Color/Graphics Adapter Register Compatibility
Original Publication Date: 1987-Aug-01
Included in the Prior Art Database: 2005-Feb-01
A technique is described whereby color/graphics adapter circuitry, as used in personal computers, is enhanced so as to provide software compatibility between various types of enhanced graphic adapters. Higher quality text and graphics images are provided through doubling the horizontal sweep rate, while maintaining compatibility at the register level of the existing software application base. (Image Omitted) In prior art, programming of video graphics applications, at early color graphics adapter (CGA) levels, was often accomplished by using direct access to hardware registers for operations, such as screen centering and mode setting, instead of using the BIOS software interface. When enhanced graphics adapters (EGA) were introduced, the programming was often not compatible.