A form of scheduling mechanism often used in multiaccess systems. Individual processes are allocated a quantum of time on the processor. A process once started is allowed to run until it has exhausted its quantum, until it initiates a transfer on a peripheral device, or until an interrupt generated by some other process occurs. If the quantum is exhausted, the process is assigned a longer quantum and rejoins the queue. If the process initiates a transfer, its quantum remains unaltered and it rejoins the queue. If an externally generated interrupt occurs, the interrupt is serviced. Servicing the interrupt may free some other process already in the queue, in which case that process may be preferentially restarted.