If you purchased your Windows PC within the last five years and have no particular interest in games or specialist applications the chances are that you have had little or nothing to do with DOS, apart from that brief flash of text when you switch on your PC, and the occasional (or possibly not so occasional) mysterious error messages. DOS, or to give it its full name is the Microsoft Disc Operating System (MS-DOS) and it is the foundation upon which Windows -- and Bill Gate’s enormous wealth -- have been built.

That’s really all you need to know, these days DOS exists mainly in the background on a Windows 95/98 PC. Its importance has gradually diminished with each subsequent release, nevertheless, it is well worth getting acquainted with DOS since it can provide a lifeline to revive your PC and recover data after a nasty crash or when Windows refuses to load. An understanding of DOS will also help you weave your way through some of the more puzzling aspects of Windows, so this week it’s back to basics for a brief but essential tutorial on how your PC works and the way it manages files. Next week we’ll delve a little deeper into the workings of DOS and run through some of the interesting things it can do for you.

When you switch on your PC from cold it ‘boots’ up – from the expression picking yourself up by your own bootstraps – and this starts a sequence of events. Stage one is a brief diagnostic routine called Power On Self Test or POST, when the computer checks its RAM chips, disc drives and other vital components, if all’s well it bleeps once and goes on to stage two (more than one bleep usually indicates a problem). The on-screen message appears ‘Starting Windows 98’ (or 95 etc.) and the first ‘Splash Screen’ with the Windows logo is displayed and then disappears; the machine now starts to load and process a number of DOS text files from the ‘root directory’ (more about that in a moment) on the hard disc, the most important ones being ‘msdos.sys’, ‘io.sys’, ‘autoexec.bat’ and ‘config.sys’. Between them they tell the PC about the devices and peripherals connected to the machine, and the software it is using. Then it’s on to stage three, DOS is shunted to the sidelines as Windows loads and takes command of the PC.   

Windows now becomes the PCs primary operating system; it controls how the computer’s hardware and software communicates and interacts and presents you with the Graphical User Interface (GUI or ‘gooey). This is the familiar Windows ‘desktop’, a simple to use pictorial analogy that allows you to use and control your PC by moving a mouse pointer and clicking on icons or menu items. Essentially DOS does the same job but without all the frills and pretty graphics; instead of clicking on icons things are made to happen by typing in text commands and keyboard actions. DOS interprets the commands and turns them into a language the computer understands, called machine code.

Because DOS uses text-based instructions and doesn’t need layers of extra software for colourful graphics it is much simpler than Windows. It is also a lot faster, which is why until recently most of the best computer games were DOS-based, though with the advent of faster processors, larger disc drives, increased memory capacity and more advanced graphics controllers many recent games work within Windows.

There are two ways to get into DOS. You can stop Windows from loading during the boot up sequence (we’ll look at that method next week), or you can start a DOS ‘session’ within Windows that allows you to peek inside DOS. Click on the MS-DOS Prompt icon in Start > Programs. This loads a program called, a black window opens on the screen and you will see a Microsoft copyright message and below that a line that reads: C:\Windows>, followed by a flashing cursor. This line is known as the Command Prompt and it tells you a number of things. C: is the identification letter assigned to your PC’s main hard disc drive, backslash Windows (\Windows) shows the directory your PC is currently using, and the greater than symbol and cursor (>_) indicates DOS is ready and waiting for an instruction or command. Now type in the command ‘dir’ (without the quotation marks), a long list of file names will flash past on the screen and the command prompt appears at the bottom of the screen once again. The command ‘dir’ is short for Directory, it instructs the computer to show the contents of the Windows directory.

At this stage it’s wise to look but not touch, DOS is extremely powerful, a few careless keystrokes can wreak havoc, so close the window in the usual way, by clicking on the ‘X’ icon in the top right hand corner. I f you’re feeling bold, type the command ‘exit’ (without the quotation marks) and the window disappears.

This brief encounter with DOS illustrates how information is organised on your PC’s hard disc. The disc drive is like a filing cabinet containing thousands of files – the basic storage unit for data and programs. Related files are collected together into folders, directories and sub directories (folders within folders). There is one exception to this rule and that is the ‘root directory’ mentioned earlier. This is a special section of the hard disc (represented by the blackslash after the C prompt (i.e. C:\). The root directory is set aside for important systems files and directories that the PC accesses when it first boots up, and this is where the DOS files live. In other words – and this is the key point -- you can load DOS, and from there gain access to any other directory on the hard disc, without Windows, that’s what makes it so useful!

Next week – Introducing DOS, part 2




The basic language of computers, usually a form of binary code, where instructions are represented by groups of ‘ones’ and ‘zeros’


Random Access Memory, a computer’s working memory, where programs store data and information when they are running


A usually pointless image or logo that appears on a PC screen whilst a program is loading



A few weeks ago in F!F!F!, we reminded you how to create a new desktop icon that instantly opens a blank message window in Outlook Express. This tip takes it one stage further, creating a personalised message window for anyone that you frequently send emails to, with their address automatically inserted. The basic procedure is the same as before; right-click into an empty part of the desktop, select New and then Shortcut from the menu. In the window that appears, in the Command Line field, type, where the part after mailto: is the recipient’s email address. Click Next, give your new Shortcut a name then click Finish.

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