What is a computer?

First of all, the development of computers

An electronic computer is an electronic device that can automatically perform arithmetic and logical operations at high speed. It is one of the greatest inventions in the development of science and technology in the 20th century, and it is also the most brilliant achievement of mankind in the third industrial revolution.

1. The birth of the world's first electronic computer

In the struggle with nature, human beings created and gradually developed computing tools. As early as 3000 BC, China people invented counting and counting bamboo pieces. At the end of the Tang Dynasty, abacus was created. In the Southern Song Dynasty, there were records of abacus calculation and Song Dynasty, and abacus calculation was a calculation tool with both "calculation" and "existence". 1633, Oughtred invented the slide rule. 1642, the French mathematician Pascal made the first gear adder and subtracter, which was the earliest machine used for calculation in the world. 167 1 year, the German mathematician Leibniz invented a mechanical calculation machine that can perform four operations. 1822, the British mathematician Charles Babbage designed the business extension, which was the first real mechanical computer in the world. 1834, Babbage designed the analyzer. This design consists of a warehouse for storing data, a factory for data operation and a control bucket for scheduling machine operation, which lays the foundation for the basic structural framework of the computer. Therefore, Babbage is called "the father of computers". In the second world war, because the trajectory problem in the development of new weapons involves many complicated operations, a high-speed automatic calculation machine is urgently needed. Therefore, with the support of the United States War Department, under the leadership of physicist John Maudslay and engineer Presper eckert who taught at the University of Pennsylvania, the world's first weapon was successfully developed in 1943 after three years' efforts. ENIAC accounts for about 170m2, weighs about 30 t, * * uses 17456 electron tube, 1500 relay, more than 7000 resistors, 10000 capacitors and other electrical components, and consumes about 150 kW during operation. Such a behemoth can only store 20 decimal numbers with the word length of 10, and the operation speed is only 5000 additions per second. However, ENIAC initiated a new era of human computer science development.

In order to overcome the shortcomings of ENIAC, people have never stopped exploring, and many experts and scholars have published research papers in this field. Von Neumann, an American mathematician who teaches at Princeton University, published a report entitled "A Preliminary Study on the Logical Structure of Electronic Computers", and proposed a program storage mode, that is, setting a memory in the computer, putting the symbol calculation process into it, taking out the stored contents in turn during the execution, and then calculating according to the decoded results, thus realizing the automation of computer work. In the process of developing EDVAC computer, Von Neumann improved the memory components and changed the decimal code inside the computer into binary code. The concept of "stored program" was established as the design system of Feng's structural machine. From then on, computers that use program storage methods are collectively referred to as von Neumann computers.

2. An important stage of computer development.

Since the birth of the first electronic computer, it has experienced more than 50 years of development, which has created three new eras in the history of human social information development, namely three important stages of computer development.

(1) The primary stage of computer development was marked by the birth of ENIAC until the popularity of personal computers. At that time, although the price of computer and its related peripheral equipment was very expensive, its application field was basically limited to military, scientific calculation and data processing of large industrial enterprises, but it initiated a new era in which human beings began to replace part of their mental work with machines.

At this stage, the computer has made rapid development and has been updated many times. Computer substitution is generally based on the types of logic elements used in computer core components.

The first generation (1946— 1956) used electronic tubes as the main logic elements, and the operation speed was 5000 ~ 40000 (times/second). Large volume, high energy consumption, slow speed, small capacity and high price limit the military and scientific computing applications.

The second generation (1957- 1964) uses transistors as the main logic elements, and adopts monitoring programs, with an operation speed of several hundred thousand to several million (times/second). Compared with the first generation computer, it has the advantages of small size, low cost, high speed, strong function and high reliability, and its application fields are extended to engineering design, data processing and transaction management.

The third generation (1965— 1970) takes small and medium-sized integrated circuits as the main logic elements, and its operation speed is from one million to one million times (times/second). This generation of computers is marked by the IBM360 computer introduced by IBM in April 1964, which has the characteristics of generalization, serialization and standardization.

The fourth generation (1971early 1980s) took large-scale and very large-scale integrated circuits as the main logic components, and the operation speed was several million to several hundred million (times/second). Adopt semiconductor memory with higher integration as main memory, and develop parallel processing technology, distributed system and computer network. In software, distributed operating system, database system, high-level language and software engineering standardization have been developed, and a software industry has gradually formed.

(2) The development of microcomputers should be in the mid-1970s. 1975, American MITS Company developed Altair8800 microcomputer with Intel8080 processor, which was highly praised by electronic enthusiasts and promoted the development of personal computer software and hardware. 1976, the American Apple Company introduced the Apple Personal Computer, which has been greatly developed. 1980, IBM set foot in the field of personal computers. In order to compete with Apple, the structural framework of PC computer was made public, and the PC-DOS operating system was launched in cooperation with Microsoft Company of Bill Gates, which made many cheap compatible computers come out. Microcomputer uses DOS as its operating system, which is rapidly popularized and widely used because of its low price. Since then, computers are no longer owned and used by a few professionals, and the development of computers has entered a brand-new era of popularization, laying the foundation for the development of computer culture.

(3) Computer Culture Stage The computer culture stage only appeared when computers were widely used. Computer hardware functions are constantly improving, and the price is lower; Information compression and full digitalization have brought rich and colorful multimedia technologies; Virtual reality technology based on multimedia technology, electronic map system realized by 3S(GIS, GPS, RS) technology, satellite remote sensing positioning tracking monitoring system, etc. It has improved the ability of human beings to understand the world and benefited mankind. The ubiquitous Internet has narrowed the distance between countries in the world, and the distance education, remote medical diagnosis system, digital library and digital wireless city realized by computer network technology are coming to us. Wireless access technology (Bluetooth technology, WAP) has realized mobile phone Internet access and wireless local area network (WLAN); Computer cards have developed from early photoelectric cards, bar code cards and magnetic cards to today's ic cards and radio frequency cards, bringing convenience to people. These have continuously expanded the application space of computers, and computers have become personal information machines, changing people's lives. When the application of computer covers all aspects of people's social life, it will inevitably cause great changes in people's way of thinking, behavior and lifestyle. This widespread use of computers with some functions of the human brain has brought about cultural changes and formed computer culture. Since the early 1990s, the birth of multimedia computer and Internet "information expressway" marked a new stage of computer development and initiated a new era of maximizing the enjoyment of resources.

3. General situation of computer development in China

The birth of New China has opened up a broad road for the development of science and technology in China, and also for the development of computer technology.

1952, the first three-person computer research group headed by Min, a professor of electrical engineering department in China, was established in Tsinghua University. 1954, the group expanded and merged into the Institute of Modern Physics of Chinese Academy of Sciences, led by physicist Qian Sanqiang, and started the computer research in China. 1956, when the state formulated the long-term plan for science and technology 12, it listed computer technology as the first of the four major technologies, set up a computer technology working group, and began substantive research and development. 1958, China successfully developed the first electron tube computer (103 computer); 1959 successfully developed a large-scale general-purpose electronic computer (104 computer) with a speed of 100 times per second, which filled the gap in the field of computer technology in China. Professor Hua is the founder of computer technology in China and one of the main founders of the first electronic computer in China. 1960, China's first self-designed general-purpose electronic computer (107 computer) was successfully developed and put into operation. 1964, China began to introduce the second generation of transistor computers, such as "108" computer and "109" computer. 197 1 year, the third generation of integrated circuit computer "150 computer" was successfully developed in China, and by 1973, DJS- 100 series domestic computers were formed. 1974 ~ 1982 realized the leap from small-scale integrated circuit computer to large-scale integrated circuit computer. 1983, China successfully developed 757 large-scale vector computers with vector operations of 10 billion times per second.

Supercomputers are a symbol of a country's scientific and technological level. From the early 1980s, China began to develop supercomputers. 1983, the giant electronic computer "Yinhe" with hundreds of millions of vector operations was born; 1992, 10 billion "Yinhe II" was put into use; 1996 "Yinhe" Ⅲ machine put into operation has a speed of1000 billion times per second. Dawning 1000 was successfully developed in 1995, and Dawning 2000- I was born in 1998. Its peak operation speed reaches 20 billion floating-point operations per second, breaking the blockade and monopoly of large-scale parallel machine technology abroad. 1999 "Dawn" 2000 Ⅱ came out, its peak operation speed reached11700 million floating-point operations per second, and its memory reached 50GB, which became a major achievement of the National 863 Program. 1999 "Shenwei" parallel computer has been successfully developed, and the peak operation speed is as high as 384 billion floating-point operations per second. The successful development of "Yinhe", "Dawning" and "Shenwei" computers indicates that China has become one of the few countries in the world with the ability to independently develop high-performance computers.

Microcomputer is a symbol of the popularization and application level of science and technology in a country. Since 1990s, China has also made rapid development in microcomputer. 20011013, the birth of China's first general-purpose CPU chip-"Godson", made China one of the few countries that can research and manufacture computer chips.

In the field of computer application, China has also made brilliant achievements. Professor Wang Xuan of Peking University's laser phototypesetting technology initiated a new era of publishing and printing, and this invention won European patents and 8 China patents. Wang Xuan led his team to launch "Huaguang" and "Fangzheng" electronic publishing systems, which are in the leading position at home and abroad, and achieved great economic and social benefits, which made China printing industry bid farewell to the history of "lead and fire" and enter the era of "electricity and light". Wang Xuan is also known as the "father of laser phototypesetting". A variety of Chinese keyboard input methods and Chinese scanning input, handwriting input and voice recognition input software make Chinese characters easily enter the computer; The development of many domestic multimedia software has promoted the popularization and application of computers; Remarkable progress has been made in the construction of the national "Information expressway". The completion of the National Public Information Network (Jinqiao), the information system among foreign trade enterprises (Golden Gate) and the financial electronic money (Gold Card) has accelerated the process of social informatization. According to CNNIC's announcement on July 23rd, 2002, the average number of citizens in China who spend at least 1 hour online every week has exceeded 45.8 million, ranking third in the world.

4. The development trend of computers

The computer has realized the transformation from "digital calculation" to "information processing". At present, the development trend of electronic computers can be summarized into four aspects: giant, miniaturization, networking and intelligence. Although we can't put forward a very exact timetable for the future development of computers at present, its development trend is very clear, that is, to develop high-performance computing and improve computing performance.

There are two ways to develop high performance computing. One is to improve the parallel processing ability on the basis of the existing semiconductor integrated circuit technology and microprocessor technology. The second is to break through the physical limitations of silicon semiconductor devices and develop non-traditional new technologies, including superconducting computing, quantum computing, biological computing and optical computing.

There are two other ways to improve computing performance. One is hardware, that is, the development of ultra-high performance devices or components, such as quantum devices, superconducting chips, optical interconnection and optical storage components, biomolecular components and so on. Second, in terms of computing model and algorithm design, it fundamentally broke through the limitations of von Neumann's computer and electronic technology, such as quantum computing and DNA computing model, and opened up new ideas for solving complex problems.

5. Research fields of computer science

Computer science stresses theory and abstraction, while computer engineering stresses abstraction and design. In fact, there is no essential difference between them. From the category of research, it is collectively called computer science. At present, research involves a wide range of fields, including: computer system structure, programming science and methodology, software engineering theory, artificial intelligence and knowledge processing, network and database, computer-aided technology, theoretical computer science and computer science history research. The influence of computer science and technology on human society exceeds that of mathematics as the basis of basic culture and that of physics produced by modern industrial revolution on human civilization. It can be predicted that the development of computers will inevitably bring a better future to human society.

Second, the classification of computers.

There are many kinds of computers, which can be classified according to the form of data processing, scope of use, scale and function.

1. Classify according to the form of processing data.

(1) Digital computer Digital computer takes binary data 0 and 1 as processing objects, which are discontinuous digital quantities, and the processing results are also output in digital form. Its advantages are high precision, large storage capacity and strong versatility. Most of the computers we usually use are digital computers.

(2) Analog Computer Simulates the size of numerical or physical quantities, such as voltage, current and temperature, with continuous data as the processing object. And the processing result is also output as continuous data. Analog computers solve problems quickly, but they are not as accurate as digital computers and have poor universality. Analog computers usually output results in the form of graphs or scales.

(3) Hybrid Computer A hybrid computer is a computer that combines the advantages of a digital computer and an analog computer.

2. Classification by scope of use

(1) general-purpose computer

(2) Special computer

3. Classification by scale and function

(1) supercomputer

(2) Host computer

(3) Small computers

(4) Microcomputer

Third, the characteristics of computers.

(1) Come on.

(2) the calculation accuracy is high

(3) large storage capacity

(4) High degree of automation

(5) Strong logical judgment.

(6) It has wide universality.

Four, the main purpose of the computer

The use of computers can probably be summarized as the following aspects:

(1) Numerical calculation is a scientific calculation in scientific research, technical development and engineering design.

(2) Data processing realizes the timely recording, sorting, retrieval, classification, statistics, synthesis and transmission of numerical values, words, charts and other information data. It is suitable for data processing in transaction processing, office automation, electronic data exchange, information management and decision support.

(3) Process control includes real-time control such as industrial automatic monitoring, automatic control and intelligent control.

(4) CAD-aided design includes computer-aided manufacturing (CAM), computer-aided testing (CAT) and computer-aided teaching (CAI), which can improve design quality and automation, shorten design cycle and reduce production cost.

(5)AI- artificial intelligence is used for the simulation of complex systems, realizing natural language understanding and generation, theorem machine proof, automatic programming, automatic translation, image recognition, voice recognition, disease diagnosis and various expert systems and robot construction. In recent years, the research of artificial intelligence has started to be practical, and it has become a frontier subject of computer application research.

(6) Computer network and network communication provide inter-regional and international communication as well as the transmission and processing of various data, so as to realize the sharing of software and hardware information resources.

(7) Multimedia technology has realized the integration of sound, text, pictures and images, which is closer to the information exchange mode used by human beings and is widely used in the fields of culture, education, entertainment, family applications and so on.