Abstract: A multitasking, graphical windowing operating system for an office machine supporting real time processing, including a method for supporting real time processing in the operating system. The operating system includes a kernel having a non-preemptive scheduler for scheduling windowing applications and a preemptive scheduler for scheduling real time applications. The kernel includes a messaging subsystem for communication among process in the system including both the real time and windowing applications, and further includes an event semaphore maintained by the kernel to manage scheduling. The method includes grouping windowing applications together for scheduling purposes and scheduling windowing applications non-preemptively. The method further includes determining priority of real time applications and scheduling real time applications preemptively with the windowing applications based on priority.

Abstract: A transmission arrangement is disclosed for recovering from faults in transmission equipment or facilities forming so-called virtual circuits for transmitting packets in a network. Faults are detected in transmission paths associated with a network node and an individual fault indication message is generated for each network facility that has at least one virtual circuit affected by the fault. Each fault indication message includes the identity of each virtual circuit on the associated network facility affected by the fault. The message is transmitted in-band on at least one of the affected virtual circuits on the associated network facility. If affected virtual circuits are terminated in the node, they are switched to alternate virtual circuits. Otherwise, the fault indication messages are transmitted over the identified facilities to other unknown nodes.

Abstract: An arrangement is disclosed for recovering from faults in transmission equipment or facilities forming so-called virtual circuits for transmitting packets in a network. Faults are detected in transmission paths associated with a network node and a fault indication is generated for any virtual circuits passing through the node that are affected by the fault. The fault indications are then transmitted on corresponding ones of the affected virtual circuits or on other designated virtual circuits. If any of the affected virtual circuits are terminated in the node, no fault indications are generated for them and they are switched to alternate virtual circuits. Otherwise, the fault indications are transmitted on corresponding virtual circuits or on other designated virtual circuits over facilities connected to the node to other unknown nodes.

Abstract: An arrangement is disclosed for recovering from faults in transmission equipment or facilities forming so-called virtual circuits for transmitting packets in a network. Faults are detected in transmission paths associated with a network node and a fault indication message is generated for each virtual circuit passing through the node that is affected by the fault. The fault indication messages are then transmitted on corresponding ones of the affected virtual circuits. If any of the affected virtual circuits are termianted in the node, they are switched to alternate virtual circuits. Otherwise, the fault indication messages are transmitted on corresponding virtual circuits over facilities connected to the node to other unknown nodes. A node receiving a fault indication message determines whether the corresponding virtual circuit is terminated at the node or passes through it to some other unknown node. If an affected virtual circuit is terminated in the node, it is switched to an alternate virtual circuit.