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Use of RAM As Data Comparator Disclosure Number: IPCOM000040235D
Original Publication Date: 1987-Oct-01
Included in the Prior Art Database: 2005-Feb-02

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Hardman, PR [+details]


A writable random-access memory (RAM) is used for comparison of data words by loading ones into RAM locations whose address corresponds to desired comparison patterns. Then when the RAM is addressed by one of those data words, a one is read out, indicating a compare equal. Conventional methods of comparing two data words employ 'exclusive-OR' gates. The comparison of long data words involves the use of large numbers of these gates, the number tending to increase exponentially with the length of the data word. Additionally, the circuitry required to enable the comparison of whole data words in their entirety, ranges of data words, or individual bits within a data word becomes extremely cumbersome, and space and power consuming, as the word length increases. The comparator disclosed overcomes these drawbacks.