第二篇(第五章).ppt

Chapter 4-6. Modern IT Architecture Chapter4. Desktop Systems (one computer) PC Hardware Software Systems Chapter5. Distributed Systems (many computers) Telecommunications Computer Networks and Enterprise Network Internet Chapter6. Managing Data Resource Database technology Data Warehousing, OLAP, Data Mining 纺织企业网络系统 Network is Computer.Network is System. TELECOMMUNICATIONS Communicating information VIA electronic means over some distance Service provided by telecom companies: telephone, mobile phone, wireless transmission, data communication, Cable TV, satellite, ………….. * Telecommunication Concept Data Communication is the electronic collection, exchange, and processing of data or information, including text, picture, voice, and other information that is digitally coded and intelligible to a variety of electronic machines. Which Business Tasks are Requiring Telecommunications Online inquiry/response Eg., POS.,airline reservation,credit checking,.., Requirement: response within seconds Online text retrieve, eg., library systems Requirement: High volume real time response Messages, eg. Email Requirement: short response/delivery time …… …… Electronic Signals Telecommunication media can carry two basic type of signals, ANALOG(模拟) and DIGITAL（数字）. Analog signals are continuous waves that “carry” information by altering the characteristics ( amplitude振幅 and frequency频率) of the wave. Digital signals are discrete on-off pulses that convey information in terms of 1s and 0s, just like the CPU in computer. Telecommunication System Computers Terminals (Input / Output Devices) Communications Channels (media) Processors (Modems调制解调器; multiplexers(多路转接器;Internetwork Processors) Network software PROTOCOL（协议） Rule and procedures to govern transmission between component in a network. * Computers Host computer (Mainframe computer) Front-end processor (Midrange computer) Network Server (Microcomputer) Terminals Personal computers Network computers