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MS-DOS in Windows 95



Why Learn DOS?
The most important and often overlooked facet of protecting your data in this day and age of the graphical user interface is to learn the basics of the DOS command line. Although with Windows 95 you can happily go on forever in your daily computing with absolutely no knowledge of working with the command line, the chances are that when and if disaster strikes you will often have no other method of retrieving your data or restoring your configuration. Although almost any fouled configuration can be restored by reinstalling Windows 95 directly over the old configuration, easier and faster methods are often available from the command line, and even if you do reinstall you may need to load your DOS CD-ROM driver to do so.

Underneath the hood, Windows is a large, complex operating system, while DOS is relatively simple in comparison (emphasis on the words in comparison). For this reason, you can often access your hard drive for recovery operations in DOS-mode when Windows 95 refuses to load at all. For this reason, we have included this turorial here, which will give you a thorough grounding in the basics. Even if you chose not to invest the time in learning it now, you may wish to print a copy for your personal reference in the event of an emergency.

In The Beginning
In the beginning, there was DOS.

When the computer is turned on, it goes through a process called booting. The word booting is derived from the process by which the computer literally picks itself up by the bootstraps. In the first stage of booting up, the computer begins by testing it\'s RAM memory chips and other components in what is termed a POST test (Power On Self Test). After the POST test successfully completes, the floppy disk drive spins and if no disk is available in the disk drive, the hard drive inside the computer initializes.

At this point, you get a message on your screen, "Starting Windows 95". A splash screen then appears -- the familiar Windows 95 logo image. It hangs around for a while as your disk chatters away in a whirlwind of activity. Eventually, the Windows 95 Desktop appears and you\'re ready to go into action.

What is happening in the background behind that splash screen? What is that frenzy of disk activity? To find out what\'s going on, try this simple method: after you turn your computer on, wait for that splash screen to appear and then press the key on your keyboard. You will see a black screen with white characters. This is DOS.

After the POST and before Windows 95 starts up, DOS takes over. Two hidden DOS files in the root directory of your boot disk (usually C:), Io.sys and Msdos.sys, are loaded and they configure certain aspects of your operating environment. Two other hidden DOS files, Config.sys and Autoexec.bat are then loaded and processed -- if they exist on your computer. These last two files are not required by Windows 95 and exist only if your computer has older software or hardware installed which requires their existence. After DOS completes its tasks, it loads Windows 95. Windows 95 replaces the DOS elements with its own components and takes over control of your computer.

Windows 95 and MS-DOS
The Operating System is the medium by which the various computer hardware devices communicate with each other. Until Windows NT and Windows 95, all earlier versions of Windows ran on top of an Operating System called MS-DOS. DOS is an acronym for Disk Operating System, and MS-DOS is Microsoft\'s version of this product. DOS was the software program which controlled the primary input and output of your computer while you used a software application.

DOS interpreted what you typed at a DOS prompt, converted this to computer language (called machine code), and then instructed the computer to execute the commands. In a sense, DOS was like a foreign language interpreter that interpreted what you typed in to the keyboard and converted it into a language that the computer could understand. Simply put, DOS was the interface between you and the computer. These earlier versions