A computer is a modern, intelligent electronic device capable of performing a large number of numerical calculations and various types of information processing automatically and at high speed according to a pre-stored program. It consists of hardware and software, which are inseparable. People call the computer without any software installed as barebones. With the development of science and technology, there are now some new computers: biological computers, photonic computers, quantum computers and so on.
Basic introduction Chinese name : computer Foreign name : computer Supercomputer, network computer, server, workstation, hub, switch, router, industrial control, personal computer, embedded computer, supercomputer Supercomputer (Supercomputers) usually refers to hundreds of thousands or even more processors (machines), can calculate the number of computers, the computer can not be completed by ordinary PCs and servers. Ordinary PCs and servers can not complete the large and complex subject of the computer. Supercomputer is the strongest computer, the fastest computing speed, the largest storage capacity of a class of computers, is the level of national scientific and technological development and an important symbol of the comprehensive national power. Supercomputer has the strongest parallel computing ability, mainly used for scientific computing. In the meteorological, military, energy, space, prospecting and other fields to undertake large-scale, high-speed computing tasks. In the structure, although supercomputers and servers may be multiprocessor systems, there is no substantial difference between the two, but the modern supercomputer is more cluster systems, more focused on the performance of floating-point operations, can be watched as a high-performance server focusing on scientific computation, and the price is very expensive. Network computer server refers to certain high-performance computer, can through the network, to provide services to the outside world. Relative to ordinary computers, stability, security, performance and other aspects are required to be higher, so in the CPU, chipset, memory, disk system, network and other hardware and ordinary computers are different. Servers are the nodes of the network, storing and processing 80% of the data and information on the network, playing a pivotal role in the network. They are for the client computer to provide a variety of services, high-performance computer, its high performance is mainly expressed in the high speed computing power, long time reliable operation, strong external data throughput capacity and so on. The composition of the server is similar to an ordinary computer, also has a processor, hard disk, memory, system bus, etc., but because it is for the specific network set of specially formulated, and thus the server and the microcomputer in the processing capacity, stability, reliability, security, scalability, manageability and other aspects of the existence of the difference is very large. Servers are mainly network servers (DNS, DHCP), print servers, terminal servers, disk servers, mail servers, file servers and so on. Workstation is a personal computer and decentralized network computing based, mainly for professional suite of fields, with powerful data computing and graphics, image processing capabilities to meet the engineering design, animation, scientific research, software development, financial management, information services, simulation and other professional fields and the design and development of high-performance computers. The most prominent feature of the workstation is that it has a strong graphic exchange capability, so it has been rapidly applied in the field of graphic image, especially in the field of computer-aided design. Typical products are the Sun series workstations of the U.S. Sun Corporation. Diskless workstation refers to no floppy disk, no hard disk, no CD-ROM drive connected to the regional network computer. In the network system, the workstation end of the operating system and the application of the software is all placed on the server, the system administrator as long as the completion of the server management and maintenance, software upgrades and installations only need to configure a time after the entire network of all computers can use the new software. Therefore, diskless workstations have the advantages of cost savings, high system security, easy management and easy maintenance, which is very attractive to network administrators. The working principle of diskless workstations is that the boot chip (Boot ROM) of the network card sends out boot request numbers to the server in different forms, and after the server receives them, it transmits boot data to the workstations according to different mechanisms; after the workstations have downloaded the boot data, the control of the system is transferred from the Boot ROM to some specific areas in the memory and guides the operating system. According to the different boot mechanisms, the more commonly used diskless workstations can be divided into RPL and PXE. RPL stands for Remote Initial Program Load, a technique commonly used in Windows 95. PXE is an upgraded version of RPL, which stands for Preboot Execution Environment. The difference between the two is that RPL is static routing, while PXE is dynamic routing, and its communication protocol adopts TCP/IP, which realizes an efficient and reliable connection with the Inter, and it is commonly used in Windows98, Windows NT, Windows2000, and Windows XP. Hub Hub (HUB) is a *** enjoy the medium of network equipment, its role can be simply understood as a number of machines connected to form a regional network, HUB itself can not recognize the destination address. HUB itself can not recognize the destination address. All the connecting ports on the hub contend for a *** enjoy the channel bandwidth, so with the increase in the number of network nodes, the amount of data transmission increases, the available bandwidth of each node will be reduced. In addition, the hub transmits data in the form of a broadcast, i.e., it transmits data to all ports. For example, when host A in the same area network transmits data to host B, the data packet is transmitted in a broadcast mode on the network with HUB as the architecture, transmitting the same information to all nodes on the network at the same time, and then each terminal determines whether to receive it or not by verifying the address information in the header of the data packet. In fact, only one terminal node receives the data, and all nodes are transmitted, in this way, it is easy to cause network congestion, and the vast majority of the data traffic is invalid, which results in the entire network data transmission efficiency is quite low. On the other hand, since the transmitted packets can be listened to by every node, it is easy to bring some insecurity to the network. Switch (Switch) is in accordance with the need to transmit information between the two ends of the communication, with manual or automatic equipment to complete the method of transmission of information to meet the requirements of the corresponding route of the technology collectively. Broadly speaking, the switch is a communication system to complete the information exchange function of the equipment, it is the hub of the upgraded products, the appearance and the hub is very similar to its role and the hub is largely the same. But there is a difference between the two in performance: hubs use the **** enjoy the bandwidth of the way of working, while the switch uses the exclusive bandwidth way. That is, all the ports on the switch have an exclusive channel bandwidth to ensure that each port on the fast and efficient transmission of data, the switch provides users with an exclusive, point-to-point connection, the data packet is transmitted only to the destination port, and will not be transmitted to all the ports, it is difficult for other nodes to listen to the information transmitted, so that in a lot of machines or a large amount of data, it is not easy to cause network congestion, but also to ensure the safety of data transmission. This ensures the safety of data transmission and greatly improves the transmission efficiency, the difference between the two is more obvious. Router Router (Router) is a network device responsible for finding the path, it is in the inter-network path from multiple paths to find the least amount of communication in a network path to provide users with communication. Routers are used to connect multiple logically separated networks to provide users with the best communication path, routers use routing tables to select paths for data transmission, routing tables contain lists of network addresses and distances between addresses, routers use routing tables to find the correct path for a packet to travel from its current location to the destination address, and routers use a least time algorithm or an optimal path algorithm to adjust the paths for the delivery of information. Routers are created after switches, just as switches are created after hubs, so routers are also somewhat related to switches and are not completely independent of the two devices. Routers mainly overcome the lack of switches that cannot forward packets to the route. Switch, router is a special network computer, its hard base CPU, memory and interface, soft base is the network interconnection operating system IOS. Switch, router and PC, the same as the central processing unit CPU, and different switches, routers, its CPU is generally not the same, the CPU is the processing center of the switch, router. Memory is where switches and routers store information and data. CISCO switches and routers have the following types of memory components: ROM (Read Only Memory) stores the switch's and router's power-on self-test (POST: Power-On Self-Test), bootstrap program, and some or all of the IOS. The ROM in the switch and router is erasable, so the IOS can be upgraded. Random Aess Memory (RAM) is similar to the random memory on a PC and provides temporary information storage, while maintaining the current routing table and configuration information. NVRAM (Nonvolatile Random Aess Memory) stores the startup configuration files of switches and routers; NVRAM is erasable, and the configuration information of switches and routers can be copied into NVRAM. FLASH flash memory, which is erasable and programmable, is used to store other versions of CISCO IOS for upgrading the IOS of switches and routers. Interfaces are used to connect switches and routers to the network and can be categorized into two types: LAN interfaces and WAN interfaces. Due to the different models of switches and routers, the number and type of interfaces are not the same. Common interfaces include the following: High-speed synchronous serial interface, which can be connected to DDN, Frame Relay, X.25, PSTN (analog telephone line). Synchronous/asynchronous serial ports, which can be set to work synchronously by software. AUI port, i.e. thick cable port. Generally requires an external converter (AUI-RJ45) to connect to a 10/100Base-T Ethernet network. ISDN port, which can be connected to ISDN network (2B+D), and can be used as an area network to access the Inter. AUX port, which is an asynchronous port, mainly used for remote configuration, can also be used for unplugging backup, and can be connected with MODEM. Supports Hardware Flow Control. Console port, which is an asynchronous port, mainly used to connect to a terminal or a computer running a terminal emulation program to configure switches and routers locally. Hardware flow control is not supported. Industrial Control A computer system that uses a bus structure to detect and control the production process, its electromechanical equipment, and process equipment. Abbreviated as industrial control. It consists of a computer and process input and output (I/O) through two major components. The computer is composed of a host computer, input and output devices and external disk drives, tape drives and so on. In the computer outside and increase part of the process input / output channel, used to complete the industrial production process detection data sent to the computer for processing; on the other hand, the computer to exercise control of the production process commands, information converted into industrial control object control variable signals, and then sent to the controller of the industrial control object to go. By the controller to exercise control over the operation of production equipment. The main categories of industrial control machine: IPC (PC bus industrial computer), PLC (programmable control system), DCS (decentralized control system), FCS (field bus system) and CNC (numerical control system) five. IPC that is based on the PC bus industrial computer. According to the 2000 IDC statistics PC has accounted for more than 95% of the general-purpose computers, because of its low price, high quality, high production, software / hardware resources, has been familiar with the majority of technicians and recognized, which is the basis of the industrial electric annoyance heat. Its main components for the industrial chassis, passive base plate and can be inserted into the composition of its various boards and cards, such as CPU card, I / O card. And take all-steel chassis, machine card pressure strip filter, double positive pressure fan design and EMC (Electro Magic Compatibility) technology to solve the industrial site of electromagnetic interference, vibration, dust, high / low temperature and other issues. IPC has the following characteristics: Reliability: Industrial PC has in dust, smoke, high / low temperature, humidity, vibration, corrosion and rapid diagnosis and maintainability, its MTTR (Mean Time to Repair) is generally more than 100,000 hours. Real-time, industrial PC on the industrial production process for real-time online detection and control, changes in working conditions to give a rapid response, timely collection and output adjustment (watchdog function which is not common PC), distress reset to ensure the normal operation of the system. Expandability, industrial PC due to the use of baseboard + CPU card structure, and thus has a strong input and output functions, up to 20 boards can be expanded, with a variety of peripherals in the industrial field, boards, such as with the road controller, video surveillance systems, vehicle detector, etc. connected to complete a variety of tasks. Compatibility, can simultaneously utilize ISA and PCI and PICMG resources, and support a variety of operating systems, multi-language compilation, multi-tasking operating systems. ProgrammableLogicController (PLC) PLC English full name ProgrammableLogicController, Chinese full name Programmable Logic Controller, the definition is: a digital algorithmic operation of the electronic system, designed for use in industrial environments and design. It uses a class of programmable memory for its internal storage program, the execution of logical operations, sequence control, timing, counting and arithmetic operations and other user-oriented instructions, and through digital or analog input/output control of various types of machinery or production processes. ProgrammableLogicController is a digital algorithmic electronic system designed for use in industrial environments. It uses a programmable memory to store instructions for performing logical operations, sequential control, timing, counting and arithmetic operations, etc., and controls various types of mechanical equipment or production processes through digital or analog inputs and outputs. Programmable controllers are a new type of general-purpose automatic control device for industrial environments developed by combining computer technology and automation control technology, and appear as a replacement for traditional relays. With the rapid development of microelectronics and computer technology, the programmable controller has more computer functions, not only to realize the logic control, but also has the data processing, communication, network and other functions. Because it can change the control process through the soft body, and has a small size, easy assembly and maintenance, simple programming, high reliability, strong anti-interference ability, etc., has been widely used in various fields of industrial control, greatly advancing the process of mechatronics. Decentralized control system (DCS) is a high-performance, high-quality, low-cost, flexible configuration of the decentralized control system series of products, can constitute a variety of independent control systems, decentralized control system DCS, monitoring and data acquisition system (SCADA), to meet the needs of a variety of industrial areas of process control and information management. The system's modular design, reasonable hardware and software function configuration and easy expansion capability can be widely used in the decentralized control of various large, medium and small power stations, the transformation of power plant automation system, and the process control of industrial production such as iron and steel, petrochemicals, papermaking, cement, and so on. Field Confluence System (FCS) is an all-digital serial, bi-directional communication system. Measuring and control devices such as probes, exciters and controllers within the system can be interconnected, monitored and controlled. In the hierarchy of plant networks, it serves as a localized network for process control (e.g. PLC, LC, etc.) and intelligent instrumentation (e.g. frequency converters, valves, barcode readers, etc.), and also has embedded functions for distributed control applications on the network. Because of its broad set of prospects, many foreign manufacturers with the strength of the competition to invest in strength, product development. Internationally known types of field convergence of more than forty types, the more typical field convergence of: FF, Profibus, LONworks, CAN, HART, CC-LINK and so on. CNC system (CNC) Modern CNC system is the use of microprocessors or special microcomputer CNC system, stored in memory by the system program in advance (soft) to realize the control logic, to achieve some or all of the functions of the CNC, and through the interface with peripheral equipment for connection, known as the computer numerical control, referred to as CNC system. CNC tooling machine is a mechatronic product formed by the penetration of new technologies represented by CNC system to the traditional machinery manufacturing industry; its technical scope covers many fields: (1) machinery manufacturing technology; (2) information processing, processing and transmission technology; (3) automatic control technology; (4) servo drive technology; (5) sensor technology; (6) software technology, etc. Personal computer Desktop machine (Desk), also known as desktop machine, is an independent and separate computer, completely unconnected with other components, compared to notebooks and netbooks are larger, the host computer, monitor and other equipment are generally relatively independent, generally need to be placed on the computer desk or a special workstation. Hence the name desktop. For the very popular microcomputer, most people's homes and companies use machines are desktops. The performance of desktops is relatively stronger than that of laptops. Desktop computers have the following characteristics: Heat dissipation. Desktop computers have advantages that are unmatched by notebook computers. The chassis of the desktop computer has a large space, good ventilation and has been widely used by people. Expandability. Desktop cases are convenient for users to upgrade their hardware, such as optical disk drives and hard disks. For example, the desktop chassis has 4-5 slots for optical disk drives and 4-5 slots for hard disk drives. It is very convenient for users to upgrade their hardware in the future. Protection. The desktop case protects the hard disk from dust. And water resistance is just fine; this development is not very good in laptops. Clarity. Desktop chassis on, key, reboot button, USB, audio ports are in the front panel of the chassis, user-friendly. But the poor portability of the desktop, compared to the laptop is very convenient. All-in-One Computer An all-in-one computer, is a computer that consists of a monitor, a computer keyboard and a mouse. It has a chip, motherboard and monitor integrated together, and the monitor is a computer, so as long as the keyboard and mouse are wired to the monitor, the machine is ready to use. With the development of wireless technology, the keyboard, mouse and monitor of the all-in-one computer can be connected wirelessly, and the machine has only one power cord. This solves the problem of the desktop computer has been criticized for many cables and mixed problems. Some all-in-one PCs also have TV reception, AV function, and also integrate specialized software, which can be used for specific industry-specific machines. Notebook (Notebook or Laptop) Also known as a laptop or laptop computer, a small, portable personal computer, usually weighing 1-3 kilograms. Laptop computers offer a TouchPad or Pointing Stick in addition to a keyboard, providing better positioning and input capabilities. Laptops can be broadly categorized into 6 types: business, fashion, multimedia suite, internet access, learning, and special purpose. Business-type laptops can generally be summarized as mobile, long battery life, business software; fashionable appearance is mainly aimed at fashionable women; multimedia-type laptops have strong graphics, image processing capabilities and multimedia capabilities, especially the ability to play for enjoyment of the product. Moreover, multimedia laptops have more powerful independent display card and sound card (both support HD), and have a larger screen. Netbook (Netbook) is a lightweight and low-configuration laptop, with Internet access, e-mail and instant messaging (IM) and other functions, and can realize the smooth playback of streaming media and music. Netbook more emphasis on portability, mostly used in business trips, travel and even public **** transportation on the mobile Internet. The learning body is designed in the shape of a notebook, with standard computer operation, fully integrated with a variety of machine functions such as learning machine, electronic dictionary, repeater, point reader, student computer and so on. Special-purpose laptop is a service for professionals, can be used in the heat, cold, low pressure, high altitude, strong radiation, war and other harsh environments, some of the more bulky, such as the Olympic Games in the "ASUS Everest Base Camp IT service area" used ASUS laptop. Pocket PC (PDA) Pocket PC is a kind of running in the embedded operating system and embedded software on top of the set, small, lightweight, easy to take, practical, inexpensive handheld computing devices. Pocket PCs are smaller, lighter, easier to carry, more practical, and less expensive than laptops in terms of size, functionality, and hardware. Pocket PC in addition to managing personal information (such as contacts, plans, etc.), but also can browse the Internet page, send and receive Email, and even as a cell phone to use, but also has: voice recorder function, English-Chinese-English dictionary function, the global clock against the function, the reminder function, recreation and entertainment functions, fax management functions and so on. The power supply of PDA usually uses ordinary alkaline batteries or rechargeable lithium batteries. The core technology of PDA is the embedded operating system, and the competition between various products is mainly here. With the rise of tablet computers and smart phones, pda has withdrawn from the digital market. Tablet PCs Tablet PCs are computers that do not require a flip-up cover, do not have a keyboard, are of different sizes and shapes, and yet are fully functional. Its components and laptop computers are basically the same, but it is the use of a stylus to write on the screen, rather than using the keyboard and mouse input, and breaks the laptop computer keyboard and screen vertical J-type design mode. It has all the functions of a laptop computer, but also supports handwriting input or voice input, mobility and portability is better. Tablet PC proposed by Bill Gates, at least should be the X86 architecture, from the concept of Microsoft's tablet PC products, tablet PC is a no flip cover, no keyboard, small enough to put into a lady's handbag, but a full-featured PC. In the Pocket PC, Tablet PC on the basis of the addition of cell phone features, it becomes a smart phone (Smartphone). In addition to the call functions of a cell phone, a smartphone has PDA functions, especially personal information management, as well as browser and e-mail functions based on wireless data communication. Smartphone for the user to provide a sufficient screen size and bandwidth, not only convenient to carry around, but also for the software operation and content services provide a broad stage, many value-added services can be carried out in this regard, such as stocks, news, weather, transportation, commodities, applications, music, pictures and video downloads and so on. Embedded computer, i.e., embedded system (Embedded Systems), is a kind of application-centered, microprocessor-based, hardware and software can be tailored to adapt to the application of the system on the function, reliability, cost, size, power consumption, and other comprehensive and stringent requirements of the special computer system. It generally consists of embedded microprocessors, peripheral hardware equipment, embedded operating systems and user applications and other four parts. It is the fastest growing area in the computer market, and also a wide variety of computer systems in many different forms. Embedded systems include almost all electrical devices in life, such as palm pda, calculators, TV set-top boxes, cell phones, digital TVs, multimedia players, automobiles, microwave ovens, digital cameras, home automation systems, elevators, air conditioners, security systems, vending machines, cellular telephones, consumer electronic devices, industrial automation instruments and medical instruments. The core component of the embedded system is the embedded processor, which is divided into four categories, i.e., Embedded Micro Contrller Unit (MCU, commonly known as microcontroller), Embedded Microprocessor Unit (Micro Processor Unit, MPU), Embedded DSP processor (Digital Signal Processor, DSP) and Embedded System-on-Chip (DSP). ) and embedded System on Chip (SOC). Embedded microprocessors generally have four characteristics: 1, real-time and multi-tasking has a strong support capacity, can complete multi-tasking and have a short interrupt echo time, so that the internal code and real-time operating system execution time is reduced to a minimum; 2, has a strong storage area protection function, this is due to the embedded system of the software structure has been modularized, and in order to avoid the modularity in the software between the module There is an error in the cross action, the need to design a strong storage area protection function, but also conducive to the soft body diagnosis; 3, scalable processor structure, in order to be able to quickly expand to meet the set of high-performance embedded microprocessor; 4, embedded microprocessor power consumption must be very low, especially for portable wireless and mobile computing and communications equipment in the battery-powered embedded systems is more so. Power consumption can only be mw or even μw level.