Search results
Results from the WOW.Com Content Network
Hard disk drives store data in the magnetic polarization of small patches of the surface coating on a disk. The maximum areal density is defined by the size of the magnetic particles in the surface, as well as the size of the "head" used to read and write the data. In 1956 the first hard drive, the IBM 350, had an areal density of 2,000 bit/in 2.
File size is a measure of how much data a computer file contains or how much storage space it is allocated. Typically, file size is expressed in units based on byte. A large value is often expressed with a metric prefix (as in megabyte and gigabyte) or a binary prefix (as in mebibyte and gibibyte). [1]
Therefore, the choice of the base b determines the unit used to measure information. In particular, if b is a positive integer, then the unit is the amount of information that can be stored in a system with b possible states. When b is 2, the unit is the shannon, equal to the information content of one "bit" (a portmanteau of binary digit [2]).
IBM's first hard drive, the IBM 350, used a stack of fifty 24-inch platters and was of a size comparable to two large refrigerators. In 1962, IBM introduced its model 1311 disk, which used six 14-inch (nominal size) platters in a removable pack and was roughly the size of a washing machine. This became a standard platter size and drive form ...
An example of primary storage. 15 GB PATA hard disk drive (HDD) from 1999. When connected to a computer it serves as secondary storage. 160 GB SDLT tape cartridge, an example of off-line storage. When used within a robotic tape library, it is classified as tertiary storage instead. Read/Write DVD drive with cradle for media extended
On the other hand, a hard disk whose capacity is specified by the manufacturer as "10 gigabytes" or "10 GB", holds 10 × 10 9 = 10 000 000 000 bytes, or a little more than that, but less than 10 × 2 30 = 10 737 418 240 and a file whose size is listed as "2.3 GB" may have a size closer to 2.3 × 2 30 ≈ 2 470 000 000 or to 2.3 × 10 9 = 2 300 ...
Get AOL Mail for FREE! Manage your email like never before with travel, photo & document views. Personalize your inbox with themes & tabs. You've Got Mail!
Since the first disk drive, the IBM 350, disk drive manufacturers expressed hard drive capacities using decimal prefixes. With the advent of gigabyte-range drive capacities, manufacturers labelled many consumer hard drive , solid-state drive and USB flash drive capacities in certain size classes expressed in decimal gigabytes, such as "500 GB".