Abstract: A method of reducing the response time upon a change-over between different display modes of a video display device, picture information from a first channel being displayed in one display mode and picture information from another channel being displayed in another display mode. Picture information from the one channel is simulated by picture information from the other channel. The two channels may carry different picture information.

Abstract: The invention relates to a method of searching a plurality of values in an ordered list. Given a data set consisting of data items. With each data item one or more attribute values are associated, which are all stored in an ordered list. Efficiently retrieving the data items associated with a particular set of entered values is accomplished by using the list. The list (partially) resides in slow secondary memory and, and a subset thereof, the sparse index, resides in primary memory. Both indexes preserve some natural ordering of the values. The invention proposes to look up the particular set of entered values in the list in one combined operation, rather than individually. The accumulated retrieval time is substantially reduced as a result.