| 摘要 |
A disk controller (HDC) constituting an interface between a disk drive (HDD) and a host system executes a series of command processes on a command issued from the host system. The HDC includes a command processing unit composed of command processing circuits that divide the series of command processes into a plurality of command processing steps and execute the individual command processing steps independently. Each of the command processing circuits is constructed so that its operating state may be controlled by the status code set in the command status register included in a command status circuit. The CPU of the HDD can refer to and change the command status register. Furthermore, the CPU decodes the specific command from the host system that the HDC does not support and controls the command processing unit via the command status circuit. This enables the CPU to cause the command processing unit to process the specific command.
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