A computer input device includes a light guide that illuminates a target area for imaging so as to permit tracking relative motion of a surface. Performance data provided to some of the tools by the analysis scheduler may be specified to be within a predetermined look-back period. A bulkhead cover auxiliary port is defined in the second side wall for receiving additional air flow admitted through the grille and thereby reducing snow ingestion through the bulkhead cover primary port. The second MOS transistor is disposed on the first well. The data freshness degree is higher than the data freshness degree of data within the faulty portion.