计算机科学与技术专业外文翻译--计算机.pdf
外文原文:computerComputer is an electronic device that can receive a set of instructions or aprogram,and then by computing numerical data,or other forms of informationprocessing to implement the program.If there is no development of computers,the modem high-tech world is notgenerated.In the whole society,different models and different sizes of computers areused to store and process various data,confidential documents from the government,banking transactions to private household accounts.The computer through theautomation technology has opened up a new era in manufacturing,but they alsoenhance the performance of modern communication systems.In almost every field ofresearch and application of technology,from building a model of the universe toproduce tomorrows weather report,computer-free is not the necessary tools and theirapplication in itself has opened up new areas of peoples speculation.Databaseservices and computer network to make a variety of information sources available.Thesame advanced technology also made violation of personal privacy and commercialsecrets possible.Computer crime has become an integral part of modern technology,the cost is one of the many risks.Outer HardwareLets start with the center of any computer system.Do you see something shapedlike a box nearby?It will have a power switch and a light or two.It should also have aplace or places to insert disks.This is the case that houses all of the importantcomputer components.If it stands up tall,it is a tower case.If it sits flat,it is adesktop case.Ask your parents to let you look at the back of the computer(never dothis without permission,because there is a lot of dangerous electricity back there!).You will see lots of cords and cables coming out of the back of the case and going toother computer parts like the monitor.Your computer case probably has a place to insert floppy disks or CDs.These arecalled the floppy disk drive and the CD-ROM.The floppy disk drive readsinformation from a very thin disk that is inside a flat,square plastic case.You can alsowrite information to these disks and save it.CD-ROM is short for Compact Disk-Read Only Memory.A compact disk is a shiny,circular disk that stores information.ACD-ROM can only read information from the disk.Many new computers have aCD-RW(RW stands for ReWrite)instead of a CD-ROM.CD-RW allows you to writeinformation to the disk as well as read from it.Also,some new computers have aDVD(Digital Video Disk)drive instead of a CD-ROM or CD-RW.A DVD looks justlike a CD,but it holds much more information.You can watch movies,listen to music,or play computer games from DVDs.One important thing to know is that you canplay CDs in a DVD player,but you cannot play DVDs in a CD player!Input Devices and Output DevicesThere are several ways to get new information or input into a computer.The twomost common ways are the keyboard and the mouse.The keyboard has keys forcharacters(letters,numbers and punctuation marks)and special commands.Pressingthe keys tells the computer what to do or what to write.The mouse has a special ballthat allows you to roll it around on a pad or desk and move the cursor around onscreen.By clicking on the buttons on the mouse,you give the computer directions onwhat to do.Other types of input devices allow you to put images into the computer.Ascanner copies a picture or document into the computer.There are several types ofscanners and some look very different,but most look like a flat tray with a glass paneand a lid to cover it.You can input photographs into a computer with a digital camera.The most common output device is a monitor.It looks a lot a like a TV andhouses the computer screen.The monitor allows you to see what you and thecomputer are doing together.Speakers are output devices that allow you to hear soundfrom your computer.A printer is another common part of a computer system.It takeswhat you see on the computer screen and prints it on paper.Hardware on the InsideComputers are made of many electronic components or parts.These componentseach have a special job and they all work together to make your computer operate.Some components are hidden inside the computer,where you cant see them.Otherscan be seen partly from the outside.Power It Up!Every computer needs a power supply,to take electricity from your house andconvert it into a current that works for your computer.When it is plugged into thewall,electricity travels from the electrical wires in your house into the computerspower supply.When your computer is turned on,the power supply allows theconverted electricity to travel to other components inside the computer.The motherboard gets its name because it is like a mother to all of the othercircuit boards.Found at the bottom of a desktop case or the side of a tower case,themotherboard is the largest circuit board and has many smaller boards plugged into it.It holds all of the most important parts of the computer.On the motherboard,you willfind several expansion cards.Each of these cards has a special purpose.The soundcard contains special circuits for operating the computers sound.The video cardhandles graphics that are displayed on the monitor.There are also expansion cards forother computer components including the drives and ports.The modem is an expansion card that allows computers to talk to eachother.Current modems can run up to 56,000 bits per second.The brain of a computer is the CPU or Central Processing Unit.Like a brain,itcontrols information and tells other parts what to do.The type of CPU in a computeralso determines how fast that computer can operate.A CPU generates lots of heat,sothere is usually a small fan nearby to cool it down.A very important computer component is the BIOS chip.BIOS stands for BasicInput Output System.In very simple terms,the BIOS chip wakes up the computerwhen you turn it on and reminds it what parts it has and what they do.RAM&ROMHave you ever heard the terms RAM and ROM?These two terms sound verysimilar and can easily be confused by beginners.However,understanding what theymean and what they do can help you to remember.RAM stands for Random Access Memory.RAM chips will remember what youtell them and can even change to remember new information.But,when the computeris turned off,RAM forgets everything you told it.This is why it is so important tosave your work on a computer-if the computer gets turned off,RAM will lose all ofyour work!ROM stands for Read Only Memory.ROM is good at remembering,but cannotchange its mind.It holds information that is built into it.ROM is like reading alibrary book-lots of information is there,but you cant change it(because you neverwrite in a library book).RAM,on the other hand,is more like a journal-you canwrite information into the journal.But if you change your mind,you can erase andwrite in new information.Operating SystemsIn computer science,the operating system(OS)is to control the computers basicsoftware.lt has three main functions:coordination and operation of computerhardware,such as computer memory,printer,disk,keyboard,mouse and monitor;in avariety of storage media presentation documents,such as a floppy disk,hard disk,CD-ROM and tape;and processing hardware errorand data loss.What is an Operating System?The most important program on any computer is the Operating System or OS.The OS is a large program made up of many smaller programs that control how theCPU communicates with other hardware components.It also makes computers easierto operate by people who don*t understand programming languages.In other words,operating systems make computers user friendly.Types of Operating SystemsDifferent computer manufacturers use different operating systems.Apple hasspecific operating systems for its line of Macintosh computers.When IBM releasedtheir Personal Computer or PC back in the early 1980s,they did not get a copyrighton it,which allowed many other companies to build similar computers that wereIBM-compatible;in other words,they used the same operating system as the IBM PC.There are different operating systems available for PCs,but the most common isWindows,which was developed by a company named Microsoft.Windows is similarto the Macintosh operating system,because it also uses a mouse and a GUI(GraphicalUser Interface)that uses graphics or pictures to help the user navigate within thecomputer system.The Computer RevolutionThe introduction of the Macintosh OS and the later introduction of Windowsplayed a large part in making computers accessible to so many people.Theuser-friendly interfaces of both operating systems made it easier for people with nocomputer training to learn to use these amazing machines.Other machines,such astypewriters and payroll calculators quickly became a thing of the past,as computersbecame so easy to use and so affordable.Programming LanguageIn computer science,programming language that can be used to write thecomputer is running a series of instructions(computer program)the artificiallanguage.And English is similar to other natural language,programming languagewith vocabulary,grammar and syntax.Howe ver,natural language not suitable forcomputer programming,because they can cause ambiguity,that is their vocabularyand grammar structure can be interpreted in several ways.Used to calculate theprogramming language must have a simple logical structure,and their grammar,spelling and punctuation rules must be precise.Programming language and general degree of complexity quite different.Some ofthe programming language in order to address certain types of computationalproblems or to use a specific type of computer systems prepared.For example,FORTRAN,and COBOL and other programming language to solve commonprogramming problems of some type of written-FORTRAN for scientific field ofapplications,and COBOL for business applications.Although these language aimed ataddressing the specific types of computer problems,but they are highly portable,meaning that they can be used for many types of computer programming.Otherlanguages,such as machine language,is a particular type of computer system,or evena specific computer,in certain fields of study,prepared for use.The most commonlyused programming languages are highly portable,can be used to effectively addressthe different types of computational problems.Such as C,PASCAL,and BASIClanguage such as belong to this category.Language TypeProgramming language can be divided into low-level language and high-levellanguage.Low-level programming language or machine language,is the most basicprogramming language type,which can be a direct understanding of the computer.Thedifference between machine language depending on the manufacturer and model ofyour computer.High-level language is before the computer can understand and dealmust first be translated into machine language programming languages.C,C+,PASCAL,and FORTRAN are examples of high-level language.Assembly language isa mid-level language,very close to machine language,there is no other high-levellanguage shown by the language of complexity,but still have to be translated intomachine language.1.Machine LanguageIn the machine language,the directive was written in a computer can directlyunderstand is called bit-sequence of 1 and O.In a machine language instruction isusually to tell the computer four things:(1)to the computer main memory(randomaccess memory)in which location to find one or two numbers,or simple data segment;(2)to perform a simple operation,for example,two figures are added together;(3)theresults of this simple operation of what is stored in main memory location;and(4)towhere to find the next instruction to execute.Although all of the executable programsare based on the final form of the machine language of the computer to read,but theyare not all written in machine language to use.The direct use of machine languageprogramming extremely difficult because the instruction is 1 and 0 sequences.In atypical machine language instruction may be 1001011001011,meaning that will storethe contents of register A,register B added to the contents of storage.2.High-level LanguageHigh-level language is to use human language in the words and syntax of arelatively complex statements.They are more than assembly language and machinelanguage is more similar to normal human language,so used to write complexprograms easier.These programming languages allow faster development of morelarge and more complex procedures.However,the computer can understand before thehigh-level language compiler must be referred to another program translated intomachine language.For this reason,and using a program written in assembly languagecompared with the high-level language programs written in running time may belonger,take up more memory.3.Assembly LanguageComputer programmers use assembly language to machine language program towrite simpler.In the assembly language,and each statement corresponds roughly to amachine-language instructions.Assembly language statement is witheasy-to-remember commands prepared.In a typical assembly language statement tostore the contents of register A,added to the contents of storage register B,the ordercan be written ADD B,A.Assembly language and machine language has certaincommon characteristics.For example,a particular bit to operate,using assemblylanguage and machine language is feasible.When the procedure to minimize therunning time is very important,the programmer on the use of assembly language,because assembly language into machine language translation is relativelysimple.When the computer to be a part of the direct control,such as when a singlepoint,or monitor the flow of the printers individual characters,then also used inassembly language.The Classification Of High-level LanguageHigh-level language is usually divided into process-oriented,functional,object-oriented or logic of language.Today most common high-level language is aprocess-oriented language.In this language,the implementation of a full-featured oneor more of the associated block the formation of a program module or process,butalso be given,such as process A name.If the rest of the program requires the samesequence of actions,you can use a simple statement to back this process.In essence,aprocess that is a small program.A large program can perform different tasks by theprocess together constitute.The process of language so that programs become moreshorter and more easily read by computers,but it requires programmers to eachprocess is designed to be generic enough,can be used for different situations.Functional languages treat the same treatment as the process of mathematicalfunctions,and allows processing program,like any other data,like dealing withthem.This makes program structure at a higher and more rigorous levelpossible.Functional language also allows for a variable-in the program is running canbe specified by the user and change the data symbols-only be assigned once.In thisway,by reducing the sentence to give attention to the imple
