Disk system with command processing function

An apparatus that processes a command from a host system and controls data transfer between a disk drive and the host system, comprising:

• means comprised of a plurality of command block means for executing command processing steps necessary for executing one command issued from the host system, the plurality of command block means corresponding in a one-to-one relationship to the command processing steps;
• command status means having register means for holding a status code set in advance in each of the command processing steps, the status code indicating a command processing step to be executed;
• means for outputting an enable signal for instructing the command block means to execute the command processing step indicated by the status code held in the register means;
• and
• CPU means for decoding the command issued from the host system, determining the command processing steps necessary for execution of the decoded command, setting a status code for indicating a series of command processing steps from start to end of the execution of the command in the register means, and updating the set status code to a status code for indicating a command processing step to be executed next when execution of a command processing step indicated by the set status code is completed.

A method of processing commands for a drive controller that controls data transfer between a disk drive and a host system and that has register means in which a status code is set for each of a series of command processing steps and executes said series of command processing steps sequentially according to the status code set in said register means, the method comprising:

• the step of accepting a command from said host system and recognizing said command;
• the step of converting an address to be accessed included in said command into a specific address;
• the step of transferring the write data from said host system to said disk drive when said command is a write command or transferring the read data read from said disk drive to said host system when said command is a read command;
• and
• the step of, when said series of command processing steps has been completed, executing a command terminating processing step where control goes to a wait state in which a subsequent command will be accepted.