Vertical Smooth Scrolling Enhancement for Video Graphics Displays
Original Publication Date: 1988-Nov-01
Included in the Prior Art Database: 2005-Feb-15
A technique is described whereby a circuit is incorporated into video graphics control circuitry so as to provide smooth vertical scrolling operations during personal computer graphic display operations. Enhanced graphic adapters (EGAs) and video graphic adapters (VGAs) typically require software to intervene at each scanline of scrolling motion. So as to provide a smoothly appearing scroll, the concept described herein provides circuitry incorporated within video graphics control circuitry so as to provide not only a smooth scrolling enhancement, but to interject interrupt advantages. The essential elements of memory address generation for EGA or VGA circuitry are shown in the figure.