Content-addressable memory system capable of fully parallel magnitude comparisons
First Claim
1. A content-addresable memory including means for storing a plurality of words, each of said words comprising a plurality of data subfields, each of said data subfields being divided into a plurality of data bits,means for providing an input field comprising a plurality of input subfields matching some of said data subfields, and each said input subfield divided into input bits so as to have a one-to-one bit correspondence to the said data bits in said data subfields in said words,query means for simultaneously comparing said plurality of input subfields to all said words, with simultaneous subfield comparisons such that each said data subfield is compared to its corresponding said input subfield, and generation of a one bit query result for each said word which is true when all said data subfields within said word which are compared to one of said input subfields compare favorably to each corresponding said input subfield,flag memory means for storing a flag bit equal to said query result for each of said words.
4 Assignments
0 Petitions
Accused Products
Abstract
A content-addressable memory for storing a plurality of words, each word comprising a plurality of data subfields, and each data subfield comprising a plurality of data bits. Query operations simultaneously compare input data to all subfields in all words and selectably test each subfield for either equality, less-than, less-than-or-equal-to, greater-than, greater-than-or-equal-to, inequality, or don'"'"'t care. A flag memory comprising a plurality of flag bits for each word stores the results of a selectable Boolean operation performed on a set of flag bits and the query results. A mask register causes selected bit positions within words to be treated as not being present. A priority resolver finds the highest priority flag bit in a particular logic state for selecting a word for reading or writing. A content-addressable memory system composed of a plurality of content-addressable memories and an external priority resolver for selecting between content-addressable memories for reading or writing.
219 Citations
25 Claims
-
1. A content-addresable memory including means for storing a plurality of words, each of said words comprising a plurality of data subfields, each of said data subfields being divided into a plurality of data bits,
means for providing an input field comprising a plurality of input subfields matching some of said data subfields, and each said input subfield divided into input bits so as to have a one-to-one bit correspondence to the said data bits in said data subfields in said words, query means for simultaneously comparing said plurality of input subfields to all said words, with simultaneous subfield comparisons such that each said data subfield is compared to its corresponding said input subfield, and generation of a one bit query result for each said word which is true when all said data subfields within said word which are compared to one of said input subfields compare favorably to each corresponding said input subfield, flag memory means for storing a flag bit equal to said query result for each of said words.
Specification