Patent US 3,949,368

A system for automatically maintaining a record for an order of data priority of data stored in locations of an associative memory which compares the data stored in the locations with newly received data to generate a comparison output and where the order of priority is based on usage of data, comprising a read only memory a bit configuration reflecting an algorithm, connected from the associative memory for generating a first set of signals defining the least recently used location of the associative memory and for generating a second set of signals defining the order of word priority in terms of the associative memory locations, and a storage unit for receiving the second set of signals for subsequent feedback to the read only memory for re-defining the word priority as effected by newly received data.