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:
Oct. 01, 1991
Filed:
Oct. 06, 1989
James L Burrows, Merrimack, NH (US);
Sanders Associates, Inc., Nashua, NH (US);
Abstract
Each word location (18-0, 18-1, 18-255) in a content-addressable memory has a tally circuit (24-0, 24-1, 24-255) associated with it. A data word on data lines (12) is compared simultaneously with the words in all of the word locations, and the tally circuit associated with each location counts the number of matches between the key word in that location and the data word represented by the signals on the data line. The tally circuits apply tally signals representing the number of matching bits in their respective word locations to comparison circuits (28-1, 28-255), each of which compares the tally output from its associated tally circuit with the output from a previous comparison circuit and forwards the higher of the two to the next comparison circuit. Each comparison circuit also applies to a priority encoder (32) an output that indicates whether the associated tally circuit has generated a tally signal representing a tally greater than that from all previious locations. The encoder circuit (32) encodes the address of the location having the highest tally, and the output of the last comparison represents the highest tally is. In this manner, the content-addressable memory (10) can be addressed by the closest match, not only by an exact match.