Storage Devices

Storage Devices - Data Storage Device - Data Storage - Computer Hard Drive - Storage - Storage Network - Data Backup

The main memory or RAM of the computer is volatile. It cannot be used as permanent storage because when computer is switched off, its contents are erased. Its storage capacity is also very small.

Storage devices are used to store data and programs permanently on storage media. A storage device is a computer hardware component that writes and reads data to and from storage media. Writing data means recording data from memory to a storage medium. Reading or retrieving data means transferring data from storage medium into the computer’s memory for use by the operating system or application program. When storage device writes data (or programs) on the storage medium, it performs function as output device. Similarly, when storage device reads data from disk and loads it into RAM, it performs function as input device. It is because; storage devices are also referred to as I/O storage devices.

The speed of storage device and memory is defined by access time. The access time of storage device is measured as the amount of time that a storage device takes to locate and retrieve a specific data on the storage medium. Similarly, the access time of RAM is measured as the time required delivering data from RAM to the processor. The access time of storage device is slower than access time of memory.

A storage media is the physical material on which data and programs are stored. It is non-volatile and is used to store information permanently for future use. The storage capacity of storage media is the number of bytes the storage media can hold. A large amount of data and programs can be stored on it. Its storage capacity is up to Gigabytes (GB) for personal computers. For example, a typical hard disk has storage capacity of 160 GB (approximately 80 billion bytes) or more. The application software and system software are stored on the secondary storage. Examples of secondary storage are floppy disk, Zip disk, hard disk, magnetic tape, CDs and DVDs.