30 days breakthrough computer level three exam (1)
For some reason, I have taken 2 written tests, 3 times. One of the written tests is around 70, and it is full of 3 times. Looking at a large number of students don't know how to prepare and should be examined for three levels. I think I should write experiences and learning methods, these methods guarantee that you can cross the third level. But do not guarantee that you can get a high score and learn knowledge, so you should use the computer system with the master of your computer or the comrades who think is the master. OK!
<---------- ====== The written test section ====== ------------>
Take network technology as an example (other three ways to methods), I summarize the method as: a book, do notes, and review.
The first stage: see the network technology textbook, take notes (20 days) in detail.
On the first side of the book, you have to look at it, copy all the places you think important to your notebook, including important forms and illustrations. For the first time I can't understand, I can jump over and wait for two days to look back. I will re-review the previous two days before I look at the new knowledge every day.
I divide the importance of the book: first, seven, eight chapters to understand (see doing notes); second, four chapters understand (understand the main knowledge points); third, five, six chapters Master (understand all the knowledge points); there is a focus on the following chapters: 2.2 Processes 2.3 Storage Management 2.4 File Management 2.5 Device Management (I have hung in this section) 3.5 Twisted pair VS coaxial cable 3.6 OSI VS TCP / IP 4.3 Ethernet 4.5 Network Technology 4.8 Network Interconnection 5.3 IP Protocol 6.4 Encryption Technology Some of the contents must be understood and mastered, if not understand, back will come down. Such as: the name of each layer of the OSI protocol and the TCP / IP protocol, various transmission media and various Ethernet parameters.
In addition, there is no need to see if there is no need to see, because there is no one in the exam. ===> Point 1: Persistence is victory, insist on watching 2 hours a day, at least 15 pages. ===> Tone 2: This copy is copied, and good memory is not as bad. ===> To point three: Pay attention to after class work questions, it may be the original question.
After this phase is completed, it should be able to understand most of the knowledge points. It is also possible to quickly find a position of a knowledge point in the book.
Second stage: review key chapter (5 days)
This review focuses on what you need to understand and master, if you understand, close the book, you can't understand it, you have to look at it, some have to remember. And I have to read the notebook twice and achieve more skilled. ===> Total 1: See if it is not necessarily remembered, be sure to form an impression in the mind, and the book can write down. ===> Tone 2: Nounted terms should be noted. ===> To point three: Abbreviation. All two times appeared in the book, must note the interpretation of Chinese and English. For example: CDMA / CD, MFLOPS, etc.
The third stage: review is not important chapter and topic (5 days)
Some people may ask, since it is not important to review what it does. wrong! Announcement cannot use a key to add some other content to be appropriate. So only in these unimportant chapters, these questions account for about 20 points. The score method is to read all the things that are not important. The more you think it is impossible, the more you want to copy it, remember. Moreover, pay special attention to the numbers, such as the transmission rate of the ATM, the wavelength of the light used in the single mode fiber. (One of the last most vomiting is the typical value of the transmission delay from the transmitting station through the satellite to the receiving station? I follow the distance of the Earth's satellite to the Earth, the transmission speed of the light, calculated to the amount of one hundred Level, but there is no specific value, so I guess a 250MS. The answer is actually 540ms. Dizzy ~!) Is the problem of simulation questions, I think the simulation question on the market is too bad, the whole test No, it's not good to say that the truth is not as good as I. So don't do much more, just look good, you can do a few sets in the last few days, familiar with the topic of the title, master the time, you will have a waste.
The above method I did my classmates to do it as I said, and the written test is higher than me. So no matter what you are smart, as long as you do it, you will be able to pass. One sentence: If you take me, you ask.
<---------- ====== The machine part ====== ----------->
The machine is only one to C language programming questions now, it is very simple. But I think the most important thing is to compile procedures and debugging programs, that is, a question you can write down on paper, you must be able to run the result on the machine, because compilation system and machine different, Some pairs may also produce a lot of errors. As long as you can find the mistake, you can have it. So I summarize the way: more thinking, multi-machine, catching insects. (Taking Tan Haoqiang's "C Language Design" as an Example)
The first stage: reading, doing notes. (15 days)
Some people say that the book is so thick, can you read 15 days? wrong! Who said that you have finished reading, if you just want to have three levels. It's enough to use the first 140 pages. That is, the first chapter, understanding, second, three chapters understand, fifth, six, seven chapters master, eighth, Chapter 10, just look at it. Because C is only required to fill a function, then the function is not to see too much, just know what the function is to use, how to call it between them. As for the pointer, all the exams can be made in an array. It is just a simple point with a pointer. It is easy to make a little more, I am strongly suggested. Chapter 9 and Tenth chapter will not look at it later.
===> Total one: Diligence, remember all important things on the notebook. Such as definition of escape characters, etc. ===> Tour: Try two programs every day (which can be an example or work question) ===> Take three: persist, stick to it.
The second stage: Do the post-class job question and debug. (10 days)
Now that you have finished reading, exercises may also make some. Now that the previous chapter, especially the five-six seventh chapter, the following questions must be thought about it. After making it out, it will be adjusted. If you can't do it, you will see the answer, after understanding, then in the machine I'm debugging it. Important Example: Example 4.10 4.12 5.4 5.5 5.6 5.7 5.8 6.6 6.8 6.10 7.2 7.2 7.8 7.9 Important Exercises: 4.5 4.9 5.5 5.7 5.8 6.1 ~ 6.10 7.1 ~ 7.14 ===> Total 1: Use the N-S flow chart when doing questions. ===> Tour: Every question is about how simple, must be called until it is correct. If the exercise 2.4 (2) I have several students can be edited, but I have to run incorrect. ===> To point three: Every day, do five topics above, preferably in the TC2.0 environment.
The third stage: Continue to debug important procedures, see a book (5 days)
Continue to debug procedures until you are skilled, then look at a book, I don't say it first, you may know many students. But I don't agree to see this book, and I advise you to look at it in the last few days, pick out some typical questions, do it, see if it is correct, familiar with the topic, don't rely on that book. That is likely because you can't find a little error. The girls in our class have been hanging for the first time because of this reason.
Or is there a word: If you are uploaded, I ask.
Chapter 1 Computer Basics
The four-character point of the computer: 1. There is a characteristic of information processing. 2. Have the characteristics of program control. 3. There is a flexible choice. 4. There is a correct application. Computer development experience 5 important phases: 1 large machine stage. 2 small machine stage. 3 microcomputer stage. 4 Client / Server Stage. 5 internet stage. Computer Reality Category: Server, Workstation, Desktop, Portrait, Handheld Devices. Computer Traditional Category: Main Machine, Small Machine, PC, Workstation, Giant Machine. Computer indicator: 1. Bit number. 2. speed. MIPS is the average execution speed of the single-word long fixed point instruction. MFLOPS is the average execution speed of the monograph long floating point command. 3. capacity. Byte is expressed in b. 1kb = 1024b. The average seek time refers to the averaging time to move along the disk to the track that needs to be read or written. The average waiting time is the average time required to rotate the sector that needs to be read or written. The data transfer rate refers to the number of bytes that can be read or written per second after the magnetic head finds the sector to be read. 4 bandwidth. BPS uses B 5 versions. 6 reliability. The average failure time MTBF and the flat fault repair time MTTR is expressed. Computer application area: 1 scientific calculation. 2 Transaction. 3 process control. 4 auxiliary project. 5 artificial intelligence. 6 network application. A complete computer system consists of two parts: software and hardware. Computer hardware constitutes four levels: 1 chip. 2 board. 3 device. 4 network. The technical characteristics of the Pentium chip: 1. Overweight scale technology. By the built-in multi-pipeline is simultaneously performed, the substantial is the spatial exchange time. 2. Superflow wire technology. By refining the water, improve the frequency, so that the machine completes one or even multiple operations in one cycle, which is essentially time-exchanged space. Classic Pentium is divided into four-stage water in each pipeline: instruction prefetch, decoding, execution, and writing results. 3. Branch prediction. 4. Double Cache Harvard Structure: Directive is separated from data. 7 Curing common instructions. 8 Enhanced 64-bit data bus. 9 Local bus using the PCI standard. 10 Error detection The function is used to verify the technology. 11 Energy efficiency technology. 12 Support multiple processing. The technical characteristics of the Anteng chip. 64-bit processor. The Pentium series is 32 bits. Inter 8080-8. Inter3088-16. Complex instruction system CISC. Streamlined instruction technology RISC. The main function of the network card: 2 Realize the communication connection with the host bus, explaining and executes the control command of the host. 3 Implement the function of the data link layer. 4 Implement the function of the physical layer. Software is the command sequence: store the reservoir in the code form. The database software is a desktop application. The program is composed of a command sequence, telling the computer how to complete a task. Three stages of software development: 2 plan. Divided into problem definition, feasibility study. 3 Development phase. Divided into demand analysis, overall design, detailed design. 4 running stage. Mainly software maintenance. In programming, people first use the machine language. Because it uses the 2-way code that is closest to computer hardware, it is a low-level language. Symbolized machine language, use help notes instead of 2 credits, Cheng Zi language. Translating the assembly language source program into a tool for a machine language target program, becoming an assembler. Put the disassembler. Translate advanced language source programs into tools for machine language target programs, there are two types: interpreter and compiler. The compiler is to perform all the translation translations of the entire source program, generate the target program of the machine language, and then let the computer execute to get the computer results. The interpreter is to input the source program, translate a sentence, execute a sentence, and do not become the entire target program. Multimedia technology is a sound-colored information processing and utilization technology.
Multimedia technology is integrated, transmit, store, and broadcast integration techniques for text, sound, image, and graphics. Multimedia technology is divided into bias software technology and biased technology. The basic components of the multimedia hardware system are: 1. CD-ROM. 2. Has A / D and D / A conversion function. 3. High-definition color display. 4. Hardware support with data compression and decompression. Key Technologies of Multimedia: 1 Data Compression and Unexpected Technologies: JPEG: Practical and continuous tones, multi-stage grayscale, color or monochrome still image. MPEG: Consider audio and video synchronization. 2 chip and card technology. 3 Multimedia operating system technology. 4 multimedia data management technology. A technique for multimedia data management is based on hyperblicic technology, and super media technology. When the information is not limited to text, it is called hyper media. 1 node. 2. chain. The composition of the super-media system: 2 editor. The editor can help users build, modify the nodes and chains in the information network. 3 Navigation tools. First, the database is based on the condition based query, one is the inquiry of the interactive style along the chain. 4 hypermedia language. Super Media Languages can describe the construction, nodes, and other various properties of the hypermedia network in a programming method. ADSL: Asymmetric Digital User Line (ADSL), ADSL is on unsuccessful user loop network, using a load telephone line to provide high-speed digital access transmission technology, users who use broadband services are economical Access method. It is characterized by transmitting, low bitmap rate, low-line digital channel, and transmission rate of upstream digital channels can reach 144kbps or 384kbps; Using a line code.) ATM: Asynchronous transmission mode ATM is a packet switching and multiplexing technology. To send information with fixed length packets (referred to as cell), each cell contains a VCI, VCI A method is provided to create multiple logical channels and multiplexed multiplexes when needed. Because the cell length is fixed, the cell may contain useless bits.
CAE: Computer Aided Project
) CAM: computer-aided manufacturing
Cat: Computer Aided Test
CSMA / CD: Random contention medium access control method, ie carrier listening multi-channel access to conflict detection. It is the core technology of Ethernet.
ENIAC: The first digital electronic computer in 1946 in Bingzhou University.
FTP: File Transfer Service (FTP) is one of the earliest service functions in the Internet. The FTP service uses a typical client / server working mode, and FTP services provide a valid means for two-way file transfer between computers. It allows Users load files in the local computer into the remote computer, or download the files in the remote computer to the local computer.
IDSL: ISDN-based digital user line (IDSL), ISDN can be counted as one of DSL technology from its current application. ISL can be considered an expansion of ISDN technology, which is used to provide users with basic Rate BRI (128kbps) ISDN service, but its transmission distance can reach 5km, and its primary application has remote communication and remote office connections.
IEEE: American Electronics Engineer Society
ISO: International Standardization Organization ISO has made a lot of work in promoting the research of open system reference model and network protocol, has an important role in the formation of network theory systems and the development of network technology, but it is also facing TCP / IP severe challenges.
JPEG: It is formulated by the International Standardization Organization (ISO) and the International Telephone Advisory Committee (ccitt). It is suitable for continuous tones. International standards of multi-level grayscale. Color or monochrome still images.
MFLOPS: Some machines use MFLOPS to indicate processing speeds in order to examine the average execution speed of the single-oriented floating point command.
MIPS: Indicates the average execution speed of the single-word long fixed point command, that is, one million instructions per second.
) MPC: multimedia computer
MPEG: MPEG is a draft standard for ISO / IEC commissions, including MPEG video. MPEG audio and MPEG systems. MPEG should take into account synchronization of audio and video, and generate a video and audio compression of a TV quality after joint compression. The form of a single stage of 5 Mbps is a single first class.
) MTBF: It is a failure to have a long time system.
) MTTR: Refers to the time required to repair a fault.
OLE: It is an object link and embedding, which is a valid technology that implements a variety of media fragments integration and processing. Use it to join the form in the user file. Sound. Graphic. Image and video, etc., and all links Embedded data is treated as an object and provides objects in the file to display. Editing. Modify, and playback operations.) OSI: International Standardization ISO ISO Published The most famous ISO standard is ISO / IEC7498, also known as X.200 Recommendation. The architecture standard defines the seven-layer framework of network interconnects, namely ISO open system interconnect reference model. Further, in this framework, the functionality of each layer is further specified in the open system environment. Interconnectivity. Interoperability and portability of applications.
P × 64: P × 64, is the H.261 of CCITT, P is variable parameters, and the value range is 1 ~) The target is a visual phone and a TV conference, it can cover the entire ISDN (integrated Business Digital Network) Channel. When P1 or 2, only video calls with fewer frames per second, can support TV conferences when P> 6.
RADSL: Rate Adaptive Digital User Line (RADSL), RADSL provides the same rate as ADSL, is also a digital subscriber line that provides high speed downlink and retaining the original voice service. The difference between ADSL is: radsl The rate can be dynamically adaptively adaptively based on the transmission distance. When the distance increases, the rate is lowered, which can be used for the user to select the transmission service.
SDSL: Single-line digital subscriber line (SDSL), SDSL is a symmetrical DSL technology, and the difference from HDSL is to use only one pair of copper wires. SDSL can support various requirements. The same application is the same, the technology is now It can be provided, running well in the two-wire circuit. However, the standard has not finally established.
) SET: Safety Electronic Trading Set is an open payment specification developed by Visa and MasterCard, which is to ensure that credit cards are set up on public Internet payments. Private key encryption technology and public key encryption technology are two most Basic encryption technology. Currently, the SET protocol uses these two technologies based digital envelope technology. Digital signature technology. Information summary technology and dual signature technology to ensure information transmission and processing.
SNA: The world's first network architecture is proposed in 1974, named: system network architecture SNA / ..
SNMP: It is a management protocol proposed by Internet Engineering Task Group Ietf (TheInterneTergergergergergergergergergergergergergergergergergergergergergergergergergergergergergergergergergergergergergergergergergergergergerge), which includes a bridge. Router. Network interconnection equipment such as switches and processing capabilities. SNMP adopts polling monitoring. Manager requests management information from a certain time interval, and the manager determines whether there is an abnormal event. SNMP is located in the application layer of the Isoosi reference model, which follows ISO's network management model. SNMP model consisting of management nodes and proxy The node is composed, which uses the proxy / management station model.
Spooling: It is the simultaneous peripheral device online, it is to solve the number of exclusive devices. The speed is slow. It does not meet the requirements of many processes, and the equipment utilization is relatively low during the process exclusive equipment. Management technology. It is a virtual equipment technology. Its core thinking is to simulate an exclusive device on a shared device (usually high speed. Large-capacity disk), transform a low-speed exclusive device into a plurality of parallel operations Virtual equipment, that is, turn exclusive devices into logically shared devices.
SSE: It is intended to stream. Multi-stream expansion instructions.
VDSL: VDSL: VDSL, is developed on the basis of ADSL, which can transmit data than ADSL higher-speed data on the basis of ADSL, with a maximum downstream rate of 51Mbps ~ 55Mbps. The transmission line length does not exceed 300m; when the transmission rate is below 13Mbps, the transmission distance can reach 5km, and the uplink rate is 6Mbps or more. In order to transmit the compressed video signal in real time, VDSL uses forward error correction (FEC) encoding technology to transmit errors control, And use the switch technology to correct the burst error due to the pulse noise. Compared to ADSL, the VDSL transmission bandwidth is higher, and due to the shortened transmission distance, the interval interference is small, the digital signal processing technology is simplified, and the cost will be significantly reduced.
) WWW customer: WWW client is called the WWW browser on the Internet, which is software used to browse the WWW page on the Internet. In the WWW service system, the WWW browser is responsible for receiving the user's request. And use the HTTP protocol to transfer the user's request to the WWW server. After sending the page of the server to send back to the browser, the browser explains the page again to display on the user's screen.
WWW service: WWW service adopts client / server working mode. It is based on Hypertext Markup Language HTML and Hypertext Transfer Protocol HTTP, providing users with an information browsing system for users. In WWW service systems, information resources are paged (Also known as web page or web page) is stored in the server (commonly referred to as a Web site), which use hypertext to organize information, connect one page information to another page through the link, which is linked to each other. The page information can be placed on the same host or on a different host. The link information of the page is maintained by the unified resource locator URL, and the user issues a request to the WWW server through the client application, ie the browser. The server returns to the client according to the request content of the client, and the browser explains it after receiving the page, eventually will eventually be mapped. Wen. Sounded picture to the user .a) Security Policy: Safety Policy refers to a specific environment that must be complied with the rules necessary to provide a certain level of security. The security policy model includes three important components of the establishment of a security environment: majestic law. Advanced technology and strict management.
Safety threat: refers to a person. Things. Events or concepts of the confidentiality. Integrity. Integrity. Availability or legality. Some attack is a specific implementation of a threat. Security threats can be divided into Deliberate and accidental two categories. Integrable threats can be further divided into passive and active two categories.
b) Version: Computer hardware. Software has different versions in different periods, and version serial numbers can often simply reflect performance of performance.
Compiler: Tools for translating advanced language source programs into machine language target programs, two types: interpreting programs and compilers. Compiler is all translational translations of the entire source program to generate machine language Then let the computer are executed to get the calculation result. Such as the language such as Fortran.cobol.Pascal and C. The advantage of the compiler is that the execution speed is faster.
Virus: Virus is capable of modifying other programs. Infection. The modified program contains a copy of the virus program, so they can continue to infect other programs.
Asymmetrical encryption algorithm: Asymmetric encryption algorithm also known as the public key algorithm, it is characterized by two key (ie public key and private key), only two of them are used to complete encryption and decryption Process. Since the asymmetric algorithm has two keys, it is especially suitable for data encryption in the distributed system, which is widely used in the Internet. The public key is published online, and the data sender is used to encrypt data. The corresponding private key for decryption is properly kept by the receiver of the data.
) Unlabeled mode: Once the CPU is assigned to a process, it has always taken the CPU until the process you enter the blocking state due to the original language operation or wait for I / O, or the time film is used up to let the CPU, Re-execute the process schedule.
) Operating system: Operating system is a collection of program modules - they can organize and manage hardware and software resources in computer systems, reasonably organize computer workflows, execution of control programs, and provide users with a variety of services Function, making users flexibly. Convenient. Effectively use computers, enabling the entire computer system to run efficiently. The operating system has two important roles: (1) Management system. Operating system is the management of resources And arbitors, by it responsible for scheduling and distribution between resources in various programs, ensuring that various resources in the system are effectively utilized. (2) Provide the user with a good interface.
c) Super Scale (Super Scar): Multiple processing by built-in multi-pipeline line, is in a space exchange time. In the classic pentium, it is used by two integer instructions (U instruction line and V instruction line) Composed with a floating point instruction pipeline.
Superpipeline technology: The superflow wire is made by refining the water. Improve the frequency, so that one or even multiple operations are completed in a machine cycle, the essence is in time exchange space. Each integer pipeline of the classic Pentium For the four-stage water, that is, the prefetch. Decodes. Perform and write back the results. Its floating-point pipeline can be divided into eight-stage water, the top 4 is the same as the whole line, including two level floating point operations. The first level is rounded and written back to floating point operations and levels are reported.
Super Media: Super Media Technology is a typical data management technology that is a chart (network) composed of chains called nodes and represents nodes, and users can browse. Query and Modify the operation.
Super Media: When the information carrier is not limited to text, it is called hyper media.
) Hypertext Transfer Protocol: HypertextTransferProtocol is the application layer transfer protocol between WWW client and WWW server. HTTP protocol is an object-oriented protocol, in order to ensure the WWW client and WWW server Communication does not generate erriness, HTTP precisely defines the format of request packets and response packets. HTTP session process includes the following four steps: 1 Connections. 2 Request. 3 Answer (Response). 4 Close (Close).) Hypertext Concept: Summary One page is read. And hypertext is non-linear. The reader can decide which part of the content according to their own interests. From essentially, hyperthermia is more in line with human thinking. People's thinking is not always linear, Multiple things may be associated with one thing.
) Metropolitan network: MetropolitanAreanetwork is a high-speed network between wide area network and local area network. The goal of metropolitan area is to meet a large number of companies within dozens of kilometers. Many companies. LAN interconnection needs to achieve data between users. Voice. Transmission function of various information such as graphics and videos. Early metropolitan network products are mainly fiber distributed data interfaces (FDDI, FiberDistributeDataInterface).
) Program: It is composed of instruction sequences to tell the computer how to complete a specific task. Main divisions. Compilation language and advanced languages. Since the current computer does not understand human natural language, you can't use natural language to write your computer. program.
) Program concurrency: The so-called program concurrency refers to multiple programs in the computer system, macro look, these programs are advanced to forward. In single CPU environments, these concurrent execution programs are alternating in CPU Run. The concurrency of the program is concrete in two aspects: the user program is concurrently executed between the user program; the user program is concurrent between the user program and the operating system program.
Transmission medium: The transmission medium is a physical path to connect to the bifroce part of the network. It is also a carrier actually transmitted in communication. The transfer media commonly used in the network is: twisted pair. Coaxial cable. Fiber cable and wireless and satellite communication channel.
) Transfer time: The actual transmission time called the transfer time information between the disk and the memory is called transmission time.
Lips Synchronization: In the process of multimedia signal transmission, if the image is not synchronized with the language, the mouth-to-speech does not match the sound. The audience feels very uncomfortable. This synchronization between this related audio stream and video stream is called / Lip synchronization / .. Lip synchronization requires the offset between audio and video within ± 80ms, so that most viewers do not feel offset. For audio services, such as calling, allowed maximum delay is 0- 25S, the time slime should be less than 10ms, otherwise the call person thinks that the dialogue is not smooth.
d) Current Directory: The system provides users with a working directory currently being used, called the current directory.
Low-level language: In the programming, people use the machine language. Because it uses the binary code that is close to the machine hardware, it is called a low-level language.
) Email service: Email service (also known as e-mail service) is the most frequently used service on the Internet, which provides a fast. Cheap modern communication means for Internet users. Email service uses client / server working modes.
) Breakpoint: The pause point of the interrupt program is called a breakpoint when an interruption is interrupted.
Symmetrical encryption: symmetrical encryption uses a single key to encrypt data, which is characterized by small computation. The encryption efficiency is high. But such algorithms are more difficult to use on distributed systems, mainly key management difficulties, Thus the cost is high, the safety performance is not easy. The representative of this algorithm is a widely used DIGITALENCRYPTIONSTANDARD.
Pertopeer Network: In the LAN, if each computer is logically equal, there is no main roleer relationship, it is called a pertopeer network.
) Multimedia technology: It is for text. Sound. Graphics and images. Transfer. Storage and playback integration technology.
) Multi-Pentium: The so-called multimedia is based on the classic Pentium to add MMX (multimedia expansion technology) function.
) Multiple processing: refers to a multi-CPU system, which is one of the most commonly used architectures in high-speed parallel processing technology.
f) Anti-assessment: Put the machine language program /. decipher the tools for assembly language programs, called disassemblers.
Firewall: Firewall refers to a combination of a series of components set between different networks (such as trusted enterprises inner networks and untrusted public networks) or network security domain. It can be monitored. Limit. Change data across firewalls Flow, as much as possible to external shielding network inside information. Structure and health to achieve network security. The firewall is generally divided into packet filtering. Application level gateway and proxy servers.) Access control: Access Control is an authorized individual or system that restricts the information in the resource resource.
Distributed Operating System: Distributed Operating System is also interconnected by communication networks to interconnect physical distribution data processing systems or computer systems, implement information exchange and resource sharing, and collaborate completion tasks.
) Time-time system: Time system allows multiple users to use computers simultaneously online. One time-time computer system has several terminals, multiple users can send a service request to the system on the respective terminals, waiting for the processing result of the computer And decide the next step. The operating system receives the command of each user, and the user's service request is handled by the time slice rotation, ie, according to certain order to each user to assign a CPU time, and perform each process. For each user In terms of /. Exclusive /. The entire computer system. Computer system with this feature is called a timing system.
Branch prediction: When running in the pipeline, the predecessible instruction always wants to prefethe it exactly the processor will execute. When the loop operation is performed, it will encounter the problem that should not be transferred. Once the transfer is successful, not Take the command to be executed after the transfer, the pipeline will be broken, which must re-tell the instruction, which affects the processing speed. To do this, a branch target bucket is built into the Pentium chip, used to dynamically predict The transfer of the program branch, thereby allowing the throughput rate of the pipeline to maintain a high level.
Service Quality: Service Quality (QoS) refers to the performance indicators of the network you see by the user and the application, such as delay. Lost and damage, corruption refers to the user-sensible. The decrease in information quality.
g) Fixed partition: means that the system divides the memory into a certain size fixed partition. When the job applies for memory, the system selects an appropriate partition and loads the memory operation. Since the partition size is fixed in advance, it can be accommodated The size of the job is limited, and some storage space is wasted when the address space of the user job is less than the storage space of the partition.
Fault: The fault is a large number or serious error requires the exception of repair.
) Fault management: Trouble management is the process of positioning issues or faults in a computer network.
) Pipe: It is an open shared file that connects two processes, dedicated to data communication between processes. The transmission process can continue to write data streams from one end of the pipe, and the receiving process can be from the pipe One end reads the data.
) WAN: WAN (WideReaNetwork) is also known as telematics. It covers geographic ranges from tens of kilometers to thousands of kilometers. WAN covers a country. Region, or across several continents to form an international remote network. The communication subnet of the WAN mainly uses packet switched technology.
h) Harvard structure: Classic Pentium has two 8KB (can be extended to 12KB) super cache, one for cache instructions, one for cache data, which greatly improves the hit rate of accessing cache, so you don't have to search the whole Memory can get the desired instructions and data. This structure that separates the instructions and data is called Harvard structure. It is of great significance for keeping the continuous flow of the pipeline.
Interoperability: Interoperability refers to the ability to access the other resource between different computer systems in the network, interoperability is implemented by high-level software.
Interconnect: Interconnection refers to at least one of the two physical networks, which provides material foundation and possibilities for data exchange of two networks, but does not guarantee two The network must be able to exchange data, which is dependent on the communication protocols of the two networks.
Interpretation: InterCommunication means that data can be exchanged between two networks.
) Assembly language: A symbolized machine language, use help notes instead of binary code. The source program written by the assembly language must be translated, translated into machine language, computer to identify and execute. This translation of assembly language source programs The tool for the machine language target program is called the assembler.
J) Hub: Hubs (HUB) is a basic connection device for a local area network. In traditional LAN, the network connection is connected to the hub through the non-shielded twisted pair and the hub, which constitutes a physical star topology. When the hub receives a The broadcast information sent by the node will forward the received data to each port, so the hub is a shared network device.
Computer Network: It is a system that is transformed into a plurality of computer systems with autonomous functions through communication facilities to achieve information exchange. Resource sharing. Interoperability and collaboration processing system. Network operating system is in its own computer operating system In accordance with the various protocol standards of the network architecture, it includes network management. Communication. Resource sharing. System security and multiple network application services operating system.) Computer network topology: Computer network topology is through the network The geometric relationship between the communication line represents the network structure, reflecting the structural relationship between the entities in the network.
Encryption: It is called another hidden form in a clear text. This transformation is called encrypted.
Encryption key: encryption algorithm and decryption algorithm are usually performed under a set of key controls, and the key used by the encryption algorithm is referred to as an encryption key.
Encryption algorithm: a set of rules employed when encrypted in plaintext is called an encryption algorithm.
Switch: The core of the switched local area network is a local area network switch, and some people call it exchanging hub. For traditional Ethernet, when the data is connected to a node in the hub, it will use broadcast mode to transfer data. To each port of the hub. Therefore, only one node is allowed to occupy a public communication channel in each time film of the Ethernet. The exchange local area network has fundamentally changed /. Shared media /. Work, it can pass Ether The network switch supports multiple concurrent connections between switch port nodes, realizing concurrent transmission between data between multi-strokes. Therefore, the switched local area network can increase network bandwidth, improve the performance and quality of service of the LAN.
) Access network: The so-called access network (AN) refers to all of the machine line devices between the switch to the user terminal.
) Access network technology: Solve the technology of end users to access the broadband network is called access network technology. Currently, it can be used as a main three categories: post and telecommunications network. Computer network and broadcast TV network.
) Structured wiring system: refers to transmission lines installed in a office building or building. This transmission line can connect all speech. Digital devices, and connect them with the telephone exchange system. Structured wiring system includes arrangement All cables and various accessories in the building, such as transfer equipment. Various user-end device interfaces and interfaces with external networks, but it does not include various swap devices. From the user's perspective, structured The wiring system is a network wiring system implemented using a standard network device that implemented in accordance with standard connection methods.
Decryption: The process of encrypting the reverse process, that is, the process of recovery from the ciphertext is referred to as decryption.
Decryption key: encryption algorithm and decryption algorithm are usually performed under a set of key controls, and the key used by the decryption algorithm is referred to as a decryption key.
Decryption algorithm: a set of rules used in ciphertext decryption is called a decryption algorithm.
Interpreter: Translate advanced language source programs into tools for machine language target programs, there are two types: interpreting programs and compilers. The interpreter is entered a source. Translate a sentence. Execute a sentence, do not form a whole target program This is like this. However, the execution speed of the explanation is slow.
) Media Access Control Method: The medium access control method refers to a method of controlling multiple nodes using a common transmission medium to transmit and receive data. STP, a twisted pair used in a STP. Shield twisted pair consisting of external protective layers. Shielding and multi-pair twisted pairs. UTP, unshielded twisted pair (UTP), one of the twisted pairs used in local area network products, non-shield twisted pair The external protective layer is composed of multi-pair twisted pair.
Process: Process is a program with a certain independent function about a running activity on a data collection. The process is a separate unit for resource allocation and scheduling. From operating system perspectives, the process can be divided into system processes and User processes. System Process Perform operating system programs to complete certain features of the operating system. The user process runs the user program directly. The priority of the system process is usually higher than the general user process. Process. Process. Data and process control blocks consist of three parts.
Process mutual exclusion: Some resources in the system are only allowed to use, which is called critical resources. The program of visiting critical resources in the process is called critical regions. Requires between processes entering the critical area Mutual exclusive relationship. In order to ensure the smooth operation of each of the concurrent processes, the process of two or more want to enter the critical regions must be mutually exclusive, the system is summarized as the principle of scheduling in the critical regions: when there is no process in the critical area, allowing A process immediately enters the critical area; if there is a process already in the critical area, other processes that require the entry into the critical regions must wait; the process enters the critical area must be met in a limited time.
Process Control Block: Process Control Block PCB, the system utilizes the PCB to describe the basic situation of the process and the process of running the process. PCB is the unique flag of the process, when the system creates a process, set a PCB for the process, reuse The PCB controls and manages the process. When the process is revoked, the system recovered its PCB. The process also died. The content of PCB can be divided into scheduling information and field information.
Process Synchronization: Process Synchronization is a direct collaborative work relationship between processes. Some process works together to complete a task. The direct interaction between processes constitutes a process synchronization.) LAN: LAN LAN, LAN, LAN Limited geographic range; LAN provides high data transmission rate (10Mbps ~ 1000Mbps). Low-error rate high-quality data transmission environment; LAN is generally all, easy to establish. Maintenance and expansion; the main technical factor of determining LAN features Network topology. Transmission medium and media access control method; from the perspective of media access control methods, local area networks can be divided into two types of shared local area networks and switched local area networks. The transfer media commonly used by local area networks are: coaxial cable. Twisted pair. Optics and Wireless communication channel.
) Deny service: refers to the normal use or management of the communication tool.
K) Variable Partition: means that the partition is established when the job is loaded, so that the size of the partition is exactly the storage space requirements. Introducing a variable partition method, making memory allocation have a large flexibility, and improves memory Utilization.
Deprivation: That is, once the priority is higher than the process of priority than the current running process priority, the process schedule is immediately performed, and the CPU is transferred immediately.
Fast Ethernet: Fast Ethernet (FasteThernet) The data transfer rate is 100Mbps, FasteThernet retains all features of the traditional 10Mbps rate Ethernet, namely the same frame format, the same media access control method CSMA / CD, the same interface and The same networking method, but only reduces Ethernet to 10NS from 100ns to 10NS. September 1995 IEEE 802 Committee officially approved the Fastethernet standard IEEE802.3U.IEE802.3U standard in LLC sublayer using IEEE802.2 standards, The CSMA / CD method is used in the MAC sub-layer, but a new physical layer standard 100Base-T is defined in the physical layer as a physical layer.
l) Routing table: Router plays an important role in the Internet, it is connected to two or more physical networks, responsible for reporting from a network receiving IP datagna, transfers to a suitable network. In the Internet, the device needs to be routed, generally uses a table-driven routing algorithm. Each device that requires routing is saved, but it is necessary to transfer IP datagrams, it will query the table, decide to put the datagram Where to send. The circuit table is the routing table. A routing table typically contains many (n, r) alarm couple, where N refers to the IP address of the destination network, R is on the network n path /. Next /. Therefore, the routing table in the router R specifies a step from the R to the destination network path, and the router does not know the full path to the destination. In order to reduce the route device in the route device Length, improve the efficiency of the routing algorithm, the N routing tables often use the purpose network address, not the destination host address. The routing table has two basic forms. One is a static routing table, and the other is a dynamic routing table.
) Router: Network layer interconnect equipment. Network layer interconnect is mainly to solve routing. Congestion control. Error handling and segmentation technology. If the network layer protocol is the same, the interconnection is mainly to solve routing problems. If the network Unlike the layer protocol, you need to use a multi-protocol router. When the network layer is interconnected with a router, the network layers of the Internet and the following layers of protocols may be the same, or may be different.
Naked Machine: There is no software supported by any software called a bare metal.
Password analysis: The process of trying to find a clear text or key is called cryptographic analysis. The password analysis process usually includes: analysis (Message material intercepted by statistics). Supplementation. Inference and confirmation steps.
m) Cipheet: It is called a ciphertext by a clear form of another concealment.
明文: The news that needs hidden is called the plaintext.
n) Memory Sharing: It refers to the same area in two or more process shared memory. The purpose is to save memory space, implement inter-process communication, and improve the utilization efficiency of memory space.
Memory Expansion: In order to improve the ability of the system running multi-channel program, and make the user not subject to the actual capacity of memory when the program can be used, it can be used as the extension of the extension as the main memory, which is used. It is memory expansion.
p) Average seek time: means that the magnetic head moves along the disk diameter to the magnetron cost of the track that needs to be read or written.
q) Gigabit Ethernet: GigabitEthernet's transmission rate is 10 times faster than fast Ethernet (FasteThernet), the data transfer rate reaches 1000Mbps.gigabitEthernet reserves all features of the traditional 10Mbps rate Ethernet (the same data frame) Format. The same media access control method. The same networking method), just reduces the transmission time of the traditional Ethernet to 1NS.L) software: is to use the user and give full play to computer performance and efficiency Program and data collective. The software can be divided into two parts: system software and application software, and system software is all programs and data for users to solve users using computers, such as operating systems. Compiler. Assembler; Application software is a program prepared to solve a particular problem.
) Software: The program is composed of procedures and related documents. The software is the bridge between the user and the computer hardware system. It reflects what the person wants to do and how to do it. This set of instruction sequences are stored in some code in memory. These instruction sequences are procedural. From the viewpoint of software engineering, software cannot simply understand is the program. Software is program and development. The sum of all documents needed to use and maintenance procedures, all the skills of all use software It belongs to the scope of software.
s) Equipment independence: When the process applies for equipment, the category of the desired device should be specified instead of specifying a specific device. The system selects an idle device in the corresponding category according to the current request and device allocation. Assigned to the application process, this is called device independence. It has two advantages: Improve device resource utilization, suppose the applicant specifies the specific device, and the specified device may be occupied, so it cannot be obtained, while other similar equipment May be idle, resource waste and wait unnecessary waiting; user program does not have to modify the program due to the change of the status of the device.
) Real memory: Real memory is the actual physical memory configured in the computer system, usually there are 3 categories: 1 memory, also known as main memory. It receives data and saves data, and can access data directly according to commands. 2 Alolvent, also It is said that it is carried out to make up for the storage space used to make up for insufficient memory capacity, which usually uses a large-capacity disk. 3 Cache. It is a high-speed small capacity memory between memory and central processing machines.
Real-time system: Real-time system is the increasingly extensive in the field of computer applications, refers to the system to respond to external events in time, and complete the processing of the event within a rigorous time range. Real-time system A specific application is used as a control device.
Authorization: Authorization refers to the process of granting access to a user. The user group or specified system process. Authorization After the user identifies its own identity, confirm what to do.
Data Transmission Rate: At the value equal to the binary ratio of the binary ratio of the data code, the unit is bits / second (bit / second), records BPS. For binary data, the data transfer rate is: S1 / T (BPS ), Where t is the time required to send each bit.
) Digital user line XDSL access technology: DSL, XDSL x Represents A / H / S / I / V / RA, etc. XDSL technology, according to upstream (user to switch) and downlink (switching to users) Whether the rate is the same as a rate symmetrical and rate asymmetric type.
Deadlock: In the multi-channel program system, each process in a set of processes is unlimited to be occupied by another process in the process, and will never release resources. This phenomenon is called the system. Lock status. The process in the deadlock state is called a deadlock process. When the system is deadlock, the number of deadlock processes is at least two.
Search Engine: The search engine is an Internet on the Internet. Its main task is to actively search for information in other WWW servers in the Internet and automatically index them, and store index content in large databases that are available for inquiry. User You can use the classification directory and query function provided by the search engine to find the information you need.
The so-called average waiting time: means that the sector that needs to be read and written is rotated to the average time spent below the head.
The so-called data transmission rate: refers to the number of bytes that can be read or written every second after the magnetic head finds the desired sector.
So-called throughput: The scale of the system efficiency is system throughput. The so-called throughput refers to the number of roads (programs) handled by the system within the unit time. If the resource utilization rate of the system is high, the unit time The effective work is more effective, the throughput is large;
) Privilege instructions: refers to instructions that only allow for the operating system, without allowing general users. These instructions such as modify the program status word. Set the interrupt mask. Start the device execute I / O operation. Set the clock. Set the interrupt vector. Qing Memory. Downtime, etc. These instructions may cause the system to fall into confusion if the user is allowed to use.
Topology: Topological is a branch of geometry, it is evolved from chart theory. Topology first abstains the entity into its size. The shape-independent point is not related to the line of the connection entity, and then research points. The relationship between the line.) Gateway: The interconnection between the transmission and the above layer protocols different networks belong to the high-level interconnection. High-level interconnection equipment. Many gateways used in high-level interconnections are the application layer gateway, It is usually referred to as ApplicationGateway. If you use the application gateway to implement two network high-level interconnections, the application layer and the following network protocols of the two networks are allowed to be different.
) NIC: NIC is an abbreviation of network interface card (NIC), which is the basic component constituting the network. On the one hand, the network is connected to the local area network, and on the other hand connects the transmission medium in the local area network.
Network security: refers to the hardware of the network system. The data in the software and its system is protected, and it will not be damaged due to accidental or malicious reasons. Changes. Less, system can be continuous. Reliable and normal operation, network service Uninterrupted. Network security is a computer science. Network technology - communication technology - Password technology - Information security technology. Application mathematics. Number of disciplines.
Network Operating System: Network Operating System (NOS) is a collection of software and protocols for network users to make network resources, providing network users, providing network users. The basic task of network operating systems is: Shield Local resources and network resources provide users with a variety of basic network service functions, complete the management of network sharing system resources, and provide security services for network systems.
Network management: Network management is a complex computer network that makes it the highest efficiency and productivity. This process usually includes data collection. Data processing. Data analysis and production Report on the management network.
w) Network Interconnection: means that it will be distributed in different geographic locations. The device is connected to constitute a larger interconnected network system to realize the sharing of Internet resources. Interconnected networks and devices can be the same type Network. Different types of networks, and equipment and systems running different network protocols.
) Network card: is one of the most commonly used cards, it is a key component of the network, also known as an adaptercard. It is inserted into the main board extension slot, on the one hand, connected to the computer, on the other aspect and transmission Cable connection. The main function is: (1) implementation of communication connection with the host bus, explaining and executes the control command for the host. (2) Implement the function of the data link layer, such as forming a data frame. Error check. Send receipt, etc. (3) Improve the function of the physical layer, such as the transmission of the transmitted signal. Saard and reception of the signal. The cache of the data and the serial parallel conversion, etc.
) Network protocol: Computer network consists of multiple interconnections, and the data and control information must be continuously exchanged between nodes. To be exchanged in an orderly manner, each node must comply with some prior approximate rules. These rules accurately specify the format and timing of the exchanged data. These rules set for network data exchange. The agreed and standards are called a network protocol (protoco1). A network protocol consists of the following three elements: (1 The syntax, that is, the structure and format of user data and control information; (2) Semantics, that is, what control information is needed, and the response to the completion of the operation; (3) Timing, that is, a detailed description of the event implementation .
Bridge: Device for data link layers. Bridge (Bridge) serves to data reception in the network interconnection. The role of address filtering and data forwarding, it is used to implement data exchange between multiple network systems. When the data link layer is interconnected with a bridge, the data link layer to which the interconnection network is allowed may be the same, or may be different.
Document: It is necessary for software development. Use and maintenance. It improves software development efficiency, ensuring the quality of the software, and guidance during software use. Help and confusion, especially in maintenance work In the documentation is an indispensable information.
) File Control Block FCB: File Control Block FCB is a data structure set by the system to manage files. Fcb is a flag existing file, which records all information required for the system management file. Fcb usually includes the following: File name , File number, user name, file physical location, file length, record size, file type, file attribute, shared instructions, file logic structure, file physical structure, date and time, last access date and time, final modification Date and time, password, save period, etc.
) File system: A set of software implemented in the operating system. The managed files and the general name of some of the data structures required to implement file management.
Wireless access network: Wireless access network refers to some or all of the transport medium connection service access node (switch) and user terminal using radio waves.
) Mrror: refers to the probability of being misalignment in the data transmission system in the data transfer system.
) Music memory: The virtual memory has two levels of meaning, one refers to the address space constituting the logical address of the user program; Second, when the memory capacity does not satisfy the user requirements, uses a combination of memory space with the outer memory space. Together with a large memory that makes the internal and external automatic scheduling method, it provides a larger access space to the user program.) Virtual storage technology: Memory expansion technology, processing memory and exemption, unified management Internal and external, providing users with a considerable virtual storage space, which is virtual storage technology.
Rotation Delay Time: Once the head reaches the specified track, you must wait for the required sector to rotate to the read / write, this time is called the delay time.
x) See Tao: First, move the head to the corresponding track or cylinder, this time is called the seek time.
Page phase out: When the memory space has been accounted for, it is necessary to eliminate a page of memory. If the page to be eliminated has been modified, you have to write this page back to Deposit, replace the new page. This process is called page elimination.
) Internet service provider: The Internet Service Provider ISP is the entry point of the user to access the Internet. Its role has two aspects. On the one hand, users provide Internet access services; on the other hand, users provide users with various types of information services, such as Email service. Information release proxy service, etc.
Y) Email Server: Email Service Adoption of Client / Server Working Mode. Email Server (Rear Reclaimed Mail Server) is the core of the Internet mail service system, the mail server is responsible for receiving the mail sent by the user, and according to the email The destination address sent, transferred to the other party's mail server; on the other hand it is responsible for receiving the mail sent from other mail servers and distributes mail into their own email according to the different recipients (referred to as mailboxes) )in.
) Original: It is a program consisting of several machine instructions to complete specific functions. The primitive is indivisible during execution, that is, once the original language is executed until it is completed, it is not allowed to be interrupted.
) Certificate authority: Certificate Authority (CA) is a third party trusted by user groups, such as government departments or financial institutions, which guarantees the effectiveness of the certificate. CA is responsible for registration certificates. Distribute the certificate, and become the information containing the certificate Remove the (reclaim) certificate after invalidation.
Interrupt: The so-called interrupt refers to a reaction that the CPU makes a response made by the system: the CPU pauses the program being executed, and automatically rotates the execution of the corresponding handler after the site, and then returns the breakpoint after processing the event. Execution is /. Interrupt /.
z) Interrupt Process: The interrupt handler for the CPU execution is called interrupt processing.
Interrupt handler: The program for processing the interrupt source is called an interrupt handler.
Interrupt Return: The process returned to breakpoints is called an interrupt return.
Interrupt mask: Interrupt shield means that the CPU does not respond to the status after the interrupt request is proposed. It is often used to prevent interruption of the interruption of the interrupt in an interrupt or to process a segment of the program that must be continuously executed. Prevent any interference from interrupt events.
Interrupt request: The request for the interrupt source to process the process is called an interrupt request.
Interrupt system: The implementation of the interrupt requires hardware and software combination, the hardware portion is called an interrupt device, and the software section is called an interrupt handler. The interrupt device and the interrupt handler are collectively referred to as an interrupt system.
Interrupt Response: The CPU has been executed, and the interrupt register is removed. If there is any interrupt request. If there is an interrupt request, the old interrupt vector unit is sent to the corresponding interrupt vector unit of the corresponding interrupt source in memory. Further, the content of the new interrupt vector unit of the corresponding interrupt source is sent to the register, form a new current program status word and instruction counter), enter the interrupt handler, which is an interrupt response.
Interrupt Response: The process of the CPU pauses the current program and rotates the response interrupt request is called an interrupt response.
Interrupt priority: At any time of computer execution, there may be several interrupts. In order to enable the system to respond and process all interrupts that occur, the system is based on the importance and urgency of the interrupt event, the hardware will be interrupted. The source is divided into several levels, called interrupt priority. If there are multiple interrupts, the hardware will first respond to the highest level of interrupt requests. For interrupts of the same priority, hardware will respond in advance in advance.
The source of the interrupt: the incident caused by the interrupt is called the interrupt source.
) Motherboard: Abbreviation motherboard or motherboard, is the main component of computer hosts. Typically, motherboard consists of 5 parts: CPU. Memory. Bus. Slot, power supply. Typically, power supply is just a socket on the motherboard, the power supply is not Plate.
Chapter II Operating System Software is to use and give a collective name of various procedures and data from computer performance and efficiency. The software is divided into system software and application software. System software is a program that all users use to solve users using computers. Application software is a program prepared to solve a particular problem. The operating system is the interface between hardware and all other software, and is the control and management center of the entire computer system. Two important roles of operating systems: 1. Manage various resources in the management system. All hardware parts are called hardware resources. Information such as procedures and data becomes software resources. 2 Provide the user with a good interface. Features of the operating system: 1 concurrency. In the computer system, there are multiple programs at the same time, macro look, these programs are advanced simultaneously. On a single CPU, these concurrent execution programs are running on the CPU. Program and developments are embodied in two aspects: concurrent execution between user programs and user programs. Concurrency between the user program and the operating system program. 2 Share. Resource sharing is the resource in operating system programs and multiple user programs shared systems. 3 random. Randomness means that the operation of the operating system is in a random environment, and a device may issue an interrupt request to the process at any time, and the system cannot know what to do when running. Computer without any software support is called bare metal. The operating system is the first layer of software expansion of the hardware. The function of the operating system: 1 Process management: Mainly processing the processor. As the system is different from the processor management method, the work processing method there is also different, such as batch processing, timing, and real-time mode. 2 Storage management: Mainly managing memory resources. When the memory is not enough, solve the memory expansion problem is the management combined with memory and existence, providing users with a capacity than the actual memory.
Multi-virtual memory, this is an important task for the storage function of the operating system. 3 file management. The information resources in the system are stored on the outer memory in the form of a file. 4 device management. Equipment management is the management of all inputs except CPU and memory in computer systems. 5 Users of users and operating systems. Classification: 1 Batch Operating System. Two Features: One is more, one is batch. Multi-channel is to accommodate multiple homework in the system, and these jobs are stored in the deposit, forming a reserve
In the sequence of sequences, the system is selected from the backup job, and the operation is selected from the backup job, and the operation is over and exits.
Running and backup jobs are running automatically by the system, thereby forming an automatic transfer continuous job stream in the system. Batch is the system
The user is not allowed to interact with his job during operation. The goal of batch system pursuit is to improve system resource utilization and automation of operating processes and operating processes. 2 minutes system. The time-time system allows multiple users to connect to the machine simultaneously. The operating system handles the service request for each user in a manner rotation. Features: Multi-course. Interactivity. Also called an interactive operating system. Independence. Timely sex. One of the main indicators of the time-time system performance is the response time, and the time from the terminal issues commands to the system and response. Usually computer systems use batch and time-time processing to serve users. Time requirements are not strong, put in the backbone approval, need frequent
Full-handed work is handled in front desk. 3 real-time system. The system can promptly respond to external events that occur, and complete the processing of the event within a rigorous time range. Real-time system as a specific
Control devices in the application are used. Divided into two categories: 1. Time control system. 2. Time information processing system. Features: Timely response and high reliability. 4 people computer operating system. PC operating system is a single-user operating system that is online interactive, which provides online interaction function and the functionality provided by the time-time system.
like. 5 network operating system. Computer networks are interconnected by communication facilities, and implementing information exchange, resource total
Enjoy, interoperability and collaborative systems. The network operating system is operated in the original computer system operation, which is developed in accordance with various protocol standards of the network architecture, which includes network management, communication, resource sharing, system security, and operating systems for multiple network application services. 6 Distributed operating system. From resource management perspective: divide the operating system into 5 main parts such as processor management, storage management, device management, file management, user and operating system interfaces. Virtue machine point of view. Users no longer use the hardware machine directly, but control and use the computer through the operating system, thereby expanding the computer to more functional, more
A convenient computer system. All functions of the operating system are called an operating system virtual machine. The hardware environment involved in the operating system: 2 privilege instructions and processor status. Privileges and non-privileged instructions. Privileges are only allowed to allow the operating system to be used without allowing general users to use instructions. The instructions of the non-privileged directive are called non-privileged instructions, and the execution of non-privileged instructions does not affect other users and systems. 3 CPU status. The CPU alternates the operating system program and user program. The status of the CPU belongs to one of the program status word PSW. Most computer systems divide the CPU execution status into homogeneous and gaze. Tannama is also called privileges, system or core states. The CPU can execute the complete set of instruction systems under homogenization. Typically, the operating system operates in homing. The genre is also called normal or user state. When the machine is in your gaze, the program can only perform non-privileged instructions. User programs can only be running, if users
The program executes the privilege instruction, and the hardware will interrupt, and the control is controlled by the operating system, and the privileged instruction is prohibited, which can prevent it.
The intentional or unintentional destruction of the house program. The only way to switch from gentle conversion is interrupted. From the perspective of the normality, it can be implemented by modifying the program status word, which will accompany this by the operating system program to the user program. 4 interrupt mechanism. The interrupt mechanism is one of the infrastructure in the modern computer system, which plays a communication network in the system to coordinate the system's various external events.
Response and processing. Interrupt is the necessary conditions for achieving multi-channel design. The interrupt is a reaction that the CPU makes a certain event that occurs in the system. Events cause interruption are called interrupt sources. The request of the interrupt source to the CPU is called an interrupt request. The pause point of the interrupted program is broken when interrupted
Breakpoint. The CPU pauses the current program to respond to the response interrupt request is called an interrupt response. The program for processing the interrupt source is called an interrupt handler. CPU
Perform the relevant interrupt handler is called interrupt processing. The process of returning breakpoint is called an interrupt return. The implementation of the interrupt implementation software and hardware is complete, the hardware part is called hardware devices, and the software part has become a software handler. The interrupt device and interrupt handler are collectively referred to as interrupt systems. Generally, the interrupt source is divided into two categories: forced interruption and voluntary interruption. The forced interrupt is not desirable, they are or happen, when can occur in advance, so running programs can be arbitrary
The location is interrupted. 2 Input Output Interrupt: This is an interrupt from channel or external device. 3 Hardware failure Interrupt 4 Clock Interrupt 5 Console Interrupt 6 Programmatic Interrupt Visualizable Interrupt is a conscious arrangement of the program, usually because the programmer is in the program, due to the service providing service, intentionally uses the intermitit instruction or The system is called, resulting in interruption, so it is also known as an intermittent interrupt. The system sets an interrupt handler for each type of interrupt. Each interrupt handler has an entry address PC and its operating environment PSW, which is called interrupt vectors, saved in the memory fixed unit. The interrupt response is to solve the discovery and acceptance of the interrupt, which is done by the interrupt device. The interrupt response is the process of the hardware to respond to the interrupt request, including the identification of the interrupt source, retains the site, and leads the interrupt handler. Every time the CPU is executed, it will go to the interrupt register and the query has no interrupt request. If there is an interrupt request, you will enter the interrupt vector.
Broken handler, this is an interrupt response. According to the importance and urgency of the interrupt event, the system will be interrupted by the hardware into several levels, called interrupt priority. Interrupt mask means that the CPU does not respond to the state after the interrupt request is proposed. It is often used to prevent interruption of interrupts in a certain interrupt or to prevent interference of any interrupt events when processing a segment that is unsearched, which must be continuously executed. Whether the CPU allows a certain type of interrupt to be determined by the interrupt mask bit in the current program status word. The shielding interrupt source is equivalent to the interrupt, the block execution executed in the interrupt state is as short as possible, otherwise the information may be lost, which will affect the system's concurrency. Interrupting Reaction Process: 1 Save the site of the interrupt program. 2 Analyze the interrupt source to determine the cause of the interrupt. 3 Turn around to perform the corresponding handler. 4 Restore the interrupted program on site and continue to perform the interrupt program. The operating system provides two types of interfaces to the user: one is used for program level, and the other is used for the job control level. 1 Program level interface. It consists of a set of system call commands. Unlike the machine instructions, the system call command is performed by the operating system core interpretation. The system call is a service-level service that the operating system is provided to the user, and the user program makes various resources to the operating system with the system call command.
Requirements and service requests. General system calls can be divided into several categories: device management classes, file management classes, process control classes, process communication classes, storage management classes. 2 work-level interface. Such interfaces are the system for users to request system services for the user, and users can use the workflow and control of this group of interface organization.
The operation of the industry. Such interfaces are divided into online interfaces and offline interfaces. 1 online interface. The online interface consists of a set of keyboard operation commands, which is a means of requesting an operating system service in an interactive manner. The job control method of the keyboard operation command is flexible, and the user can intervene in his own job according to the operation situation, but the system utilization is not high. 2 offline interface. It consists of a set of job control commands for online users. This interface is mainly used for batch mode operating systems. Its advantage is that the operation of the operation is automatically scheduling or system operator intervention, so
The system utilization is high.
The processor is the most important resource in the computer system. Multi-channel programming is the most basic, most important technique used by operating systems. Its fundamental purpose is to improve the efficiency of the entire system. Measuring the scale of system efficiency is system throughput. The so-called throughput is the number of times of the job handled in the system within the unit.
The process is a program with a certain independent function about a running movement on a data collection, and the process is a system core resource allocation and dispatch.
Independent unit. The process can be divided into two types of system processes and user processes. The priority of the system process is usually highly priority with the general user process. From a static point of view, the process is composed of procedures, data, and process control block PCB. The difference between the processes and programs is static, and the process is dynamic. One process can perform one or more programs, and a program can also constitute multiple processes. The process created becomes a child process, and the creator is called a parent process, which constitutes a process family. The concurrency and sharing of operating systems are reflected in the activity of the process. 1 concurrency. 2 Dynamics. 3 independent. 4 interact. 5 asynchronous. The process in progress can be one of the following: running, ready, waiting. The operating state is that the process has got the CPU and the state executed on the CPU. Obviously, on a single CPU system, only one process is in operation.
Row status. Ready state, is a process already has operating conditions, but since the CPU is not obtained without running the status. Waiting status, also called blocking state or blocking state. It is the state that the process is not allowed to run for a certain event. At any time, any process is in one of the three states only. In order to facilitate system control and description process, the process is defined as a specialized data structure in the operating system core, making it a process control.
The block PCB. The PCB information can be divided into two parts: dispatch information and field information. Each process has its own work storage area, and other processes do not change its content. The process is a three part of the program, data, and process control block PCB. The process queue in the system is divided into 3 categories: 1 ready queue. 2 Wait for the queue. 3 run queue. There is only one throughout the system in the stand-alone system. In fact, there is only one process in a run queue. Process synchronization is a direct collaborative work relationship between processes, and some process work together to complete a task. Indirections between processes
The role constitutes the process synchronization. Each process excludes these resources, this relationship between the process is the mutual exclusion of the process. The indirect interaction between the processes is called the mutual exclusion of the process. Some resources in the system only allow only one process to be used at a time, this resource is called critical resources. The program of visiting the critical resources in the process said
For the critical area. The system is summarized as: when there is no process in the critical area, allowing a process to enter the critical regions; if there is a process already
In critical regions, other processes that require access to critical regions must wait, the process enters the critical area must be met in a limited time. signal. Working by P and V. The primitive is a program consisting of several machine instructions to complete a specific function. The primitive is indivisible during the execution process. Advanced communication primitives, solve a large amount of information exchange issues. At present, advanced communication mechanisms include 1 message buffering communication, 2 pipe communication and 3 mailbox communication. 2 Realize information buffering communication, use to send primitives and acceptance of primitives. 3 Pipeline communication is based on a file system. The essence is to use exemption to carry out data communication, so it has the advantages of transmitting data. 4 mailbox communication. Divided into one-way mailbox and two-way mailbox.
Process control is achieved by primitives. 1. Create primitives. The control of the process is achieved by primitive. The primary task for creating a process is to establish a process control block PCB. The essence of the revoked process is to revoke the process control block PCB. 3 Undo primitive. 4 blocking primitives. 5 Wake the original language. The process schedule is the processor scheduling. 1 Record the execution status of all processes in the system. 2 According to a certain scheduling algorithm, select a process from the ready queue, ready to give it a CPU. 3 Put the CPU to the process. The process schedule is generally occurring in the case: 1 The process being executed is completed. 2 The process called the blocking block blocking primitives to block yourself and enter the wait state. 3 The process being executed calls the P primitive operation, which is blocked due to insufficient resources, or calls V primary language operation to hit the process of waiting for resources.
. 4 The time sheet is used in the minute system. When the CPU mode is a deprived, there is also a high level of the priority edge of a process in the 12 ready of the queue, causing the progress schedule. The process scheduling algorithm solves the assignment of the processor for each ready process and what time proportion is to occupy the processor. 1 Advanced first out algorithm. 2 Time slice rotation algorithm. 3 Maximum priority algorithm. Static priority. Dynamic priority.
In the multi-channel programming system, each process in a set of processes is waiting to be occupied by another process in this group and will never release it.
Resources, this phenomenon is in a deadlock state. The process of dummy is called a snivible process. Denuity is died, and there are at least two of the drenal progression. Instant
There is a walnic process, where there are at least two kinds of cultural processes take up resources. Permanent resource and temporary resources. The cause of dabin is: 3 The number of resources provided by the system is limited, and the use of each process cannot be met. 4 multi-channel programming, the process advances the order. 4 essential conditions for died: 1 mutual exclusion conditions. 2 Do not deprive conditions. 3 Partial assignment. 4 cycle waiting. Resource allocation map (note 40 pages B figure problem)
Three precautions: 2 use static resource pre-allocation, destroying "partial allocation" conditions. 3 Allow the process to deprive the resources occupied by other processes, thereby destroying the "non-deprivable" condition. 4 Using resource ordered distribution method, destroying "loop" conditions. The security status is no dirty state. When to make a deceased test, it depends mainly on the frequency of death and the number of people involved in the dinner. Dinnamon release: 1 resource deprived method. 2 Cancel process method. Basic units that can run independently than the process: threads. Each thread has a unique identifier and a thread description table. Different threads can perform the same procedure. The thread in the same process shares the memory address space of the process. The thread is the independent scheduling unit of the processor, and multiple threads can be executed concurrently. The benefits of introducing threads: 1 Create a new wire cost less time. 2 Two threads have less switching time. 3 Due to the ready-to-shared memory and files in the same process, the threads communicate with each other must call the kernel. 4 Threads can perform independently, make full use of the ability to work in parallel with peripheral devices.
Storage management is mainly managed by memory space. The memory space is divided into: system area; user area. Memory Sharing is the same area in two or more threads shared memory, and its purpose is to save memory space, implement communication between processes, improve memory
The utilization of space. Storage shared content can be the code of the program, but also data, if it is a code sharing, must be a pure code, or called "renewable program"
It does not modify itself during operation. The purpose of code sharing is to save memory. Storage protection: 1 Prevent the address base. 2 Prevent operational estimation.
Real memory: memory, deposit, cache. Music memory: 1. The address space of the logical address of the user program. 2. When the memory capacity does not satisfy the user requirements, uses a memory space with the existing space to use the exemption.
The automatic mobilization method constitutes a large memory. Address image: In order to ensure that the CPU execution program command can correctly access the storage unit correctly, you need to convert the logical address in the user program to runtime.
Physical address can be directly addressed by the machine. Divided into: static address and dynamic address. Memory Expansion: Under hardware support, the extension is used as a memory expansion part for user program. Virtual storage technology: Using memory expansion technology, the operating system handles memory and exemption, unified management inside and outside, and provides a capacity to users
Very large virtual storage space. 1 Distribution of static and other longitibular regions. The memory space is divided into a number of regions equal, each area called a page. 2 Distribution of dynamic heterogeneous partitions. The system manages these areas with idle area tables. Includes: idle area first address and idle area length. Debris: some of the scattered small space area that appears in memory. Utilization: Compact. Compact technology.
Partition management is the easiest storage management scheme that meets multi-channel operations. Partition is divided into fixed partitions and variable partitions. The base register is used to store the starting address in the memory, and the limit register is used to store the length of the user program. Single Continuous Area Storage Management Scheme: A single channel system. Page storage management. Page storage management divides memory space into a plurality of regions, each area called a physical page, sometimes referred to as a memory block or block. All physical pages of memory are numbered from 0, namely do physical page numbers or memory block numbers. The address is started from 0 in each physical page called the page. The page size is generally 2 integers. Lenovo Register (associated memory): consists of a high speed register and becomes a quick table. Quick Tables are used to store the page number of currently accessing the most frequent minority activity page. Find a quick table and lookup memory page is synchronized.
Each physical segment has a start position in memory, called the first site. Logically continuous sections are not stored in memory.
When the process is running, in a period of time, the execution of the program often presents a height of locality, including time locality and space topical. Time locality is performed once an instruction is executed, and it may be executed in the near future. Space part is to be accessed once a instruction is accessed, then the unit near it will also be accessed. The partial principle of the program is the premise of virtual storage technology introduction. The implementation principle of virtual storage is that when the process requires running, it is not loaded into memory, but part of the memory is loaded, and the other is not loaded into memory. Virtual storage management is divided into virtual page, virtual segment, virtual segment. Page phase out: When the memory space has been accounted for, it must be eliminated in a page of memory. If the page is eliminated
The face has been modified, but also write this page back to the exemption, then change to a new page. Bump is introduced by the high pages. The system specifies the upper and lower bounds of the missing page. The switching technology is: the dynamic adjustment between the process between memory space and the outer space is an effective method for mitigating memory space.
The file is an ordered sequence with a symbolic name and a set of relevant information items that have a complete set of information items. The information item is the basic unit constituting the content of the file. Read the pointer to record the read position before the file current file, pointing to the information item that will be read. The write pointer is used to record the current write location of the file, and the next information item to be written is written. Category by nature and use: system files. User files. Divided by the logical structure of the file: streaming file. Recording file. Category by saving: Temporary files. Permanent file. Archive file. Classify the physical structure of the file: sequential file. Link file. Index file. Hash file. Index sequence file. Press the way of access: sequentially access files. Random access files. Files in UNIX systems: normal files. Directory file. Special document. File system: A set of software, managed files, managed files, and some data required to implement file management
The general name of the structure. The logical structure of the file is the external organizational form of the file. 3 flow files. The basic unit is a character. Flow file is a collection of ordered characters, which is the number of characters included in the file, so called the word.
Strong file. 4 record file. The basic unit is a record. Divided into: fixed-length record files and becomes the log file. The way the file has the way is determined by the nature of the file and the case of the user. 1 Sequential access. 2 Random access. Tape is sequentially accessed. Disks are random access.
Document physical structure: 1 sequential structure. 2 link structure. 3 index structure. If it is a three-level index, the file length is maximum: 256 * 256 * 256 256 * 256 256 10
One of the biggest file system is that "by name Acquisition" file directory is an ordered collection of file control blocks. The directory file is a length fixed recording file. Most operating systems such as UNIX, DOS use multi-level catalog mechanism, called the tree directory structure. From the root catalog, there is only one path from any one non-leaf node or a tree page. The system provides users with a currently used working directory called the current directory. Directory Decomposition: Divide the directory item into: Directory item, basic directory item. Directory files are also divided into number directory files and basic directory files. File access control is embodied in three aspects of the sharing, protection and confidentiality of the file. The sharing of files is a file that allows multiple users to use together. The access control of the file is divided into two levels: 2 visitor's identification. File owner. The same group of users or collaborators of the file owner. Other users. 3 Identification of access rights. Access control tables are typically placed in a file control block.
Document operation: Open. CLOSE. READ. Write. Creat. DELETE. Method for ensuring the security of the file system is backup. 1 massive dump. 2 Incremental dumps.
Device management is the management of all inputs other than CPU and memory in computer systems. 4 Press the equipment working characteristics to: storage devices, input and output devices. 5 Classify the data organization in the device: block device, character device. 6 Classification by resource allocation: exclusive equipment. Sharing device. Virtual equipment. Dirty technology. A virtual equipment. Spooling technology is a typical virtual equipment technology. CUP is divided into control mode of external devices into: 1 interrupt processing mode. Whenever the device completes I / O operation, the interrupt request will notify the CPU and then processed. 2 cycle test mode. 3 Direct memory storage mode DMA. The DMA mode is used for the transmission of batch data between high speed devices and memory. 6 channel mode. The channel is a hardware mechanism for controlling external devices, quite a simple processor. Is implementing calculation and transmission
The basis of transderring the line. The host is implemented three levels of external devices, both channels, controllers and devices. A channel can control multiple controllers, one controller can connect to the same type of external device. The connection of the general device can be connected. The benefit is: 1 Improve system reliability. 2 Improve the parallelism of the equipment. The channel is divided into: 3 bytes multiple channels. Connect the printer, terminal, etc. low speed and medium speed devices. 4 Select the channel. Connecting a high speed device such as a disk, a tape. 5 into a group multipath. The operational control components of the channel include: 1 channel address word: CAW. 2 channel command words: CCW. 3 channel status words: CSW. Channel access memory adopts "cycle stealing" mode. Buffering is a technique commonly used in computer systems. Generally, data buffering techniques can be employed in places where data arrival speed and leaving does not match. Buffer pool. The task assigned by the device is to assign appropriate devices, controllers, and channels for the process of the application device in accordance with certain methods. Spooling is a virtual equipment technology. Its core thinking is to simulate the operation of exclusive equipment on a shared device. Enter well and output wells. In systems with channels, I / O program is called channel programs.
Access access time of the active head disks generally have three parts: 1 seek time. 2 Rotate the delay time. 3 Transfer time. Disk Optimization Scheduling Algorithm: 2 First Serial Service Disk Scheduling Algorithm FCFS. 3 minimum time priority disk scheduling algorithm SSTF. 4 scanning algorithm.
Chapter III Network Basic Concept Computer Network Formation and Development is roughly divided into the following four phases: 1 The first stage can be followed by the 1950s. 2 The second stage is an important symbol in the 1960s US APPANET and group exchange technology. 3 The third stage begins since the mid-1970s. 4 The fourth stage is the beginning of the 1990s. The hottest topic is Internet and asynchronous transmission mode ATM technology. The application of information technology and network has become an important criterion for the competitiveness of 21 world strengths and enterprises. National Information Infrastructure Construction Plan, NII is known as the information highway. Internet, Intranet and Extranet and e-commerce have become a hot spot for enterprise network research and application. The main goal of computer network establishment is to achieve sharing of computer resources. Computer resources are primarily computer hardware, software and data. We judge that the computer is or interconnected into a computer network, mainly to see if they are independent "self-government". The distributed operating system is to manage system resources in a global manner, which automatically schedules network resources for user tasks. The main difference between the distributed system and the computer network is not in their physical structure, but on the high-level software. Divided into: 1 by transmission technology. Broadcasting network. 2. Point-point network. Packet storage forwarding and routing is one of the important differences between point-point network and broadcast networks. Classification by scale: LAN, Member Network and WAN. WAN (remote network) The following features: 1 Adapt to large capacity and burst communication requirements. 2 Adapt to the requirements of the integrated business service. 3 Open equipment interface and standardized protocol. 4 Perfect Communication Service and Network Management. X. 25 network is a typical public packet switched network, which is also a communication subnet widely used in early WAN. The change is mainly three aspects: 1 The transfer medium is moving to the fiber by the original cable. More and more demonsions between more than 2 LANs are more and more strong. 3 User equipment is greatly improved. Use a simple protocol to reduce the delay of the network, and the necessary error control functions will be completed by the user equipment. This is the background generated by FR, Frame Relay technology. The main technical factors determined by the local area network are the network topology, transmission media and media access control methods. From the perspective of the local area network media control method, the local area network is divided into a shared LAN and a switched local area network. Metropolitan Network MAN is in a high-speed network between WAN and LAN. FDDI is a high-speed backbone network with fiber as a transmission medium, which can be used to interconnect local area networks and computers. Several of various metropolitan network construction programs: transmission media uses fibers, exchange contacts use IP exchange-based high-speed routing switches or ATM exchange
Machine, in the architecture, the core exchange layer is used, and the business aggregation layer and the access layer three-layer mode are used.
The topology of the computer network is mainly the topology of the communication subnet. The network topology can be divided into: 4-point-point line communication subnet. Topology of 4 o'clock. Star type, ring type, tree type, mesh type. 5 Topology of the broadcast communication subnet. Bus type, tree type, ring type, wireless communication and satellite communication type.
The transmission medium is a physical pathway that connects to the bifse between the network, and is also a carrier actually transmitted in the communication. Common transmission media: twisted pair, coaxial cable, fiber optic cable and wireless communication and satellite communication channel.
The twisted pair is composed of two, four or eight insulated wires arranged in rule spiral structures. Shield twisted pair STP and non-shielded twisted pair UTP. The shielded twisted pair consists of an external protective layer, a shield and a multi-pair twisted pair. The non-shielded twisted pair consists of an external protective layer and a multi-twisted pair. Three types of lines, four types of lines, five types. Twisted pairs are used to do a remote temperature, up to 15 km; when used for 100Mbps LAN, the maximum distance from the hub is 100 meters.
Coaxial cables are made from inner conductors, outer shielding layers, insulating layers, and external protective layers. Divided into: baseband coaxial cable and broadband coaxial cable. SLR broadband: Broadband coaxial cable can also be used only high-speed digital communication of a communication channel. The fiber optic cable is referred to as a cable. Composed of the fiber core, the optical layer and the external protective layer. In the optical fiber transmit terminal, two light sources are used: light emitting diode LEDs and injection laser diode ILD. Optical fiber transmission is divided into single mode and multimode. Different from the angle to the optical brake angle or the distribution of the multi-light wire. Single mode fiber optimal and multimode fiber.
There are two ways to spread electromagnetic waves: 1. It is spread freely in space, both wireless. 2. In limited space, both cable mode propagation. Mobile communication: Mobile communication with fixed, moving communication between moving objects. Mobile Communication Means: 1 Wireless Communication System. 2 microwave communication system. The frequency of the frequency at 100 MHz-10GHz is called a microwave signal, which corresponds to a signal wavelength of 3 m-3 cm. 3 cellular mobile communication system. The multiple access method is mainly: frequency division multiple access to the FDMA, and the time division multiple access TDMA and the code division multiple access are connected to CDMA. 4 Satellite mobile communication system. Commercial communication satellite is generally transmitted on a synchronous track that is transmitted 35900km above the equator
Two basic technical parameters describing data communication: data transfer rate and bit error rate. The data transfer rate is one of the important indicators describing the data transmission system. S = 1 / t. The relationship between the maximum data transfer rate Rmax and communication channel bandwidth b (b = f, unit is Hz) can be written as: rmax = 2 * f (bps
When transmitting data signals on the channel with randomized thermal noise, the data transmission rate Rmax and the channel bandwidth B, the signal-to-noise ratio S / N relationship is: rmax = b * log ⒉ (
1 S / N) The bit error rate is the probability of the binary code element being misaligned in the data transmission system. It is approximately equal to: PE = NE / N (divided by total) for the actual data transmission system If the transfer is not binary code element, it is calculated as a binary code element.
These rules specified for the switching of network data, the agreed and criteria are called a network protocol. The protocol is divided into three parts: grammar. Semantics. Timing. The collection of computer network hierarchies and layers of protocols is defined as a computer network architecture. The hierarchy is used in the computer network, which may have the following benefits: 1 of each layer is independent of each other. 2 Flexible. 3 The layers can be achieved by the most suitable techniques, and the changes in the implementation of each layer do not affect other layers. 4 is easy to implement and maintain. 5 is conducive to promoting standardization.
The architecture standard defines a seven-layer framework of network interconnects, both ISO open system interconnect reference models. Further detail in this framework
One layer of functionality to enable interconnect, interoperability and application of interconnectivity, interoperability and application in an open system environment. The method used in the OSI standard development process is to divide the entire large and complex problem into a number of easy-to-handed small problems, which is a hierarchical body.
System structure. In OSI, a three-level abstraction, both architectural, service definition, protocol specification description. OSI seven layers: 2 Physical layer: Mainly by providing physical connections to the data link layer so that the transparent transmission bitstream. 3 Data Link Layer. A data link connection is established between the communication entity, transmitting data in units of frame, using error control, flow control method. 4 Network layer: Select the most appropriate path to the packet through the routing algorithm. 5 Transportation: Yes provide users with reliable end-to-end service, transparent transfer packets. 6 Conference Layer: Organize communication between two session processes and manage data exchange. 7 represents layer: handling in two **************************************************** *********************************************************** ***************************************
<------------------ ====== The written test portion ====== --------------- ----->
I divide the importance of the book: first, seven, eight chapters to understand (see doing notes); second, four chapters understand (understand the main knowledge points); third, five, six chapters Master (understand all the knowledge points); there is a focus on the following chapters: 2.2 Processes 2.3 Storage Management 2.4 File Management 2.5 Device Management (I have hung in this section) 3.5 Twisted pair VS coaxial cable 3.6 OSI VS TCP / IP 4.3 Ethernet 4.5 Network Technology 4.8 Network Interconnection 5.3 IP Protocol 6.4 Encryption Technology Some of the contents must be understood and mastered, if not understand, back will come down. Such as: the name of each layer of the OSI protocol and the TCP / IP protocol, various transmission media and various Ethernet parameters.
<------------------ ====== Poard the machine part ====== -------------- ------> (That is an example of the second edition of Tan Haoqiang "Edition) Important Example: Example 4.10 4.12 5.4 5.5 5.6 5.7 5.8 6.6 6.8 6.10 7.2 7.2 7.8 7.9 Important Exercises: 4.5 4.9 5.5 5.7 5.8 6.1 ~ 6.10 7.1 ~ 7.14 ===> Point 1: Use the NS flowchart when doing questions. ===> Tour: Every question is about how simple, must be called until it is correct. If the exercise 2.4 (2) I have several students can be edited, but I have to run incorrect. ===> Take 3: Every day, do five topics above, preferably in the TC2.0 environment
