STORAGE

STORAGE

1. REASONS FOR STORING DATA

   • Data may need to be transferred from one device to another
   • Backup copies need to be taken in case the original files are lost or have become corrupt.
   • Basic setup information and operating systems are required for the computer to function
   • Files created by user need to be stored so that they can be used again.

2. TYPES OF STORAGE

   • INTERNAL
     • Internal Storage refers to storage devices that are inside the computer case.
       • ROM: When a personal computer backs up, it uses data stored in ROM (Read Only Memory which holds programs and data whilst the computer is being booted) to load the BIOS (Basic Input/Ouput System) to make the computer work.
       • HARD DISK: Stores the operating software. Applications software and data files are also called up from the hard drive as the user requests them.
   • MAGNETIC
     • Hard Disks and Floppy Disks work by storing data on magnetised surfaces.
       • HARD DISKS
         • Main storage device in computer. Contains a number of metal platters which have been coated with a special magnetic material. The data is stored in the magnetic material. Read and write heads move between the disks as they spin to read the data from the surfaces.
   • EXTERNAL
     • A computer needs backing storage for mass storage of data and prorgrams. This is usually done by using external storage devices.
       • EXTERNAL HARD DRIVE: Connect through the USB port, allowing safe backup of internally stored data.
       • DAT TAPE: Often used to back up servers. Small but can hold a lot of data. Slow to write to and very slow to retrieve data.

3. REMOVABLE MEDIA (Includes External Devices)

   • Optical Memory (CD/DVD/Blue-Ray/HD DVD)
     • Optical technology is used to etch data onto a plastic coated metal disc. Laser beams are then passed over teh surface to read the data.
       • CD-ROM/DVD-ROM: Read only. Used to supply software. No further data can be written to them
       • CD-R/DVD-R: Can have data written to them once, but the storage space cannot be overwritten with new data. Write once, then read only.
       • CD-RW/DVD-RW: Can have data written to them many times rather than just once, with the new data overwriting the old. Can be used to transfer data between machines, as they are reusable.
   • USB Flash Drives
     • Flash memory has a very small size., so it tends to be used for portable devices such as digital cameras, MP3 Players, mobile phones etc. USB Flash Drives are ussed for transferring data between machines. Consist of flash memory built into a case with a USB connection, and most operating systems will recognise the drive and allow data to be transferred without installing drivers.
   • FLOPPY DISKS
     • A floppy disk stores data on a circular piece of magnetic film, built into a plastic case for protection. No longer a practical storage method as they only store 1.44mb of data.

4. Online Storage

   • The increased upload and download speeds made possible by broadband Internet connections means that it is now feasable for more people to store their data away from their own computer. The Cloud is a new way to store data online.

5. FILE COMPRESSION

   • Reducing the size of a file by converting it to a different format
     • 1MB = 1024 KB
     • 1GB = 1024MB
     • 1TB = 1024GB