In the 1970s, large time-sharing systems were replaced by smaller microcomputer systems. The microcomputer system adopts time-sharing system in a small range. Therefore, it was not until the invention of PC in the 1970s that today's network concept came into being.
On the basis of time-sharing computer system, remote terminal computer system provides computer resources to many geographically dispersed remote terminal users through modems and PSTN. Although this is not a real computer network system, it is the first attempt to combine computers with communication systems. Remote end users seem to have felt the taste of using "computer network".
On the basis of remote terminal computer system, people began to study the interconnection between computers through existing communication systems such as PSTN. In order to make the communication connection between computers reliable, a hierarchical communication system and the corresponding network communication protocol were established, so the computer network with the main purpose of resource sharing was born. Because of the data exchange ability between computers in the network, it provides the ability of computers to work together in a wider range and realize distributed processing or even parallel processing, and the communication ability of information exchange between networked users directly through computer networks is greatly enhanced.
196965438+February, the predecessor of the internet, the ARPA network in the United States, was put into operation, which marked the rise of the computer network that we often say. This computer internet system is a packet-switched network. Packet switching technology fundamentally changed the concept, structure and network design of computer networks, and laid the foundation for later computer networks.
In the early 1980s, with the popularization of PC personal computer applications, the demand for PC networking increased, and various computer local area networks based on PC interconnection were launched one after another. The typical structure of microcomputer LAN system in this period is the shared file server structure on the shared media communication network platform, that is, all networked PCs are equipped with a dedicated and shareable network file server. PC is a "small but complete" small computer. Each PC user's main task is still running on his own PC, and only when he needs to access the shared disk file can he access the file server through the network, which embodies the cooperative work between computers in the computer network. Because of the use of high-speed transmission media such as coaxial cable and optical fiber, which are much higher than PSTN, the data rate and efficiency of PC accessing shared resources on the Internet are greatly improved. This microcomputer network based on file server divides the computers in the network: PC is user-oriented and microcomputer server is dedicated to providing shared file resources. So it is actually a client/server model.
The computer network system is a very complicated system, and the communication between computers involves many complicated technical problems. In order to realize computer network communication, computer network adopts layered method to solve network technical problems. However, due to the existence of different levels of network system architecture, it is difficult to realize the interconnection between its products. Therefore, the International Organization for Standardization (ISO) officially promulgated the OSI international standard "Basic Reference Model of Open Systems Interconnection" in 1984, which standardized the computer network architecture.
In 1990s, computer technology, communication technology and computer network technology based on computer and network technology developed rapidly. Especially after the United States 1993 announced the establishment of national information infrastructure NII, many countries in the world have formulated and established their own NII, which greatly promoted the development of computer network technology and made computer networks enter a brand-new stage. At present, the global high-speed computer internet with the United States as the core has been formed, and the Internet has become the most important and greatest treasure house of human knowledge. The U.S. government began to develop faster and more reliable 2(Internet 2 and Next Generation Internet at 1996 and 1997 respectively. It can be said that network interconnection and high-speed computer network are becoming the development direction of the latest generation of computer networks.