TABLE OF CONTENTS So, we can never reach a Final Understanding of anything because it will change as we develop understanding. If we did reach a Final Understanding, simultaneously the "subject" would have changed, rendering our understanding as past tense .
Robert Fripp
A cache (also called "look-aside" [Bloom et al. 1962] or "slave memory" [Wilkes 1965]) can speed up accesses to all manners of storage devices, including tape drives, disk drives, main memory, servers on the network (e.g., web servers are a type of storage device), and even other caches. It works on the principle of locality of reference, the tendency of applications to reference a predictably small amount of data within a given window of time [Belady 1966, Denning 1970]. Any storage device can be characterized by its access time and cost per bit, where faster storage technologies tend to have a lower access time and cost more per bit than slower technologies. A cache fronting a given storage device would be built from a technology that is faster than that of the storage device in question; the cache technology would typically cost more on a per-bit basis, but to be effective the cache would only need to be large enough to hold the application's working set the set of instructions and/or data...
