AS - Storage Devices

AS - Storage Devices

1. Magnetic Storage Devices

   • Hard Disk
     • Most common storage device. Housed witihin rhw box containing the processor. Can hold many gigabytes of data. Used to store the operating system and other software as well as data files. Can be divided into folders to allow files to be found and organised, hence helps to produce an effective folder structure.
   • External Hard Disk
     • Increasingly common that a computer system will have an external hard drive which connects to the computer via a USB port. Can be used as a backup in the case of a failure with the internal hard disk. Can be used to increase the storage capacity of a computer, if the internal hard drive is full. Can be used to transfer data from one computer to another.
   • Floppy Disk
     • A small, flexible plastic, magnetic disk inside a hard plastic case. Data transfer is slow. Capacity of the device is generally very small (1.44 MB). Used for keeping backup copies of small files, such as text files of letters or small documents, or for transferring small files between two or more computers. Very cheap option.
   • Magnetic Tape
     • Cartridges are used for backing up entire networks due to their high capacity. Is a serial medium. This means that the data has been read in the order in which it is stored on the tape. Sometimes used for archiving large volumes of data.

2. Optical Storage Devices

   • CD-ROM
     • Compact Disk-Read Only Memory. Can be moved from computer to computer. They store larger quantities of data permanently in comparison to a floppy disk. Data stored on this is less prone to damage than on a floppy disk as the data storage method uses laser rather than magnetic technology. Can be read from but not written.
   • CD-Rs
     • Compact Disk-Recordable. Writable compact disk. Data can be recorded onto a blank disk. This data cannot be altered but can be read by any other PC with a standard CD-ROM drive. Suitable for archiving data that can be removed from the computer's hard drive. Useful for storing multimedia applications such as sound, graphics and animation files.
   • CD-RWs
     • Compact Disk-Rewritable. Rewritable compact disk. Up to 650 MB of data can be recorded, deleted, re-recorded on this disk. Can be used in the same way as a floppy disk without the limitation on file size.
   • DVD
     • Digital Versatile Disk. High capacity optical disk. Current disks store between 4.7 and 17GB. They are used for films as well as audio.
     • DVD-R (Recordable DVD) and DVD-RW (Rewritable DVD) are available as well but the capacity is reduced.

3. Flash Memory

   • Removable backing storage developed for small devices such as digital cameras and is not a portable medium.
   • USB Memory Stick
     • Portable storage device. Plug memory stick into USB port and the computer recognises the stick as a removable drive. Do not require any battery or cables and are available in capacities ranging from 128 MB to 4 GB. Used to record various types of data: graphical images, music, moving images and videos.