Backing Storage Devices

Difference between Backing Storage Devices and Media A backing storage device is used to read the media. For example –A CD drive is a device –A CD is the media Device

Need for backing storage Main memory only stores the software and data whilst the computer is using it. Backing storage is way of storing the software and data permanently. Backing storage has a certain capacity (amount of storage) which is usually measured in megabytes or gigabytes

Hard Disk Hard Disks are fitted in almost every computer and can be removable or included as part of the base unit Hard Disks stores data using magnetic charge

Compact Disk-Recordable CDs are optical disks which use laser technology to read and write data CD-R discs allows you to record data once. Once data is recorded on it, it becomes read only

Compact Disk-ReWritable CD-RW discs can be written to and read from many times over

Compact Disk-Read Only Memory CD-ROM discs cannot be written to but only read CD-ROMs cannot be used to back up data

Digital Versatile Disks DVDs are optical disks which use red laser technology to read and write data DVD-Rs are Write Once Read Many discs DVD-RWs allow users to write data to the disc so they may be used in the same way as a normal hard disc. DVD-ROMs are read only and are excellent for storing movies

Blu-Ray Disks Blu-Rays are optical disks which use blue laser technology to read and write data BD-Rs are Write Once Read Many discs BD-REs allow users to write data to the disc so they may be used in the same way as a normal hard disc. BD-ROMs are read only and are excellent for storing HD movies

Flash Memory Flash memory is a solid state device which means it has no moving parts Some flash memory needs a special connector (USB) Flash memory is used in digital cameras, laptops and some games consoles Flash memory is portable and can be used in lots of different devices

Memory Capacity BitBinary Digit – a 1 or 0 Byte8 bits, eg (one character eg the letter A) Kilobyte1024 bytes Megabyte1024 kilobytes Gigabyte1024 Megabytes Terabyte1024 Gigabytes

Capacities CD700 Megabytes700 Mb DVD Single layer4.7 Gigabytes4,813 Mb DVD Double layer17 Gigabytes17,408 Mb Blu-Ray Single layer 25 Gigabytes25,600 Mb Blu-Ray Double layer 50 Gigabytes51,200 Mb Flash Drive4 Gigabytes – 64 Gigabytes 4,096 Mb – 65,536 Mb Hard Disk 500 Gigabytes – 2 Terabytes 512,000 Mb – 2,097,152Mb

Magnetic Tape Magnetic tape uses plastic tape coated with magnetic material to store digital data Capacity will depend on the length of tape being used

Types Of Access Magnetic tape uses sequential access –To get to a piece of data you have to fast forward or rewind All other media uses random access –To get to a piece of data the device will jump straight to it