Video attributes decoder for color or monochrome display in a videotext mode or a high-resolution alphanumeric mode

摘要

The present invention relates to a video attributes decoder for color or monochrome display in the videotext mode or in the high- resolution alphanumeric mode, with a choice, in the videotext mode, between the alphanumeric and the semigraphic mode. The decoder is made up of a clock circuit (25), a configuration register (23), a character atrributes register (22), a line attributes register (32, 33), an attributes decoding circuit (21) connected to these various registers, a character masking circuit (41), a serializer (40) connected to the masking circuit (41) and to the clock circuit (25), a background inversion circuit (53), a character color control circuit (51) and a background color control circuit (52). The last three circuits are connected at the input to the attribute decoder circuit and at the output to the circuit (50) for multiplexing and controlling the monitor guns. The output (402) of the serializer circuit (40) is transmitted over a dot broadening circuit (54). The output (542) of the dot broadening circuit is connected to an input of the multiplexing circuit. A double-height logic circuit (31) is operably connected between the line attributes register (33) and selection lines (LC0, LC3) for selecting one group of characters within a character generator read-only memory (15).