Hardware Reference
In-Depth Information
In 2006, the HDD celebrated its 50th anniversary, a milestone in computing technology.
By the time PCs arrived on the scene in 1981, hard drives of 5MB in capacity were avail-
able.Togiveyouanideaofhowfarharddriveshavecomeinthe30orsoyearstheyhave
beenusedinPCs,I'veoutlinedsomeofthemoreprofoundchangesinPC-basedharddisk
storage:
• Maximum storage capacities have increased from the 5MB 5 1/4-inch full-height
drives available in 1981 to 3TB in 2011 for 3 1/2-inch half-height drives, 1.5TB for
laptop 2 1/2-inch drives, and 250GB for 1.8-inch drives. Hard drives smaller than
200GB are rare in new desktop or even laptop systems.
•Datatransferratestoandfromthemedia(sustainedtransferrates)haveincreasedfrom
about 100KBps for the original IBM XT in 1983 to an average of over 100MBps for
some of the fastest drives today, or more than 130MBps average for the fastest SAS
drives.
• Average
seek times
(how long it takes to move the heads to a particular cylinder) have
decreased from more than 85ms (milliseconds) for the 10MB drives IBM used in the
1983 vintage PC-XT to as low as 3.3ms for 15,000 rpm drives today.
• My first 10MB hard drive/controller cost $1,695 for the drive and $695 for the con-
troller in 1983. That's equal to more than $5,280 today! Currently you can get 1TB
drives (with integrated controller) for around $50 (or less), which means that the price
of a typical hard drive today costs well over 100 times less than what it did nearly 30
years ago. HDDs used to be an expensive high-end component; now they are a cheap,
almost disposable commodity.
Note
IBM left the hard disk business when it sold its Hard Disk Drive operations division to
Hitachi on January 6, 2003. Hitachi Global Storage Technologies (
www.hitachigst.com
)
,
which was formed to manufacture, sell, and support both Hitachi and former IBM disk drive
products such as Travelstar, Microdrive, Ultrastar, and Deskstar product lines, announced
March 7, 2011 that it was being acquired by Western Digital.
Form Factors
ThecornerstoneofthePCindustryhasalwaysbeenstandardization.Withdiskdrives,this
is evident in the physical and electrical form factors that comprise modern drives. By us-
ing industry-standard form factors, you can purchase a system or chassis from one man-
ufacturer and yet physically and electrically install a drive from a different manufacturer.
Form factor standards ensure that available drives will fit in the bay, the screw holes will
lineup,andthestandardcablesandconnectionswillplugin.Withouttheseindustrystand-
