HOST INTERFACE CIRCUIT OF DISK DEVICE, AND DISK DEVICE

PROBLEM TO BE SOLVED: To prevent a malfunction due to an ineffective parameter sent during execution of a processing corresponding to a command issued from a host computer. SOLUTION: When an address signal to select a parameter register 11 is sent from a host computer H, an address decoding circuit a(7) of a host interface circuit 2 generates a temporary register write clock 24 to store parameter data in a temporary register 9, and when an address signal to select a command register 10 is sent, the circuit a(7) generates a command resister write clock 23 to store command data in a command register 10 and stores parameter data in the temporary register 9 in a parameter register 11.