| 摘要 |
A method for providing field updates through the use of a memory emulation circuit with a content addressable memory (CAM) as the intelligent portion of the emulation circuit's arbiter. CAM circuit 200 is comprised of configurable memory and is initially unprogrammed. Address requests are passed straight through multiplexer 201 to Read Only Memory (ROM) 202. As a result the data in the data location in ROM 202 that corresponds to the requested address will be output to data bus 205. If data locations in ROM 202 become defective or contain data that needs to be upgraded the circuit implements a remapping of the data location. CAM circuit 200 is programmed with direct addresses to be replaced in ROM 202. The direct addresses are paired to emulation addresses of data locations in configurable memory 203. Upgraded or substitute data is programmed into the configurable memory 203 at the paired emulation address. When address requests are received thereafter, CAM circuit 200 compares the address request to its stored direct addresses. If a match is found the paired emulation address is passed through multiplexer 201 instead of the direct address. As a result, the substitute or upgraded data in configurable memory 203 is output to data bus 205 in place of the old data.
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