mask bits 212 and sets certain bits in query data 201 to a predetermined value i e logical 1 or 0 the function of mask block 226 is similar to mask block 225 the output of mask block 226 is represented by arrow 213 and is supplied to parity generator 223 parity generator 223 outputs query parity bit s represented by arrow 206 the query parity bit s 206 generated by parity generator 223 would typically be the same encoding as those produced by parity generator 222 however it may differ from the encoding generated by parity generator 222 by certain inversions or other transformations etc depending upon the functioning of parity compare 224 mask blocks 225 and 226 parity generators 222 and 223 and ram 221 parity bit s 206 and stored parity output 207 are compared by a comparator 224 the result of this compare 208 indicates whether or not there was a bit error in the queried entry in the cam 221 the mask bits either in the cam 221 or in the stored parity or mask bits corresponding to that entry fig3 is a flowchart illustrating steps to detect cam bit errors these steps are applicable to the block diagram in fig1 but are not limited to application with only that arrangement of blocks other arrangements of blocks may be used to complete these steps in fig3 in a step 302 input parity is generated on input data that is being written into the cam the generated input parity may be a simple single bit parity such as odd or even parity or a more complex multi bit parity such as an error correcting code ecc in a step 304 the input data is stored in a cam at.