What Goes on in a Hard Drive
The hard disk drive, commonly referred to as HDD or HD, is the computer’s primary permanent storage device. Introduced in September 1956 with the IBM 305 RAMAC computer, the first hard disk drive was capable of storing five million characters. The IBM 350 moving head hard disk drive contained 50 discs, each measuring 24 inches, and it weighed over a ton.
Today’s hard drive contains one or more disks, which are air sealed in a casing. A desktop computer’s hard drive is usually permanently stored in a drive bay in the front of the computer.
The hard drive consists of four basic components: the platters, the head arm, the head actuator, and the chassis. All hard drives are composed of these components; however they may not perform the same way. Generally, hard drives that are built will higher quality materials will outperform those that are not.
The disks within the hard drive that store magnetized data are called platters. The platters store information on magnetic layers on both sides of the disk. The platters rotate in unison on a motorized spindle while data is written to them by read/write heads on both sides. The hard drive may spin as fast as 7200 rotations per minute.
The head arm, also referred to as the actuator arm, moves the read/write heads around the platter in pulses. All of the heads are attached to a single head arm, which moves to locations on the disk where data needs to be read or written to. The head actuator is a motorized electronic device which is responsible for moving the head arm.
The chassis is the housing that holds the hard disk drive components, and is stored inside the computer. Also known as the case, the chassis is stored inside of the computer tower, or within a laptop assembly.
Data is stored in the hard disk drive as files, and there are numerous types. When a computer program requests a file, the job of the hard disk drive is to retrieve it and send it to the central processing unit, one byte at a time.
Hard drive performance may be measured by its capacity, seek time, and data rate. The capacity refers to the size of the hard drive and number of bytes of data it can hold. Seek time is the amount of time it takes to retrieve and send a file after the central processing unit requests. The data rate refers to how many bytes each second the hard drive can deliver to the central processing unit.
With the necessity for reliable and versatile storage solutions, external portable hard drives were created. External hard drives are commonly used to back up important information to prevent data loss and lead to data recovery.
Hard drives were initially created for use in computers. With the advancement in modern technology and the popularity of handheld devices, hard drives are now used in personal data assistants, mobile phones, mp3 players, video games, digital cameras, voice recorders, and more.
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