Abstract: In a storage device, such as a magnetic rigid disk drive, data is stored at varying linear densities in the user data storage portions to increase the effective storage capacity of the device as a function of the differences in soft error rate tolerance associated with the various types of data being stored and the ability of non-alphanumeric data to be enhanced by reconstruction or smoothing rather than by an error correction code. A data type signal included with incoming data dictates the recording frequency and a control signal associated with the recorded data block is read when data is addressed to appropriately adjust the clock frequency for reading such addressed stored data.

Abstract: A controller device interfacing method and a low level device interface are provided for use between at least one controller and a plurality of devices in a direct access storage device. Message and command and data information are received and transmitted between the controller and the device. Responsive to a received predetermined read data command, read data function hardware transmits the requested data to the controller. Responsive to a received predetermined write data command, write data function hardware writes the received data from the controller to a device. Received message information is blocked from received data information so that message information is transmitted at any time within and between data information transmissions. The low level device interface supports two wire serial data transfer and provides improved data rate performance.