Abstract: A raster display can be built up from a number of zones. A data processor is described for controlling the intensity and hue of such a zone from information supplied defining the boundaries of the zone, its intensity and hue. The control and allocation to zones of a number of such data processors is also described.

Abstract: Data processing apparatus, particularly for use with a computer, is described which includes a primary store and an address translator. The primary store which has a fast access time compared with the main computer store is addressed by virtual addresses applied to the translator, each virtual address being associated with a particular real address for the primary store. The associations between real and virtual addresses can be changed by program instructions so leading to shorter programs and faster computer operation. Similar advantages are also gained by logic circuits for changing one or more of the more significant bits of the virtual addresses, under program instructions, and of addresses for a secondary store also of fast access time.

Abstract: A switch for use in a keyboard consists of an input light pipe, one or more output light pipes and means selectively operable to cause light to be reflected from the input light pipe into the output light pipes. The output light pipes are preferably connected to photodetectors which detect whether or not the switch is actuated by determining the amount of light incident thereon. When such a switch is to be used in a keyboard which is required to produce a coded output, one photodetector is provided for each digit of the code and output light pipes on the various switches are connected to the photodetectors in accordance with the code.