Disk drives are described in which blocks of data spanning multiple sectors are encoded into a plurality of codewords which are then divided into segments that are physically separated on the disk surface over multiple sectors in a distributed codeword block so that the codewords have an improved worst case SNR in comparison to individual sectors. A plurality of the photoelectric converter and the transfer element are disposed at least in a horizontal direction share the amplifier and the read signal line. Screws are provided in one embodiment and are dimensioned or configured to be inserted into a bony structure and to lock against each other to retain the screws and consequently secure the plate in place against the bony structure. The ground of the low pass filter is separated within the multilayer ceramic substrate from the grounds of the other circuit. Or, alternatively between the applications and programs that created them and the pay station sales, and the control system takes account of these correlation data sets in replaying the data or in selecting the programs or applications. In an alternate embodiment of the invention, the fan is mounted on the carrier and the rack has a lateral opening.