Microsoft's MS-DOS is an operating system developed for the PC in 1980. Originally designed to run on 8088-architecture computers with less than 640KB of available RAM, the operating system went through many iterations over the years. Today, a modified version serves as the Command Line Prompt inside Windows operating systems, and it can still perform many of the same basic functions as the original release of MS-DOS.
One of the aspects of MS-DOS that still survives in Windows is the drive and directory system. The OS uses letters to identify drives, and directories and subdirectories with eight-character names denoted by a backslash character. "C:\GAMES" represents one level down from root, while "C:\GAMES\CARDS" is one further subdirectory level down. You can move through these directory levels using the CD or "change directory" command, using "CD .." to return to a higher level. The "mkdir" or MD command creates directories, while the "rmdir" or RD command deletes them. Since most tasks in MS-DOS take place in the current subdirectory, navigation is an important function of the operating system.
Files in MS-DOS use an "8.3" naming system, eight characters for the file name and three characters for an identifying suffix that tells the operating system what type of file it is. Wildcards are available for file manipulation, with "?" representing a single character and "" representing any number of characters. For instance, the command "COPY .* C:\GAMES" will copy all files in the current directory into the C:\GAMES directory. To move files from one folder to another in early versions of DOS, you would first copy them into the target directory and then delete the originals, as the "Move" command did not exist until DOS 6.0.
Running programs under MS-DOS simply requires you to enter the eight-character name of the program, if the file is a type that the operating system understands as an executable. Files with the .exe and .com suffixes are binary executables, while .bat files are text scripts that can trigger multiple programs in succession. These programs often allow you to perform more complex operations than MS-DOS would allow, as well as take advantage of more installed memory. Early versions of Windows required you to boot into MS-DOS and run WIN.EXE to load the graphic user interface.
MS-DOS also contains a number of utilities for disk and drive management. If a drive begins began showing symptoms of structural problems, the CHKDSK or "checkdisk" command scans for errors and, if possible, corrects them. The FDISK command allows you to "low-level format" a drive, altering its partition structure, while FORMAT wipes any disk and prepares it for re-use. In modern Windows operating systems, however, a set of more user-friendly tools replace these functions, helping prevent accidental data loss.