Prime Computer Inc.

Richard Olsen

William Leo Gross

A video mixing system that is adapted to receive respective video and graphic control signals for controlling the display content on a video monitor. A video decoder processes the video and graphic control signals, thus making it possible to mix two or more video sources, one of which is typically an in-house data terminal source and the other of which is typically connected as a graphics option. At the output of the decoder is a gate means for providing selective voltage stepped intensity control signals for controlling the video monitor.

Video prioritizer and mixer

A horizontal scrolling apparatus that provides scrolling on a character-by-character basis including a screen memory and associated visual attribute memory having associated therewith a scroll control memory for storing at least one bit for controlling horizontal scrolling. A latch controls writing into the scroll control memory to provide an enable bit therein, only in those locations corresponding to characters that are to be scrolled. An offset number is stored in an offset register, which number is variable under computer control. Operation of an adding circuit is responsive to sensing of the enable bit for adding the offset number to the present screen address to provide an offset address. The offset address is coupled to the video memory for display of the character associated with the offset address in the screen address position.

Horizontal scroll method and apparatus

An apparatus for controlling visual attributes associated with characters displayed on a video display screen including a video memory for storing multiple data words corresponding to screen character locations, an attribute memory associated with the video memory for storing visual attribute codes and an attribute propagation store associated with the attribute memory for controlling visual attribute code propagation. A latch controls writing into the attribute propagation memory, a control bit for controlling visual attribute code propagation. The apparatus also includes a video display generator and control logic responsive to the control bit for causing a predetermined attribute code to be propagated for a preselected number of screen character locations.

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Littleton, MA, United States of America

Richard Olsen