Modified Set Associatne Tlb

Virtual memory is supported In almost all modern computer systems [10]. In 1959, Kilburn et al. [8] introduced the concept of a one-level store�, known now as virtual memory, to allow larger programs than available physical memory. Since then, a number of new mechanisms have been created to utilize the advantages of virtual memory to benefit the computer systems. One of these techniques is paging. In a paging scheme, physical memory is broken into fixed sized blocks called frames, logical memory is also broken into blocks of the same size called pages. Every address generated by the CPU is divided into two parts: page number and page offset. We locate pages by using a full table called a page table that contains the base address of each page in physical memory. Since the page tables are stored in main memory, every memory access by a program can take at Ieast twice as long: one memory access to obtain the physical address and another access to get the data. Since most of the references exhibit both temporal and spatial locality, modern machines include a special cache that keeps track of recently used translations. This special address translation cache is called Translation-Lookaside Buffer (TLB) [6]