计算机专业英语科技论文

海外英语杂志欢迎投稿，详情见我的空间

Good Moring, ladies and gentlemen, Today my topic of my speech is the advantages and the disadvantages of computers. In this information age/era, computer is very important in our everyday lives. It definitely make our lives easier in many ways. First of all, it helps us communicate with people all around the world, which means it not only save a lot of time when we have to send a message from one country to another, but also save a large of unnecessary troubles for us. Secondly, it gives many unemployed people chances to get a job. We can use computers and the Internet to sell and buy almost anything nowadays. Last but not least, many wonderful games come along with the advent of computers. And playing computer games is one of the most popular ways to entertain and to relax. So, computers are really good for our human beings in many different aspects.However, every coin has two sides. Computers also bring us many troubles. It gets across much unhealthy information and causes many crimes. But if we can use computer properly, it is still an amazing invention to us. Therefore, I hope that everyone, especially the young people, like me, can really appreciate the help of computers and make the best use of them.很多的，我分次发~~~~~~~~~~~~~~~~~~~~

Abstract: A firewall is a technological measure developed in recent years to protect the security of a computer network, it's also the most widely used technology of a network security protection now. A firewall is one or a set of system to access controling policies, it can be software, hardware or a combination of them, whose aim is to provide security protection for the network. A firewalls is usually located between internal and external networks, and it can monitor, control and change communications in the internal and external networks, and controling external computers can visit internal protected environment and determine the access time, authorities, the types of service and quality.It checks the spread of the internal information to avoid the outflow of confidential information and resist external invasion and prevent internal information leaking. This paper presents the importance of firewall configuration in the network security, and explains that the set of firewall rules is an important measure for firewall product security. Key words: firewall,configuration,network,security

Information literacy Knowing how to find data from several sources, select relevant material, analyse and organise it into a form that can be used to make decisions. Computers have become the tools people use to access and manage information. Information technologists are people who analyse and design the tools. What is a computer? Tradition definitions of computers include • A machine that accepts data and processes it into use information. • A computer is a binary, digital, electronic, stored program machine. • While a computer is commonly a digital machine, analogue machine do exist. An electronic device, operating under the control of instructions stored in its own memory unit, that can accept data (input), process data arithmetically and logically, produce results (output) from the processing and stores results for future use. Many computers receive and send data (communicate) across networks LAN and Wan. A computer system consists of hardware and software. What is hardware? Hardware Hardware is physical devices or components that can be physically handled – you can thou it. Input Devices Input devices convert data that humans collect into coded electrical signals that a computer can process. The central processing unit The electronic processing takes place in the CPU. The CPU consists of • A control unit that controls all of the computer’s functions and an • Arithmetic and logical unit (ALU) that performs any calculation Memory Memory holds all programs and What is RAM currently open? Data (notes) Word processor O.S Output devices Output devices convert the computer’s electronic signals back into information Secondary storage devices These devices store programs and data permanently. The programs and data are not necessarily (or likely to be) in current use. E.g. DVD CD Communication devices These devices enable a computer to connect to another computer. List the six different type of hardware? Secondary storage(external), input, processor, output , memory, Communication. Name eight pieces of hardware USB, keyboard, monitor, screen, RAM, ROM, VDU, Modem. The system unit and peripheral devices The system unit is the computer box. Peripheral devices are any devices around the outside, or in other words, plugged into the (back of) the machine. Peripheral devices include the key board, mouse, printer, joy stick and others. Peripheral devices are any devices around the outside, or in other words, plugged into the (back of) the machine. Peripheral devices include the keyboard, mouse, printer, joy stick and others. What else does a computer have? Software Software is a computer program ,which is a detailed set of instructions that directs a computer to perform the tasks necessary to process data into information. These instructions are written in languages that computer can interpret. Software includes computer games, a word processing packing, an accounting package, amongst Definition of a computer system • A computer system is the configuration of hardware and software, functioning together, to process data into useful information, in order to achieve a purpose for a human user. What is data? • Data is raw facts, be they numbers, words, images and sounds, that can be input into a computer. e.g. Mary a name is a piece of data What is information? • Information is processed data, that has meaning and is useful. e.g. John is a list of names who scored an A grade on an exam John A Chai A Pam A e.g. Commodore $23 500 Magna $21 500 Falcon $19 800 The system unit contains the • Motherboard • CPU • Memory • Other electronics It is where the computer program instructions are executed and the data is manipulatedThe Processor CPU The CPU interprets and carries out basic instructions that operate the computer, the CPU contain the • Control unit and the • Arithmetic logic unit Control unit The control unit directs and coordinates the computer’s operations. For every single instruction, the control unit repeats four basic operations, • Fetching • Decoding • Executing • Storing CPU speed The CPU’s speed may be measured in MIPS The number of millions of instructions per second Arithmetic/logic unit The ALU performs all calculations, which involve • Arithmetic operations 2+3 • Comparison operations age>=17 • Logical operations pass Processing instructions A CPU may begin executing a second machine cycle before completing the first-referred to as pipelining. Current CPU’s can pipeline up to 4 instructions. Storage within the CPU Registers temporarily hold data and instructions. The computer’s clock A System clock is necessary to control the timing of all computer operations. Each tick of the clock is referred to as a clock cycle. Clock speed is the speed at which a processor executes instructions. A hertz is one cycle per second and a megahertz is 1024 by1024 and a gigahertz is 1024 by 1024 by1024. Memory Memory is the temporary storage place for data and (program) instructions. Memory is measured in • Kilobytes 1024 bytes 2^10 • Megabytes 1024* 1024 bytes 2^20 • Gigabytes 1024*1024*1024 bytes 2^30 Representation of data Digital computers are built from many small electronic circuits. Each circuit, at any point of time can be turned OFF or ON. Hence these devices are called two state devices. Binary Digit 0and 1 Each off or on digital value is called a bit, short for binary digit. A 1 bit computer would be able to distinguish between two values-characters, symbols or numbers. Hardly sufficient for the characters on the keyboard Bits Characters 1 2 2 4 3 8 4 16 5 32 6 64 7 128 8 256

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