Shulou(Shulou.com)06/02 Report--

Computer is a kind of modern electronic computing machine for high-speed computing, which can not only carry out numerical calculation, but also logical calculation, but also has the function of storage and memory. It is a modern intelligent electronic device that can run according to the program and process large amounts of data automatically and at high speed. It is composed of hardware system and software system, and the computer without any software is called bare metal. It can be divided into five categories: supercomputer, industrial control computer, network computer, personal computer and embedded computer. The more advanced computers are biological computer, photon computer, quantum computer and so on.

Computer inventor John von Neumann. Computer is one of the most advanced scientific and technological inventions in the 20th century, which has an extremely important impact on human production and social activities, and develops rapidly with strong vitality. Its application field has expanded from the initial military scientific research to all fields of society, and has formed a large-scale computer industry, which has led to global technological progress, which has led to profound social changes. computers have spread throughout ordinary schools, enterprises and institutions, entered the homes of ordinary people, and become an indispensable tool in the information society.

The application of computer is becoming more and more common in China. After the reform and opening up, the number of computer users in China continues to rise, and the level of application continues to improve, especially in the fields of Internet, communications, multimedia and so on. From 1996 to 2009, the number of computer users increased from 6.3 million to 67.1 million, and the number of networked computers increased from 29000 to 59.4 million. The number of Internet users has reached 316 million, and the wireless Internet has 670 million mobile users, of which 117 million are mobile Internet users, ranking first in the world.

-from Baidu encyclopedia

Feng. Neumann's system consists of five major components, namely:

Arithmetic unit (core), controller (coordinate operation between operation unit and other devices), memory (random access memory RAM), input device, output device.

The arithmetic unit is a component that performs various arithmetic and logical operations in the computer. The basic operation of the arithmetic unit includes addition, subtraction, multiplication and division, logic operations such as and, OR, no, XOR, and shift, comparison and transmission, also known as arithmetic logic unit (ALU).

The controller is responsible for controlling and coordinating the action of the whole computer. Control usually requires program counter (PC), instruction register (IR), instruction decoder (ID), timing and control circuit, pulse source, interrupt and so on.

The main function of memory is to store programs and all kinds of data, and to access programs or data at high speed and automatically during the operation of the computer. Memory is a device with "memory" function, which uses physical devices with two stable states to store information. These devices are also called memory elements. In a computer, a binary system with only two digits "0" and "1" is used to represent data. The two stable states of memory elements are expressed as "0" and "1", respectively.

An input device (InputDevice) is a device that people or externally interact with a computer to input raw data and programs that process these numbers into the computer. The computer can receive all kinds of data, which can be either numerical data or non-numerical data, such as graphics, images, sound, etc., which can be input to the computer through different types of input devices for storage, processing and output.

Output device (Output Device) is a kind of device that the computer displays its data through display, print, sound, control peripheral equipment and so on. The common output devices are display, printer, plotter, image output system, voice output system, magnetic recording equipment and so on.

Because of the characteristics of the current in the computer, binary must be used for data storage and processing. (it is OK to use the decimal system, but it will bring a lot of unnecessary trouble. for example, using the decimal system is to divide the current flowing through the computer into ten different states. however, there is an essential consumption in the computer circuit that will change the state of the current as it passes through the device.)

With these hardware, the computer can run, but this can only achieve simple addition and subtraction operations, so people have developed software on the basis of these hardware to integrate these operations to achieve more complex operations. In the beginning, programmers programmed the program and typed it into the machine, which became a single process, but this input way is very time-consuming and the processing speed of CPU is very fast, so someone came up with a way to separate the input and output from CPU, and use CPU to process a batch of programs, which is called single batch processing. Later, people could not satisfy the one-by-one processing program, so multiple batches were born. Since then, the development of computers has been out of control.

With the development of computer today, people can easily use the mouse and keyboard to operate the computer to complete a variety of functions. In order to make it more convenient to use computers, people have developed an operating system.

Different hardware requires different microcode software. In order to make good use of the hardware, you need the operating system, which encapsulates many microcode programs into a whole, that is, the operating system kernel, which can be a good connecting link between the preceding and the next, managing the hardware of the computer downwards, and providing encapsulated interfaces to the software. The process of software finding the operating system interface and using the operating system interface is called system call, using this interface to transfer the information we need and the operations we need to do to the kernel of the operating system, that is, system calls. It is not the program but the process that calls the system interface.

Process is a method conceived by the operating system in order to better allocate computer resources. In this method, the information needed by the program is built into a table called PCB table, so the program is static, while the process is dynamic and alive, and it has its own life cycle.

Another function of the operating system is to abstract the hardware virtualization, not to use the hardware directly, but to use the hardware in a substitute, virtual way. For example, the D disk icon is only a drive letter called D in the eyes of computer users, but for the computer, this D disk is much more complex, which greatly facilitates our use. At the same time, the operating system also allocates resources to the hardware to monitor and prevent unreasonable resource allocation, which greatly reduces the difficulty of operating the computer. When the allocation of resources is unreasonable, the waste of resources will cause the system not to run or crash.

The general working principle of the computer is that the application program through the operation interface shell, through the system call to the operating system kernel, the kernel assembles, translates the high-level language into assembly language and then into the machine language that the computer can understand, so as to call the hardware. Software is composed of code, which can be roughly divided into microcode language and high-level language according to the way it is written. The efficiency of transforming microcode language into machine language is high, but the coding process is very complex. Therefore, for the sake of convenience and development, high-level language is produced, which is a kind of natural language close to human beings. It is inefficient to convert into machine language, and it will generate a lot of intermediate code, which requires additional overhead at run time. In terms of overhead, it was avoided as far as possible in the early days of computers, but now computers are getting cheaper and faster, and these extra expenses are acceptable. The use of advanced language greatly reduces the difficulty of coding, so it promotes the development of computer software. More and more high-level languages are developed.

High-level language can be divided into system level and application level. According to the idea of programming, it can also be divided into process-oriented programming, that is, writing code and object-oriented programming according to strict logical structure, which is relatively free. pay more attention to the process of data processing rather than data structure. And if according to the way of compilation can also be divided into strong language, this is a compiling language, such as: C ~ (10) C ~ (13) C language Java, this kind of program source code must be compiled, can not be used without compilation. Weak language, which is an interpretive language, such as PHP,Python,shell, this kind of code can be used without declaring variables, without compilation and through the interpreter.

At present, the mainstream operating systems are linux and windows. In the traditional sense, Linux refers to the kernel of Linux. It has a variety of distributions, which are developed by encapsulating some commonly used software on the basis of this kernel. Windows is basically the same, but linux is open source software, but windows is not. The windows operating system refers to its kernel, but because it is not open source software, we can only use this distribution operating system packaged for us by windows, which brings together some commonly used software, such as the original IE browser and the current edge browser, although this greatly facilitates our use. But there is always a sense of passivity. All kinds of software in linux can be installed at will, you can use the distribution that comes from it, and you can even make your own distribution when necessary. The version number of linux is regular in version 2, for example, Linux 2.6.32-573 (2 is the major version, 6 is the minor version, if the even number is the stable version, the odd number is the unstable factor of the development version, and the latter 32 is the number of revisions made on the basis of the original version, 573 is customized) of course, this rule is not applicable in the third version, and the parity version number is no longer regular. When we want to install linux, we don't have to install the latest version, because the latest version is not necessarily the best to use, sometimes it is possible to update a version just with a small update, but this small place may not be compatible with your machine.

The above comes from beginners in operation and maintenance.

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.