Operating Systems
An operating system (OS) is a set of programs that handle the interactions among computer devices, software, and people. A computer doesn't do anything by itself; it needs a set of instructions that tell it what to do and how to do it.
There is not one single way an operating system can work, so there many different operating systems that have been developed. Some of the most commonly encountered operating systems include:
Microsoft Disk Operating System (MS-DOS, or just "DOS")
DOS is a "command-line" operating system, meaning that you are faced with a "prompt" (C:\>) at which you type commands like "copy" or "del". DOS does one thing at a time, so it can be referred to as a "single-tasking" operating system. DOS was actually fashioned after a more sophisticated operating system called "Unix" (see below).
Microsoft Windows 3.1 and 3.11 (Windows 3.x)
These are Microsoft's first popular forays into a "graphical user interface" (GUI). Instead of typing commands at a prompt, you use a pointing device (usually a mouse) to select icons that execute commands.
Despite what Microsoft wants you to think, these are not really operating systems. They are merely "shells," layers of software between the user and the real operating system. Here, the real operating system is still DOS.
Nevertheless, Windows 3.x is an improvement over DOS. Not only is it more visually appealing and intuitive, it allows access to additional memory. This permits more complex programs to run and allows access to every single dot on a computer screen. It can thus support beautiful graphics and lots of colors. However, it still does not allow more than one program to actually run at the same time.
Windows 3.1 is aimed at the "stand-alone" desktop PC. Windows 3.11 (a.k.a. Windows for Workgroups) is nearly identical in appearance but more suited for use in a network.
Microsoft Windows 95
When it first came out, Microsoft advertised Windows 95 as "a new operating system." This is not entirely true. It is still partly DOS at the core. However, it is another significant improvement over the DOS/Windows environment. It allows true "multi-tasking" (running more than one program at a time). Also, Win95 is much more compatible with networks and many different kinds of computer hardware.
The Win95 interface (the "desktop" metaphor) was heavily influenced by Apple Computer Corporation's Macintosh operating system (see below), and legal battles over copyrights ensued. Apple lost.
Windows, in all its incarnations, has been the subject of much criticism. Some say Microsoft has vastly oversold its capabilities. It certainly does have many technical limitations that it inherits from DOS, especially the cumbersome way it manages a computer's memory and its inefficiency in the way it stores data on disks. Despite many improvements, Windows 95 still "crashes" all too frequently, usually at the most inopportune times. Nevertheless, it has provided a very powerful and standardized operating environment for which many, many software packages have been developed, and it is likely that Windows in some form will be with us for at least the next 5 years.
Microsoft Windows NT
Windows NT ("New Technology") really is a distinct operating system. (NT has actually been around at least since the early 1990s.) It does not have DOS at the core like other versions of Windows. NT provides much more sophisticated control over access to networks, files, and disk drives, and as such is best suited to use within a network. As you might guess, however, it is also more difficult to install and configure than Win95. (Bill Gates is working on that.)
There are a couple of versions of NT floating around. Version 3.51 looks like Windows 3.11, and Version 4.0 looks like Windows 95. NT Version 5.0 should soon be released, and will probably be sold as "Windows 2000".
You will see more of Windows NT in the future, because Microsoft is positioning it to be the prime competitor of the Unix operating system (see below).
Macintosh OS (Mac OS)
The Mac OS was the first popular operating system to use a GUI. It was developed by Steven Jobs and Steve Wosniak of Apple Computer Corporation. Its ease of use and superb graphical capabilities almost made it the most popular OS in the world, but it was overtaken by Microsoft Windows.
There are still many "Macs" being used, and there is a dedicated group of people that support Apple Computer Corp. However, the Microsoft juggernaut has begun to influence Apple's future significantly, and it is possible that the Mac will eventually be snuffed out.
VMS
VMS was a command-line operating system developed for "mainframe" computers, especially the Digital Equipment Corporation's VAX line of mainframes. The VAX and VMS are essentially extinct. VAX computers were the size of a car and cost hundreds of thousands of dollars to buy, and thousands more per year to maintain. These days you can buy an equally powerful computer that is the size of a pizza box and that costs only a few thousand dollars.
Unix
Unix was one of the first widely-used operating systems. It is extremely powerful, extremely flexible, and extremely complicated. Like DOS, it is a command-line operating system. (In fact, DOS was constructed as a stripped-down version of Unix, better suited to the stand-alone desktop PC.) Unix is best suited for use as a network operating system because of its multi-tasking capability and its ability to specify unique "permission codes" for every single file, directory, and program. These codes can allow the user to control access to files by other people, as well as what other people can do with those files. For example, you can create a file that no one else can see, open up, or alter. Or you can let others see it and read it, but not alter it (like a web page). You will occasionally run into these "permission codes" while surfing the web. If you ever follow a web link and see a "Permission Denied" message (or something similar), this means that someone doesn't have their permission codes set correctly. (This is sort of like saying "Come on in!" but forgetting to unlock the door.)
The enormous power, flexibility, stability, and security of Unix has made it the preferred operating system for networks, especially those with connections to the internet. Much of the entire internet runs on computers using Unix. If you use the internet at all, you will encounter Unix and some of its power and peculiarities.
Interestingly, Unix was not developed by one company and is not really proprietary software. Although its core programming code (the "kernel") was developed way back in 1969 by Ken Thompson and Dennis Ritchie of Bell Laboratories, many of its capabilities were added on by many different people for many different purposes. As a result, Unix has been criticized as being a bloated, piecemeal dinosaur whose future utility is highly questionable. For example, check out the preface to "The Unix-Haters Handbook." (The book's cover is a real gem!)
Efforts to make Unix easier to use have resulted in something called "X-Windows" (or just "X"). This is a Windows-like graphical interface to Unix (of which there are several versions). Instead of just having one screen with one command prompt, the user can have several windows open, each running its own command prompt or other application (such as an e-mail or file manager utility). While such an arrangement is a vast improvement over the simple command-line mode of traditional Unix, X-Windows is slow, complicated to set up, and heavily criticized as yet another layer of complexity on top of an already cumbersome and archaic operating system.
Linux
Linux (pronounced "lin-ux" or "line-ux") is a Unix-like OS developed by Linus Torvald. Linux is well-suited for an individual desktop PC, but it interacts well within a network too. There has been a great deal of excitement about Linux as a replacement for Unix and as a potentially serious competitor to Windows. Keep a close eye on Linux. All of these things are subject to rapid change!
International Business Machines OS/2
This operating system uses a GUI similar to Windows. It is notoriously difficult to set up but supposedly wonderful once you get it going. Not many computers use OS/2 anymore.
Novell NetWare
NetWare is a network operating system. It is designed primarily to handle networks of PCs running DOS and Windows, although it interacts reasonably well with computers running Unix. NetWare has become the most popular OS for running so-called "local area networks" (LANs), such as one might find within an academic or corporate setting.
People take their operating systems quite seriously, but none of these systems are perfect. A little humor always helps put things in perspective. Here's a tongue-in-cheek view of different operating systems:
Airplanes
That Run On Operating Systems, Not Jet Fuel
(author unknown)
DOS: Everybody pushes it till it glides, then jumps on and lets it coast till it skids, then jumps off, pushes, jumps back on, etc.
DOS with Quarterdeck Expanded Memory Manager: Same as DOS, but with more leg room for pushing.
Macintosh: All the flight attendants, captains, and baggage handlers look the same, act the same and talk the same. Every time you ask a question, you are told you don't need to know, don't want to know and everything will be done for you without your knowing, so just shut up.
OS/2: To get on board, you have to have your ticket stamped 10 different times by standing in 10 different lines. Then you fill out a form asking how you want your seating arranged--with the look and feel of an ocean liner, a passenger train or a bus. If you get on board and off the ground, you will have a wonderful trip, except when the rudder and flaps freeze, in which case you have time to say your prayers before you crash.
Windows: Colorful airport terminal, friendly flight attendants, easy access to a plane, uneventful takeoff. Then: BOOM! You blow up without any warning whatsoever.
NT: The terminal and flight attendants all look like those the Windows plane uses, but the process of checking in and going through security is a nightmare. Once aboard, those passengers with first class tickets can go anywhere they want and arrive in half the time, while the vast majority of passengers with coach tickets can't even get aboard.
Unix: Everyone brings one piece of the plane. Then they go on the runway and piece it together, all the while arguing about what kind of plane they're building.
