An extended OpenStep API implementation the Yellow Box A Java virtual machine A Display PostScript based windowing system e A user interface that was Mac OS like but also had features from OPENSTEP Mac OS X Internals www osxbook com 115
124. pple was introduced in 1980 as a computer for business users Apple originally planned to ship the Apple with a suite of office programs a spread sheet a word processor a database program and a business graphics program However the Apple shipped late and initially ran only the VisiCalc spreadsheet program It had a new operating system called SOS 1 1 3 1 Apple SOS SOS officially stood for Sophisticated Operating System although it was appar ently an acronym for Sara s Operating System named after an engineer s daugh ter Every SOS program loaded the operating system into memory A SOS applica tion disk consisted of a kernel SOS Kerne1 an interpreter SOS Interp which could be the application itself or something that the application used and a set of drivers SOS Driver Unlike the Apple IL which used ROM based device drivers 6 CP M was created by Gary Kildall who founded a company called Intergalactic Digital Research to market the system 7 Unrelated to Mac OS 9 8 Pronounced sauce which would make it Apple Sauce Mac OS X Internals www osxbook com 11 such as those residing on I O card ROMs SOS device drivers were RAM based and could be installed which was a first for a commercial operating system at that time Figure 1 4 shows a screenshot from SOS FIGURE 1 4 Apple SOS The Apple also had a Pascal system that was derived from Apple
125. py paste and cut paste operations commands Mac OS X Internals www osxbook com 49 The Clipboard was implemented as a globally shared data segment accessible by all processes Data was stored in the Clipboard in multiple formats including a generic format that could be used by a process that did not understand the application specific version of that data There were graphic representations icons of objects typically found in an office environment such as files folders blank stationery clipboard and trash can or wastebasket The icons were active in that they could be clicked They were used to represent both objects and tasks Double clicking on a folder icon would display the folder s contents in a window whereas double clicking on a document icon would launch the appropriate application to open the document each docu ment could have an associated application with it The resultant windows came up animated An object could be renamed by pointing at its icon and simply typing the desired name New folders and documents were created by tearing off items from pads of empty folders and documents respectively Items were deleted by dragging them to a trash can icon Figure 1 15 shows a screenshot of Lisa s user interface Advanced Features In addition to bringing graphical user interfaces to mainstream computing Lisa was among the first to provide software controls for hitherto mechanical ones It had instant on c
126. r 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 sys tem 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 ad dress spaces and several other modern features After languishing for many years at Apple Pink would move out to Zaligent a company jointly run by Apple and IBM We will briefly discuss Taligent in Section 1 6 4 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 were drawing to an end the system software was at major ver sion 6 System 7 a result of the Blue project would be Apple s most significant system yet both relatively and absolutely However that would not be until 1991 Apple would come out with two interesting operating systems before that GS OS and A UX In 1989 Apple introduced a system call named Gestalt in version 6 0 4 of the operating system Gestalt allowed applications to dynamically query the capabilities that were present in a running system configuration It would go on to become a widely used system call and continues to exist in Mac OS X as a Carbon function 62 Chapter 1 A Technic
127. r login Classic startup OpenGL and Java Other key features of this release included the following e The ability to move the Dock from its usual place at the bottom to the left or right e System status icons on the menu bar to provide easier access to com monly used functions such as volume control display settings date and time Internet connection settings wireless network monitoring and bat tery charging e iTunes and iMovie as part of system installation and the introduction of iDVD e Anew DVD player with a simplified interface e Improved iDisk functionality based on WebDAV e A built in image capturing application to automatically download and enhance pictures from digital cameras 126 Chapter 1 A Technical History of Apple s Operating Systems e The ability to burn over 4GB of data to a DVD with support for burning recordable DVD discs directly in the Finder e An integrated SMB CIFS client The Carbon API implementation in 10 1 was complete enough to allow impor tant third party applications to be released Carbonized versions of Microsoft Of fice Adobe Photoshop and Macromedia Freehand were released soon after 10 1 s release 1 10 4 3 Mac OS X 10 2 Jaguar was released at 10 20 pm to emphasize its version number Its important feature additions included the following e Quartz Extreme an integrated hardware acceleration layer for rendering on screen objects by compositing them using primarily th
128. rating systems System 7 5 and later included OpenTransport a networking subsystem based on Mentat Port able STREAMS Other noteworthy features added to Systems 7 5 x included QuickDraw 3D a Java runtime and the OpenDoc component software architecture that could be lik ened to Microsoft s Object Linking and Embedding OLE Visual enhancements such as a startup screen with a Mac OS logo and a progress bar were also added around this time In the 1990s Apple also made some forays into server computing Let us briefly look at some of these endeavors 1 5 5 Apple Workgroup Server Apple Workgroup Server was a line of servers intended for use as file print and database servers for workgroups These systems were initially 68K based but PowerPC based systems were also available eventually The following are some examples of systems from this line e WGS 60 50 25 MHz Motorola 68040 used System 7 1 ran AppleShare 4 0 and was targeted at small businesses and classroom lab environ ments e WGS 80 66 MHz Motorola 68040 used System 7 1 ran AppleShare 4 0 and was targeted at medium sized business environments where it could act as a communications server for example as an Internet router and a SNA ps X 25 or X 400 gateway e WGS 95 66 MHz Motorola 68040 used A UX 3 1 as the server operat ing system ran AppleShare Pro and was targeted at large or data intensive workgroups for example as a high performance AppleShar
129. rial ports and three expansion slots on the motherboard that could be accessed by removing the main unit s back panel It also had a composite video output allowing it to be connected to compatible ex ternal monitors 1 3 1 6 Lisa OS Lisa was introduced with a proprietary operating system the Lisa Office System or Lisa OS and a suite of office applications Several aspects of Lisa s software would become part of Apple s systems to come and in fact many such concepts exist in Mac OS X in some form Lisa was not tied to a particular operating system Unlike its successor the Macintosh Lisa did not have portions of the operating system in ROM This al lowed it to support multiple operating systems It presented the user with an interac tive screen called the Environments Window if multiple bootable environments for example Lisa OS and Lisa Workshop were found on attached storage devices At the time of Lisa s release Apple announced that Microsoft had been working on a version of Xenix for Lisa Eventually SCO Xenix was available for Lisa Most of Lisa s system and application software was written in an extended version of Pascal Lisa Pascal During Lisa s development Apple even considered using a p Chip that would run p Code natively Lisa OS was designed to support Lisa s graphical user interface Figure 1 14 shows a logical view of Lisa s software architecture 44 Chapter 1 A Technical History of Apple
130. ro csessetenavaryieavieste i atibege Deene diester A eee ts 74 1 5 2 1 A RISCy Look DIC iit aia eebe ee 74 1 5 2 2 Apple Wants RISO iticciidiebictecsnyece tuietieeiivva i EEEE ERE E E 76 1 5 2 3 Apple Likes RISC ADM 78 1 5 3 Mac OS for Power PO daeina ianen tseden aea aera eniin asoa yanana Raah 79 1 5 4 E 80 1 5 5 Apple Workgroup Serve ccccccsceeeeeceteneeeeeaeeeseaeeeseaeeeseeeeseaeeeteaeeeeaas 84 1 5 6 NetWare for Powerbt tenses eeeeeeeneeetenaeeeeeaeeseeaeeeeeaeeee 85 135 7 ALX for POWerP Gin ise ha eet anata aeai 85 1 6 Quest for the Operating SyStem cs eeecceseeeeeeeeeeeeeeeeeeees 87 1 6id Stare OKs geet eke eet E el Satta du Sti dace 88 Bee e EE 89 1 6 3 NUKeMeh eu sepa Aisle chins A aed a denge ENEE ENEE 89 1 6 4 Tale et naiesieteat ehexchedscceviines a a a aE a aai 89 1 6 5 COPAN daas e eeraa ea niin ae a aaa e ae e a aaea 90 1 6 6 Gers hW eaire aaea aasta a i iaka na Aa a a aaas 93 16 7 BOOS fees tiy hoiran ut ennaii eatea a ee aa aa iea eaaa iaaiaee 93 16 8 PaA EE 95 1 7 The NeXT Chaplet aeietete geiergert 95 e al NEXTSTE EH 96 17 2 OPENSTE P res alle ane ei eA 101 1 8 The Mach Fartot eu tse egetgeurseenekkkukSkgr ueEEe edee NC Ce eEgNlEketueCEg 102 1 8 1 Rochester s Intelligent Oateway 103 18 2 ACCOM ets catia Aa Ee te eaten ee 104 TEI Mach geed a ed de es EE 106 1 8 4 Mk mus 111 1 8 5 Musical N mes cccccccececcceeeeeececeeeeeeeeeeeeeeeseeeeeeeensaeeeeeseseeneeneeneieeeeeten
131. s 112 1 9 SUaAteGl6S seiccuis ciisisess sisi svc sdacecciadevnneniautivanraasnesdsavsdenssansadivcavean 113 1 9 1 Mac ee EEN 115 1 92 ele EE 117 139 234 BIUC BOX EE 119 Mac OS X Internals www osxbook com 3 1 922 YEUOW BOX eee aaa dee a e ee aiaa EEE AE A E apaa a E EEE 120 1 10 Towards Mac OS leese 121 1 10 1 Mac OS X Server Xisescccccdevessiviveusasscccvervensaceasevenccccansaecrcaueeyanceacexve EE 123 1 10 2 Mac OS X Developer PDreviews 123 EE DP EE 123 PAO2 2 RE 124 TEV OPS Eben 124 VAO2 E D e oi voici Danie seins ea en de dee ae 125 1 10 38 Mac OS X Public Beta sess cs ciiusassestonsteesscvctiesssaveeansdsccweasaisaseutenaaaaveens 125 1 104 Mac OS X TO KEE 127 1 104 1 MaC OS X 10 ME 128 1 10 4 2 Mac OS KIT 129 1 10 4 3 MacG OS X J0 Eessen REENEN 130 TT 131 1 10 4 5 MacOS X 10 4 E 131 a a R E dn 133 1 11 1 Mac OS on the Pipopin ccc cee ee eeeeeeeceeeeeeeeeeeeeeeeseaeeeseaeeeseaaeeeeaes 133 1 11 2 Newton OS 137 1 11 21 Newton OS EE 137 1 11 2 2 System Gervdces AAA 138 1 11 2 3 Application Components 138 1 11 3 The iPod s Operating Gvstem 139 A Technical History of Apple s Operating Systems CHAPTER 1 A Technical History of Apple s Operating Systems Most ideas come from previous ideas Alan Curtis Kay T he 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 g
132. s Operating Systems Lisa OS was designed to support Lisa s graphical user interface Figure 1 14 shows a logical view of Lisa s software architecture CsePriect dawe Applications HisaTerminal Desktop Manage lisaCale gt LisaGraph lt LisaDraw gt Table Editor Print Manager Alert Manager Printing Window Support Manager Font Manager Floating Point Support Pascal Library PasLib Exception File Memory Process Handling Management Management Management Hard Disk Drives b Floppy Diskettes Database Routines RAM MMU CPU Display Peripheral Devices FIGURE 1 14 Lisa s software architecture Process Management Hardware Interface ai Library __ nput Device Interrupts Core OS Hardware Lisa OS implemented non preemptive multitasking Although the scheduling algo rithm was simple in the absence of preemption it supported process priorities A process could only be created by another process except the initial process which was created by the operating system as the shell process upon booting The shell process ran the Desktop Manager application by default The system s process management API included calls for creating terminating suspending and resuming Mac OS X Internals www osxbook com 45 processes Terminating a process also resulted in the termination of all its descen dants Examples of Lisa pr
133. s a low cost shrinkage of POWER onto a single chip whereas the others were multiple chip The lowest end RS 6000 model the 33 MHz Model 220 was released in January 1992 In the early 1980s Berkeley and Stanford Universities were working on the RISC and MIPS projects respectively By 1990 there were several competing RISC architectures in the market MIPS HP Precision Architecture PA RISC SPARC V8 Motorola 88K and IBM RS 6000 The Intel i860 was introduced in 1989 as a general purpose 64 bit RISC processor with 3D graphics capabilities The Alpha AXP from Digital Equipment Corporation joined the RISC crowd in 1992 as another 64 bit RISC processor 1 5 2 2 Apple Wants RISC As part of a project code named Jaguar Apple had briefly considered using a Mo torola 88K variant as their future RISC based hardware platform They turned to the POWER architecture next In 1991 Apple IBM and Motorola joined forces to form the AIM Alliance with the goal of creating a Common Hardware Reference Platform CHRP The collaboration resulted in the PowerPC Architecture a derivative of POWER Pow erPC included most of the POWER instructions while adding some new ones and excluding some rarely used instructions Important PowerPC improvements in cluded the following e It supported both 32 bit and 64 bit computing with an implementation being free to only implement the 32 bit subset An implementation sup porting both would be able to
134. s of system calls included those for timers and for manipulating sys Operating System library The Graphical User Interface Perhaps the best known aspect of Lisa is the graphical user interface GUI of the Lisa OS The system s shell the Desktop Manager used icons of documents and folders to act as an electronic analog of a real desk with a filing system Some noteworthy aspects of the user interface included the following 33 Lisa s menu bar did not have the Apple menu found in latter systems However menu commands did use an Apple symbol Apple later started using the cloverleaf symbol the cmd key for menu Multiple overlapping windows Hierarchical pull down menus A menu bar that was always visible at the top of the screen and changed automatically as the active application changed revealing options that were relevant to that application Dialog boxes for prompts error messages and other interactions with the user Horizontal and vertical scroll bars Use of the mouse for pointing clicking double clicking dragging and selecting optionally in conjunction with key presses A cursor whose shape changed depending on its current function Special or modifier keys on the keyboard including the Apple key with support for direct invocation of frequently used menu commands from the keyboard Editing commands such as copy cut paste and undo A scrap folder called the Clipboard for use by co
135. s would be shipped with future releases of their existing system beginning with the upcoming System 7 6 whose name was formally changed to Mac OS 7 6 Mac OS X Internals www osxbook com 89 1 6 6 Gershwin After the Copland debacle Apple s need for a new operating system was direr than ever Focus shifted briefly to a project named Gershwin which was to include the painfully elusive memory protection among other things However it was appar ently nothing more than a codename and it is believed that nobody ever worked on Gershwin 1 6 7 BeOS Apple briefly considered partnering with Microsoft to create an Apple OS based on Windows NT Other systems under consideration were Solaris from Sun Microsys tems and BeOS from Be In fact Apple s acquisition of Be came rather close to ma terializing Be was founded in 1990 by Jean Louis Gass e Apple s former head of Prod uct Development Be s capable engineering team had created an impressive operat ing system in BeOS It had memory protection preemptive multitasking and sym metric multiprocessing It even ran on the PowerPC thus fitting with Apple s hardware agenda BeOS was designed to be especially adept at handling multime dia It had a metadata rich file system called BeFS that allowed files to be accessed via multiple attributes However BeOS was still an unfinished and unproven prod uct For example it did not yet support file sharing or printing and only
136. sa s user interface standards An Icon Named Trash The Macintosh trash can is sometimes criticized for being poorly designed as it is not only meant to destroy files but also for ejecting disks so that they can be safely put away Apple s interface designers once explained the rationale behind this design Since the original Macintosh only had a single floppy disk drive and no hard disk it was expected that users would typically use several diskettes while working on the Macintosh A convenience feature of the system was that it cached in memo ry the list of files on a diskette The cache was retained even after the diskette had been ejected A grayed out Desktop icon for that diskette indicated this fact Clicking on such an icon prompted the user to insert the appropriate diskette in the drive Drag ging a grayed out icon to the trash freed up the memory used by that diskette s cache Thus even if a user intended to permanently eject a diskette two actions were required the eject command and dragging an icon to the trash The redundancy was removed by combining these actions to a single action dragging an active non grayed out icon to the trash caused the diskette to be ejected and its cache to be de leted Mac OS X Internals www osxbook com 59 At its introduction the Macintosh was targeted for two primary markets knowledge workers and students Referring to the telephone as the first desktop appliance
137. sensnsssesessaseceseeeeeerers 24 1 2 3 9 The eendeitege dE aol aie nied La A heli dee 24 ET 25 12275 XOTOX Alt E 30 TEE ege ees Ee See ege 33 12 9 2 AO Eeer eeg een deeg Eet eegend ae ege 35 U 36 1 2 5 4 Programming Facilities 0 0 eeetceeceteeetseeeeeteneeeteneeeeseeeeteneeetenaeeeseeeeeenneeteaaes 37 12 0 5 ADPliCaliOns an a a sain al eat oceans 38 T 2 5 6 NCLWOTKING ET 38 n 40 1 2 6 Xerox STAR Gvsiem 41 1 3 The Graphical Age at Apple c sscccccseeseeeeeeeeeeeeeseeneeeeenees 43 KC E EE 44 1 3511 PACKAGING stevie chi nea ee a ed 45 1 3 1 2 Processor and MOMOP ccccscccccecscnesereneesnenenenensuonenesaneneneaensnenenenvanenenes 45 1 3 1 3 DiSpla yta a i a a eer Ae Ae 46 181i Stora EE 46 VBALS EXPaniSlOn n gt tise AE AE Eden aa levees ewe pete PR ae 47 2 A Technical History of Apple s Operating Systems SE EE 47 133 17 Li8a WOrKSNOD EE 55 TABS EISAS Fale sc caziiesvat is case vies idea ce dace dunes besten pea aa ten Eiaa kaa AR a S 56 1 3 2 Ehe Macintosn visti aati d aie Satie ae 57 1 4 Many Systems for Many Apples eecceeeeeeeseeeeeeeeeeeenees 63 1 4 1 System Software Releases 2 8 63 1 4 2 What Color is Your Gvstem 65 TA SAG SIOS eieia hectic deer el heated tele eas et teil aia ted eaten T 66 VAAL AIK eee ete EN Ne ees te ke SN Se ERAS 68 1 5 Seeking POWGS Mis saiecsssawenscsieteniats ous cacsuba nce wiiaidneensbaacwtinmaltiwatengi 72 E EE 72 1 52 AIM tor POWER ot
138. server approach the monolithic Linux kernel ran as a single Mach task Mac OS X uses a kernel base derived from osfmk and includes many MkLinux enhancements However all kernel components in Mac OS X in cluding the BSD portions reside in the same address space Machten Besides A UX there was another avenue a third party one on which the Mac intosh had close encounters of the Unix kind The Machen product from Tenon Sys tems was introduced as an unobtrusive Unix solution for MacOS it ran as an applica tion atop Apple s operating system In contrast A UX ran directly on top of hardware Machen was based on the Mach kernel with a BSD environment It provided preemptive multitasking for Unix applications running within it although the MacOS execution environment remained cooperative multitasking 108 Chapter 1 A Technical History of Apple s Operating Systems Although the marriage of Mach BSD and Macintosh in Mach 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 Machen 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 prov
139. sions so you will be able to boot your Macintosh correctly Warning Incorrect use of this control panel may cause problems with your Macintosh Sets wi WorldScript II wi WorldScript Power Adapter wi Applevision Control Panels wi Apple Menu Options v Auto Power On Off wi dAutoRemounter wi Cache Switch wi Close i V ColorSe Reminder to self 3 wi Control Upgrade to Mac OB X HIER About This Macintosh Note Pad Unde Dear Reader Hel MacTCP Ether Talk 0 Ethernet Poo wEaED FIGURE 1 21 System 7 24 Macintosh AppleCD Audio PL 334k HD Total Memory 32 768K Largest Unused Block zax D 120k H System Software 3 504K el System Software 7 5 5 Apple Computer Inc 1983 1995 System 7 also had several usability improvements such as the following e Users could view and switch between running applications via a menu e The trash can now had the same status as any other folder It now had to be proactively emptied instead of the system automatically emptying it e In addition to cut and paste text selections could be dragged between applications e Aliases could be created for access to documents and applications from two or more locations e Control Panels and Extensions were organized hierarchically on disk Certain machines such as the Macintosh Il IIx Ilcx and the SE 30 could 70 Chapter 1 A T
140. story of Apple s Operating Systems strived to shift the burden of programming from application developers to applica tion system engineers Note that even though there existed other commercial systems such as NEXT STEP that had object oriented application frameworks Taligent aimed to build its entire programming model around objects In NEXTSTEP the developers who cre ated frameworks had to map object behavior to the underlying libraries Unix sys tem calls Display PostScript and so on all of which had procedural APIs In con trast Taligent s CommonPoint applications were not meant to use the host OS 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 seek ing 1 6 5 Copland Apple made an announcement in early 1994 that it would channel more than a dec ade 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 such as the follow ing e Adopt RISC as a key foundation technology by making the system fully PowerPC native e Integrate improve and leverage existing Apple technologies such as ColorSync OpenDoc PowerShare PowerTalk QuickDraw 3D and QuickDraw GX
141. t looks up in its superclass and so on The set of messages an object responds to constitutes the object s proto col Figure 1 6 shows an example of Smalltalk code note the similarities to modern day Objective C The Towers of Hanoi moveDisk fromTower to toTower Transcript cr Transcript show fromTower printString gt toTower printString doHanoi n from fromTower using usingTower to toTower n gt 0 iffrue self doHanoi n 1 from fromTower using toTower to usingTower self moveDisk fromTower to toTower Self doHanoi n 1 from usingTower using fromTower to toTower Object new doHanoi 3 from 1 using 2 to 3 FIGURE 1 6 The Towers of Hanoi implemented in Smalltalk Perhaps the most consequential contribution of Smalltalk to personal comput ing was the Smalltalk environment s highly interactive user interface As was the case with its predecessor the FLEX machine an important early goal of Smalltalk research had been to make computing systems more accessible to those who are not professional computer scientists The hardware of a computer running Smalltalk consisted of a high resolution bitmapped display screen a mouse and a keyboard The user interface incorporated concepts such as the following e Overlapping and resizable windows that were essential to increasing the virtual real estate of the display screen providing an illusion of multiple 24 Chapter 1 A Technical History of
142. te a mod em operating system while maintaining backwards compatibility Figure 1 16 shows a screenshot of the first Macintosh operating system File Edit View Control Panel System Folder 7 items 173K in folder 200K a Note Pad d All work and no play makes Jack Ee Bee d a dull boy Al work and no play makes Jack a dull boy All work angaa d a dull boy KL All werk and nn nlan mabac lark FIGURE 1 16 Macintosh System 1 the first Macintosh operating system The Finder was the default application that ran as the system came up It was an interface for browsing the file system and launching applications Owing to the 58 Chapter 1 A Technical History of Apple s Operating Systems single tasking operating system the user had to quit any running application to work in the Finder The Macintosh File System MFS was a flat file system all files were stored in a single directory However the system software presented a hierarchical view that showed nested folders Each disk contained a folder called Empty Folder at its root level Renaming this folder created a new folder with a replacement Empty Folder appearing as a side effect There was a menu bar at the top like in the case of Lisa but with an Apple menu There was also an iconic trash can that was automatically emptied every time the system booted The Macintosh also heralded Apple s Human Interface Guide lines which partially evolved from Li
143. the original The Lisa 2 5 variant came with a 5MB external ProFile disk drive whereas the Lisa 2 10 variant came with an internal 10MB Widget drive A year after the Macintosh was introduced Lisa 2 was re branded as the Macintosh XL It ran the Macintosh operating system courtesy of the MacWorks XL software which implemented Macintosh ROM emulation Lisa was discontinued in 1985 In September 1989 Apple buried about 2700 Lisa computers in the Logan landfill in Utah The value of the computers had de preciated so much that the tax break received from scrapping the computers resulted in more money for Apple than could be obtained by selling them Although Lisa failed to become the perfect computer it was designed to be it introduced several aspects that would become part of Apple s systems to come In this sense Lisa was a technological success 35 Hollywood actor Kevin Costner appeared as a businessman in a 1983 Lisa advertisement Mac OS X Internals www osxbook com 53 1 3 2 The Macintosh At the turn of the 1980s there was a project called Annie inside Apple Apple em ployee Jef Raskins was not happy with names such as Lisa and Annie which represented a sexist approach according to him He changed the project s name to Macintosh a deliberate misspelling of McIntosh which is a variety of Apples McIntosh was also part of the name of a stereo manufacturer called Mcln tosh Labs The name was brou
144. tions behind Smalltalk was the first language to use object concepts It originated at the Norwegian Computing Center Oslo in the mid 1960s as a form of Algol 60 extended with classes and coroutines It was intended to be suitable for discrete event simulation hence the name Later on Smalltalk would be one of the inspirations behind the Objective C programming language which would be the language of choice on the NEXTSTEP platform Apple would inherit NeXT s technologies and Objective C would be a key language for Apple as well Many similarities can be readily seen between Smalltalk and Objective C Every Smalltalk variable refers to an object Every 7 The LINC Laboratory INstrument Computer was a small stored program computer built by Wesley Clark and Charles Molnar at MIT s Lincoln Laboratory in 1962 Digital Equipment Corpora tion subsequently manufactured the LINC It is widely regarded as the first personal computer Mac OS X Internals www osxbook com 23 Smalltalk object is an instance of a class whose ancestor is a single base class named Object Smalltalk uses a message based model of computation An operation involves sending a message to an object which is the only way to interact with an object The sender requests the receiver to perform an action named by a selector A receiving object responds to a message by looking up in its class for a method with the same selector If the method is not found the objec
145. tiple logical volumes on one physical volume e Support for up to 20 different file types of which 10 could be user defined e Up to 8 open files at any given time e An arbitrary number of files in a subdirectory although the volume di rectory was limited to a maximum of 51 files When the 16 bit Apple was released ProDOS was at version 1 1 1 It forked into ProDOS 8 and ProDOS 16 for 8 bit and 16 bit processors respectively 1 2 INSPIRATIONS 1984 is well known in the Apple world as the year the Macintosh was introduced In 1983 Apple had released the Lisa computer which represented a fundamental step forward in mainstream personal computing Lisa and Macintosh were greatly in spired directly or indirectly by the work done at Xerox Palo Alto Research Cen ter PARC Sources of such inspirations included the Smalltalk environment the Xerox STAR system and the Xerox Alto Most of the ideas pioneered in these sys tems remain relevant today in Mac OS X and in other modern systems To fully understand the lineage of the Macintosh we must take a few detours and go further back in time first to 1945 then to 1963 and finally to 1968 before the advent of UNIX long before Apple or Microsoft were even founded and in fact decades before the first version of Microsoft Windows or the Macintosh were released H The first version of Microsoft Windows was released on June 28 1985 Microsoft had made the first Windows ann
146. topologies were stored in special files using data structures optimized for fast editing of the drawings Sutherland received the Turing award in 1988 for his pioneering contribu 11 Sketchpad could be seen as an object oriented graphics editor and a precursor to object oriented programming 12 Thus Sketchpad provided the first example of the Prototype design pattern Mac OS X Internals www osxbook com 17 tions to the field of computer graphics His work on Sketchpad would prove inspirational in the development of Smalltalk which in turn would be an in spiration for the advent of the graphical user interface at Apple 1 2 3 NLS The oNLine System On December 9 1968 an array of astounding technologies was demonstrated at the Convention Center in San Francisco during the Fall Joint Computer Conference FJCC Douglas Engelbart and his team of seventeen colleagues working in the Augmentation Research Center at the Stanford Research Institute SRI in Menlo Park California presented NLS oNLine System NLS was an online system they had been working on since 1962 The astounding adjective is justified by the quantity and quality of innovation demonstrated on that single day Engelbart said 4 at the beginning of his presentation The research program that I am going to describe to you today is quickly characterizable by saying if in your office you as an intellectual worker were supplied with a computer display b
147. tures included the following e The Mac OS Extended file system HFS Plus which was introduced with Mac OS 8 1 e Contextual menus activated by a control click e Spring loaded folders e Personal web hosting e Web browsers Microsoft Internet Explorer and Netscape Navigator bundled with the system e Macintosh Runtime for Java MRJ Apple s implementation of the Java environment part of the system e Enhancements to power management USB and FireWire Figure 1 29 shows a screenshot of Mac OS 8 60 Spring loaded folders are a feature of the Finder s user interface If the user pauses briefly while dragging an item onto a folder icon a window springs open displaying the folder s contents This al lows the user to choose where to put the item Continuing to hold the item causes a subfolder to spring open and so on 112 Chapter 1 A Technical History of Apple s Operating Systems T File Edit View Special Help J Sherlock 7 Find File Find by Content Search Internet Find items on local disks name LA Mac 0S 8 5 Mac OS Built in Memory irtual Memory 49 MB used on Mac HD Largest Unused Block 32 8 MB amp Apple Computer Inc 1983 1998 A Graphing Calculator E Internet Explorer 4 01 E Mac os Ai Sherlock FIGURE 1 29 Mac OS 8 Mac OS 8 5 was PowerPC only The nanokernel was overhauled in Mac OS 8 6 to integrate multitasking and multiprocessing It inclu
148. ty storage media and the critical dependence of computer users on searching are re sounding testimonies to Bush s foresight 1 2 2 Sketchpad In January 1963 Ivan Edward Sutherland who was a graduate student at the Mas sachusetts Institute of Technology submitted his Ph D thesis titled Sketchpad A Man Machine Graphical Communication System Sutherland s thesis advisor was Claude Elwood Shannon the world renowned mathematical engineer who is known as the father of information theory Sutherland had begun work on a drawing system for the TX 2 computer in the fall of 1961 The Sketchpad system was primarily designed and developed within the next year and a half The TX 2 computer was built in 1956 It had a word length of 36 bits but it sup ported breaking a 36 bit word into independent sub words even allowing sub word lengths to differ It had a large amount of memory for its time a vacuum tube driven core of 64K words and a faster transistor driven core of 4K words It had a paper tape reader and could also use magnetic tape as auxiliary storage 16 Chapter 1 A Technical History of Apple s Operating Systems The primary input device of Sketchpad was the light pen a hand held photo diode device with the shape and dimensions of a pen The light pen was connected to the computer by a coaxial cable through which it communicated to the computer when its field of view encompassed a spot on the TX 2 s display The p
149. ty Task e Networking Ethernet Task 30 Chapter 1 A Technical History of Apple s Operating Systems A technique called Junta allowed BCPL programs to eliminate layers of the Alto operating system that were not required by a particular subsystem Another technique called Counter Junta could bring back the layers removed through Junta Consequently exceptionally large programs could run on the Alto with a clean re turn path to the operating system To facilitate Junta the operating system was di vided into a series of levels Each level had a known approximate size Examples of levels include levBcp1 BCPL runtime routines levDisplay display driver and levMain the main operating system including code for Junta itself Figure 1 9 shows a pseudocode example of using Junta All levels below levName will be de activated that is levName will be the last level retained Thereafter ProcedureName will be called it should not return Junta levName ProcedureName Code could be fcOK or fcAbort This will also perform the CounterJunta OsFinish fCode FIGURE 1 9 Using Junta The Alto provided powerful and flexible graphics capabilities For example a set of BIT BLT routines was available as a BCPL driver The BIT BLT algorithm was also implemented by a complex Alto instruction called BITBLT Figure 1 10 shows an assembly language excerpt from the source code of these routines circa November 1
150. ude lt stdio h gt lint maintarge argy 4 int argc char argy EEN ac gege Suster 4 avai lable Macintosh SE 30 Apple loc lhost nont halio Ve flopp Built in Memory 8 192K Larges bis is AUX 1 0 Accele Total M d 2192K localhost root zU SCSI CD HD otal Memory i d Alarm Clock zo E FIGURE 1 19 The A UX operating system More interestingly A UX combined various features of the Macintosh operat ing system with Unix A UX 2 x used Macintosh System 6 whereas A UX 3 x combined a Unix environment with System 7 The default user environment con sisted of the Macintosh Finder which was essentially a graphical shell hosted by A UX The A UX file system appeared as a disk drive icon in the Finder Files could be accessed and manipulated through their icons It was possible to run Macintosh 66 Chapter 1 A Technical History of Apple s Operating Systems applications Unix command line or X Window applications and even MS DOS applications side by side The MacX display server allowed X Window System client applications to be displayed on the A UX Desktop The OSF Motif toolkit for the X Window system was available as a third party addition A UX supported hybrid applications that made use of both the Unix sys tem call interface and the Macintosh Toolbox All types of applications could be launched from within the Finder Whereas Unix processes ran with preemptive multitasking under A UX th
151. umulator that was used for arithmetic and logical operations e Two 8 bit index registers X and Y which were typically used in indexed addressing modes e A 16 bit program counter logically divided into PCL low bits 0 7 and PCH high bits 8 15 halves e An 8 bit processor status register consisting of the following flags Nega tive N Overflow V Break Command B Decimal mode D Inter rupt Disable I Zero Z and Carry C e An 8 bit stack pointer the high byte of the logical stack pointer was hardwired to the value 1 limiting the stack to be 256 bytes in size and to lie between addresses 0x100 and 0x1FF The Apple I used 16 pin dynamic RAM It had sockets for up to 8KB of on board memory The total memory could be expanded to 64KB through a 44 pin edge connector All refreshing of dynamic memory including the off board expan sion memory was performed automatically The crystal oscillator was the source for the entire system timing The Apple I had a built in video terminal The output video signal was a com posite signal consisting of sync and video information It could be sent to any stan dard raster scan based video display monitor In particular the Apple I could be directly connected to a television with an RF modulator yielding an automatic scrolling display with 24 lines per page and a frame rate of 60 05 Hz Each line had 40 characters with the character matrix being 5x7 in size Owing to the high
152. unning MS DOS applications required the SoftPC product Mac OS X Internals www osxbook com Macintosh Desktop Unix X Window System Motif based Application Unix X Window System Application Unix Command line Application MSDOS Application Macintosh Application Toolbox Calls Macintosh OS Calls Unix System Calls Memory Manager SerialManager Time Manager Sound Manager C Library Slot Manager File Manager A UX Library Calls Redirection Macintosh OS reimplemented Multitasking Virtual Memory Interprocess Device UO and Process Management Communication and Driver Kernel Scheduling Interfacing Drivers ROM resident Macintosh User Interface Routines Hardware FIGURE 1 20 A UX architecture The last version of A UX 3 1 1 was released in 1995 68 Chapter 1 A Technical History of Apple s Operating Systems 1 5 SEEKING POWER As the 1990s began Apple was making great efforts to overhaul its operating sys tem Of the three colorful projects mentioned earlier Blue would emerge as Sys tem 7 1 5 1 System 7 When released in 1991 System 7 represented a gigantic leap forward in comparison to earlier Macintosh systems Some of its key features included a built in Multi Finder built in networking AppleTalk Phase 2 built in file sharing Apple Share support for 32 bit memory addressing a virtual memory implementation and a multitude of ne
153. w technologies such as the following e AppleScript a system level macro language for automating tasks e ColorSync a color management system e PowerTalk a collaboration and email software e QuickTime a cross platform multimedia software for viewing and ma nipulating video animations images and audio e TrueType a font technology e WorldScript a multilingual text rendering engine and programming interface The first Macintosh with an MMU was introduced in 1987 the Macintosh II Whereas A UX required an MMU it was not until System 7 that a Macintosh operating system would use the MMU However the virtual memory sup port was only preliminary features such as protected address spaces memory mapped files page locking and shared memory were not present 40 AppleTalk Phase 2 was introduced in 1989 It was based on the original version of AppleTalk but included several improvements and performance enhancements 41 Some of these technologies were not bundled with the first release of System 7 Mac OS X Internals www osxbook com 69 File Edit Note Color Track Elapsed Time Extensions M anager Labels Essential li n Progress Cool ersonal 5 roject 1 ornar Lane eros ei v3 03 i Use this control panel to turn off problematic exten
154. way to notify the failure of a process to a dependent process without explicit registration of such dependencies 100 Chapter 1 A Technical History of Apple s Operating Systems e Networking not an area of emphasis in the original design RIG port numbers were global allowing any process to create or use them Therefore any process could send a message to any other process However RIG processes which were single threaded did have protected address spaces 1 8 2 Accent Richard Rashid was one of the people who worked on RIG In 1979 Rashid moved to Carnegie Mellon University where he would work on Accent a network operat ing system kernel Active development of Accent began in April 1981 Like RIG Accent was also a communication oriented system that used IPC as the basic system structuring tool or glue However Accent addressed many of RIG s shortcomings for example e Processes had large 4GB sparse virtual address spaces that were line arly addressable e There was flexible and powerful virtual memory management that was integrated with IPC and file storage The kernel itself could be paged although certain critical parts of the kernel such as I O memory and the virtual memory table were wired in physical memory e Copy on write COW memory mapping was used to facilitate large message transfers Based on experience with RIG it was expected that most messages would be simple There were optimizations
155. wed graphical user interface Its operating system was object oriented The user interacted with the computer what Kay called a personal reactive minicomputer using text and pictures The machine s primary language was also called FLEX It was a simple interactive programming language designed to run on a hardware interpreter Kay s work had inspirations from many existing works of research such as GRAIL 22 Chapter 1 A Technical History of Apple s Operating Systems LINC LOGO NLS Simula and Sketchpad Kay described the design and im plementation of the FLEX machine in his 1969 Ph D Thesis titled The Reactive Engine Kay s doctoral work at Utah led to the development of Smalltalk the first version of which was deployed at Xerox PARC in 1972 Kay was one of the found ing members at PARC Besides Kay Daniel H H Ingalls Adele Goldberg and others at PARC were involved in Smalltalk s development Smalltalk was both a truly object oriented programming language and an operating environment with an integrated user inter face Daniel H H Ingalls wrote the first Smalltalk evaluator in October 1972 as a thousand line BASIC program The first program to run on this evaluator was the summation 3 4 Shortly afterwards the Smalltalk 72 system appeared It was im plemented in Nova assembly language Several versions followed with perhaps the best known being Smalltalk 80 Simula which was one of the inspira
156. where objects could be dragged and dropped OpenDoc was supported by several key technologies Document Level Services Component Level Services Open Scripting Architecture OSA System Object Model SOM and Open Linking and Embedding of Objects interoperable with Microsoft s OLE The OLE inspired COM and DCOM were OpenDoc s competitors Whereas OpenDoc failed COM is heavily used by modern versions of Microsoft Windows 59 OSA is an automation and scripting API that also exists in Mac OS X It supports application independent scripting allowing multiple scripting systems and languages to coexist AppleScript is the primary language that supports OSA Mac OS X Internals www osxbook com 111 1 9 1 Mac OS 8 and 9 As we saw earlier Copland and Pink were potential candidates for Mac OS 8 at one time or another Similarly Gershwin was a candidate for Mac OS 9 Over the years some important features that were either created or improved for Copland were added to Mac OS 8 and 9 as was originally intended The following are examples of such features e A search engine that could search on local drives network servers and the Internet released as Sherlock e The Copland API which gradually evolved into Carbon e The Platinum look user interface e Multiple users with support for per user preferences Mac OS 8 had a multithreaded Finder that allowed several file oriented opera tions simultaneously Other notable fea
157. y was only available through Carbon in Mac OS X versions prior to 10 4 Ap ple introduced the QTKit framework for Cocoa in Mac OS X 10 4 which reduces or eliminates Carbon dependencies for QuickTime 1 10 2 3 DP3 The Aqua user interface was first demonstrated during the San Francisco Macworld Expo in January 2000 Mac OS X DP3 included Aqua along with its distinctive elements water like elements pinstripes pulsating default buttons traffic light window buttons drop shadows transparency animations sheets and so on The 62 Apple had referred to the Mac OS X user interface as Advanced Mac OS Look and Feel Mac OS X Internals www osxbook com 121 DP3 Finder was Aqua based as well The Dock was introduced with support for photorealistic icons that were dynamically scalable up to 128x128 pixels 1 10 2 4 DP4 The Finder was renamed the Desktop in DP4 The System Preferences application Preferences app the precursor to System Preferences app made its first appearance in Mac OS X allowing the user to view and set a multitude of sys tem preferences such as Classic ColorSync Date amp Time Energy Saver Internet Keyboard Login Items Monitors Mouse Network Password and others Prior to DP4 the Finder and the Dock were implemented within the same application The Dock was an independent application Dock app in DP4 It was divided into two sections the left side for applications and t
158. y the Mach API and several user mode operating system interfaces were demonstrated to execute on top of Mach The Mach US symmetric multiserver op erating system contained a set of server processes that provided generic system services such as local interprocess communication networking and management of devices files processes and terminals Each server typically ran in a separate Mach task An emulation library which was loaded into each user process provided an operating system personality Such libraries used generic services to emulate differ ent operating systems by intercepting system calls and redirecting them to the ap Mac OS X Internals www osxbook com 107 propriate handlers Mach emulators existed for BSD DOS HP UX OS 2 OSF 1 SVR4 VMS and even the Macintosh operating system Richard Rashid went on to become the head of Microsoft Research Mach coinventor Avie Tevanian would be the Chief Software Technology Officer at Apple 1 8 4 MkLinux Apple and OSF began a project to port Linux to run on various Power Macintosh platforms with Linux hosted on top of OSF s Mach implementation The project led to a core system called osfmk The overall system was known as MkLinux The first version of MkLinux was based on Linux 1 3 It was released as MkLinux DR1 in early 1996 Subsequent releases moved to Linux 2 0 and beyond One of the re leases was incorporated into Apple s Reference Release MkLinux used a single

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