Abstract: An operating system for scheduling execution of a random set of periodically recurring hard, real-time tasks encountered in multi-media computer system applications and which is useful in a multi-tasking computer operating environment. Periodically recurring computer tasks having relatively short execution periods for which execution results are absolutely required in hard, real-time environments such as multi-media systems, create a significant task scheduling overhead reducing the available processor resource. Overhead processing at task invocation is eliminated in the invention by placing all active recurrent tasks in an execution queue, regardless of the task's current state of activity and by reprioritizing the order of execution of the tasks in the queue whenever a given task execution is completed. Measured by reduction in task scheduling overhead consumed by the processor in scheduling the tasks, this achieves a 50-100% improvement over conventional scheduling and operating systems.

Abstract: A data processing system for executing multimedia applications which interface with multimedia devices that consume or produce at least one of real-time and asynchronous streamed data includes a CPU for execution of one or more multimedia applications and a DSP for processing data including streamed data. A plurality of modular multimedia software tasks may be called by the multimedia application for execution in the DSP. A plurality of data communication modules are provided for linking selected ones of the software tasks with selected others of the software tasks, and linking selected multimedia devices with selected ones of the software tasks. Each of the communications modules allows continuous, real-time and unidirectional communication of streamed data.

Abstract: A data processing system is provided for executing multimedia applications which interface with multimedia end devices that consume or produce at least one of (a) real-time and (b) asynchronous streamed data. The data processing system includes a central processing unit for data processing operations including execution of the multimedia application, a digital signal processor for processing data including the streamed data, and a plurality of modular components which cooperate to provide a substantially open architecture.

Abstract: A system for providing a time-based interrupt signal to a processor for executing a real time interrupt event with reduced interrupt latency, involves: a first programmable counter, which is capable of interrupting the processor by generating an interrupt signal on a regular time period based on the decrementing of an initial count value loaded therein, which value is re-loaded in the counter when the count is exhausted and the interrupt signal is generated; one or more second programmable counters, also having initial count values loaded therein that are decremented, and each of which, if the count is exhausted before that of the first counter, will not allow certain types of instructions or events, respectively associated with each second counter, to execute, if the execution of such instructions or events would cause an unwanted latency in the interrupt caused by the interrupt signal from the first counter.

Abstract: A multi-media user task (host) computer is interfaced to a high speed DSP which provides support functions to the host computer via an interprocessor DMA bus master and controller. Support of multiple dynamic hard real-time signal processing task requirements are met by posting signal processor support task requests from the host processor through the interprocessor DMA controller to the signal processor and its operating system. The signal processor builds data transfer packet request execution lists in a partitioned queue in its own memory and executes internal signal processor tasks invoked by users at the host system by extracting signal sample data from incoming data packets presented by the interprocessor DMA controller in response to its execution of the DMA packet transfer request queues built by the signal processor in the partitioned queue. Processed signal values etc.

Abstract: A method and apparatus for controlling the readout rate of information from a sequential storage medium, such as a CD-ROM, to maintain synchronism between the device containing the medium and an independent receiver receiving the information. Information is loaded from the media into a buffer at a rate controlled by pulses from a device clock. Information is unloaded from the buffer for utilization by the receiver independently of the loading of the buffer. The amount of free space available in the buffer is measured as information is loaded into the buffer. The rate of the clock is dynamically adjusted in response to the amount of free buffer space to maintain the full state of the buffer within predetermined limits. In this manner, the buffer never empties or fills in response to the unloading by the independent receiver.