Wednesday, August 22, 2012

Essay on Computer Memory

Short Essay on Computer Memory

Computer Memory Advancements
Computer memory, also known as computer data storage, is various digital and recording devices that store information for a designated period of time ( The predominant form of computer memory, as the permanent data-retention capability of various types of information ensures reliable storage. The ability to write and rewrite to the same device an unlimited number of times substantially increases the utility of data storage over non rewritable technologies. The large marketplace for computer-based storage has resulted in significant R&D effort being deployed, which has successfully reduced the cost per bit of storage.

Tape-based storage
Magnetic storage was first used widely in early voice recorders, which originally utilized an iron based (ferrite) wire for storage and later a thin tape, coated with a magnetic oxide, which revolved around a tape head (, 2007). The head could either apply an electric field, which would magnetize the material under the head at that instant in a particular orientation to write data, or, alternatively, sense an electric field induced by the previously magnetized material passing close to a coil of wire, to read the data.

This tape-based storage was widely used for data retention in early computer systems. However, the spool-based nature of tapes means that the access time for information is a function of the current position of the tape and the location of the data. Where information is located close to the current tape position, data is much more quickly accessed than information stored further away. This time difference can be a matter of minutes. Where the order of access to data is not known in advance, this results in slow and unpredictable operating speeds as the tape is wound forwards and backwards. Furthermore, this rapid acceleration and deceleration can lead to tape stretching or even snapping, both of which affect reliability. For archival storage, tape offers an attractive combination of low cost and high data-storage capacity and is widely used in this application area (, 2007).

Magnetic disks
The precursor of the magnetic disk was the drum. Obsolete today, the drum provided the first device where the speed of data access was largely independent of its location. A drum comprised a cylinder of magnetic coated material mounted on a spindle and rotating at up to several hundred revolutions per minute. Close to the outer surface of the drum is a line of read- write heads. Each head is associated with one slice of the drum, known as a track, and reads/ writes data on that track only (Tyson, 2007). Since the drive is continuously rotating, it takes only a few milliseconds for a piece of data to be accessed. This is in marked contrast to tapes, where spooling from one end of a tape to another may take minutes. However, the cost and complexity of drum-based storage meant that originally only the largest computer systems could make use of it.

The benefits of drum-based storage led to a demand for a lower-cost method of storage for mass-market applications. The magnetic disk was developed in response to this demand. As its name implies, a disk is a single flat circular sheet of material coated with a magnetic layer, once again organized as concentric tracks. Each track comprises a number of sectors with inter-sector gaps to permit easy determination of where the head is (Tyson, 2007).

The disk spins horizontally and a single head moves across its surface to read/write data. The single head reduces costs. Furthermore, since the disk is lighter than the drum it could be rotated more quickly, hence reducing access time. It is this essential approach, developed in the 1960s, to using a disk (or sometimes a platter of vertically stacked disks) that contemporary disk-based systems use.

Developments since the 1960s have been many, but the essential structure has been retained. Storage density has been improved by using materials with much more powerful magnetic properties, permitting more bits per unit area to be stored. Disk heads have moved closer to the disk platter (sometimes only a fraction of a millimeter away) in order to pick up the weaker currents induced by high-density storage (Tyson, 2007). This latter development has necessitated hermetically sealing the disk and head within a dust-free environment. Such an encapsulated storage device is often known as a Winchester disk. These disks are the most widely used today in contemporary information storage systems.

The floppy disk, a device that uses flexible plastic coated with magnetic material for the disk, has been widely used since the mid-1970s as a low-cost, low-density, portable storage medium.

Future developments
By the early 1990s the predominance of magnetic disk storage was coming to an end. The text-based nature of information storage was challenged by multimedia data. Such databases required orders of magnitude more storage than text. Consequently, the demand for storage capacity rapidly increased. Second, new materials with superior magnetic characteristics proved to be expensive and difficult to manufacture. For applications where data is read-only or for applications such as archiving where data is only written once, compact-disc (CD) technology was rapidly adopted. The development of writeable and erasable optical-disk technology in the mid-1990s changed the whole data storage process.

MP3 is a file extension which describes one of a series of software formats that allow efficient compression of digital video and audio data, mp3 stands for ‘MPEG (Moving Picture Experts Group), audio layer 3’. MP3 uses ‘psychoacoustic compression’ to remove all superfluous aural information, including the elements of a recording that a human ear cannot detect, allowing it shrink the size of a music track on a CD by a factor of 12 without noticeably sacrificing audio quality. The availability of music in this format accounts for a high level of web and Internet use by people, who can download tracks and albums to highly portable mp3 personal stereos, car stereos and home stereos.

A computer-based information storage and retrieval medium based on laser-technology and a strong, highly resistant optical disk CD-ROM (Compact Disc - Read Only Memory) is one of the most popular and familiar of computer-based media (, 2007). It can hold the equivalent of about 250,000 typewritten pages, or 500,000 catalogue cards or 500 high-density floppy diskettes. Its capacity ranges between 500 and 680 million characters (Mb) depending on the type of CD used. It uses the same technology as the audio CD for recording and reading data, and can have full multimedia functionality. CD-ROM players have become standard microcomputer peripherals, and CD writers with which users can record their own CDs are becoming increasingly common.

Computers are, in numerous ways, machines for remembering. Most obviously, they store data and programs in a variety of formats, and come equipped with a number of different memory storage devices (on PCs labelled ‘A-drive’, ‘C-drive’, etc.). One of the prime selling-points of computational devices is their memory capacity, their RAM size and their gigabytes of storage space.

But computers are memory devices in other ways —not just in their ability to store our files and thoughts, but also in terms of the memories that accrete around them. Like many of the significant objects that are assembled computers are woven into the life narratives and accommodated in the life patterns. Understanding the complexity of the human-computer interaction—and acknowledging that it involves emotion as much as calculation—can give one a much fuller understanding, therefore, of the many memory-making uses of the computer.
Warning!!! All free online essays, sample essays and essay examples on Computer Memory topics are plagiarized and cannot be completely used in your school, college or university education.

Order Custom Essay on Computer Memory
If you need a custom essay, dissertation, thesis, term paper or research paper on your topic, will write your papers from scratch. We work with experienced PhD and Master's freelance writers to help you with writing any academic papers in any subject! We guarantee each customer great quality and no plagiarism!