Variable size dot matrix character generator in which a height signal and an aspect ratio signal actuate the same

摘要

A variable size and position character generator is described for use with a cathode ray tube raster scanning system to display characters as matrices of dots. The keyboard includes controls for permitting a user to select a particular height, aspect ratio and baseline for each character selected to be displayed. A unique character address signal is developed for each such selected character and serves to identify a unique, fixed size dot matrix for the selected character which is stored in a first read-only memory. A character converter, in the form of a second read- only memory, receives the selected height, aspect ratio and baseline information signals along with normal scan line counter signals and modifies the latter to develop scan control signals that are fed to the first read-only memory for controlling the height and position of the character selected to be displayed. The width of the character is also controlled by a dot rate selection signal developed in the character converter memory, which permits selection of one of a plurality of clock rates whose signals are then utilized to read out the contents of a parallel-to serial shift register that stores the individual dot signals for a given scan line segment.