In 1972， IBM introduced flexible diskettes as a medium for loading programs into mainframe Because the disks were so flexible， they were nicknamed floppy They are inexpensive， small， and easy to handle， store， and send through the Most computers have at least one floppy disk Floppy disks， also called diskettes， are available in two sizes: 5 and 25 For MS-DOS based computers， the 5-inch disks are available in 720-kilobyte (double - density)， 44-megabyte (high - density)， and 88-megabyte (extended - density) The 25-inch disks have a density of 48 tracks per inch， whereas high-density disks have a density of 96 tracks per Almost all 5-inch floppy disks have a density of 135tracks per The earliest models of floppy disks were single- The addition of another read/write head in the disk drive led to the use of double-sided floppy disk， and doubled the capacity of the Today， all floppy disks are double- If you examine a 5-inch floppy disk， you will see that a metal sleeve covers the read/write When you insert the disk into a disk into a disk drive， the metal sleeve slides back， exposing the read/write The read/write head of the floppy disk drive can position itself over specific Because of the metal sleeve and the rigid plastic casing， the 5-inch floppy disk is less vulnerable to damage than the 25-inch floppy To use the files or programs that are on a floppy disk， you must first insert the disk into a floppy disk Floppy disk drives are commonly referred to as the A drive and the B Check your computer manual to see which drive is A and which is B
The computer is a wonderful It has a lot of Today most computers have a That means information can be stored in it and be taken out any time So computers are used a great deal in many Computers are being made kinds of They can be used in doing business work smaller and cheaper while at the same time they have been made easier for Computers have worked faster and faster Computers can do many in science research work， in science of medicine， in some large factories; and even in our daily People also have been buying hone computers to plat computer games at They have become very popular
