Before any work can be done on the microcomputer, the disk operating the system must be present. Most of the work of an operating system is done behind the scenes, and it determines the "personality" of the computer -- whether the user executes a program with a command or the the click of a mouse button. Data from the input device is interpreted by the operating system into language understood by the computer. It reads the keyboard, updates the monitor screen as data is input, maintains disk directories, allocates memory to application programs, and allows programs to share routines. Software programs that are written to run through a particular disk operating system like DOS have routines in common. These routines are performed by DOS and, therefore, do not need to be included in each program.
A disk operating system allows users to perform certain functions such as naming files, copying files, formatting disks, creating directories and sub-directories, and deleting files. DOS also represents the most popular operating system for IBM and compatible personal computers, ensuring that many different programs can run on a computer that is suing this operating system.
Microcomputers containing internal hard disks load the disk operating system into memory when the machine is turned on. The computer is now ready for your input. However, because the computer is basically stupid, you must enter commands exactly as the computer has been programmed to receive and understand them. Computers are not yet intuitive. Therefore, commands to perform a specific operation must be remembered and entered in exact and specific formats.
If you boot a DOS computer which does not contain a menu system,
you will probably be greeted with a blank screen except this : C:/>.
The blinking cursor mean that DOS is waiting for your instructions. DOS
is present in the memory of the computer. The drive currently active is
the "C drive.