What an operating system is

There's been a lot of fuss lately in some of my favorite tech-related news sites about something Microsoft has done recently, claiming that Linux and OpenOffice violate some of its patents. This is unlikely, for a number of reasons, but I spent some time trying to figure out how to explain it to people who don't know the first thing about Linux or the issues here.

In the end, I realized that there was just too much Stuff to explain to the average person. I'd need to explain what Linux is, and very probably I'd need to explain what an operating system is, first, and that together with explaining the real significance of Microsoft's claims would make for an entry longer than the Encyclopedia Britannica -- well, maybe not that long, but too long for me to enjoy typing and way too long for most people to want to read.

So instead, I'll use this entry to explain what an operating system is. In fact, I'm going to copy an entry that appeared in a LiveJournal of mine a few years ago, edited a bit.


What an Operating System is

As simply as possible, it's what negotiates between you and the physical computer itself. It also communicates between the computer hardware and whatever software is on the computer. It even lets the keyboard, monitor, mouse, CD/DVD tray and other stuff talk with the hardware inside the computer itself. It's not stuff like Microsoft Office -- that's an application, not the OS itself. Two examples of operating systems are Windows XP and Windows 98. Without an operating system (usually shorted to OS), the computer is pretty much an expensive doorstop. It doesn't know how to talk to its various parts; it doesn't know how to set up the things it needs to work, such as its memory; it doesn't understand what you type into the keyboard, or what you do with the mouse; it can't print anything back onto the monitor. It can't do much of anything at all.

In fact, Windows is an OS, or more accurately a series of OS's produced by Microsoft. Windows is not the only OS that there is. Macintosh (on Apple computers) is another OS, probably the best-known besides Windows. There are also Unix, Linux (which you don't have to pay for!), BSD, OS/2, and lots more, some of them specialized for certain kinds of machines.

One early OS was MS-DOS, which was kind of the predecessor to the Windows OS's. I'm going to talk about it because it illustrates some things about what OS's were like many years ago, and because chances are you can see it for yourself. If you're running Windows XP, you can still see and play with MS-DOS: click on the Start button, click on Run . . . (on the lower right) and type cmd into the text box that springs up, then click on OK. You'll see this odd little box spring up, with nothing inside but white letters on a black background. That's actually MS-DOS.

Now, look at the MS-DOS box. You'll see something like C:\Documents and Settings\Mary Joe>, and a blinking cursor at the end of that. (The "Mary Joe" part could actually be anything -- it's your username on Windows XP, nothing more.) This is called a command prompt. With early OS's, that was all you saw on the screen -- not the pretty "Bliss" wallpaper you see on Windows XP, not the taskbar at the bottom, nothing but a black screen with text on it. You used it like so:

Type dir. Yes, this is perfectly harmless (I promise you). You'll see the letters dir appear after the >. Now, press the Enter key on your keyboard. You'll see some words and letters and numbers and stuff appear on the screen, which may look pretty mysterious to you, but what MS-DOS is really doing is telling you stuff about your hard drive and the files inside the folder with your username on it. That's what you had to do before modern OS's -- you had to type in commands and understand what the computer was saying back to you.

Imagine that little black window being your whole screen -- no Task Bar at the bottom of your window, no mouse, no nothing. Imagine not being able to get back to your regular desktop -- because there is no colorful, pretty desktop, just that black and white window. That was what it was like to work in old operating systems, before the advent of Macintosh and Windows. OS's such as this are called command-line OS's, because you type lines of commands into them instead of clicking on buttons and menus with a mouse. Today, if you've got Windows XP installed on your computer, you can't even boot into MS-DOS any more . . . which most people don't miss.

(You can close the window now by typing exit into it, and hitting Enter again. And I promise I won't expose you to MS-DOS again in this entry.)

See, OS's weren't always these colorful things with pretty graphics. Once they were all like MS-DOS -- no pictures, nothing to click on; you just typed stuff in, and it would show plain old letters, numbers and words back at you. That was how you ran MS-DOS, for example. Yes, a surprising number of people did manage to cope, at least in workplaces. I wasn't one of them; at the time, I was afraid of computers other than Apple. I hated my first exposure to MS-DOS back in the early 1990s, and never did figure it out. I had a full-scale technophobia attack, near-tears and shaking, and went running back to Macintosh (more on Macintosh in a moment).

Why on earth did computer users put up with this? Computers back then didn't have the horsepower to run pretty graphics all the time. Even games were quite basic compared to today. At first, no one even had the idea that anything else was possible, any more than Mesolithic hunter-gatherers guessed that guns or farming were possible.

Today, of course, things are different -- and somewhat easier. What we have today, with the buttons to click on and menus and the colorful desktop wallpaper picture and all, is called a graphical user interface (GUI). The average person did not even begin to think about buying a home computer until the GUI became common during the 1990s, because the command line was too hard to use for anyone who didn't want to spend a lot of time learning how. Thus, GUI's were a Great Leap Forward in making computers popular. Apple Computers, which makes the Macintosh OS, wasn't really the first company to make a GUI for its OS -- but it was the first to popularize it on computers intended intended for use at home instead of a business. In fact, you couldn't get into a command line at all with Macintosh -- you could only use the GUI. At the time, this struck a lot of computer geeks as really strange. They laughed at it, saying it would never catch on. But the first computers I ever worked on were Apple computers, running early versions of Macintosh. I was fascinated by the After Dark screensaver collection and loved to play with changing the screensaver and the wallpaper tiling. Then Adobe Photoshop 1.0 came out, and I was even more fascinated. Without the GUI, I would never have become interested in computers in the first place. And that was true for a lot of people.

Windows XP has a modified version of MS-DOS built into it for the convenience of power users like me, but it isn't actually based on MS-DOS. You can't boot into MS-DOS at all if you have Windows XP installed. Today, virtually all OS's have a GUI, and you control them through that GUI rather than through a command line prompt. Linux is an exception to this rule; while most versions of Linux today do have GUI's, you can also boot into a command line, and go back to the black screens with text of yesterday. The reasons for that would be hard for non-geeks to understand. Let's just say that most Linux users, myself included, like it that way.

To summarize: operating systems let you talk to and control the computer and let the hardware run and talk to its parts. An OS does NOT have to have a beautiful interface. There are several different OS's, such as Windows, Linux and Macintosh.

Now, here's an important thing to remember: you have a choice of OS's, even after you have bought your computer. Even if your computer came with Windows already installed on it, it is your legal right as the computer owner to wipe Windows off of it and install another OS, such as Linux. Better yet, you can even install another OS, such as Linux, alongside Windows. If you do this, when the computer boots up you'll be given a choice of which OS you want to boot into. It's also possible to buy computers with Linux preinstalled instead of Windows, if you so desire, such as you could buy a Macintosh computer with the Apple OS preinstalled. And finally, you can buy a separate CD or DVD of an OS, just like you would buy a packaged CD or DVD of Microsoft Office or a game, and install it on your computer. Usually, you would do this for Windows, or for a commercial version of Linux such as Red Hat Linux or SUSE Linux. Most versions of Linux are free, amazingly enough, so you can just download the CD or DVD and burn it yourself if you know how, so you don't need to buy them in a store -- in fact, you usually can't buy them in a physical store (although you can order pre-burned ones at certain online stores). However, you cannot buy Macintosh in a store at all; you can only get it preinstalled on an Apple computer. But there are versions of Linux that you can install on Apple computers!

So for now, just remember: Windows is not the only OS, and you can put whatever the heck you want on your home computer. As for how you'd do this, and why, that's a topic for another, more technical entry. This one is long enough already.