On-screen display controller

Claim 1

A display controller of the character-based type for superimposing text and other graphic images on a video signal, said display controller including a logic control circuit for receiving control signals from a control system for controlling said display controller, a page memory coupled to said logic control circuit for storing text codes and attribute codes for characters in a character set to be displayed, said attribute codes identifying data for controlling colors and intensities of colors for respective characters to be displayed, a character memory having stored therein character data, forming patterns on display corresponding to said characters in said character set, and attribute data for selectively supplying characters with corresponding attributes in response to signals applied to an input thereof, said character memory being coupled to an output of said page memory, and output means coupled to an output of said character memory for supplying the text and other graphic images to be superimposed on the video signal, wherein said display controller further comprises: means, incorporated in said logic control circuit and said character memory, for enabling variable width text characters to be displayed; means, coupled between said logic control circuit and said page memory, and between said logic control circuit and said character memory, for providing multiple modes of using the data stored in said character memory; means, coupled between said page memory and said output means, for selectively bypassing said character memory; and means coupled to said logic control circuit for line-by-line modification of signals in said logic control circuit, said modifiable signals including signals for controlling said means for providing multiple modes of using said character memory data, signals for controlling said means for selectively bypassing said character memory, and signals for controlling a page format of the text on display.