The Mysteries of DOS

DOS is an acronym for "Disk Operating System." DOS consists of a small but powerful set of programs which manage most of the Hardware and some of the Software resources of the Personal Computer (PC). The resources managed by DOS include Hardware items such as the CPU (central processing unit), Memory, HDDs (Hard Disk Drives), Keyboard etc. The Operating System provides a stable and consistent way for applications (eg. an accounting or other special purpose program) to communicate with and/or control the Hardware without having to know all the details of the Hardware.

Twenty years ago at the beginning of the PC era Microsoft produced MS DOS for IBM the original makers of the PC. Many PC users today are still using the same or though more advanced DOS Operating System even if they are running Microsoft Windows. It may not be visible to the user but it is the underlying foundation for Windows 95/98/ME. There are exceptions which include users of Windows NT, Windows 2000 and the soon to be released Windows XP which are operating systems in their own right - although many DOS commands are still available to the user even in these products.

With the ease of use provided by the Windows GUI (Graphical User Interface) Operating System why should we bother to learn anything about DOS?. Put simply, if you need to repair a faulty Computer, there are times when nothing else will do. If your Hard Drive fails, you cannot start Windows 95/98 from a diskette. DOS is a command line operating system, meaning that commands must be typed in at the command line, or "DOS prompt." Every command you type must be put into effect by pressing the ENTER key.

Lets look at a very simplified history of DOS. In the beginning the first Computers operated just with the DOS Operating System. Some programs supported a mouse which was a luxury. Most functions within programs were achieved by keyboard key combinations. With the release of Windows 3.1 the ease of the GUI was introduced however before the user could actually get to the functionality of Windows the PC had to first load DOS. This was an obvious process and the user could observe DOS loading then Windows loading once DOS had completed its processes.

You could consider Windows 3.1 actually sat on top of DOS providing a nice easy to use menu system and very basic multi tasking functions. With the advent of Windows 95 DOS was integrated within the Operating System and no longer visible to the user as the computer started up. This process has continued with Windows 98 and Windows ME. The DOS programs are normally located in a folder C:\windows\command.

You can reach the DOS prompt from Windows 95/98/ME by clicking START, PROGRAMS, MS DOS prompt. This will start a "DOS Windows Session" or "DOS Box" and the screen should look similar to the message below.

Microsoft(R) Windows 98
(C)Copyright Microsoft Corp 1981-1998.

C:\WINDOWS>_

For Windows 95/98 users only, when the computer is booting up pressing the F8 key just after the BIOS messages will bring up a menu. You can select from that menu to start at the Command Prompt. If this option is used then the Computer should show the screen prompt below. This is what is called a real mode DOS prompt.

C:\ >_

The C: tells you that you're currently using the C: Drive. To change drives, simply type the drive letter and a colon at the prompt. For example, to change to the A: Drive, you would type A: and press the ENTER key on the keyboard. To change back to C: just type C: then ENTER.

With DOS commands every entry must be followed by the ENTER key. Try changing to the Windows folder using the following command

CD Windows

The prompt should now look like this.

C:\Windows>_

When you are at the DOS prompt try some very simple commands. Type DIR and (enter) and observe the listing of all the files in the current folder. Please note that DOS may hide some files from your view depending on the attributes set for the files in that folder. Typing DIR /? will display a list of all the switches applicable to the DIR command.

Try the CLS command and see what happens. You may even wish to try copying a few files to a diskette using the following command. Please may sure you have a blank diskette in the A: Drive.

COPY *.LOG A:

This command copies all files in the current folder with the file extension .LOG to the diskette drive. The * means to copy every .log file irrespective of the first part of the file name.