高等计算机系统机构.ppt

iPad: Apple’s profit comes from margins in hardware The principle of locality states that programs access a relatively small portion of the address space at any instant of time. This is kind of like in real life, we all have a lot of friends. But at any given time most of us can only keep in touch with a small group of them. There are two different types of locality: Temporal and Spatial. Temporal locality is the locality in time which says if an item is referenced, it will tend to be referenced again soon. This is like saying if you just talk to one of your friends, it is likely that you will talk to him or her again soon. This makes sense. For example, if you just have lunch with a friend, you may say, let’s go to the ball game this Sunday. So you will talk to him again soon. Spatial locality is the locality in space. It says if an item is referenced, items whose addresses are close by tend to be referenced soon. Once again, using our analogy. We can usually divide our friends into groups. Like friends from high school, friends from work, friends from home. Let’s say you just talk to one of your friends from high school and she may say something like: “So did you hear so and so just won the lottery.” You probably will say NO, I better give him a call and find out more. So this is an example of spatial locality. You just talked to a friend from your high school days. As a result, you end up talking to another high school friend. Or at least in this case, you hope he still remember you are his friend. +3 = 10 min. (X:50) Von Neumann (1903-1957) was born in Budapest. Great quantities of work in set theory to quantum physics. Celebrated for his theory of games and its application to economics. Report was the formal specification of EDVAC. Before that the documentation on ENIAC or EDVAC was non-existent. Von Neumann devised a mathematical logical notation which expressed fundamental ideas of the fetch-execute-decode loop. Five major components: Arithm