Patent ID: 6606715
Filing Date: 2003-08-12
Classification: G06F

Abstract:
A device control apparatus comprising:a host interface control unit controlling a communication with an upper apparatus; a cache memory in which user data and a management table have been stored; a cache control unit controlling said cache memory; and a main control unit controlling each of said control units by executing a control program stored in a main memory, wherein said cache control unit has a protection data control unit controlling such that in a writing operation to write the user data from the upper apparatus into said cache memory, protection data is formed in said user data and written into said cache memory, when an interruption of a transfer of said user data is detected, a forming state of the protection data upon interruption is stored in said cache memory, when a transfer restart of said user data is detected, the forming state is returned to the forming state of the protection data upon interruption stored in said cache memory, and the formation of the protection data is restarted and wherein said protection data control unit compares an OP code at the start of transfer which is set by the control program of said main control unit with an OP code during the transfer, detects a transfer interruption when a change in OP code is confirmed, compares an OP code upon interruption with an OP code during the interruption after the transfer interruption, and detects a transfer restart when a change in OP code is confirmed.