Static information storage and retrieval – Associative memories – Ferroelectric cell
Reexamination Certificate
2000-06-14
2001-06-05
Hoang, Huan (Department: 2818)
Static information storage and retrieval
Associative memories
Ferroelectric cell
C365S230030, C365S230060
Reexamination Certificate
active
06243281
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to content addressable memories (CAMs), and more particularly to intra-row configurability of a CAM array.
BACKGROUND
A content addressable memory (CAM) system is a storage system that can be instructed to compare a specific pattern of comparand data with data stored in its associative CAM array. The entire CAM array, or segments thereof, is searched in parallel for a match with the comparand data. The CAM device typically includes a priority encoder to translate the highest priority matching location into a match address or CAM index.
The CAM array has rows of CAM cells that each store a number of bits of a data word. U.S. Pat. No. 5,440,715 describes a technique for expanding the width of the data words beyond that of a single row of CAM cells. This inter-row configurability provides flexibility in the use of the single CAM array to store data words larger than that available in a single addressable row of CAM cells.
It would be desirable to have a CAM system that includes intra-row configurability to provide additional flexibility in the use of a single CAM array to be used in multiple array configurations. Intra-row configurability is the ability to access and operate upon one or more segments of rows of CAM cells.
SUMMARY OF THE INVENTION
A method and apparatus for accessing a segment of CAM cells in an intra-row configurable CAM system is disclosed. For one embodiment, the CAM system includes a CAM array and address logic. The CAM array has a plurality of rows of CAM cells each segmented into a plurality of row segments having a plurality of CAM cells coupled to a corresponding match line segment. The address logic uniquely addresses one of the row segments in response to first configuration information, and uniquely addresses a group of the row segments in response to second configuration information. The first configuration information is indicative of a first width and depth configuration of the CAM array, and the second configuration information is indicative of a second width and depth configuration of the CAM array. The CAM system may also include data access circuitry coupled to the address logic and the CAM array to communicate data with the row segment in response to the first configuration information, and to communicate data with the group of row segments in response to the second configuration information. The data access circuitry may include a read circuit and a write circuit.
Other objects, features, and advantages of the present invention will be apparent from the accompanying drawings and from the detailed description that follows below.
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Blakely & Sokoloff, Taylor & Zafman
Hoang Huan
NetLogic Microsystems, Inc.
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