The CONFIG.SYS file contains commands that are used to instruct MS-DOS^® to install devices, set the number of possible open files, set the number of logical drives available, etc. The CONFIG.SYS file has certain commands that are exclusive to it.

Example:

The DEVICE command is used to load an installable device driver into the operating system.

e.g. DEVICE = C:\MOUSE\MOUSE.SYS
installs the mouse driver into memory.