Abstract: A data handling arrangement for a computer system, with particular application to multimedia systems, allows device adapters (control units) attached to the system to autonomously (without interrupting the system processor) control processing of a data stream of arbitrary length through memory buffers which are smaller than the stream. In this (stream processing) operation, data constituting the data stream flows through devices controlled by the adapter in succession, and is held in shared memory buffers as it passes between devices. The adapters are prepared for the stream processing operation by a system processor, indicate their preparation status to the processor, receive an initiating signal from the processor, and then proceed to direct the operation to completion without further assistance from the processor. In the operation, the adapters coordinate usage of the memory buffers by respective devices.

Abstract: An improved data processing system and operating system having a selectable scheduler. An operating system kernel is provided having a standardized interface for permitting the installation of a selected one of multiple diverse schedulers for use in different environments. System resources which may include memory, input/output devices and file systems are thereafter optimally allocated for a selected set of applications and a particular environment within the data processing system by permitting a user to install a selected one of the multiple schedulers which directly controls allocation of processor time, thereby indirectly allocating system resources. The standardized interface within the operating system kernel is preferably provided utilizing a kernel extension mechanism and installation of a selected one of the multiple schedulers may occur automatically, in response to system initialization, or may be selectively achieved during operation of the data processing system.