| 摘要 |
<p>PURPOSE:To make it possible to reduce power consumption in a bus controller when no option apparatus is connected to an extended bus. CONSTITUTION:When a system is activated at the time of turning on a system power supply, an inquiry signal is sent to the respective connection ports of an external bus 5 by an apparatus connection checking circuit 31 in a bus controller 3 and their responses are monitored to check whether an option apparatus 6 is connected to this system (at least one of the connection ports of the bus 5) or not and the checked result is communicated to an operation/stop control circuit 32. When the circuit 32 is informed of that there is no connected option apparatus 6, the circuit 32 lets the bus controller 3 itself be in an aborted state to stop the drive/control for the bus 5, and when the circuit 32 is informed of the existence of one or more option apparatuses, the circuit 32 lets the controller 3 itself be in the normal bus driving/controlling state to start the processing of original control operation.</p> |
