Abstract: A television receiver is provided with a decoder (32) for decoding and displaying data which is included in a wide band video signal. In order to provide high resolution graphics, a processor (45) is connected to a data page store (41) of the decoder (32) and a program store (47). Instructions for the processor (45) are received `off air` and are stored in the store (41). The instructions are executed using programs stored in the store (47). A clock circuit (45a) is provided for the processor (45) to enable delays and other timed sequences to be introduced and a rounding circuit (46a) ensures as smooth an output display as possible. Data can additionally be received from another soce via a telephone line and selected for display in place of the `off air` data.