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File Management System

The File Management System (or simply File System) is the layer of system software responsible for organising and managing the storage of data on permanent media.

This media is often magnetic, eg: hard and floppy disk drives and tape streamers, but optical media such as CD-ROM and DVD are also commonplace, and solid state memory devices, such as pen drives or flash drives are becoming increasingly common.

As you know, each storage device on a computer has a drive letter assigned to it. The table below shows a typical allocation of drive letters:

Drive Description
A: First floppy disk drive
B: Second floppy disk drive (only normally found on older machines)
C: Hard disk drive
D: Optical drive (CD/DVD reader/rewriter)
E: USB drive

If a machine has two hard disks, the second one is referred to as D: and the letters for subsequent devices are incremented, eg: the CD/DVD drive would then be E: and so on.

Many of these devices are bootable, meaning that the operating system can be loaded from them. The usual boot device is the hard disk, but a computer can also be booted from a floppy disk (often used in emergencies) or from a CD-ROM (often used for installing the operating system). The order in which the computer attempts to boot from the various devices is known as the boot sequence. This can be adjusted via the BIOS, a set of instructions stored in a read-only memory chip which enable a computer to start the operating system and communicate with system devices.

A computer's file system can be regarded as analogous to a filing cabinet, as used for storing paper documents. The disk drives correspond to the drawers in the filing cabinet and the directories correspond to the folders stored in the drawers. The individual files, such as Word documents, spreadsheets etc. correspond to the sheets of paper stored in the folders of the filing cabinet.

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