Patent ID: 7937613

Claim:
A central processing apparatus for use in a computer system which comprises the present central processing apparatus and a plurality of external storage apparatuses, comprising: an access unit which accesses a specific target among the external storage apparatuses in order to read an operating system; a response information obtainment unit which obtains response information sent from the external storage apparatuses in response to the access; and an access control unit which changes the address of the access to that of an external storage apparatus that is different from the sender of response information by controlling the access unit and which then makes the access unit access the present post-change address if the present response information obtained from the response information obtainment unit is a predefined specific access error, wherein the access unit repeats the accesses until the response information obtainment unit obtains the response information and also continues the repetition of the present access until a passage of a predetermined waiting time if obtained response information includes an error which is different from the specific access error even in case the response information obtainment unit has obtained the present response information, and the access control unit makes the access unit stop the repetition of the access temporarily even before the passage of the predetermined waiting time, change the address of the access, and then restart the access if response information obtained by the response information obtainment unit includes the predefined specific access error.