Q. Illustrate Associative Memory?

The time required to find an item which is stored in memory can be decreased significantly if stored data can be identified for access by contents of data itself instead of by an address. A memory unit accessed by content of data is termed as associative memory or content addressable memory (CAM). This kind of memory is accessed concurrently and in parallel on the basis of data content rather than by particular location or address. When a word is written in an associative memory then no address is given. Memory is capable of finding an empty unused location to store that word. When a word is to be read from associative memory then content of the word or portion of word is specified. Memory locates all words that matches specified content as well as marks them for reading.

Due to its organization associative memory is uniquely suited to do parallel searches by data association. Furthermore searches can be done on a complete word or on a specific field within a word. An associative memory is more costly than a random access memory since every cell should have storage capability in addition of logic circuits for matching its content with an external argument. Because of this cause associative memories are used in applications where search time is extremely critical and should be very short.