Abstract: A method for identifying a principal tooth in a series of teeth extending along at least a portion of a periphery of a rotatable object includes the steps of rotating the rotatable object, setting a counter to a predetermined value, measuring a first tooth in the series of teeth to obtain a first measurement, adding a qualifying value to the measurement to obtain a qualification measurement, measuring a second tooth in the series of teeth to obtain a second measurement, comparing the second measurement to the qualification measurement, and identifying the second tooth as the principal tooth when the second measurement exceeds the qualification measurement.

Abstract: Referring to FIGS. 1 and 2, I/O control modules (IOCMs 25-29) have channels which communicate by way of timer buses (71, 72) and pin/status buses (75-77). Channels (86, 87) are partitioned by each timer bus (71, 72) into separate blocks of channels (86, 87) which are provided with access to different timebase values from timebase channels (80, 81) by their respective timer bus (71, 72), so there is no loss of resolution because each channel in a timer bus block (e.g. 86) can concurrently receive the same timebase value from its corresponding timer bus (71). Pin/status buses (75-77) allow simultaneity of control among the channels (e.g. 58) coupled to the same pin/status bus (e.g. 76). Pin/status buses (75-77) and timer buses (71, 72) can be independently partitioned.

Abstract: Referring to FIGS. 2, 13, and 14, the tag value transferred by timebase select signals (50) indicates which timebase is presently available on timer bus (71). In one embodiment, each channel (61, 62, 80, 81, and 86) compares the tag value of the timebase select signals (50) with a user programmed tag value stored in a register portion (264). If the stored tag value matches the tag value being driven on the timebase select signals (50), then the match signal (263) is asserted to indicate that the channel is either to provide a timebase value to the timer bus (71) for timebase channels (80, 81), or to receive the timebase value from the timer bus (71) for work and other channels (86). FIG. 15 illustrates examples of how timebase values (namely TB1-TB8) may be selectively provided during the different time slots of a timer bus (e.g. 71).

Abstract: A timer system comprises multiple channels, each of which is capable of performing input and output timer functions referenced to any of a plurality of timer reference signals. In the preferred embodiment, sixteen independent channels are serviced by a processor dedicated to that purpose and each can perform capture and match functions referenced to either of two free-running counters.

Abstract: A system comprises a service processor and a plurality of operating units dependent on the service processor. The service processor responds to service requests from the operating units and services the operating units one at a time. A scheduler is responsible for assigning priority to the operating units and determining the order in which the service requests are handled. A register contains a value indicative of the operating unit currently being serviced and is under control of the scheduler. According to one aspect of the present invention the register is also under control of the service processor itself. Another register, under control of the service processor, is coupled to the scheduler to generate service requests thereto independent of the operating units. A memory addressable by the service processor stores data. The service processor is capable of generating addresses for the memory derived from the contents of the register indicative of the operating unit currently being serviced.

Abstract: A timer subsystem which provides a data processor servicing the timer subsystem with the ability to inhibit the match recognition logic of the timer subsystem while the processor is servicing the subsystem. The disclosed embodiment comprises a sixteen-channel timer subsystem with a dedicated service processor. The service processor, under control of the micro-coded programs executing thereon, is capable of disabling a match recognition latch in the timer channel currently being serviced. This feature provides the ability to prevent unwanted matches which occur while the service processor is updating the match register, for instance. Another feature of the timer subsystem is the inhibition of multiple matches to a single match register value by disabling the match recognition latch upon the occurrence of a match and re-enabling it only when the match register is written by the data processor.

Abstract: A timer channel with multiple timer reference signals available to it which is capable of performing any input or output timer function with reference to any of the available reference signals. In addition, input timer functions may be related to the occurrence of output functions. For instance, the state of one timer reference may be captured automatically at a specified time referenced to another timer reference. Another feature of the invention provides for the creation of a time-out window for an input timer function through the use of a concurrent output function.

Abstract: A timer system comprises multiple channels, each of which is capable of performing input and output timer functions referenced to any of a plurality of timer reference signals. In the preferred embodiment, sixteen independent channels are serviced by a processor dedicated to that purpose and each can perform capture and match functions referenced to either of two free-running counters.