Supercomputers
Supercomputers are usually composed of hundreds, thousands or even more processors (machines) that can calculate what ordinary PCs and servers can’t do. Computers for large and complex subjects. Supercomputers are a class of computers with the strongest functions, the fastest computing speed, and the largest storage capacity among the computers. They are an important symbol of the country's scientific and technological development level and overall national strength. Supercomputers have the strongest parallel computing capabilities and are mainly used for scientific computing. Undertake large-scale and high-speed computing tasks in the fields of meteorology, military, energy, aerospace, and mining. In terms of structure, although both supercomputers and servers may be multi-processor systems, there is no substantial difference between the two, but modern supercomputers often use cluster systems and pay more attention to the performance of floating-point operations. High-performance servers for scientific computing, and the price is very expensive.
Network computer
Server
Specifically refers to certain high-performance computers that can provide services to the outside world through the network.
Compared with ordinary computers, stability, security, performance and other aspects are more demanding, so the CPU, chipset, memory, disk system, network and other hardware are different from ordinary computers. The server is a node of the network, storing and processing 80% of the data and information on the network, and plays a decisive role in the network. They are high-performance computers that provide various services to client computers. Their high performance is mainly manifested in high-speed computing power, long-term reliable operation, and powerful external data throughput capabilities. The structure of the server is similar to that of an ordinary computer. It also has a processor, hard disk, memory, system bus, etc., but because it is specially formulated for specific network applications, the server and the microcomputer are in terms of processing capacity, stability, reliability, security, There are big differences in scalability and manageability. Servers mainly include network servers (DNS, DHCP), print servers, terminal servers, disk servers, mail servers, file servers, etc.
Workstation
It is a kind of workstation based on personal computer and distributed network computing, mainly for professional applications, with powerful data computing, graphics, and image processing capabilities, in order to meet the needs of engineering High-performance computers designed and developed for professional fields such as design, animation production, scientific research, software development, financial management, information services, and simulation. The most prominent feature of the workstation is its strong graphics exchange capability, so it has been rapidly applied in the field of graphics and images, especially in the field of computer-aided design. Typical products are the Sun series workstations of American Sun Company.
A diskless workstation refers to a computer connected to a local area network without floppy disks, hard disks, and optical drives. In the network system, the operating system and application software used by the workstation are all placed on the server. The system administrator only needs to complete the management and maintenance on the server, and the software upgrade and installation only need to be configured once, then the entire network All computers in the country can use the new software. Therefore, diskless workstations have the advantages of cost saving, high system security, easy management and easy maintenance, which are very attractive to network administrators.
The working principle of a diskless workstation is that the boot chip (Boot ROM) of the network card sends a startup request number to the server in different forms. After the server receives it, it sends startup data to the workstation according to different mechanisms. After the workstation downloads the boot data, the system control is transferred from the Boot ROM to some specific areas in the memory and the operating system is booted.
According to different startup mechanisms, the more commonly used diskless workstations can be divided into RPL and PXE. RPL is the abbreviation of Remote Initial Program Load, this technology is often used in Windows95. PXE is an upgrade of RPL, it is the abbreviation of Preboot Execution Environment. The difference between the two is that RPL is a static route, while PXE is a dynamic route. Its communication protocol uses TCP/IP, which realizes an efficient and reliable connection to the Internet. It is often used in Windows 98, Windows NT, Windows 2000, and Windows XP.
Hub
A hub (HUB) is a network device that shares media. Its function can be simply understood as connecting some machines to form a local area network. The HUB itself cannot identify the purpose. Address. All ports on the hub compete for the bandwidth of a shared channel, so as the number of network nodes increases and the amount of data transmission increases, the available bandwidth of each node will decrease accordingly. In addition, the hub transmits data in the form of broadcast, that is, transmits data to all ports. For example, when a host A in the same LAN transmits data to a host B, the data packet is transmitted in a broadcast mode on the HUB-based network, and the same information is sent to all nodes on the network at the same time, and then each terminal passes through it. Verify the address information in the header of the data packet to determine whether to receive it. In fact, generally speaking, there is only one terminal node that receives data, and all nodes are sent. In this way, it is easy to cause network congestion, and most of the data traffic is invalid, which causes the entire network data transmission efficiency to be quite Low. On the other hand, since the data packets sent can be heard by every node, it is easy to bring some hidden dangers to the network.
Switch
The switch (Switch) is based on the needs of transmitting information at both ends of the communication, using manual or automatic equipment to complete the information to be transmitted to the corresponding route that meets the requirements Technology collectively. A switch in a broad sense is a device that completes the function of information exchange in a communication system. It is an upgraded product of a hub. Its appearance is very similar to a hub, and its function is roughly the same as that of a hub. But there is a difference in performance between the two: the hub uses a shared bandwidth mode of work, while the switch uses a dedicated bandwidth mode. That is, all ports on the switch have exclusive channel bandwidth to ensure the fast and effective transmission of data on each port. The switch provides users with an exclusive, point-to-point connection, and data packets are only sent to the destination port. It will be sent to all ports, and it is difficult for other nodes to listen to the sent information. This will not easily cause network congestion when there are many machines or large amounts of data. It also ensures the safety of data transmission and greatly improves the transmission efficiency. The difference between the two is more obvious.
Router
Router is a network device responsible for path finding. It finds the network path with the least amount of traffic from multiple paths in the Internet and provides it to users Communication. The router is used to connect multiple logically separated networks to provide users with the best communication path. The router uses a routing table to select a path for data transmission. The routing table contains a list of network addresses and the distance between each address. The router uses the routing table to look up The correct path of the data packet from the current location to the destination address, the router uses the least time algorithm or the optimal path algorithm to adjust the path of information transmission. The router is generated after the switch, just like the switch is generated after the hub, so the router and the switch are also connected to a certain extent, and they are not completely independent of the two devices. The router mainly overcomes the insufficiency of the switch not being able to forward data packets to the router.
Switches and routers are a special network computer. Its hardware base is CPU, memory and interface, and its software base is network interconnection operating system IOS.
Switches and routers, like PCs, have a central processing unit CPU, and different switches and routers generally have different CPUs. The CPU is the processing center of the switch and router.
Memory is the place where switches and routers store information and data. CISCO switches and routers have the following memory components:
ROM (Read Only Memory) storage switches and routers are automatically powered on. Check (POST: Power-On Self-Test), boot program (Bootstrap Program) and part or all of IOS. The ROM in switches and routers is rewritable, so IOS can be upgraded.
RAM (Random Access Memory) is similar to the random access memory on the PC. It provides temporary information storage, while keeping the current routing table and configuration information.
NVRAM (Nonvolatile Random Access Memory) stores the startup configuration files of switches and routers. NVRAM is rewritable, and the configuration information of switches and routers can be copied to NVRAM.
FLASH flash memory is rewritable and programmable. It is used to store other versions of CISCO IOS and to upgrade the IOS of switches and routers.
Interfaces are used to connect switches and routers to the network and can be divided into two types: LAN interface and WAN interface. Due to the different models of switches and routers, the number and types of interfaces are also different. Common interfaces are mainly as follows:
High-speed synchronous serial port, which can be connected to DDN, Frame Relay, X.25, PSTN (analog telephone line).
Synchronous/asynchronous serial port, you can use software to set the port to synchronous working mode.
AUI port, that is, thick cable port. Generally, an external converter (AUI-RJ45) is required to connect to a 10/100Base-T Ethernet network.
The ISDN port can be connected to an ISDN network (2B+D) and can be used as a LAN to access the Internet.
AUX port, this port is an asynchronous port, mainly used for remote configuration, but also for dial-up backup, and can be connected to a MODEM. Support hardware flow control (Hardware Flow Control).
Console port, which is an asynchronous port, is mainly connected to a terminal or a computer running a terminal emulation program, and switches and routers are configured locally. Does not support hardware flow control.
Industrial control
It is a general term for a computer system that uses a bus structure to detect and control the production process and its electromechanical equipment and process equipment. Referred to as industrial computer. It is composed of computer and process input and output (I/O) through two parts. The computer is composed of a host, input and output devices, external disk drives, tape drives, and so on. A part of the process input/output channels are added outside the computer to complete the inspection data of the industrial production process to be sent to the computer for processing; on the other hand, the computer must exercise the commands and information to control the production process into the control variables of the industrial control object The signal is sent to the controller of the industrial control object. The controller exercises control over the operation of the production equipment. The main categories of industrial computer are: IPC (PC bus industrial computer), PLC (programmable control system), DCS (distributed control system), FCS (field bus system) and CNC (numerical control system).
IPC
Is an industrial computer based on the PC bus. According to IDC statistics in 2000, PCs accounted for more than 95% of general-purpose computers. Because of their low price, high quality, large output, and rich software/hardware resources, they have been familiar and recognized by the majority of technical personnel. Annoying foundation. Its main components are industrial chassis, passive backplane and various boards that can be inserted into it, such as CPU card, I/O card, etc. And adopt the design of all-steel casing, machine card layering filter, double positive pressure fan and EMC (Electro Magnetic Compatibility) technology to solve the problems of electromagnetic interference, vibration, dust, high/low temperature and so on in the industrial field.
IPC has the following characteristics:
Reliability: Industrial PC has the advantages of dust, smoke, high/low temperature, humidity, vibration, corrosion and rapid diagnosis and maintainability, and its MTTR ( Mean Time to Repair) is generally more than 100,000 hours.
Real-time, industrial PC performs real-time online detection and control of the industrial production process, responds quickly to changes in working conditions, and conducts timely collection and output adjustments (watchdog function is not available in ordinary PCs) ), self-reset in distress to ensure the normal operation of the system.
Expansibility, industrial PC has strong input and output functions due to its backplane + CPU card structure. It can be expanded up to 20 boards, and can be integrated with various peripherals and boards in the industrial field. Connect with road controller, video monitoring system, vehicle detector, etc. to complete various tasks.
Compatibility, can use ISA, PCI and PICMG resources at the same time, and support various operating systems, multi-language assembly, and multi-task operating systems.
Programmable Logic Controller (PLC)
The full name of PLC in English is ProgrammableLogicController, and the full name of PLC in Chinese is Programmable Logic Controller. The definition is: an electronic system for digital operations, designed for Designed for use in industrial environments. It uses a type of programmable memory for its internal storage of programs, executes logic operations, sequence control, timing, counting and arithmetic operations and other user-oriented instructions, and controls various types of machinery through digital or analog input/output Or the production process. Programmable Logic Controller (Programmable Logic Controller) is a digital operation electronic system specially designed for applications in industrial environments. It uses a programmable memory to store instructions for performing logic operations, sequence control, timing, counting and arithmetic operations, and control various types of mechanical equipment or production through digital or analog input and output. Process.
Programmable controller is a new type of universal automatic control device suitable for industrial environment developed by combining computer technology and automation control technology. It appears as a replacement for traditional relays. With the rapid development of microelectronics and computer technology, programmable controllers have more computer functions, not only can realize logic control, but also have functions such as data processing, communication, and networking. Because it can change the control process through software, and has the characteristics of small size, easy assembly and maintenance, simple programming, high reliability, and strong anti-interference ability, it has been widely used in various fields of industrial control and greatly promoted the integration of mechatronics. Process.
Distributed Control System (DCS)
It is a series of high-performance, high-quality, low-cost, and flexible distributed control system products, which can form a variety of independent control systems , Distributed control system DCS, monitoring and data acquisition system (SCADA), can meet the needs of process control and information management in various industrial fields. The modular design of the system, reasonable hardware and software configuration and easy-to-expandable capabilities can be widely used for distributed control of various large, medium and small power stations, transformation of power plant automation systems, and steel, petrochemical, paper, cement, etc. Industrial production process control.
Field Bus System (FCS)
is an all-digital serial, two-way communication system. The measurement and control equipment in the system such as probes, exciters and controllers can be interconnected, monitored and controlled. In the classification of the factory network, it is used as a local network for process control (such as PLC, LC, etc.) and application of intelligent instruments (such as inverters, valves, barcode readers, etc.), and it has an embedded network for distributed control applications on the network Function. Due to its broad application prospects, many powerful foreign manufacturers are competing to invest in product development. There are more than forty types of fieldbuses known internationally, and the more typical fieldbuses are: FF, Profibus, LONworks, CAN, HART, CC-LINK, etc.
Numerical Control System (CNC)
Modern numerical control system is a numerical control system that uses a microprocessor or a special microcomputer. The control logic is realized by the system program (software) stored in the memory in advance. Realize part or all of the numerical control functions, and connect with peripheral equipment through the interface, which is called computer numerical control, or CNC system for short.
CNC machine tools are mechatronics products formed by the penetration of new technology represented by CNC systems into the traditional machinery manufacturing industry; its technical scope covers many areas: (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
Also called desktop, it is an independent and separated computer, completely unrelated to other components Compared with the larger size of notebooks and netbooks, the host, display and other devices are generally relatively independent, and generally need to be placed on a computer desk or a special workbench. Hence the name Desktop. As a very popular microcomputer, most people's home and company machines are desktop computers. The performance of desktop computers is relatively stronger than that of notebook computers. Desktop computers have the following characteristics:
Heat dissipation. Desktop computers have advantages that notebook computers can't match. The desktop chassis has the factors of large space and good ventilation conditions, and has been widely used by people all the time.
Scalability. The desktop chassis is convenient for users to upgrade hardware, such as optical drives and hard disks. For example, there are 4-5 optical drive slots in a desktop case and 4-5 hard drive slots. It is very convenient for users to upgrade their hardware in the future.
Protective. The desktop computer protects the hardware from dust in all aspects. And water resistance is good; this development is not very good in notebooks.
Clarity. The open, key, restart keys, USB, and audio interfaces of the desktop case are all on the front panel of the case, which is convenient for users to use.
But the portability of desktop computers is poor, which is very convenient compared to notebooks.
All-in-one computer
All-in-one computer is a computer composed of a monitor, a computer keyboard and a mouse. Its chip, motherboard and monitor are integrated together. The monitor is a computer, so as long as the keyboard and mouse are connected to the monitor, the machine can be used. With the development of wireless technology, the keyboard, mouse, and monitor of the all-in-one computer can be wirelessly linked, and the machine has only one power cord. This solves the problem of many and complicated desktop cables that have been criticized. Some computer all-in-ones also have TV reception, AV functions, and also integrate special software, which can be used for special machines in specific industries.
Notebook (Notebook or Laptop)
Also called laptop or laptop, it is a small, portable personal computer, usually weighing 1-3 kg. In addition to the keyboard, the laptop also provides a touchpad (TouchPad) or a touch point (Pointing Stick), which provides better positioning and input functions.
Notebook computers can be roughly divided into 6 categories: business type, fashion type, multimedia application, Internet type, learning type, and special purpose. Business notebook computers can generally be summarized as mobile, long battery life, and more business software; stylish appearance is mainly aimed at fashionable women; multimedia application notebook computers have strong graphics, image processing capabilities and multimedia capabilities, especially It is the ability to play, and it is an enjoyable product. Moreover, most multimedia notebook computers have more powerful discrete graphics and sound cards (both support HD), and have larger screens. A netbook is a lightweight and low-profile notebook computer with functions such as surfing the Internet, sending and receiving emails, and instant messaging (IM), and can play streaming media and music smoothly. Netbooks emphasize portability and are mostly used for mobile Internet access on business trips, tourism and even public transportation. The learning-type body is designed in the shape of a notebook, using standard computer operations, fully integrating learning machine, electronic dictionary, repeating machine, point reading machine, student computer and other machine functions. Special-purpose laptops are models that serve professionals and can be used in harsh environments such as scorching heat, severe cold, low pressure, high altitude, strong radiation, and war. Some of them are heavy and bulky. ASUS laptops used in the IT service area.
Handheld computer (PDA)
Handheld computer is a kind of small, lightweight, easy to carry, practical and cost-effective running on embedded operating system and embedded application software. Cheap handheld computing devices. It is simpler and lighter than a laptop in terms of size, function and hardware equipment. In addition to managing personal information (such as address books, plans, etc.), handheld computers can also browse pages on the Internet, send and receive Email, and even be used as a mobile phone. It also has: voice recorder function, English-Chinese Chinese-English dictionary function, global Clock comparison function, reminding function, leisure and entertainment function, fax management function and so on. The power source of the palmtop computer usually adopts the ordinary alkaline battery or the rechargeable lithium battery. The core technology of handheld computers is the embedded operating system, and the competition among various products is mainly here.
With the rise of tablet computers and smart phones, pda has withdrawn from the digital market.
Tablet PC
The tablet PC is a computer that does not require a flip, does not have a keyboard, is of various sizes, and shapes, but is fully functional. Its components are basically the same as the notebook computer, but it uses a stylus to write on the screen instead of using the keyboard and mouse to input, and it breaks the J-shaped design pattern of the notebook computer keyboard being perpendicular to the screen. In addition to having all the functions of a notebook computer, it also supports handwriting input or voice input, which is more mobile and portable. The tablet computer was proposed by Bill Gates, at least it should be an X86 architecture. From the perspective of the tablet concept product proposed by Microsoft, the tablet computer is a fully functional PC that does not require a flip, does not have a keyboard, and is small enough to fit in a lady's handbag. .
On the basis of handheld computers and tablets, with mobile phone functions, it becomes a smart phone (Smartphone). In addition to the phone call function, the smart phone also has the PDA function, especially the personal information management and the browser and e-mail function based on wireless data communication. Smart phones provide users with sufficient screen size and bandwidth, not only convenient to carry around, but also provide a broad stage for software operation and content services. Many value-added services can be launched, such as stocks, news, weather, transportation, commodities, and applications. Program download, music, picture and video download, etc.
Embedded computer
It is embedded system (Embedded Systems), which is application-centric, microprocessor-based, software and hardware can be tailored to adapt to the application system Special-purpose computer systems with strict requirements on functions, reliability, cost, size, power consumption, etc. It is generally composed of four parts: embedded microprocessor, peripheral hardware equipment, embedded operating system, and user's application program. It is the fastest growing field in the computer market, and it is also a wide variety of computer systems in various forms. Embedded systems almost include all electrical equipment in life, such as handheld PDAs, calculators, TV set-top boxes, mobile phones, digital TVs, multimedia players, automobiles, microwave ovens, digital cameras, home automation systems, elevators, air conditioning, security systems, Vending machines, cellular phones, consumer electronic equipment, industrial automation instruments and medical instruments, etc.
The core component of the embedded system is the embedded processor, which is divided into 4 categories, namely embedded microcontroller (Micro Contrller Unit, MCU, commonly known as single-chip microcomputer), embedded microprocessor (Micro Processor Unit, MPU) , Embedded DSP processor (Digital Signal Processor, DSP) and embedded system on chip (System on Chip, SOC). Embedded microprocessors generally have four characteristics:
1. It has strong support for real-time and multitasking, can complete multitasking and has a short interrupt response time, so that the internal code and The execution time of the real-time operating system is reduced to a minimum;
2, it has a powerful storage area protection function. This is because the software structure of the embedded system has been modularized, and in order to avoid The cross-effects of errors need to be designed with a powerful storage area protection function, which is also conducive to software diagnosis;
3. Scalable processor structure to quickly expand to meet the high performance of the application Embedded microprocessors;
4. The power consumption of embedded microprocessors must be very low, especially for battery-powered embedded systems used in portable wireless and mobile computing and communication equipment In this way, the power consumption can only be mw or even μw level.