This research report gives a general description of virtual memory systems. The mechanisms and policies and their effect on the operation and efficiency of virtual memory are explained. A virtual memory using a real time virtual address decoder, to decode a 32 bits of virtual address for the secondary memory to obtain the primary address location discussed. The decoder is developed with the use of associative or content-addressable memories. Replacement algorithms, used for selecting the pages of the main memory to be replaced, are described. The hardware implementation of the least recently used and least often used replacement policies using associative memories is presented
