Abstract: A method of processing data using a data processor having an operating system for performing tasks of an application program, and a power and performance controller controlling parameters and modes of execution of the tasks by the data processor. The power and performance controller includes a performance predictor producing an estimation of required performance of the data processor for the tasks taking account of inactive periods of the tasks and adjusting the performance and power consumption of the data processor in response to the estimation. The performance predictor distinguishes for each of the tasks between: —available inactive periods of the task during which the operating system is available to continue to process the same task, and—unavailable inactive periods of the task during which the operating system is not available to continue to process the same task. A substantial improvement is obtained in quality of service, with fewer missed deadlines in performance of the tasks.

Abstract: A method of processing data using a data processor having an operating system for performing tasks of an application programme, and a power and performance controller controlling parameters and modes of execution of the tasks by the data processor. The power and performance controller includes a performance predictor producing an estimation of required performance of the data processor for the tasks taking account of inactive periods of the tasks and adjusting the performance and power consumption of the data processor in response to the estimation. The performance predictor distinguishes for each of the tasks between: —available inactive periods of the task during which the operating system is available to continue to process the same task, and —unavailable inactive periods of the task during which the operating system is not available to continue to process the same task. A substantial improvement is obtained in quality of service, with fewer missed deadlines in performance of the tasks.

Abstract: A mobile subscriber unit is provided with a memory (8) containing the cell selection and re-selection functions relating to a plurality of different radio networks (4 to 6) eg. GSM, UMTS, satelite, available in its locality, thus enabling the subscriber unit to identify and camp on to any one of the networks. Once a communications link is established, the subscriber unit requests over-the-air download of the full operating protocol from the chosen network. A self-check procedure is optionally provided to ensure that the downloaded data is fuctioning correctly. The choice of network may be influenced by user preference data held in a memory (10). The invention enables operation of a subscriber unit on a choice of many networks without the need for a large memory for holding the full protocols for all available networks.