ARBITRATION LOGIC.

Abstract

A machine environment where several independent devices can request simultaneously a service from a shared resource (memory, interrupt logic, etc. ) is considered. Logic is described which allows the arbitration between the different requests to be performed with the following characteristics: arbitration resolution done in one LSSD (Level Sensitive Scan Design) clock cycle; Automatic adaptation to the activity of the requesting devices, thanks to a simple mechanism. The arbitration logic only looks at the 'Service Request' leads from the attached devices and needs no additional information on the device configuration (device installed, or not). The arbitration mechanism does not spend time to poll inactive or not installed devices.