Color pattern and alphanumeric character generator for use with raster-scan display devices

摘要

A color pattern and alphanumeric character generator for use with raster-scanned CRT display devices wherein the color background patterns and the characters are generated in an integrated manner. As a result, the apparatus utilized is considerably simplified and the color pattern display obtainable is more complex and more easily varied than hitherto was possible in an apparatus of this type. The viewing area of the raster-scan CRT is divided into a matrix of character cells. Each character cell is in turn divided into a plurality of color cells, each color cell being a matrix of dot positions on the display area of the CRT. The relationship of the number of color cells in each character cell and the number of dot positions in each color cell is an even integer. A display RAM, addressed by a microprocessor, stores display information therein. The RAM is addressed by the display circuitry during the display cycle. Each address location in the RAM has a plurality of bytes associated therewith which define a particular character cell on the CRT, both as to the color pattern therein and the character therein, if any. This information is used by the color and video network of the raster-scan display to generate the composite character and color pattern signal for each scan line.