Level 3 Network Technology Review Notes (Chapter 1-2) Chapter 1 Computer Basics Computer Four Tites: 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 B5 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. 7 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. Chapter 2 Operating System Software is to use and give a collective discussion of various programs 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 memory is not enough, the memory expansion problem is solved is the management combining memory and existence, providing users with a larger virtual memory larger than the actual memory, which 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. Multiple is to accommodate multiple homework in the system. These jobs are stored in the deposit, form a reserve job sequence, and the system is selected from the backup job, and runs jobs every time from the backup job according to certain scheduling principles. End and exiting the run and the backup job running are automatically implemented by the system, thereby forming an automatic transfer continuous job stream in the system. The batch is that the system is not allowed to interact between users and his jobs. 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 into the backbone approval, and jobs that require frequent interaction in the 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 systems are used as control devices in a particular application. Divided into two categories: 1. Time control system. 2. Time information processing system. Features: Timely response and high reliability. 4 people computer operating system. The personal computer operating system is a single-user operating system that online interaction, which provides online interaction functionality and the functionality provided by the scheduled system. 5 network operating system. Computer networks are interconnected by communicating facilities that are geographically dispersed with autonomous functions, implement information exchange, resource sharing, 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 hardware machines directly, but control and use computers through operating systems, thereby expanding computer-expanding computers, using more convenient computer systems. 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 the user program executes privilege instructions, hardware will interrupt, and the operating system obtains control, the privilege instruction is prohibited, which prevents the user program from intended or unintentionally destroying the system. 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 role in the system to coordinate the response and processing of various external events. 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 an interruption occurs. 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. The interrupt handler for the CPU execution 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 to run the procedure, which is or happened, when can occur in advance, so the operation program can be interrupted at any location. 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, enter the interrupt handler by switching the interrupt vector, which 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. System call is a service-level service that the operating system provides the user-supplied program, and the user program makes various resource requirements and service requests to the operating system with the system invoking commands. 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 set by the system to request system services at the job level, and users can use this set of interface organization's workflow and control operation. 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 system. It has the advantage 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 on a running movement on a data collection, and the process is a separate unit of system core resource allocation and scheduling. 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. 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 describe the process of the process, the process is defined as a special data structure in the operating system core, which is a process control 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. Indirect interaction between processes constitutes a 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 critical resources in the process is called critical regions. The system is summarized as: When there is no process in the critical regions, a process is allowed to enter the critical regions; if there is a process already in the critical regions, other processes required to enter the critical regions must wait, the process enters the critical regions Requirements 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 the V primary language to operate 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 in the process of being occupied by another process in this group and never release 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. All dirty processs have a waiting resource, of which at least two died 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 diagram with problems) Three preventive measures: 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 spaces, implement communication between processes, and improve the utilization of memory space. The storage shared content can be the code of the program, but it is data. If it is a code sharing, it must be a pure code, or called "renewable program", which 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's requirements, a method of using an exemplary automatic mobilization method is used to use a method of automatically mobilizing the memory space with the outer memory space to form a large memory. Address Image: To ensure that the CPU executive programming can access the storage unit correctly, you need to convert the logical addresses in the user program into runtime, which 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 processes the relationship between memory and exemption, and manages internal and exemption, providing users with a considerable 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 being eliminated is modified, you have to 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 that implements file unified management in the operating system, managed files, and general names for the implementation of some of the data structures they need. The logical structure of the file is the external organizational form of the file. 3 flow files. The basic unit is a character. The flow file is a collection of ordered characters, which is the number of characters included in the file, so it is called a character stream 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 File system The biggest feature is "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.
