The VGA is the standard video adapter card for x86-based computers. This hardware can operate in both text and graphics modes. A number of accelerators, such as the S3, are built on top of VGA-compatible hardware. There are three sample VGA display drivers: VGA, VGA64K, and VGA256.
The VGA display driver is the standard VGA 16-color driver, supporting any resolution up to 2K pixels across and any number of vertical scanlines. The VGA256 sample driver is designed for 256-color VGA. Both the VGA and the VGA256 use optimized assembly code to implement accelerations. The VGA256 driver does screen-to-screen scrolls, solid and pattern fills, and text with fast assembly language, using the VGA hardware for acceleration wherever possible. The VGA64K and VGA256 drivers are banked frame buffer drivers. Most other functions are punted to GDI one bank at a time. A driver built on VGA-compatible hardware could be derived from the VGA256 driver by hooking and implementing the appropriate functionality.