1946 In February, the first electronic computer ENIAC came out in California, USA. ENIAC uses 18000 electron tubes and 86000 other electronic components, which are as big as two classrooms, but the operation speed is only 300 operations or 5000 additions per second, and the cost is more than1000. Although ENIAC has many shortcomings, it is, after all, the ancestor of computers, which opened the prelude to the computer age. Up to now, the development of computers has experienced four times, from 1946 to 1959, which we call "the era of electronic tube computers". The internal components of the first generation computers used electron tubes. Because a computer needs thousands of lamps, each lamp will emit a lot of heat, so how to dissipate heat is a headache. The longest service life of the electron tube is only 3000 hours, and the computer often crashes when it is running because the electron tube is burnt out. The first generation of computers were mainly used for scientific research and engineering calculation. From 1960 to 1964, we call this period "the era of transistor computers" because transistors more advanced than electron tubes are used in computers. Transistors are much smaller than electron tubes, do not need preheating time, consume less energy, and process faster and more reliably. The programming language of the second generation computer has developed from machine language to assembly language. Then, high-level languages FORTRAN and cOBOL were developed and widely used. At this point, disks and tapes are used as secondary storage. The size and price of the second generation computers have decreased, and the number of users has increased. The computer industry is developing rapidly. The second generation computers are mainly used in business, university teaching and government agencies. From 1965 to 1970, integrated circuits were used in computers, so this period was called "the computer age of small and medium-sized integrated circuits". Integrated circuit (R) is a complete electronic circuit made on a chip, which is smaller than a nail, but contains thousands of transistor elements. The third generation computer is characterized by smaller size, lower price, higher reliability and faster calculation speed. The representative of the third generation computer is IBM 360 series, which was developed by IBM at a cost of $5 billion. From 197 1 to now, it has been called "the age of large-scale integrated circuit computers". The components used in the fourth generation computer are still integrated circuits. But this kind of integrated circuit has been greatly improved, including hundreds of thousands to millions of transistors. People call it LSI and VLSI. 1975, the American company 1BM introduced the personal computer (PersonaI Computer PC. Since then, people are no longer strangers to computers, and computers have begun to penetrate into all aspects of human life.