摘要 : State-of-the-art design of communication networks is characterized by the ubiquitous appearance of computer technology. All significant message-switching systems designed in the last ten years have used stored program processor co... 展开 State-of-the-art design of communication networks is characterized by the ubiquitous appearance of computer technology. All significant message-switching systems designed in the last ten years have used stored program processor controlled switching. Sophisticated terminals are also using small computers, and are otherwise dominated by the use of digital electronics. The telecommunications technological environment is characterized by rapidly changing cost-benefit relationships among system components, due primarily to the cost decline of digital logic. 收起