Silicon-on-sapphire complementary MOS circuits for high speed associative memory

Abstract

The utility of associative memory in a wide variety of information handling systems has been long recognized and in the early 1950's such memory systems were proposed for implementation through cryotron logic and storage arrays. Cryogenic element technology afforded the ingredient of compatible logic and memory within a basic cell, a requirement essential to the practical realization of associative memories. To date, such an approach has not been successful due mainly to processing difficulties connected with thin film elements operating in a liquid helium environment. Other approaches, involving the use of multi-apertured magnetic elements, have been proposed and implemented, but the resultant cost was prohibitive due to complexities of peripheral electronics as well as the magnetic storage element itself. Furthermore, systems of this type have relatively long parallel search times (~ 10 μsecs) especially if access is on a serial-by-bit basis. These considerations have seriously limited the applicability of associative concepts in all forms of data processing and have resulted in a situation where system designers do not consider associative memory as a solution to a given problem in spite of many obvious advantages in applications such as sorting, merging, pattern recognition, and most recently, memory allocation in time shared computers.