Use of EGA SR Register for Improved Performance and Appearance of APA Character Displaying for Selected Color Combinations
Original Publication Date: 1988-Aug-01
Included in the Prior Art Database: 2005-Feb-15
Text is displayed in all-points-addressable (APA) display modes as characters composed of a pattern of dots (pixels) defined in a "character box" of n columns of dots by m rows of dots. The dots are represented by some number of bits in the display adapter memory. Using one memory bit per pixel allows differentiation of the character foreground (FG) from the background (BG). Using multiple bits per pixel allows individual dots to be any of several colors. For example, the Enhanced Graphic Adapter (EGA) can use 4 bits per pixel, providing 1 of 16 selectable colors for each dot. The entire Text character box is intentionally displayed with just two colors, FG and BG. EGA memory is arranged in groups of 8 adjacent bits in each of 4 separate memory planes, representing 8 adjacent dots on the screen.