cache (cache memory) A type of memory that is used in high-performance systems, inserted between the processor and memory proper. The memory hierarchy on a system contains registers in the processor, which are the highest-speed storage, and, at a slightly lower level of accessibility, the contents of the main memory. The cache is intended to reduce the discrepancy in accessibility between these two types of unit, and functions by holding small regions that map the contents of main memory. The formal behavior of the cache corresponds closely to that of the working set in a paging system.

Some magnetic disk controllers have a cache. The working of the cache is not visible to the main CPU, but again provides a mapping of the current contents of part of the disk units in order to provide improved performance.

Some magnetic tape units have built-in cache memory. In this case the aim is to allow a streaming tape transport to emulate the behavior of a (more expensive) start-stop unit so that it can be attached to a system designed to support only the latter without substantial software modification. The arrangement was introduced by Cipher in the early 1980s.

See also disk cache.

cache / kash/ • n. a collection of items of the same type stored in a hidden or inaccessible place: an arms cache a cache of gold coins. ∎  a hidden or inaccessible storage place for valuables, provisions, or ammunition. ∎  (also cache memory) Comput. an auxiliary memory from which high-speed retrieval is possible.• v. [tr.] store away in hiding or for future use. ∎  Comput. store (data) in a cache memory. ∎  Comput. provide (hardware) with a cache memory.

Cache

a hiding place, hence, the items hidden; the stores of provisions hidden by travellers or explorers on their journeys.

Examples: cache of green boughs, 1866; of jewels; of meat, 1865; of a barrel of pork, 1842; of provisions; of silver, 1860; of treasure.

cache XIX. — F., f. cacher hide (see next).