Content-addressable memory with soft-match capability
US5053991A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 6, 1989 |
| Grant date | Oct 1, 1991 |
| Priority date | — |
| Expiry date | Oct 6, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F16/90339
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
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) ca…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.