Computer-Controlled Teletext System

34 LOCAL Il FROST I weather MOSTLY CLOUDY RAIN IN PLACES FROM THE MET OFFICE 890112. 14c carrier, and no noise added to the picture during transmission. Also possible within the system at any level is Telesoftware, which is normally seen as a BASIC listing for BBC compu- ters. It can however be machine code for any computer, and encrypted to limit ac- cess. Levels 4 and 5 exist as specifications, although level 4 was transmitted by the IBA as long ago as 1981. There appear to be no TV sets able to handle these levels, and until the editors of CEEFAX and ORACLE use it, the extra cost would not be worth while. Given the TV producers" liking for computer graphics on everything from weather maps to pop videos, hopefully they will come very soon. Hidden pages The specification for Teletext is wider than apparent from the familiar remote control handset. Page numbers, for example, are chosen from a key pad with digits 0 to 9. A displayed page has 24 lines. Less known is the fact that th...