Computer opertions We could begin by ensuring that the power supply to the system is intact. Press now the switches on the monitor and the CPU and the computer has begun its function.   What the computer does first is to test its memory. This process requires less than a minute. While memory test is going on numbers will hit across the screen at great speed. At the end of it there will appear a number which mentions the capacity of the computer's memory. Completion of memory testing is denoted by a symbol, c:>. You can now use the key board to input data or access information. This entire process is known as booting. We can now give the necessary instructions to the computer. The system that enables the functioning of the computer in this manner is called DOS   DOS is an essential program that should be known to any computer operator.IBM, world's leading computer establishment developed the DOS in 1980. Its distribution rights are now vested with Microsoft, another world renowned computer company. Once the DOS reaches the computer memory, we can make it perform several functions following the instructions DOS contains. Some of the instruction as well as their purpose in DOS are given below ; ----------------------------------------------------------------------- INSTRUCTIONS        PURPOSE/USE ------------------------------------------------------------------------ DATE    :      To check and rectify the date if need needed. TIME : To check and rectify the time VER : Denotes the version of DOS DIR : Shows the entire list of files in the concerned drive COPY : Copying data from one floppy to another. REN : Renaming of files DEL : Deleting of unwanted files FORMAT : Layout, presentation or arrangement of a text to be stored in a disk. CLS : Clear the complete matter on the screen. BACKUP : Copying and keeping of important files SORT : Arranges directory in the specific order needed. ATTRIB : Makes the file in a disk readable PATH : Indicates the way TREE : Shows the directory and sub - directories of a drive After each of the above instructions the enter key should be pressed for the implementation of the instructions. Preparation of a file A file is a set of information that are co - related. A large number of files can be stored in a single disk. It is important to give each file a name which helps in identification.Certain points should be noted while naming a file. The name of a file has two portions - a primary file name and an extension name. Primary name can have a maximum of eight letters. We can use alphabets and numbers from 0 to 9. If the file name has more than eight letters the computer selects the first eight letters as the file name. There are some special codes which have exclusive use in a computer viz. com to com4, con,  AVX, LPT1, LPT2, LPT3, PRN, NUL. These codes cannot be used for naming the files.The extension name can have a maximum three letters. As an identity, unlike the primary name, there is a full stop mark along with the extension name. While selecting a file name be sure that it has not been used earlier.