This guide explains: how the DOS operating system is structured so that you can understand what happens when you first switch on your computer; how directories and subdirectories can be employed to structure your hard disc for maximum efficiency; how to manage disc files and how to use the MS-DOS Editor to fully configure your system by writing your own CONFIG.SYS and AUTOEXEC.BAT files; how to optimise your system by either increasing its conventional memory manually or automatically with the use of MemMaker, or increasing its speed; how to write batch files to automate the operation of your system,and how to write and implement multiple configurations; how to use the Microsoft Utilities, such as DoubleSpace, MsBackup, Undelete, and Anti-Virus; how to resurrect MS-DOS 7 which is buried under Window 95.