The first lesson of operation and maintenance--computer composition and operation

Computer is one of the modern computers used for high-speed computing, which can be calculated numerically, can be calculated logically, and has memory function. is able to operate according to the program, automatic, high-speed processing of massive data of modern intelligent electronic equipment. A computer consisting of hardware systems and software systems that does not have any software installed is called bare metal. Can be divided into super computer, industrial control computer, network computer, personal computer, embedded computer five categories, more advanced computers have biological computers, photon computers, quantum computers and so on.

Computer inventor John Feng Neumann. Computer is one of the most advanced scientific and technological inventions in the 20th century, which has an extremely important influence on human production and social activities, and develops rapidly with strong vitality. Its application field extends from the initial military research application to all areas of society, has formed a large scale computer industry, led the global technological progress, resulting in profound social change, the computer has spread throughout the general school, enterprises and institutions, into the ordinary people's homes, become an indispensable tool in the information society.

Computer application in China is more and more common, after the reform and opening up, the number of Chinese computer users has been rising, the application level is constantly improving, especially in the Internet, communications, multimedia and other fields of application has achieved good results. From 1996 to 2009, the number of computer users grew from 6.3 million to 67.1 million units, and the number of networked computers rose from 29,000 to 59.4 million units. Internet users have reached 316 million, wireless internet has 670 million mobile users, of which mobile internet users up to 117 million, the world's first.

———————— from Baidu Encyclopedia

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

The operator (core), the controller (coordinates the operation between the operator and other devices), the memory (random access memory RAM), the input device, the output device.

Where an operator is a component that performs various arithmetic and logical operations on a computer. The basic operations of an operator include addition, subtraction, multiplication, addition of arithmetic, and, or, non-, XOR, or other logical operations, as well as shifts, comparisons, and transfer operations, also known as arithmetic logic components (ALU).

The controller is responsible for controlling and coordinating the operation of the whole computer, the control usually requires the program counter (PC), instruction Register (IR), instruction Decoder (ID), timing and control circuit, as well as pulse source, interrupt and other joint completion.

The main function of memory is to store the program and various data, and to complete the program or data access at high speed and automatically during the computer running. Memory is a device with a "memory" function, which uses physical devices with two stable states to store information. These devices are also known as memory components. The data is represented in a computer using only two digital "0" and "1" binary. The two stable states of the memory element are expressed as "0" and "1" respectively.

An input device (InputDevice) is a device for human or external interaction with a computer that is used to input raw data and programs that process these numbers into a computer. The computer can receive a variety of data, can be either numerical data, or a variety of non-numerical data, shape, image, sound, etc. can be entered into the computer by different types of input devices for storage, processing and output.

An output device is a device by which a computer displays its data through display, printing, sound, control peripherals, and so on. Common output devices are display, printer, plotter, image output system, voice output system, magnetic recording equipment and so on.

In the computer because of the characteristics of the current, you must use the binary for data storage and processing. (If using decimal is also possible, but it will bring a lot of unnecessary trouble, such as the use of decimal to the computer through the flow of the current into 10 different states, but in the computer circuit is essential to the existence of consumption will make the current through the device change state)

When these hardware is available, the computer can run, but this only allows for simple addition and subtraction, so the software is developed on the basis of these hardware to synthesize these operations for more complex operations. At the very beginning of the programmer will be programmed to hit the paper into the machine, this way to become a single processing, but this type of input is very time-consuming and CPU processing speed is very fast, so someone came up with a way to separate the input and output from the CPU, CPU to process a batch of programs, this is called a single-channel batch processing. Later, people could not meet a one-off process, so the birth of multi-channel batch processing. Since then, the development of computers has been out of hand.

Computer development today, people have been able to easily use the mouse keyboard and other computer operations to complete a variety of functions. In order to use the computer more conveniently, people developed the operating system.

Different hardware requires different microcode software. To use the hardware well requires the operating system, many microcode programs are encapsulated into a whole, that is, the operating system kernel, the operating system core can be a good link between the management of the computer hardware, on the software to provide a packaged interface. The process of finding the operating system interface and using the interface of the operating system is called system call, which uses this interface to pass the information we need, and what needs to be done, through the interface to the kernel of the operating system, which is called by systems. Calling the system interface is not a program but a process.

Process is the operating system in order to better allocate computer resources, the method is conceived, this method of the program needs resources and other information to build a table called the PCB table, so that the program is static, and the process is dynamic, is alive, it has its own life cycle.

Another function of the operating system is to abstract the hardware virtualization, not directly to use the hardware, but with a substitute, virtual way to use the hardware, such as the D-disk icon in the computer's user's view it is just a drive letter D, and for the computer this D disk can be more complex, This is greatly convenient for our use. At the same time, the operating system also allocates resources to hardware, monitors and prevents the unreasonable allocation of resources, and greatly reduces the difficulty of operating the computer. When resource allocation is unreasonable, wasting resources can cause the system not to run or crash.

The computer basically works for the application through the interface shell, through the system call to the operating system kernel, compiled by the kernel, the high-level language translated into assembly language and then translated into the computer can understand the machine language, so that the hardware calls. The software is made up of code, which is composed in many ways that can be roughly divided into microcode and high-level languages as written. The microcode language translates into machine language efficiency, but the coding process is complex. So for the sake of convenience, more for the development, has produced the high-level language, this is a kind of close to human natural language, translates into the machine language inefficient, will produce many intermediate code, in the run time needs the extra cost. As far as the cost of the computer is concerned, it is possible to avoid the time when computers have just been created, but now that computers are getting cheaper and faster, these additional costs are acceptable. The use of high-level language greatly reduces the difficulty of coding, so it promotes the development of computer software. More and more high-level languages have been developed.

High-level language can be divided into system-level and application-level, if according to the idea of programming can be divided into process-oriented programming, that is, according to strict logical structure to write code and object-oriented programming, this kind of programming is relatively free, more attention to the process of data processing, rather than data structure. If you can also be divided into strong language according to the compilation, this is a compiler language, such as: C,c++,java, this program source code must be compiled, not compiled can not be used. Weak language, which is an explanatory language, such as: Php,python,shell, this code does not declare variables can also be used, not compiled, can be used by the interpreter.

The current mainstream operating system has Linux and Windows, the traditional Linux refers to the Linux kernel, it has a variety of distributions, these distributions are on the basis of this kernel on the encapsulation of some common software developed. Windows is basically the same, but Linux is open source software, and Windows is not, the Windows operating system refers to its kernel, but because he is not open source software, so we can only use Windows for our packaged version of the operating system, It is a collection of common software, such as: the original IE browser and the current Edge browser, although this greatly facilitates our use, but there is always a passive feeling. Linux can be installed in a variety of software, or can be used from its distribution, and even when necessary to make their own distribution. Linux version number in the 2 version of the rules, such as Linux 2.6.32-573 (2 is the main version, 6 is the minor version number, if the even is stable version, the odd number is the development of the instability factor, the subsequent 32 for the original version of the revision of how many times, 573 is Custom) Of course this rule does not apply in the 3 version, and the parity version number is no longer regular. We don't have to install the latest version when we want to install Linux, because it's not necessarily the latest version, and sometimes it's possible to update a version in a small place, but it's probably not compatible with your machine.

Above, from operation and maintenance beginners.

The first lesson of operation and maintenance--computer composition and operation