A 2 K-word dictionary search processor (DISP) LSI with an approximate word search capability

Abstract

A 2K-word dictionary search processor (DISP) LSl has been developed. The DISP LSl consists mainly of a 160-kb content addressable memory (CAM) to store keywords and a cellular automaton processor (CAP) to perform concurrent and approximate word searches against the stored keywords. This newly developed CAP performs distance calculation based on dynamic programming (DP), which is necessary in approximate word searches, through the use of an array of extremely simple processor elements. CAP hardware size is less than 1/10 of that of a conventional systolic array processor. The DISP LSI, which was fabricated using a 0.8-pm, triple-layer-AI, CMOS fabrication technology, has a die size of 13.02 x 12.51 mmz and contains about 1.2-million transistors. It operates at a clock frequency of 33 MHz with a 5-V power supply, and it typically consumes 800 mW.

A keyword match processor architecture using content addressable memory

“…The uniqueness of the KMP is in the processor element (PE) array. The PE array is similar in concept to the cellular automaton processor arrays proposed by [10,11]. The array is comprised of an n x D + 1 array of processing elements (PE) where each PE is an finite state machine that carries out the match algorithm described below.…”

“…The cellular automata methods cascade CAMs temporally and then use pointers to propagate matches from one CAM set to another [9]. Motomura et al have described an cellular automata based architecture to do dictionary search in VLSI [11]. The keywords grouped in 4 characters segments and they allow for concatenating groups to create larger keywords.…”

“…The use of content addressable memories for text search has centered around two strategies: cellular automata [12,10,11] and finite state machines [14,7]. The cellular automata methods cascade CAMs temporally and then use pointers to propagate matches from one CAM set to another [9].…”

A generic lookup cache architecture for network processing applications

“…The PE array is similar in concept to the cellular automaton processor arrays proposed by Motomura et. al [1]. To perform a search on the lookup cache, the network processor will on successive clock cycles apply each character of the key to the CAM array.…”

FPGA Based Network Intrusion Detection using Content Addressable Memories

“…The keyword match array is similar in concept to systolic processing arrays that have been proposed for approximate word search matching in CAMbased dictionaries [4]. The array is comprised of an n x 1 array of processing elements (PE) where each PE contains a register and circuitry that implements the keyword match algorithm.…”