Computer system is a collection of different hardware components.
An OS is a collection of system program that together controls the operations of computer system. Example:UNIX, MS-DOS, MS-Windows, Linux etc.
in broad approach, we can classify the operating system on the basis user interface like command or character user interface operating system and graphical user interface operating system.
CUI provides the interactive terminal where user could enter the command to interpret.
GUI consists of different components such as text box, icon, desktop, pointing devices etc.
MS-DOS stands for Microsoft Disk Operating System.
MS-DOS has three essential files and many command files. These essential files are: IO. SYS (Input Output System), MS DOS, SYS (Microsoft Disk Operating System), and COMMAND.COM.