Information away in hard disk represent which type of signal
Answers
"Hard drive" redirects here. For other uses, see Hard drive (disambiguation).
A hard disk drive (HDD), hard disk, hard drive, or fixed disk,[b] is an electromechanical data storage device that uses magnetic storage to store and retrieve digital information using one or more rigid rapidly rotating disks (platters) coated with magnetic material. The platters are paired with magnetic heads, usually arranged on a moving actuator arm, which read and write data to the platter surfaces.[2] Data is accessed in a random-access manner, meaning that individual blocks of data can be stored or retrieved in any order and not only sequentially. HDDs are a type of non-volatile storage, retaining stored data even when powered off.[3][4][5]
Hard disk drive
Laptop-hard-drive-exposed.jpg
Internals of a 2.5-inch SATA hard disk drive
Date invented
24 December 1954; 64 years ago[a]
Invented by
IBM team led by Rey Johnson
A disassembled and labeled 1997 HDD lying atop a mirror
File:Harddrive-engineerguy.ogvPlay media
An overview of how HDDs work
Introduced by IBM in 1956,[6] HDDs became the dominant secondary storage device for general-purpose computers by the early 1960s. Continuously improved, HDDs have maintained this position into the modern era of servers and personal computers. More than 200 companies have produced HDDs historically, though after extensive industry consolidation most units are manufactured by Seagate, Toshiba, and Western Digital. HDDs dominate the volume of storage produced (exabytes per year) for servers. Though production is growing slowly, sales revenues and unit shipments are declining because solid-state drives (SSDs) have higher data-transfer rates, higher areal storage density, better reliability,[7] and much lower latency and access times.[8][9][10][11