Graphics display system

Claim 1

A graphics generator for use in a video display system, said video display system including a video monitor and means for applying a video signal to said video monitor to provide a video picture on said video monitor, said graphics generator comprising: video timing means for providing a line rate clock signal and a pixel rate clock signal to synchronize said video signal for display on said video monitor; a microprocessor configured to provide digital data representative of graphical icons for display on said video monitor, a memory load clock signal of slower frequency than said pixel rate clock signal, and position data indicating the line and pixel on said video monitor at which selected ones of the graphical icons are to be displayed; graphics memory means for selectively writing in, storing, and reading out said digital data; graphics positioning means operating in synchronism with said line rate and pixel rate clock signals for generating an actuating signal at a time determined by said position data; addressing means responsive to said microprocessor for generating write addresses to address said graphics memory means and write said digital data serially into said graphics memory means bit-by-bit in synchronism with said load clock signal, said addressing means further responsive to both said microprocessor and said actuating signal for generating read addresses to address said graphics memory means and read said digital data serially out of said graphics memory means bit-by-bit in synchronism with said pixel rate clock signal; means for providing a graphics signal to display a selected color on said video monitor; and means responsive to the digital data read from said graphics memory means for selecting said video signal or said graphics signal for display on said video monitor.