BACKGROUND o Program must be brought(from disk)into memory and placed within a process for it to be run o Main memory and registers are only storage CPU can access directly o Register access in one CPU clock (or less) o Main memory can take many cycles o Cache sits between main memory and CPU registers o Protection of memory required to ensure correct operationBACKGROUND  Program must be brought (from disk) into memory and placed within a process for it to be run  Main memory and registers are only storage CPU can access directly  Register access in one CPU clock (or less)  Main memory can take many cycles  Cache sits between main memory and CPU registers  Protection of memory required to ensure correct operation