[CLUE-Talk] Roots of Mac OS X: BSD info

[Kevin Cullis]

Thought you all might like to know this.

Kevin

TidBITS Editors wrote:
> 
> TidBITS#558/04-Dec-00
> =====================
> 
>   Mac OS X is coming soon, and there's much more to it than the Aqua
>   interface. This week Chris Pepper looks at Mac OS X's Unix
>   foundation. And if a digital camera is on your gift list, Arthur
>   Bleich offers advice about essential accouterments like printers,
>   batteries, and memory cards. In the news, Nisus Software releases
>   Nisus Writer 6.0.1 (including 68K support and the TidBITS
>   AutoCorrect Dictionary), and we ask you to vote in our poll on how
>   TidBITS should cover product announcements.
> 
> Topics:
>     MailBITS/04-Dec-00
>     Digital Camera Accouterments
>     Unix Coming to a Mac Near You, Part 1
> 
> <http://www.tidbits.com/tb-issues/TidBITS-558.html>
> <ftp://ftp.tidbits.com/issues/2000/TidBITS#558_04-Dec-00.etx>
> 
> Copyright 2000 TidBITS Electronic Publishing. All rights reserved.
>    Information: <info at tidbits.com> Comments: <editors at tidbits.com>


> 
> Unix Coming to a Mac Near You, Part 1
> -------------------------------------
>   by Chris Pepper <pepper at reppep.com>
> 
>   With Mac OS X, Apple is building Unix into the Mac OS, and this
>   has technical, social, and political ramifications for Mac users
>   and the rest of the industry. To understand the implications of
>   this change, let's take a look this week at the Unix family of
>   operating systems and how they constitute a part of Mac OS X. In
>   the next part of this article, I'll address how the fusion of
>   these two operating systems will impact not only Mac and Unix
>   users, but the computer industry as a whole.
> 
> **Unix 101: The History of the Machine** -- In the beginning (or
>   as far back as we want to go), there was Unix, which was
>   originally developed at AT&T's Bell Labs. In many ways, Unix grew
>   up in symbiosis with the C programming language, which became an
>   important facet of its underlying philosophy - that programming is
>   good for you. (For more information, see some of the resources
>   provided by Dennis Ritchie, one of the creators of C, as well as
>   an interesting timeline of the history of Unix). In sharp
>   contrast, the Macintosh was revolutionary because of Apple's
>   concept that computer users could be insulated from the underlying
>   workings of their computers, and not have to be programmers.
>   Apple's vision of the Mac OS was as a system for managing a
>   computing appliance, whereas Unix was published as a research
>   project with an open invitation to tinkerers.
> 
> <http://www.cs.bell-labs.com/cm/cs/who/dmr/>
> <http://perso.wanadoo.fr/levenez/unix/>
> <http://db.tidbits.com/getbits.acgi?tlkthrd=1194>
> 
>   Over time, various companies and individuals contributed to Unix,
>   each under their own licenses, some of which required payment for
>   use. Several companies, most notably Sun Microsystems, licensed
>   Unix to use as the basis of their own operating systems to run on
>   their own computer hardware. There are now hundreds of derivatives
>   of the original Bell Labs Unix. A crucial point in the development
>   of Unix came when AT&T sued the University of California at
>   Berkeley to halt distribution of Unix systems without paid
>   licenses from AT&T, but the suit failed. After the settlement,
>   Berkeley released the free and redistributable 4.4BSD-Lite (BSD
>   stands for "Berkeley Software Distribution"), which contained no
>   AT&T code and no licensing restrictions. The current BSD flavors
>   of Unix - NetBSD, FreeBSD, OpenBSD, BSDI, and now Apple's Darwin -
>   are all descendants of BSD-Lite.
> 
> <http://www.oreillynet.com/pub/a/network/2000/03/17/bsd.html?page=3>
> <http://www.bsd.org/>
> 
>   During the 1980s, Richard Stallman formed the Free Software
>   Foundation (FSF) to write a completely compatible Unix
>   replacement, free of restrictive licensing requirements. In
>   rejection of these licenses, the FSF created the GNU General
>   Public License (GPL), which requires licensed software to be
>   freely redistributable, and has a "viral" clause requiring that
>   derivative works also be licensed under the GPL, and thus freely
>   available and modifiable. The GNU (which stands for "GNU's Not
>   Unix") project was highly successful in creating powerful tools,
>   such as the ubiquitous gcc compiler and gzip compression program,
>   now considered standard parts of Unix environments. The GNU
>   operating system kernel, known as Hurd, is still under
>   development.
> 
> <http://www.gnu.org/copyleft/gpl.html>
> <http://www.gnu.org/philosophy/philosophy.html#AbouttheGNUproject>
> <http://www.fsf.org/software/hurd/hurd.html>
> 
>   Linus Torvalds began the Linux project with a similar goal: to
>   develop a free Unix-compatible kernel for Intel PCs, without
>   license encumbrances. To ensure that Linux would be free, it was
>   also licensed under the GPL. An operating system kernel isn't
>   useful by itself, so Linux distributions combine Linux kernels
>   with other free GNU and non-GNU components to build complete
>   operating systems. Thus the FSF's goal of a free Unix-like
>   operating system was attained, though not quite as its founders
>   expected.
> 
> <http://www.gnu.org/gnu/linux-and-gnu.html>
> 
>   Linux is generally portrayed as a better, faster, and more stable
>   server alternative to Windows NT/2000. In contrast, BSD Unix
>   rarely crops up in casual conversation, but its users consider it
>   better and more stable than relative newcomer Linux. A number of
>   high-profile Web sites, such as Yahoo and MCI, apparently share
>   this conviction and rely on BSD-backed Web servers.
> 
> **The Mac OS X Layer Cake** -- Although Apple is introducing Unix
>   to millions of Mac users through Mac OS X, you don't need to start
>   memorizing Unix commands to use it (in fact, you'll have to work
>   to see the Unix command line at all). However, it will be helpful
>   to have a working knowledge of how Unix fits into the inner
>   workings of your Mac.
> 
>   Think of Mac OS X as a three-layer cake, borrowing its basic
>   recipe from the NeXTstep operating system, leavened with
>   components of Mac OS 9. The lowest level is derived from Carnegie
>   Mellon University's Mach microkernel research project, which
>   interacts with the hardware and helps different parts of the next
>   level up communicate with one another, and the BSD kernel, which
>   provides facilities such as networking, device drivers, and file
>   systems - HFS+ and UFS (Universal or Unix File System) are
>   included in Mac OS X. Within Darwin, the second level is a fairly
>   standard Unix environment, including tools ranging from the ls
>   program that lists files and the cp program that copies files, to
>   the aforementioned gzip and the Apache Web server. These two
>   layers are available now from Apple, packaged together as the free
>   open source Darwin operating system.
> 
> <http://www.cs.cmu.edu/afs/cs.cmu.edu/project/mach/public/www/mach.html>
> <http://www.publicsource.apple.com/projects/darwin/>
> <http://db.tidbits.com/getbits.acgi?tbart=05994>
> 
>   Darwin is a fully capable Unix-like operating system on its own,
>   but it's limited in comparison to the Mac OS. In particular,
>   Darwin lacks graphics capabilities entirely - in a typical Unix
>   system those would be provided by the X Window System, but Darwin
>   can only display text on the connected monitor. Apple has released
>   Darwin as open source, so people with recent Macs who want to run
>   BSD-style Unix now have another free option (projects such as
>   OpenBSD and NetBSD also support many Macintosh hardware
>   configurations). Darwin has already drawn some attention in the
>   computer industry, but it's mostly relevant for Mac users, since
>   several mature BSD options for Intel-based PCs already exist. It
>   remains to be seen whether people will actually use Darwin as an
>   independent product, but it may find popularity on slightly older
>   machines or in dedicated server environments.
> 
> <http://www.x.org/>
> <http://www.macosxinfo.org/kernel.html>
> <http://www.openbsd.org/>
> <http://www.netbsd.org/>
> 
>   Confusingly, Apple uses the name Darwin for several related
>   projects which have different releases but the same source code:
>   the self-contained Darwin operating system package and the bottom
>   layer of Mac OS X. Direct access to Unix applications on a Mac OS
>   X system is entirely optional, which makes the system much more
>   palatable for Mac users who prefer to avoid Unix. But double-
>   clicking the Terminal program included in Mac OS X Public Beta
>   invokes a command line, giving full access to Unix functionality,
>   just like logging into a machine running the free Darwin operating
>   system.
> 
> <http://db.tidbits.com/getbits.acgi?tlkthrd=1188>
> 
>   The second and third levels of the Mac OS X layer cake, not
>   included in the free Darwin package, are the proprietary code that
>   makes it a Macintosh operating system with a graphical interface:
>   the QuickDraw and Quartz graphic environments that programs use to
>   draw to the screen and the whole set of Application Programming
>   Interfaces (APIs) that enable Macintosh programs (as opposed to
>   Unix programs) to run. The main APIs in Mac OS 9 are collectively
>   called the Macintosh Toolbox. Mac OS X includes a much larger set
>   of overlapping APIs, due to its hybrid Unix/NeXT/Apple heritage.
> 
>   Classic applications rely on the venerable QuickDraw for display
>   of text and graphics. Carbon applications can use Apple's new
>   Quartz display engine, but QuickDraw remains available to them as
>   well, and so they'll probably stick with QuickDraw as long as
>   developers want to provide a single application file that can run
>   under both Mac OS 9 and Mac OS X. Cocoa applications rely entirely
>   on Quartz, which is based on Adobe's Portable Document Format
>   (PDF), and provides improved capabilities for print and layout. In
>   addition, Mac OS X also provides OpenGL and QuickTime, which may
>   help availability and performance of games and scientific
>   computing software for Macs.
> 
>   Macintosh programs that can run under Mac OS X come in three main
>   flavors: Carbon, Classic (existing Mac OS 9 programs), and Cocoa.
>   New and updated programs which use Carbon are full-fledged Mac OS
>   X applications and take advantage of Mac OS X's protected memory
>   and preemptive multitasking. Current programs run under Mac OS 9
>   within the Classic environment, providing compatibility with
>   existing software. And Cocoa programs rely on a set of APIs
>   originally derived from NeXTstep, so Mac OS X can run NeXTstep-
>   derived programs.
> 
>   The frosting on this layer cake is a new graphical design for Mac
>   OS X, called Aqua. All Carbon and Cocoa applications in Mac OS X
>   use Aqua, which specifies larger text and buttons, heavy usage of
>   anti-aliased text and transparency, and a new set of design
>   guidelines for windows, menus, and other interface elements. As a
>   result, Mac OS X applications are prettier and livelier, with
>   correspondingly increased demands on processor power and screen
>   size. Specifically, Mac OS X effectively requires a minimum screen
>   resolution of 800 by 600 pixels, while Mac OS 9 was usable at 640
>   by 480 pixels. (Also see "A Quick Dip into Aqua, the Mac OS X
>   Interface" in TidBITS-513_.)
> 
> <http://www.apple.com/macosx/technologies/inside.html>
> <http://db.tidbits.com/getbits.acgi?tbart=05773>
> 
>   Okay, let's see if we can put it all together - this diagram may
>   look more like a game of Hack than a layer cake, but it should
>   give you an overview of where everything fits. Remember there's no
>   graphical environment under BSD Unix in Darwin.
> 
> >   | (Platinum)  |       (Aqua)       |   |   (Text)   |
> >   +-------------+----------+---------+   +------------+
> > 3 |   Classic   |  Carbon  |  Cocoa  |   |  BSD Unix  |\
> >   +-------------+----+-----+---------+   +-----++-----+ \
> > 2 |     QuickDraw    |   Quartz      |         ||        (Darwin)
> >   +------------------+---------------+---------++-----+ /
> > 1 |                 Mach+BSD kernel                   |/
> >   +---------------------------------------------------+
> 
>   To continue our analogy, the Mac OS X Public Beta available now
>   includes candles on the cake - user applications (both included
>   with Mac OS X and installed by users), which use either the
>   Platinum (Classic) or Aqua appearance, depending on the APIs to
>   which they're written. Bundled applications include the
>   Finder/Desktop, Internet Explorer, Mail, Sherlock, System
>   Preferences, an MP3/CD player, and others. The whole installation
>   provides approximately the same feature set as Mac OS 9, but as
>   you'd expect in a beta, some of the new components are more
>   primitive than the mature ones from Mac OS 9. The best example of
>   this is the new Dock, which replaces Mac OS 9's Apple and
>   Application menus and desktop, but doesn't offer the same level of
>   flexibility as the older tools in Mac OS 9.
> 
>   As a Macintosh system, the most obvious changes in Mac OS X are
>   the visual interface - Aqua - and the file system layout. The
>   underlying system is already more stable, but this is a less
>   obvious change. Classic Mac developers are beginning to move their
>   software to Carbon, and as they do so they will begin to take
>   advantage of Carbon's new capabilities and advantages. For those
>   interested in exploring further, there's a wealth of new
>   territory. NeXT developers are quickly moving over to Mac OS X,
>   and adapting their applications for Cocoa. Darwin's Unix
>   environment provides a whole new range of capabilities,
>   particularly in the areas of networking and programming. This is
>   foreign ground for many Mac users, but the potential is
>   considerable.
> 
>   In the next installment of this article, I'll talk about how the
>   computer industry stands to be affected by Mac OS X's merger of an
>   underlying Unix structure with the qualities that make a
>   Macintosh.
> 
>   [Chris Pepper is a systems administrator in New York, and he's
>   just delighted that his "personal" Mac workstations are now
>   running Unix like the servers he coddles for a living. Check out
>   his Mac OS X Software and Information site for more on Apple's new
>   operating system.]
> 
> <http://www.mosxsw.com/>
>