Research And Design Of A Gigabit GAP Based On MIPS Processor

Network security becomes worse with the widely use of the Internet. The gap technology strips out all TCP/IP. This technology doesn't depend on operation systems. It disconnects internal web from the Internet at the physical layer of OSI model. By doing that, it is a solution to the design flaws, which are the foundation of firewalls. So it is widely used in many important systems. As there are some problems in the air gap products such as bad quantity manufacture, high broke-down, low exchanging rate, the Suzhou CAS IC Design Center decided to develop hardware of a gigabit GAP based on MIPS processor. The project supplies the gap for gigabit Ethernet GAP applications in inland. The project is valuable attempt to extend the MIPS processor -the Godson II applications. The project team will get some experiences in develop a GAP based on Godson II. The research of a gigabit GAP based on MIPS processor can enhance the research of the relatable OS, the development of application software. And it has realism meaning for our computer researching, for our products' performance and competition.Firstly, this paper gives an introduction to the principle of the gap technology and the GAP. Secondly, a new theory - dual-tunnel real-time switcher with cyclic buffer based on SDRAM bus was advanced, and an architecture design of gigabit GAP using this theory was given. With this, it solves the problem that the data exchanging rate is too low. It also gives a particular description of PS/2 module in BIOS, with some resource codes in MIPS GAP system. Thirdly, the paper analyzes the signal integrity in MIPS GAP high-speed board design, and it gives the solution of the signal delay, reflectibility, crosstalk and EMC problems in MIPS GAP design. Finally, it introduces the process of testing and debugging to MIPS GAP system. The data exchanging result of the system achieves satisfied performance, and meeting the gigabit Ethernet application.