storage devices Essay

733 WordsFeb 18, 20093 Pages
Different Types of storage devices Storage devices can either be magnetic or optical Magnetic Backing Storage devices Hard Disks Hard Disks are usually found inside computer. They have a large capacity which allows large programs to be stored as well as large files (eg a multimedia document with sound and video). A hard disk consists of of rigid circular plates that have been magnetised, and each hard drive usually contains several disks stacked on top of each other. These disks are fairly quick as they spin around. The read and write heads float above the disks on nothing more than a cushion of air. They are so close that a speck of dust would ruin the hard drive. This would be quite serious, because if there is a problem with the hard drive, all of the data stored on it may be lost, Floppy Disks The most common external backing store is a 3.5 inch floppy disk. Floppy Disks only have small capacities (1.44 Mb) and are fairly slow but they allow files to be taken from one computer to another. The disk inside the casing a circular piece of magnetised plastic. Because it is floppy, it gets easily damaged. A floppy disk works quite similarly to a hard disk. The read and write head actually makes contact with the circular disk, thus reducing the life span of the disk Tape Magnetic tape is often used when large amounts of data need to be backed up. This means that tape is often used to backup data so that if a disk crashes then there is a second copy of the data which can be recovered onto a new disk. Tapes are not useful for data which is being constantly used because the actual tape could be 100's of metres long and it would take a long time to get from one end to another. The access time is slow, because the read and write head can’t go directly to a particular piece of data, it has to wind through the whole tape. This is known as serial or sequential

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