Abstract: A selective, non-manual power controller provides the selective, non-manual power control of various components of a data processing equipment from and reports the power status of such components to a central location. As opposed to pass power controllers which were limited to powering on or off all of the computer equipment controlled by a given controlling element, this invention provides a non-manual capability for remotely powering on or off any one or more components of a system or systems in a selective manner and providing the power status thereof. By being able to selectively activate or deactivate any or all of the components of a data processing system, the ability to conserve electrical energy is optimized. In many cases, a single component or a set of components are not used for extended periods of time, such as an entire production period or at least a large portion of a production period.

Abstract: In a system wherein a central computer complex is connected through central control modules (CCM) and channel modules (CM) to the control units of peripheral subsystems, a first queue is maintained in a CCM for Start I/O Fast (SIOF) commands waiting to be accepted by the CMs connected thereto. After a CM accepts an SIOF command and passes it on to a control unit, the control unit may return to the CM a busy status which is then passed through to the CCM. The CCM maintains a control unit busy (CUB) queue and an entry is made therein when busy status is returned. When a control unit reports control unit end status to the CCM, the CUB queue is linked to the top of the SIOF so that the CMs may again be informed that the SIOF commands are available. The arrangement avoids two interruptions of the central computer complex to report first that the control unit is busy and then that the control unit is available.