US Patent 7212363 Magnetic disk apparatus

A magnetic disk apparatus formats a single data frame as a single sector. The magnetic disk apparatus includes a read-out control unit that controls to read-out sector data by emulating an existing format (e.g., “512 bytes/sector”), and a write-in control unit that controls to write sector data by emulating the existing format (e.g., “512 bytes/sector”), when the magnetic disk apparatus receives a read command or a write command based on a format (e.g., “512 bytes/sector”) that is different from a format of the magnetic disk apparatus (i.e., one sector/one data frame) from a host.