What are the typical computer network architecture
OSI seven-layer model, TCP / IP four-layer model, five-layer architecture
OSI seven-layer model
OSI seven-layer protocol model is: application layer (Application), the representation layer (Presentation), the session layer (Session, Transport, Network, DataLink, Physical). Session), Transport, Network, DataLink, and Physical.
TCP/IP four-layer model
TCP/IP is a four-layer architecture, including: application layer, transport layer, inter-network layer and network interface layer. In essence, there are only the upper three layers, and there is nothing specific about the network interface layer.
Three, five-layer architecture
Five-layer architecture includes: application layer, transportation layer, network layer, data link layer and physical layer. Five-layer protocol is only a combination of OSI and TCP/IP, the actual application or TCP/IP four-layer structure. For convenience you can refer to the next two layers as the network interface layer.
The world’s first network architecture is the United States IBM in 1974, it took the name of the system network architecture SNA (SystemNetworkArchitecture). Any device that follows SNA is called SNA device. These SNA devices can be easily interconnected. Since then, many companies have built their own network architectures, which are similar and use hierarchical techniques.
What are the components of a computer?
The computer has two parts, software and hardware system. There are many hardware, such as motherboard, cpu, memory, hard disk, monitor, video card, sound card, optical drive, floppy drive, keyboard, mouse, chassis; software is divided into system software and application software.
February 1946, the United States developed the first successful computer eniac, in June, von Neumann put forward the idea of stored procedures, laid the foundation for the structure of modern computers: the computer is composed of input devices, output devices, operators, memories and controllers of the five major components, which is the basic hardware organization of the computer. Usually the operator and the controller called cpu, the cpu and the main memory (memory) called the host, the input and output devices and external memory called external devices, referred to as io devices.
The software system of a computer is composed of system software and application software.
System software is a set of basic software to ensure the efficient and correct operation of the computer, usually as a system resource provided to the user. Mainly: 1, the operating system: responsible for managing and controlling the computer’s hardware resources, software resources and the operation of the program, is the interface between the user and the computer, provides a software development environment and operating environment. 2, the language processing program: because computer hardware can only recognize and process the machine language expressed in digital code, so any other language written programs must be translated into machine language program after To be executed by the computer hardware to complete the translation of the program is the language processing program. 3, database management system: in the information processing, intelligence retrieval and a variety of management systems, the computer needs to deal with a large number of data, retrieval and establishment of a variety of forms, these data and forms are organized according to a certain law, it became a database. In order to facilitate the user according to the need to establish, query, display, modify the contents of the database, output and print all kinds of forms, there must be a database management system. 4, distributed software: mainly used for distributed computing environment, management of distributed computing resources, control the operation of distributed programs and provide distributed program development and design tools, etc. 5, the network software system: the computer is a part of the life of people. A part of people’s lives, such as sending and receiving e-mail, online shopping, etc., network software system is used to support these network activities and digital communication system software. Including network operating systems, communication software, network protocol software, network applications, etc. 6, a variety of service programs: a perfect computer system is often configured with a number of service programs, mainly to help users to use and maintain the computer, to provide the service means to prepare the program. For example, installation programs, editing programs, diagnostic programs, etc., there are a number of general-purpose software that can be called, such as word, excel, etc. can also be considered this type of program.
Application software refers to the user to solve certain applications in the field of various types of problems and the development of the program, this application program is diverse, extremely rich, many general-purpose programs can be composed of different packages according to its function, for users to download and use!
System architecture of computers
System architecture of computers: stand-alone systems, distributed systems, cluster systems, cloud computing systems, etc.
The system structure of a computer is the external characteristics of the computer as seen by the machine language programmer or compiler writer of the computer. The so-called external characteristics of the conceptual structure and functional characteristics of the computer, mainly to study the basic working principles of computer systems, as well as in the hardware, software interface division of the trade-off strategy, to establish a complete, systematic computer hardware and software overall concept.
ComputerArchitecture, also known as the computer architecture, is composed of the external characteristics of the computer structure, internal characteristics, micro-external characteristics.
The classical definition of computer system architecture refers to the structure of the machine language machine level of the multi-level hierarchy of a computer system, which is the main interface between software and hardware/firmware, and the interface structure and functionality that should be present for a machine language target program generated from the translation of a machine language program, an assembly language source program, and a high-level language source program to run correctly on a machine.
What does computer system architecture refer to? Is it the exterior of a computer? Or does it refer to the structure of the boards inside a computer? Neither, then what is it? The architecture of a computer system is the external characteristics of the computer as seen by the machine language programmer or compiler.
The external properties are the conceptual structure and functional properties of the computer. To use an inappropriate analogy, an animal, for example, what does its “system structure” mean? Its conceptual structure and functional properties.
It is equivalent to the composition of the animal’s organs and their functional characteristics, such as the chicken has a stomach, the stomach can digest food. As to what shape the chicken’s stomach is, what the chicken’s stomach consists of is not a matter of “system structure” research.
The main features of the von Neumann computer were: the way programs were stored; instructions were executed serially and centrally controlled by a controller; the memory was a one-dimensional linear space with a fixed length of cells; a low-level machine language was used, and the data were expressed in binary; and a single-processor architecture centered on the operator.
The improved von Neumann computer evolved from being operator-centered to being memory-centered. In terms of system structure, the main thing is to improve the performance of the computer system through a variety of parallel processing means.