ACCESS PERMISSION

PURPOSE: To control the number of users given access by forming a list of permitted users, and returning access permission to a requesting side only in the case where the list is scanned within the range of a depth parameter, and an identifier matches. CONSTITUTION: A CPU 1 contains application which is connected to terminals 17 to 23 through buses 9 to 15, and which can be executed in communication relation with one terminal on a down-load interface for a work station being accessed through the designated bus. The CPU 1 forms the list of the permitted users, and encodes the depth parameter N as the key of a CPU identifier and the function of an offset. In response to an application software request from the work station or the user, the list is accessed, and depth N is decoded by the key. Then, the list is scanned within the range of the depth N, and only when the identifier matches, the access permission is given to the requesting side.