Associative Memory

Associative Memory

• Also called as Content-addressable memory (CAM), associative storage, or associative array
• Content-addressed or associative memory refers to a memory organization in which the memory is accessed by its content (as opposed to an explicit address).
• It is a special type of computer memory used in certain very high speed searching applications.
• In standard computer memory (random access memory or RAM) the user supplies a memory address and the RAM returns the data word stored at that address.
• In CAM the user supplies a data word and then CAM searches its entire memory to see if that data word is stored anywhere in it. If the data word is found, the CAM returns a list of one or more storage addresses where the word was found.
• CAM is designed to search its entire memory in a single operation.
• It is much faster than RAM in virtually all search applications.
• An associative memory is more expensive than RAM, as each cell must have storage capability as well as  logic circuits for matching its content with an external argument.
• Associative memories are used in applications where the search time is very critical and short.
• Associative memories are expensive compared to RAMs because of the add logic associated with each cell.