GEC Plessey Semiconductors Ltd and Dutch company Music Semiconductors BV have collaborated on a Content-Addressable Memory as an alternative to a Random Access Memory, or RAM, for bridges and routers. An important function of bridges and routers is to compare incoming source and destination addresses in transmitted data against a station list – this is known as address filtering. It is generally done using a RAM device and according GEC can often cause a bottleneck on the network. The company claims that its Content-Addressable Memory, or CAM, reduces bottlenecks. The basic difference between RAM and CAM is that the RAM sequentially searches through its data to find an address location to match the incoming data whereas a CAM does a search and a match in one cycle, without going through other stored data. GEC says that a bridge with a 1Kb of RAM could theoretically have to do 1,000 searches to find the correct address and on average must have to do 500 searches and says that its method is much quicker. GEC says it is talking to Digital Equipment Corp, among others, about the concept and in the long term is considering using the idea in image processing and in ARCnet personal computer boards.
