An Answer To "What is Mac OS X?"

XCube writes: "'What is Mac OS X?' is a fascinating article over at KernelThread.com. According to Amit Singh it's a hacker-over-friendly answer to that question and a low-level taste of Apple's OS. The extensive article covers many details on Mac OS X: history, Mac firmware & boot loader, system architecture, kernel, startup, file systems, app environments, programming facilities, available software, and more. A great read if you are interested in Mac OS X, though some stuff is too technical methinks. On second thought, this may be a better read if you're *not* interested in Mac OS X! The author says he wrote it to introduce Mac OS X to the Linux User's Group at his work."

Hey, Wait a second

On second thought, this may be a better read if you're *not* interested in OS X!

But if I wasn't interested, then why would I be reading it?

Re:Hey, Wait a second

And even if you were interested, you probably still wouldn't read the article. This is Slashdot, after all.

Conclusion from reading the article

OS X is the UNIX desktop Linux has been trying to be for 10+ years now. If OS X came out for x86, would the drive for desktop Linux effectively die?

Re:Hey, Wait a second

You know what else pisses people off?

Sticking pins in them! Some people say it's wrong, but that's what makes it fun!!!

Carbon's roots are older

Carbon. This is a set of procedural C-based APIs for Mac OS X that are based on the old Mac OS 9 API (actually dating back as far back as Mac OS 8.1)

To nitpick: actually, a lot of the Carbon APIs go as far back as System 1.0 -- most of QuickDraw for example.

Re:Carbon's roots are older

The article is conflating two different things - either an accidental mis-edit or an intentional oversimplification.

Carbon is based on the classic Mac APIs which go way back to 1984, while the Carbon API actually exists (and is available for calls) in MacOS 8.1 and higher via the CarbonLib classic extension.

Re:Carbon's roots are older

Carbon is based on the classic Mac APIs which go way back to 1984, while the Carbon API actually exists (and is available for calls) in MacOS 8.1 and higher via the CarbonLib classic extension.

Actually (if you care about all the historical details of Mac OS X's evolution) Carbon was originally based on the QuickTime library, which in turn was based on the classic Mac APIs. I was an engineer on the QuickTime team during the early Rhapsody days up through Mac OS X beta.

When Rhapsody (basically the NextStep OS) was being developed it quickly became obvious we needed to support classic Macintosh applications. QuickTime had already been ported to an early Rhapsody version, and it just so happened QuickTime already carried around an API that contained about 70% of the Mac OS functionality. This is how QuickTime runs on Windows and why porting Carbon/classic Mac apps to Windows is (relatively) painless if you know to call the QTW libraries. So Apple effectively had the start of Carbon on NextStep as a result of the QuickTime port. Rhapsody became Mac OS X, the QuickTime library support was spun out to its own team and became Carbon.

None of which really disagrees with your post, just a little more detail on the exact process.

Re:Carbon's roots are older

So if most of the Classic Mac's functionality is based on Carbon, which is based on QuickTime, and QuickTime has been ported to Windows...

aaaannnd, most of the NextStep functionality was available to x86 early on, with the YellowBox environment as well as seen in Rhapsody and WebObjects...

aaaaannnd Darwin, the OSX xnu kernel and personalities on Mach run on x86...

We have pretty complete coverage of the state of the Mac on x86. Interesting. I suspect with QuickTime installed, the hardest thing about iTunes on Windows was getting the GUI right. Which really is hard.

Yes, this is indeed the case. However...

First you're missing some important components, for example the Quartz rendering layer and the Aqua UI components. Neither of these are at all trivial.

Second, even ignorning Quartz and Aqua, you now have a set of about 70% of the components you need to build a Mac OS X-like operating system on Intel. As they say, the first 70% of the work takes 90% of the time, the other 30% of the work takes the other 90% of the time. It gives you a head-start, sure but you still have an immense effort ahead of you.

Apple spent (very, very approximately) a team of 1,000 engineers for 3 years to get to Mac OS X 10.0, from about the starting point you describe. That's 3,000 engineer-years of effort to find. Panther is another 3,000 engineer-years beyond that. It could be done, but its not trivial.

That said, when I was at Apple we did builds of Mac OS X (the entire stack) for PowerPC and Intel. From colleagues still at Infinite Loop I understand they still do every build for both platforms. I don't believe that it is technical barriers that are stopping Mac OS X for Intel...

The question

It's been at the back of your mind all along, always there, you're always asking...

"What is Mac OS X?"

Do you want me to show you, Neo...er...Steve? Eat the blue apple, and you'll go on living your life, believing whatever you want to believe. Eat the red apple, and I'll show you how deep the worm hole goes. And you'll realize that there is no Mac OS X. It's only your mind that has unfathomably sexy UI elements.

Re:The question

I took a bit out of a rainbow-colored apple and ended up in a wormhole to my life in the 70's...

What is Mac OS X?

Mac OS X is:

stable

easy to use

gorgeous

well rounded

interesting Kind of sounds like the perfect boyfriend/girlfriend. But remember, we're talking about software here... :P

Re:What is Mac OS X?

Mac OS X is:

stable

asy to use

gorgeous

well rounded

You forgot "lickable"

Potential Linux Switchers: Read Up

If you've been under a rock and haven't read much about OS X, still view Linux as a strong desktop OS, but hate having to fight to get the latest software, hardware, or other common computer accessories working without a call to your other Linux buddies, you should get a kick out of this article.

While the author disavows the article to a degree, it may be of great use to Linux and other UNIX users who haven't a clue of the true nature of OS X beneath its GUI interface. From the kernel, to a typical Mac's boot firmware, to its BSD origins, this is probably one of the better free web-accessible summaries that Linux geeks could appreciate.

OK, it might not make you switch, but note that this guy admits to using OS X for only 3 years or so, and he's gained quite an understanding of it.

Will OS X work for you best? YMMV.

Re:Potential Linux Switchers: Read Up

I started using OS X with the Public Beta - in September 1999. And, yes, it was on my production machine. Thus, OS X has been with us for 4 years and 4 months, not 3 years.

Re:Potential Linux Switchers: Read Up

I'm sorry, I'm not using Linux because it's a strong desktop (it's good enough for me, i'd call it adequate). I don't fight to get the latest software, I use what works and don't need to have the hottest, newest bits running through my processor. Most security updates are irellevant as I have hardly any services running, but I update the ones I need. If I had accesories, i'd make sure they worked with Linux before buying them, or were from a company who has a history of devulging enough specs for people to write device drivers themselves.

I use personally use Linux to get away from the liscensing nonsense that MicroAppleSunSoft tries to cram down my throat and sockets. They force too much upon me. It's my hardware, not theirs. I use Linux because it is Free. I use OSX at work and MS-Windows at work because I have to. What management decides is out of my control.

"...without a call to your other Linux buddies..."

Half the fun of Linux is the community built around it.

Re:Potential Linux Switchers: Read Up

Makes sense to me, all you've said. Apologies if I sound like I am pigeonholing the typical Linux user.

But OS X is much like any other BSD. Don't want to pay Roxio for a burn app? Just use the exact same CD burn tools you're using now. Same is true for Apache and many, many other tools that are built in OS X as they are in Linux and BSD. Else, compile the darn things.

Just note that not everyone (not even here on /.) are whizzes that can build anything they need or tinker for hours. How much do you consider your time is worth? Some of us just want to buy something, use it, and take the remaining time in the date to do something else, like, hell--I don't know--date or something.

Re:Potential Linux Switchers: Read Up

I'm sure you know of Darwin, which is the OS X OS core that runs on x86, so I won't discuss a Mac OS X port, per se. It will never happen, having a complete OS X version for x86, since Apple leverages its OS to sell its hardware, not software. Best example: the iTunes Music Store is built not to make money, but sell iPods.

Again, when it comes to buying a basic PC box, assembling it yourself and installing an OS, or buying a Mac box, you get what you pay for. There is a very good reason why Porsche doesn't offer a "build-it-yourself" option for their cars, and Apple feels the same way. Why are Macs a tad more expensive on average? Because they don't use the low-cost crappy commedity parts, and because they add the hardware they know many PC users may skip buying today but will eventually buy later (FireWire, a better video card, and other niceties). The only thing really unique in any Mac today is its chassis, motherboard and processor. The rest is the same stuff you find in any other PC.

The various UNIXes and clones out there all have their joys and laments, but none have hit the overall consistency, useability, and business software availability (Microsoft Office) than OS X--yet. You may be right--but not right now.

I understand truly about the joys of geekhood as well, and I don't think I should lose a point from my Geek License for suggesting that tinkering is a sin. In fact, unlike the original Mac OS (which was mostly closed up), I have gained far more repair and software options with the advent of OS X, since the UNIX side allows me to truly get under the hood of the damn thing in the few instances where it gets cranky or if I need to compile some app that's not included with OS X (like any other UNIX).

Re:Potential Linux Switchers: Read Up

I agree that open firmware is a thing of beauty. However we should eventually attain the same level of convenience with LinuxBIOS. (The problem right now is diminutive EEPROM/FLASH bios.) However on PCs you no longer have to worry about IRQs, DMA conflicts, or IO ranges, as long as you're not using legacy hardware. These days, some machines even have no ISA bus whatsoever - Even the legacy PS/2 keyboard and mouse are on PCI. Macs still have to deal with interrupts and such, they just don't bother you with it, and neither do modern PCs. I haven't had to deal with IRQs and shit since the last time I installed a non-pnp ISA card. Which was a long, LONG time ago.

Mac hardware hasn't been special since PCs went to the PCI bus and apple hardware stopped having the drivers in rom on the card. NuBus was a paragon of autoconfiguration equalled by no one but the Amiga. But now that drivers are in the software and not adapter ROM, that advantage is nonexistent.

It's also worth pointing out that until the G5, apple hardware has had poor bus architecture and slow memory buses. So while the designs are supposedly clean (I have a yosemite so I know that is a lie; I am also familiar with the IIfx, which didn't even follow Apple's standards, let alone anyone else's, and even needed a nonstandard SCSI terminator) they have usually been dated. The G5 is an exception; it sure would be nice if OSX were 64 bit though. Apple finally has the superbadass hardware, and their OS doesn't even take full advantage of it. By the time they have a 64 bit OSX, AMD's hammer chips will have come down further in price, and XP-64 will be running on them, and they'll squander their "lead" once more.

Re:Potential Linux Switchers: Read Up

And this was the way some proprietary software was going for a while. In the beginning, it was unclear how copyright applied to software, so the proprietarists came up with licensing instead. Like humans coming down out of the trees, this is generally been regarded as a bad move. But once it became clear that copyright applied to software, some proprietarists thought it silly to saddle their users with contracts, or to spend years in court arguing that "read-to-agree" schemes constituted contractual assent. They didn't want to control their users, they just wanted to make sure their software wasn't redistributed. Standard copyright law (plus an attached disclaimer of warranty) was all they needed.

I think Borland was the first major software vendor to use a copyright-based proprietary license (the famous "book" license). Some other companies followed suit, Apple included. Unfortunately, the old unilateral-contract-based schemes required hordes of lawyers, and lawyers love nothing better than to control other people.

Apple's proprietary software is still proprietary. But it's in a completely different class then Microsoft software. Nothing is being crammed down anyone's throat. While I still prefer Free Software, I have no problems buying and using proprietary software if the license terms are based on copyright rather than on some lawyer's delusion of how the world should work.

Re:Potential Linux Switchers: Read Up

"Half the fun of Linux is the community built around it."

Half the frustration of Linux is the community built around it, also.

That goes for every operating system. Use what makes YOU more productive. I could care less about free/open source/closed source. I prefer to use an OS that makes me more productive, with the least amount of hassle. Apple gives me that. Microsoft does not. Linux sure doesn't either.

Re:Potential Linux Switchers: Read Up

1) KDE, while less polished than Aqua, is much more powerful.

Howso? I'm working with KDE in my current job, and I've yet to find anything that KDE can do that Aqua can't seem to. I suppose this depends on your definition of "power" too. GTK+ is very "powerful" as I'd define it, but a triply nested button inside other buttons doesn't seem like power I really need.

In general, I think Apple's rapid development tools and APIs in the Cocoa environment (along with the language used) knock the socks off just about anything else I've worked with for overall usability (both from a user and developer's standpoint).

Especially in the area of rapid development, few environments can even begin to work as well, or produce such clean and maintainable results, as Apple's tools for this job.

Re:Potential Linux Switchers: Read Up

A few things about this:

1. Apple has a unified hotkey system. In panther, all the system-wide hotkeys are rebindable. Applications override this, and they can (and do) offer to change the keybindings. There are also tools to change keybindings arbitrarily, and even on regexs of the menu items. :)
2. Apple's text widgets are configurable in the extreme. This can be accomplished both at the application level, or at a global level. Developers can override this functionality in the individual application case. You might notice that OS X text widgets respond to many C-(something) keys (C-a to go to the beginning of a line, etc...). This is because of a global config file which individual users and appliations can override to taste. It's quite possible to make the text widgets perform in almost any manner possible (although it's unlikely that you'll see Emacs or VIM behavior without an InputManager.
3. The component methodology is more pervasive in KDE because developers want it to be. Nothing restricts people in the OS X world from writing their widgets in that fashion (most do!). Few people take it to that level in OS X. Not because it's hard, but because there is seldom reason to. This is nice, I'll grant, but it's not really that much of a benefit.
4. KDE's MDI suffers from the general problems of MDI everywhere. I'd say Apple's minimalistic MDI stuff is a feature. Especially with Expose, MDI is seldom necessary. The notable examples are web-browsers. Even then, I find myself using tabs in Safari less and less. Why, when I get a better idea of what's going on with Expose?
5. KDevelop is probably more mature than XCode, which is quite new (albeit based off the venerable ProjectManager, it's a very different machine under the hood as some Apple developers have intimated to me.
6. NOTHING KDE has comes even close to the awesome power of the Developer suite that you get when you sign on with OSX. When it was designed, it was 20 years ahead of its time, and no one else has even begun to catch up.
7. As a developer, I balk at C++ frameworks. Sorry, C++ is rapidly becoming more of a nuisance than anything else.
   
   This is, of course, subjective. Since I win my daily bread as a C++ and Ruby coder, I'll leave it as obvious which language I prefer to work in.

OS X does most of these things!

Mac OS X's environment already has almost all these things.

The configurability is a Mac vs. Linux philosophy thing. Don't tout it, you'll start a flamewar. Suffice to say, Apple has decided that for UI, One Consistent Way is better than a huge amount of configurability.

You need CocoaGestures [macupdate.com] to get system wide gestures. The hotkeys support is already there.

The system-wide password manager? Prithee, sir, what then would we call KeyChain [apple.com]?

System wide spellchecking is part and parcel of the very good Apple text widgets. You use their widgets, you get it for free. You can configure it specially, or you can let all the code in NSApp just do it for you (usually what you want).

Apple doesn't do things like auto-completion in a generic fashion (although you never see it mentioned, they do provide a completion service [macosxhints.com], and other people have cheerfully extended this functionality with supplemental abilities. [lorax.com]) because they haven't decided on their One Consistent Way to do it. Until then, we have a plethora of software, free and commercial, that does most anything we want. The OS X software community is very happy correcting any perceived flaws or blank spots a dozen different ways.

UI is a very subjective matter, so Apple (that makes money off of their good, consistent user experience) takes the middle road in most everything. It's smarter for them that way, since it's so incredibly easy to extend their input mechanisms.

Re:Potential Linux Switchers: Read Up

"Is OS-X available for non-Apple machines? "

A lot of us running Windows wish it was.

OS-X Quartz display blows away X-Windows

I hate X-Windows, crappy widgets and horrible fonts. As much as people criticize OS-X for being an "expensive" FreeBSD the display engine is light years ahead, its better than anything currently being used on Linux or FreeBSD.

Even NeXtstep and OPENSTEP's use of Display Postscript was excellent on low powered Intel based hardware.

Re:OS-X Quartz display blows away X-Windows

Um, what crappy widgets, and what horrible fonts?

Widgets are the domain of the toolkits, and I think Qt's are quite pretty. And FreeType is a much better font-renderer than the Apple one. Apple's renderer hints too little (leading to uneven color weight on normal-res screens) and Microsoft's hints too much (very forced, distored glyph shapes). Freetype has a nice mix balance between contrast and proper glyph shapes.

though i love linux

i must admit that i admire apple's os x platform. for example one *can* use the command line as much as one likes but one doesnt't *have* to. i can't say that i love editing my xf86config for example. tho os x is far from perfect (it *is* after all proprietary) but it seems like an evolution of linux in ways of usability. i think however that the major OSS desktop environments aren't that far away from obtaining equally powerfull yet userfriendly operation (having only working knowledge of the gentoo distro) it's been a while since i used os x (10.1 in fact) and i must admit i regret lacking the funds to buy myself a peachy powermac g5 cuz i'm quite tempted by os x panther and the ilife bundle (man garageband look awesome!) sometimes i've wished linux was a bit more 'it just works' although i know huge progess is being made in that field every day (ie getting alsa to work has been a major pita for me) i for one just think os x gives the user still a much smoother computer experience than linux can at the moment. i consider it to be a best of both worlds - operation system. only, personally, i think os x could do with decent skinning features as simple far from everybody likes apple's aqua interface. way to go apple

Re:though i love linux

i consider it to be a best of both worlds

When a company does such a good job, then the intelligent consumer would pay the company so it can improve. Apple does not survive by your applause, but by your purchasing dollars. Even your dollars spent on Microsoft Office for the Mac is partially a powerful vote for Apple.

Point is, if all we are going to do is to sit around and dish out glowing reviews, then we should not be surprised when (not if) a company we so approve of fails. Put your money where your mouth is.

i regret lacking the funds to buy myself a peachy powermac g5 cuz i'm quite tempted by os x panther and the ilife bundle (man garageband look awesome!)

GarageBand requires a G4 with DVD drive for full operations. The entry-level eMac satisfies this at $800 brand new, or under $700 refurbished. The $800 price, if you wait a few weeks, would include the $50 iLife.

Don't get me wrong. $800 is still real money, and is still more expensive than a Dell box. However, it's not $1,800, which is what an entry-level G5 would cost, and the Dell box won't have GarageBand, its big brother Soundtrack, or Final Cut Express and big brother Final Cut Pro.

interesting article...

It's good to explain more of the underpinnings OS X. You see, NeXTSTEP was almost the perfect operating system and development environment.

The NS environment (living on in Aqua today) is just so cool. Well-designed interfaces abound. Design patterns everywhere, created when the term "Design Pattern" had barely been explored in the computer world. For instance: most objects use delegation to extend their behavior. Not subclassing! Just compare building a GUI in Swing to Cocoa, it's like salt and sugar.

Objective-C is a wonderful semi-dynamic language, much nicer than C++.

Programming the mac is a true joy, even if all this dynamic dispatch is a little slow and hardly anybody uses macs. :-)

Re:interesting article...

I've worked for Apple and I can tell you just about all the new core stuff is being done or being converted to C or C++.

If you've worked for Apple you'd know that all the CoreFoundation classes have always been written in C/C++ and are (mostly) "toll-bridged" with their corresponding Objective-C Foundation classes.

If you are writing in Objective-C and discover a performance hit from the dynamic binding there is nothing to prevent you from using the CF classes (other than having to write C/C++) and including it in your Objective-C code.

Re:interesting article...

"Maybe in look and feel but it performs like crap. It's too disconnected; too much stuff done at runtime; too dynamic to be used for core components."

As others said you can optimize individual areas in C++. Also you are now discussing core components which seem a different issue to the person using frameworks. They don't care how the framework is written. Certainly even obj-C advocates don't think it the solution to everything. Other languages have their place.

I wonder though, why you criticize obj-C when even Microsoft is moving to a more runtime oriented system with .NET. It seems obj-C's main competitors are C#/VB.net and Java.

Tired of linux?

I loved some of the concepts behind linux, but I think Linux's greatest advantage is also it's greatest weakness. The fact that there is no central governing body for most projects means that you get lots of fragmentation (X11: freedesktop.org, fresco, XFree; Distros: Gentoo, Debian, Mandrake, Redhat, etc) which makes it very difficult to stick to one standard. Thankfully, over time some projects fork (gcc) and wind up becoming the project that takes over. It's this fragmentation that helps linux adapt so rapidly. However because of all this, developers can't code for one toolkit api, one kernel api, etc. Mac OS X, to linux users, is like linux controlled by ONE group who says yes or no to all issues so that the complex fragmented software base can concentrate on one goal: a good consistent end user experience. I honestly would say Mac OS X couldn't exist without Linux or BSD because it wouldn't be where it was today without the OSS community. People complain that OS X is too proprietary, but i believe it is the perfect mix. On one hand you have OSS [opendarwin.org] software [sf.net]. On the other hand you have commercial [microsoft.com] software [adobe.com]. It's truely the best of both worlds! Isn't this what many linux users want? Linux grandma can use? Companies to write native software? Games? Gaim and KMail side by side with safari and photoshop? You don't have to wait if that's what you want. Linux is a great server OS, but mac os x has it by leaps and bounds as a good desktop platform. Am i saying Gnome and KDE should die off and we should all just use mac os x? of course not. But i am saying if you want a usable unix desktop now, not later, you don't have to look much further.

Re:Tired of linux?

bogie, you have a really negative attitude towards a system i don't think you really understand much yet.

a lot of users tried to get away from windows because linux works better from a day to day basis for getting work done. just about any linux advocate with agree with you there. what most linux users won't say is how wonderfuly nice and easy to setup linux is, or so what if i takes 5 hours to compile KDE from source.

you're confusing philosophical matters with an argument that's not predominantly philosophical. for people who want to *completely* escape proprietary software, yes linux is the answer. for people, like myself, who want UNIX, want it to WORK easily, and want to spend more time getting word done than compiling/configuring/installing linux then os x might be for you.

switching to mac os x is NOTHING like windows xp. lets take a brief look:
kernel: open source under an apple license. just got OSS approved if i remember correctly.
rendevous: open standard (zeroconf) for allowing instant networking
xcode: based off gcc, and is completely FREE unlike visual studio .net.
preferences system: no harry registry in os x. preferences are done in xml files, and each program has it's own xml file (~/Library/Preferences/com.apple.Addressbook.plist ) for example.
open packages: i can right click on Safari, choose show package contents, and naviagte to safari's gui file. i can open up safari's gui and MOVE buttons around. i can rebind keys, i can delete menus, i can do a heck of a lot. isn't safari closed source? yep. but GUIs in os x are extremely easy to hack if you install XCode.
build in tools: os x ships with perl, ruby, python, and many standard unix tools. for what you can't get in the base system, you simply install darwinports and install it similar to ports in BSD. i can type sudo ifconfig en1 down and turn my wireless off. i can type ssh -X user@host and forward linux apps to my powerbook with apple's built in x11 server.
build off standards: os x's rendering system is based off opengl and displaypdf. it also has nfs and smb built in so i can mount shares off my linux machine.

you complain about how much more expensive macs are, but you get a hell of a lot more "built in" and free software compared to windows.

if your issues are that you don't have complete control over your environment, then stick with linux. if you are fed up with the day to day ease of use of linux, then consider ponying up the extra cash to get a machine that does all your unix goodness and everything "just works"

Why would someone be tired of Linux?

Personally, I got tired of having to re-locate the the set of arcana I needed to get my USB and DVD stuff working again on my Linux box after each kernel update. When the time came for a new machine, I bought a Powerbook.

I still have my Linux servers, but for daily use, my Mac is a dream.

Adobe and Microsoft..

Folks it just seems to me that Mac OS X relies heavily on Adobe (Photoshop, Illustrator, Go live, et al) and Microsoft (Office, Outlook, Messenger, Media player, el al). Then pretty much everything is either proprietary apple software or free GNU tools. To me it just doesn't justify the profound cost of owning an Apple.

Re:Adobe and Microsoft..

And this is opposed to Windows users that rely "heavily on Adobe (Photoshop, Illustrator, Go live, et al) and Microsoft (Office, Outlook, Messenger, Media player, el al)"? I think you over-estimate the diversity of applications on any platform. Most people don't go much further than the software that is already installed on their system for most uses (games being the biggest exception).

Of the applications currently running on my doc I have 3 from OmniGroup (Web, Outliner, and Graffle), 4 Apple apps (the Finder, Mail.app, Terminal.app, and TextEdit), and 4 other applications from other companies (a tn5250 emulator, Comcastic, Chicken of the VNC, and NetNewsWire Lite).

And I think you need to do some research before saying "profound cost of owning an Apple". Make sure you know what you are talking about before you say that again.

Excellent read!

This is one of the very best "OS Review" articles I've ever come across - especially the way that it brings in all aspects of history, influences, etc to address ignorance & common misconceptions.

Good Job!
-tor

I did the best thing

I did the next best thing I could do when I got my Mac. fdisk that dang OS X and installed Yellow Dog.