Von Neumann led the design of the EDVAC (Electronic Discrete Variable Automata Computer), a report that described the concept of a computer and has been called "the most influential paper in the history of computer science". Von Neumann referred to computers as "automatic computing systems", stating that a "computer" is an electronic device that accepts inputs, processes data, stores data, and produces outputs under the control of a program.
Now, electronic computers can not only be used as a computing tool for numerical calculations, but also for information processing, and often used in a variety of fields such as automatic control. With the development of computers, the expansion of the field of application, computers are more used for information processing. Some statistics show that more than 80% of today's computers will be mainly used for information processing. Because the computer in its initial stage of emergence is mainly for the sake of numerical calculations, so we continue to down the "computer" this name. Therefore, when we use the name "computer", we should have a more comprehensive understanding of the meaning of computer. Nowadays, more people call it "computer", which mainly refers to the computer as an extension of the human brain function and extension.
The reason why computers are different from other computing devices, mainly because it has the following three outstanding features.
1. The basic device consists of electronic devices
Modern electronic computers are based on the working principle of digital circuits. Theoretically, the speed at which a computer can process data is limited only by the speed of propagation of electricity, and therefore, computers can achieve very high operating speeds.
2. has the ability to store information internally, the internal information is expressed in binary
Digital circuits only "0" and "1" two pulse signals, in order to facilitate the design of the hardware, the computer's internal information is expressed in binary. The information inside the computer is expressed in binary. Because of the internal storage capacity, it is not necessary to obtain data from the outside every time, so that the time for processing data can be minimized and program control is possible. This is an important difference between electronic computers and other types of computing devices.
3. The operation process is automatically controlled by the program
Because the computer has internal storage capacity, the computer can be taken out of the internal storage unit in order to control the operation of the computer instructions and data, this way of working is called stored program control. It is one of the most important features of electronic computers. Application of computers: Now, the application of computers has been widely and y penetrated into various fields of human society. From scientific research, production, national defense, culture, education, health and family life, are inseparable from the services provided by computers. Computers have greatly improved the efficiency of production, so that social productivity has reached an unprecedented level. It is estimated that computers now have more than 5000 kinds of uses, and every year to 300 to 500 kinds of speed increase, in order to discuss the convenience, we will be its application areas are summarized into the following categories.
1. scientific computing
Scientific computing, also known as numerical computing, refers to the use of computers to solve complex computational problems in scientific research and engineering technology. In areas such as mathematics, physics, chemistry, astronomy, geography and other natural sciences, as well as aerospace, automotive, shipbuilding, construction and other engineering fields, the workload of the calculation is very large, to carry out these calculations is the computer's specialty. At present, there are many numerical calculation program packages for various fields in the world, which greatly facilitates the majority of calculation workers. The use of computers for numerical calculations can save a lot of time, manpower and material resources.
2. Information processing
Information processing, also known as data processing, refers to the use of computers to collect, store, organize, classify, statistics, processing, use and dissemination of a variety of information on the process, the purpose is to obtain useful information as a basis for decision-making. Information processing is currently one of the most widely used areas of computer applications, some data show that today more than 80% of the world's computers are mainly used for information processing. Modern society is an information society, with the high development of productive forces, resulting in a sharp expansion of the amount of information. At present, information has been listed as one of the three pillars of human social activities together with matter and energy. Therefore, in all social activities carried out by human beings, not only to consider the material conditions, but also to seriously study the information.
Computer information processing has been widely used in office automation (OA), enterprises and institutions of computer-aided management and decision-making, word processing, document management, intelligence retrieval, laser phototypesetting, film and television animation design, computerized accounting, library management, medical diagnostics, and other industries. Information has formed an independent industry, multimedia technology is more information industry took off and inserted the wings. With multimedia, show in front of people is no longer just those boring numbers, text, and increase the people happy to see, sound and image information.
3. Automatic control
Automatic control of industrial production processes can effectively improve labor productivity. In the past, industrial control mainly uses analog circuits, slow response time, low precision, has now been gradually replaced by computer control. Computer control system to the industrial site of the analog, switching and pulse quantities through the amplifier circuit and analog / digital (A/D), digital / analog (D / A) conversion circuit to the computer, the computer for data acquisition, display and control of the site. Computer control systems are widely used in transportation, post and telecommunications, satellite communications, etc., in addition to industrial production. Based on the characteristics of computerized industrial control, people also often refer to this application of computers as real-time control or process control.
4. Computer-aided engineering
Computers can be used to assist in design, manufacturing, teaching, testing, etc., collectively referred to as computer-aided engineering.
Since the 1960s, many countries have begun the exploration of computer-aided design (CAD) and computer-aided manufacturing (CAM). The application of computer graphics, you can calculate, analyze, compare and map the product structure, components and parts, etc. The convenience is to be able to change the parameters at any time, repeated iterations, optimization until satisfied. On this basis, and then further output parts table, material table and CNC machine tool processing with paper or magnetic tape, you can design the product processing, which is the concept of computer-aided manufacturing.
Computer-aided instruction (CAI) refers to the use of computers to help learn the automatic system, which will be the content of the teaching, teaching methods, as well as learning, etc. stored in the computer, so that students can easily and comfortably from the learning to the required knowledge.
Computer-assisted testing (CAT) refers to the use of computers to perform a large number of complex tests.
5. Artificial Intelligence
Artificial Intelligence (AI) refers to the use of computers to simulate human intelligent activities such as perception, reasoning, learning, and understanding. Artificial Intelligence is a new field of computer applications, and research in this area is still in its infancy. The main areas of research in artificial intelligence include natural language understanding, intelligent robotics, gaming, expert systems, automatic theorem proving and so on.
6. Computer network
The combination of computer technology and communication technology, can be distributed in different locations of the computer connected together, thus forming a computer network, people in the network can realize the software, hardware and information resources **** enjoy. In particular, the emergence of the Internet, is to break the geographical restrictions, shorten the time and distance of people to transfer information, changing the way of life of human beings. On this point, we will also discuss in more detail in later chapters. Main Technical Indicators of Computer System and System Configuration 1. Main Performance Indicators of Computer 1) Word length: word length is the number of binary data bits that the CPU can directly process, which is directly related to the computer's computational accuracy, functionality and speed. The longer the word length, the stronger the processing power. Common microcomputer word length of 8-bit, 16-bit and 32-bit. (2) arithmetic speed: arithmetic speed refers to the number of instructions that can be executed by the computer per second, usually in units of MIPS. (3) main frequency: the main frequency is the clock frequency of the computer, expressed in MHz. (4) Memory capacity: memory capacity refers to the total number of bytes of information that can be stored in the internal memory, generally in KB, MB as a unit. (5) peripheral configuration: peripherals are the computer's input/output devices (6) software configuration: including operating systems, computer languages, database languages, database management systems, network communications software, Chinese character support software and various other application software. /2. Main Configurations of Microcomputer System The basic configurations of a microcomputer mainly include the mainframe, keyboard, disk drive, hard disk, and monitor. Hardware system of microcomputer /1. Microprocessor Microprocessor consists of operator and controller, which is the core of microcomputer. Various microprocessors are usually categorized by word length: 8-bit, 16-bit, 32-bit and 64-bit. /Memory Memory is divided into memory and external memory, memory is the CPU can be directly addressed by the address line memory. Memory is divided into RAM, ROM two, RAM is readable and writable memory, it is used to store frequently changing programs and data. As soon as the power is cut off, the program and data in RAM will be lost.ROM is read-only memory, the program and data in ROM will not be lost even if the power is cut off. /3. Input device It is a device that transmits information from the outside world to the computer. In microcomputer systems, the most commonly used input device is the keyboard. A disk machine (i.e. disk drive) is also an input device. /4. Output devices It is the role of the computer in the data information transmitted to the external media, the most commonly used output devices are monitors and printers.