Abstract: A system whereby a central processor continues operation beyond a serialization point before the architecture defines that it is permissible to do so. According to the system, it is ascertained whether correct results are being achieved after the serializing point. If some doubt develops about the correctness of the results, the processor is returned to its status at the serialization point and the processing is repeated. In one embodiment, correctness of results is determined by way of a monitoring mechanism which depends on the fact that interactions between CPUs are confined to references to storage. The operations which are performed prior to the time that the architecture allows them, are restricted to ones which depend on fetches made from storage.

Abstract: A combination foam and steam carpet cleaning machine incorporating separate storage compartments for the hot water and the foaming liquid, automatic control of vacuum wands positioned ahead and to the rear of the steam jets to permit forward and reverse motion during the steam cleaning operation, individual height adjustments for the cleaning brush and the vacuum wand and spring loading of the vacuum wand to insure adequate pressure of the wand against the carpet for maximum vacuuming efficiency. The machine is self-propelled in both forward and reverse directions.