Definition of a 60GB Hard Drive in a Computer
A 60GB (gigabyte) hard disk drive (HDD) is a computer storage device that is able to store up to 60GB of data. The HDD is the largest and most important storage media in a computer, containing the operating system (OS) files, program, and all user files and data. HDDs are partitioned to create separate drives, a process which usually compromises some physical space on the drive. After partition, a 60GB HDD may have 56 to 58GB of usable space. A typical 60GB HDD may have three drives, each within 15 to 20GB.
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Basic Features
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The HDD is a metallic box found inside the tower casing, connected to the motherboard and power supply unit (PSU) with internal cables. An HDD differs from other computer storage media such as optical drives (CD-ROM and DVD-ROM) and thumb drives in that it has a much larger capacity, it is usually faster, and is permanently attached to the computer. Data in a hard disk is stored magnetically as sequences of 0s and 1s, in which a magnetic orientation in one direction corresponds to a 0, and in the opposite direction, it corresponds to a 1.
Internal Arrangement
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Inside the HDD, round flat discs known as platters are stacked vertically. These discs have tracks running from the inner edge to the outer edge; data is recorded magnetically on regions within the tracks known as sectors. In a 60GB HDD, the cumulative space provided by all the sectors in all the discs add up to 60GB. Data is written on both sides of the discs, using tiny arrangements known as read/write heads. There are two heads --one for the top layer and one for the bottom layer--For each double-sided disc.
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Writing
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When a new piece of data is about to be recorded into an HDD, the information is first encoded in a temporary cache (pronounced cash) to ensure that any subsequent errors in the recording process can be promptly corrected. Next, free sectors large enough to house the new data are located on the platter discs. The actual writing process involves movable components known as actuator arms that bring the read/write heads over the selected sector in the disc. Electrical pulses representing the new data influence a magnetic field on the writing head, which alter the magnetic orientation of bits on the disc. The new data is successfully written, as altered bits on the disc.
HDD & RAM
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When a computer is working on a process, such as running an application, the files associated with the software program are loaded on the RAM (random-access memory) from the HDD. This data transfer is necessary because when the processor accesses data from RAM, it can execute instructions much faster than when it accesses data directly from the HDD. The information is retained in the RAM as long as the processor keeps working on the program and is only removed from RAM when the application is shut down.
Saving Data
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Data is not permanently stored in the RAM because it has limited capacity, and it is a volatile medium, which means that RAM cannot store information without power. The HDD is non-volatile, meaning the device can retain information without a power source. That is why files have to be 'saved,' a process that copies the latest version of data from the RAM and records it in the HDD permanently.
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References
- Photo Credit hard disk drive image by BlueMiniu from Fotolia.com
