ted information, which consists of the user's privileges. A CAM can thus operate as a data-parallel or single instruction/ multiple data (SIMD) processor.
             CAM can be used to accelerate any application ranging from LANs, database management, file-storage management, and table look up to pattern recognition, artificial intelligence, fully associative and processor-specific cache memories, to disk cache memories. Although CAM has many applications, it's particularly well suited to performing search operations. In each one of these applications the user may not know the addresses of words that have particular pieces of information stored within a specific portion of the word length.
             Associative processing using content addressable memories has its modern antecedent in a thought experiment proposed by Vannevar Bush in 1945. Bush envisioned a database machine called MEMEX that would help people cope with the ever-growing body of general knowledge by storing textual information and retrieving it. Twelve years later, Slade and McMahon succeeded in taking the first step toward creating an electronic digital associative memory. In their system called the Crytron Catalog Memory, a pattern of bits was input in parallel to the memory and an output line indicated whether a match was found. The Cryotron Catalog Memory could tell the user whether a pattern was found in memory but could not return associated information. In the sixties and seventies, interest in content addressable memory grew rapidly with many designs being proposed and built. All of the designs in this period let users query the memory for an exact match to a broadcast value called the comparand.
             A basic CAM element consists of input data, a storage location, and a comparator.
             The general structure of a CAM is shown in Figure 1. It includes a set of words, each consisting of a number of bits. It is common for such a memory to have very large word sizes, often 100...