Editing Content-addressable memory (section)

==Semiconductor implementations==
[[File:Binary CAM cell schematic.jpg|thumb|CMOS binary CAM Cell consisting of a 6T SRAM cell plus 4 comparison transistors. When the data on the search lines (SL) differs from the data stored in the cell through the bit lines (BL), the match line (ML) will be pulled low to indicate a mismatch. If none of the cells on a match line indicate a mismatched bit, the match line will remain high at the precharge level to indicate a word match. Both search lines can be held at logic '0' as a don't care search condition. Search lines and bit lines can be merged into a single pair of data lines.]]
CAM is much faster than RAM in data search applications. There are cost disadvantages to CAM, however.  Unlike a RAM [[integrated circuit|chip]], which has simple storage cells, each individual memory [[bit]] in a fully parallel CAM must have its own associated comparison circuit to detect a match between the stored bit and the input bit.  Additionally, match outputs from each cell in the data word must be combined to yield a complete data word match signal.  The additional circuitry increases the physical size and manufacturing cost of the CAM chip. The extra circuitry also increases power dissipation since every comparison circuit is active on every clock cycle.  Consequently, CAM is used only in specialized applications where searching speed cannot be accomplished using a less costly method. One successful early implementation was a General Purpose Associative Processor IC and System.<ref>{{Cite journal |title=A general-purpose CMOS associative processor IC and system |journal=IEEE Micro |date=December 1992 |volume=12 |issue=6 |pages=68–78 |doi=10.1109/40.180249|s2cid=206432751 |url=https://ieeexplore.ieee.org/document/180249 |last1=Stormon |first1=C. D. |last2=Troullinos |first2=N. B. |last3=Saleh |first3=E. M. |last4=Chavan |first4=A. V. |last5=Brule |first5=M. R. |last6=Oldfield |first6=J. V.|url-access=subscription }}</ref>

In the early 2000s several semiconductor companies including [[Cypress Semiconductor|Cypress]], [[Integrated Device Technology|IDT]], [[NetLogic Microsystems|Netlogic]], Sibercore,<ref>{{Cite web|title=Sibercore Technologies - Silicon Solutions for Cyberspace|url=http://sibercore.com/|archive-url=https://web.archive.org/web/20030419174703/http://sibercore.com/|archive-date=2003-04-19|url-status=live}}</ref> and [[MOSAID]] introduced CAM products targeting networking applications. These products were labelled Network Search Engines (NSE), Network Search Accelerators (NSA), and Knowledge-based Processors (KBP) but were essentially CAM with specialized interfaces and features optimized for networking. Currently [[Broadcom]] offers several families of KBPs.<ref>{{Cite web|title=16nm Heterogeneous Knowledge-Based Processors (KBPs)|url=https://www.broadcom.com/products/embedded-and-networking-processors/knowledge-based/bcm15k|url-status=live|archive-url=https://web.archive.org/web/20170519075444/https://www.broadcom.com/products/embedded-and-networking-processors/knowledge-based/bcm15k |archive-date=2017-05-19 }}</ref>