ACCESS CONTROL SYSTEM

PURPOSE:To provide a highest-speed system, which can be designed corresponding to the number of peripheral devices to be connected while keeping the versatility of the system, without any problem for reliability concerning a general-purpose electronic computer system for which a CPU and plural peripheral equipments are connected by one bus and access control from the CPU to the respective peripheral equipment is enabled. CONSTITUTION:A mounting state detecting mechanism 6 detects bus load capacity corresponding to the number of peripheral equipments connected to a common bus 8 or the like. The more the load capacity of signals is enlarged, the longer the propagation delay time of signals is prolonged. Thus, the maximum propagation delay time of respective signal lines is changed corresponding to the bus load capacity and by keeping this and selecting the cycle of a clock signal outputted to the common bus 8 at a velocity selecting circuit 7 so as to provide the highest velocity, access velocity can be varied.