The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 07, 1999
Filed:
Apr. 17, 1997
Robert J Simcoe, Westboro, MA (US);
Cabletron Systems, Inc., Rochester, NH (US);
Abstract
A content addressable memory (CAM) structure, and a method for its use, wherein data items of different selected lengths stored in the CAM may be located by matching sequences of CAM data words with sequences of input data words. Extension bits associated with each CAM data word control a sequence of comparison cycles to permit an input data item to be compared simultaneously with multiple input data items of the same length stored in the CAM structure. The CAM structure can be used without modification to store data items of various selected lengths. A begin bit associated with each CAM data word is used to mark the beginning of each stored data item and, in an exact match mode of operation, a global line is used to mark the beginning of an input data item. Match logic associated with each CAM data word generates a match till now signal in each comparison cycle, and the signal is propagated to the end of the data item if an exact match is detected. The exact match and match till now signals are used to generate various global match indications in the CAM structure. The same CAM structure can also be operated in a sliding match mode in which each stored data item is compared with every possible sequence of input data words.