Perpendicular Hard Disk Drives
What is a Hard Disk Drive?
A Hard Disk Drive (HDD) is a device used by modern computers to permanently store information. The Hard Disk Drive is arguable the most essential part of a computer system in that all the information that is permanently stored is contained within its enclosure, including your computer’s Operating System (OS). Thanks to Hard Disk Drives, long gone are the days when you would have had to keep all your programs and documents stored on removable media such as Floppy Disks or CD-ROMs.
Originally invented in the mid 1950’s and made commercially available in 1956 by International Business Machines (IBM). Called RAMAC (Random Access Method of Accounting and Control), the first Hard Disk Drives contained as much as 50 platters which were 24 inches in diameter and were computers in their own right albeit with a single purpose – to store data. The entire unit which housed the hard drive was the approximate size of two large refrigerators placed side by side. In the 50 or so years since their invention, Hard Disk Drives have steadily and aggressively far out paced Moore’s law. Which stipulates that memory in computers will increase by 100% approximately every 18 months. Hard Disk Drives on the other hand have increased capacity in the same period by approximately 130%, an increase of 100% every nine months in many cases. Such capacity increases are being threatened, however. I
n the years since the first Hard Disk Drive very little has changed apart from logical steps in technology such as the increased speed or improved interfaces, the basic technology has changed very little. There have been no technological leaps, as it were, for Hard Disk Drives beyond their increased miniaturisation. Apart from miniaturisation and recording media improvements the Hard Disk Drive as a device is almost identical technologically speaking, to the very first, the RAMAC.Hard Disk Drives use a similar technology as is employed in audio and video cassettes. Such audio and video cassettes use a magnetic ribbon wound around a two wheels to store data. To access a particular portion of the data contained on the magnetic ribbon, the device must wind the tape such that the beginning of the section containing the data is underneath the device that reads the data (the magnetic read/write head). This process is called sequential data retrieval because in the process of accessing the particular data, the device must sequentially read each piece of data until the data it’s looking for is found. This process is very time consuming and contributes to wear.
