To shorten the waiting time to improve the performance of a computer or a communication system by adding an incoming request into a schedule according to a prescribed parameter.

Each of function modules 101-109 confirms a specific job to be executed, and this confirming means is used every time when the function module wants to execute a certain job via a PMC 200. When a certain function module must transmit and receive the data to and from a host component 130, the function module supplies its identification information to the PMC 200 together with the data and requests an access. The PMC 200 evaluates the incoming access request and compares this request with an undecided access request of another function module. Then the PMC 200 can simultaneously process plural access requests and adds them into a schedule in a sequence that is decided according to the priorities, efficiency, timing and/or other prescribed parameters of these requests.