Dos Tutorial

                         Every computer needs an 
operating system. Operating system 
controls all the computer equipment
and allows to check itself. DOS 
co-ordinates the computer system,
just as the conductor co-ordinate 
the orchestra. Your application 
programs run in concert with DOS, 
trusting it to keep the system humming.
DOS lets you control the things you care
about such as which program to run what 
report to print what disks to format or 
what files to erase. These functions 
share an important characteristic, the
disks and disk drives.
           There are two major types of
software They are system program which 
control the operation of the computer 
system and the application program which performs more obviously useful tasks, such as word processing , data base management spreadsheet, calculations etc. 
             The program user hardware. It must be able to receive instructions from the keybord. display and print results, read and write files from to a disk send and receive data through the computers communication connections change the colors on the color display, and so on through all the capabilities of the hardware.
             Each program doesn't have to perform all these functions for itself. A system program called the operating system manages the hardware, the operating system allows an application program to concentrate on what it does best, where it is moving paragraphs about, tracking account receivable bill or calculating stress in a bridge beam, etc.