Abstract: A method of processing video data in a receiver/decoder including at least one port (31) for receiving data and memory means (40) including a data buffer area (45A0, 45A1) for storing incoming data for display, and a graphics buffer area (45Ai) for storing graphics data, said method including passing graphics data stored in the graphics buffer area to the data buffer area for combination with display data stored therein.

Abstract: A device interface for use in a receiver/decoder for a broadcast digital television system in which received signals are passed through a receiver to the receiver/decoder and then to a television set. The receiver/decoder decodes a compressed MPEG-type signal, and is controlled by a remote controller handset, through an interface in the receiver/decoder. The operation of the receiver/decoder is controlled by a virtual machine (VM) which includes a run time engine (RTE). The receiver/decoder includes a plurality of interfaces to external units. The device interface enables an application run by the RTE to access an IEEE 1394 interface.

Abstract: In a digital satellite television system in which a television receives its signal via receiver/decoder, such as a set top box, interactive applications can be downloaded and run on the receiver/decoder. The application code is arranged as modules, and the downloading of modules is preceded by searching a directory module within a specified local address. The modules are signed and the directory module is signed and encrypted so that a single encryption applies to all of the modules making up the application. Multiple public encryption keys are stored in ROM in the receiver/decoder, so that applications can be created by different sources, without the sources needing to know each other's private encryption keys. A facility is provided to enable an encryption key to be temporarily stored in RAM in the receiver/decoder, so that a manufacturer of the receiver/decoder can check its functionality. A signature of the directory may be hidden at a variable position in a block of dummy data in the directory module.

Abstract: A modem device driver, particularly for use in a receiver/decoder (2020) for a digital broadcast system in which received signals are passed through a receiver to the receiver/decoder and thence to a television set. The receiver/decoder is controlled by a virtual machine (4007) which includes a run time engine (4008). The receiver/decoder includes a plurality of interfaces to external units, and logical driver devices for the interfaces. A device driver (500) for controlling a modem interface comprises a buffer memory (503) for receiving messages, a control memory (502) for storing control parameters, and a logic unit (501) for controlling the device driver and the flow of messages. The logic unit includes a comparator (511) for matching Event, ACK, an NACK patterns stored in the control memory against the end of messages stored in the buffer memory.

Abstract: The present invention discloses a routing apparatus for routing data in a receiver/decoder. The routing apparatus comprises means for receiving realtime user routing control information and means for routing the data from an input to an output, to storage means, and to both the output and the storage means in accordance with the received realtime user routing control information. In other aspects, a command for controlling a data transfer of a bit stream between a source and a destination, where the command is adapted to change at least one of the source and destination of the transfer, and apparatus for receiving and processing data comprising means for receiving the data and means for synchronising the data in two or more different modes, are also disclosed.