Research Of The Computer Adapter And Students' Terminal Subsystem In Pure Digital Audio System

Varieties of educational methods have been emerged with the development of science and technology, and multimedia is especially prominent as one of them. Multimedia system is able to offer ideological teaching environment where student and teacher are able to communicate more conveniently, also it can improve the efficiency of both teaching and studying. The audio system is an important part of multimedia system, which can assist student to improve their ability of speaking and listening of foreign language. Most of the related multimedia products are analogue systems; also they have many inevitable shortages in compare to the digital products. Ttherefore, the development of Pure Digital Audio system has very important theoretical and practical value.The Pure Digital Audio system in this paper has been divided into five parts by functions: computer and managing subsystem, computer adapter, primary exchange, second exchange and students' terminal subsystem. Students' terminal subsystem offers a platform for students to communicate within system. The managing subsystem is the heart of this system. It is a program on computer, which analyses the request of each students' terminal subsystem and responds correctly and quickly. Also the other three parts have formed a data transmission channel between the managing subsystem and students' terminal subsystem. The Pure Digital Audio system is developed by a good coordination of teamwork. Author of this paper has primarily taken charge of computer adapter and students' terminal subsystem.The primary work of this paper is as follows:(1) The author has taken part in the project formulation and devices selection, then independently designed, adjusted and debugged the hardware and software of both computer adapter and students' terminal subsystem. Also, the author has accomplished the whole system with other group members, which can be used for in-class teaching, self-studying, class testing etc.(2) A special ISA adapter has been designed to transmit data with the baud rate of 16 Mbps by means of 16-bit port. Subsequently the author has developed the built-up connection circuit from PCI bus to ISA bus, and then designed the PCI adapter for this system.(3) The author has analyzed the characters of A-law PCM code, and found someregularities in it. The interconnection of A-law PCM code and linear PCM code was carried out by means of software in MPU or hardware in High Density Programmable Logic Device.This Pure Digital Audio system has been conducted in foreign language education successfully, and it has important extensive value when teaching in courses of similar fields or self-studying.