РефератыИностранный языкCoComputers Essay Research Paper Computers Computer are

Computers Essay Research Paper Computers Computer are

Computers Essay, Research Paper


Computers


Computer are electronic device that can receive a set of instructions,


or program, and then carry out a program by performing calculations on numbered


data or by compiling and correlating other forms of information. The old world


of technology could not believe about the making of computers. Different types


and sizes of computers find uses throughout our world in the handling of data


including secret governmental files and making banking transactions to private


household accounts. Computers have opened up a new world in manufacturing


through the developments of automation, and they have made modern communication


systems. They are great tools in almost everything you want to do research and


applied technology, including constructing models of the universe to producing


tomorrow’s weather reports, and their use has in itself opened up new areas of


development. Database services and computer networks make available a great


variety of information sources. The same new designs also make possible ideas of


privacy and of restricted information sources, but computer crime has become a


very important risk that society must face if it would enjoy the benefits of


modern technology. Two main types of computers are in use today, analog and


digital, although the term computer is often used to mean only the digital type.


Everything that a digital computer does is based on one operation the ability to


determine if a switch, or gate is open or closed. That is, the computer can


recognize only two states in any of its microscopic circuits on or off, high


voltage or low voltage, or?in the case of numbers?0 or 1. The speed at which the


computer performs this simple act, however, is what makes it a marvel of modern


technology. Computer speeds are measured in megaHertz, or millions of cycles per


second. A computer with a “clock speed” of 10 mHz?a fairly representative speed


for a microcomputer?is capable of executing 10 million discrete operations each


second. Business microcomputers can perform 15 to 40 million operations per


second, and supercomputers used in research and defense applications attain


speeds of billions of cycles per second. Digital computer speed and calculating


power are further enhanced by the amount of data handled during each cycle. If a


computer checks only one switch at a time, that switch can represent only two


commands or numbers; thus ON would symbolize one operation or number, and OFF


would symbolize another. By checking groups of switches linked as a unit,


however, the computer increases the number of operations it can recognize at


each cycle. The first adding machine, a precursor of the digital computer, was


devised in 1642 by the French philosopher Blaise Pascal. This device employed a


series of ten-toothed wheels, each tooth representing a digit from 0 to 9. The


wheels were connected so that numbers could be added to each other by advancing


the wheels by a correct number of teeth. In the 1670s the German philosopher and


mathematician Gottfried Wilhelm von Leibniz improved on this machine by devising


one that could also multiply. The French inventor Joseph Marie Jacquard , in


designing an automatic loom, used thin, perforated wooden boards to control the


weaving of complicated designs. Analog computers began to be built at the start


of the 20th century. Early models calculated by means of rotating shafts and


gears. Numerical approximations of equations too difficult to solve in any other


way were evaluated with such machines. During both world wars, mechanical and,


later, electrical analog computing systems we

re used as torpedo course


predictors in submarines and as bombsight controllers in aircraft. Another


system was designed to predict spring floods in the Mississippi River Basin. In


the 1940s, Howard Aiken, a Harvard University mathematician, created what is


usually considered the first digital computer. This machine was constructed from


mechanical adding machine parts. The instruction sequence to be used to solve a


problem was fed into the machine on a roll of punched paper tape, rather than


being stored in the computer. In 1945, however, a computer with program storage


was built, based on the concepts of the Hungarian-American mathematician John


von Neumann. The instructions were stored within a so-called memory, freeing the


computer from the speed limitations of the paper tape reader during execution


and permitting problems to be solved without rewiring the computer. The rapidly


advancing field of electronics led to construction of the first general-purpose


all-electronic computer in 1946 at the University of Pennsylvania by the


American engineer John Presper Eckert, Jr. and the American physicist John


William Mauchly. (Another American physicist, John Vincent Atanasoff, later


successfully claimed that certain basic techniques he had developed were used in


this computer.) Called ENIAC, for Electronic Numerical Integrator And Computer,


the device contained 18,000 vacuum tubes and had a speed of several hundred


multiplications per minute. Its program was wired into the processor and had to


be manually altered.


The use of the transistor in computers in the late 1950s marked the advent


of smaller, faster, and more versatile logical elements than were possible with


vacuum- tube machines. Because transistors use much less power and have a much


longer life, this development alone was responsible for the improved machines


called second-generation computers. Components became smaller, as did


intercomponent spacings, and the system became much less expensive to build.


Different types of peripheral devices?disk drives, printers, communications


networks, and so on?handle and store data differently from the way the computer


handles and stores it. Internal operating systems, usually stored in ROM memory,


were developed primarily to coordinate and translate data flows from dissimilar


sources, such as disk drives or co-processors (processing chips that perform


simultaneous but different operations from the central unit). An operating


system is a master control program, permanently stored in memory, that


interprets user c ommands requesting various kinds of services, such as display,


print, or copy a data file; list all files in a directory; or execute a


particular program. A program is a sequence of instructions that tells the


hardware of a computer what operations to perform on data. Programs can be built


into the hardware itself, or they may exist independently in a form known as


software. In some specialized, or “dedicated,” computers the operating


instructions are embedded in their circuitry; common examples are the


microcomputers found in calculators, wristwatches, automobile engines, and


microwave ovens. A general-purpose computer, on the other hand, contains some


built-in programs (in ROM) or instructions, in a chip, but it depends on


external programs to perform useful tasks. Once a computer has been programmed,


it can do only as much or as little as the software controlling it at any given


moment enables it to do. Software in widespread use includes a wide range of


applications programs?instructions to the compute r on how to perform various


tasks.

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