<P> Modern processors have multiple interacting on - chip caches . The operation of a particular cache can be completely specified by the cache size, the cache block size, the number of blocks in a set, the cache set replacement policy, and the cache write policy (write - through or write - back). </P> <P> While all of the cache blocks in a particular cache are the same size and have the same associativity, typically the "lower - level" caches (called Level 1 cache) have a smaller number of blocks, smaller block size, and fewer blocks in a set, but have very short access times . "Higher - level" caches (i.e. Level 2 and above) have progressively larger numbers of blocks, larger block size, more blocks in a set, and relatively longer access times, but are still much faster than main memory . </P> <P> Cache entry replacement policy is determined by a cache algorithm selected to be implemented by the processor designers . In some cases, multiple algorithms are provided for different kinds of work loads . </P> <P> Pipelined CPUs access memory from multiple points in the pipeline: instruction fetch, virtual - to - physical address translation, and data fetch (see classic RISC pipeline). The natural design is to use different physical caches for each of these points, so that no one physical resource has to be scheduled to service two points in the pipeline . Thus the pipeline naturally ends up with at least three separate caches (instruction, TLB, and data), each specialized to its particular role . </P>

How does a neural network differ from the central processing unit of a computer