The VGA is generally upwardly-compatible with the CGA , EGA , and MDA ,
but it has increased graphics resolution and color capabilities.  It was
introduced in 1987 with IBM's PS/2 line and is currently the most often
seen video standard.  TECH Help! covers the following VGA and general
video topics:

Video Modes ........... includes VGA modes
Video Services ........ INT 10H video services
Video Memory Layouts .. accessing VGA video memory

VGA Data Areas ........ BIOS data variables specific to EGA
BIOS Data Area ........ includes video-specific variables in low memory

Screen Attributes ..... codes determine colors for text mode
Color Table ........... exhaustive listing of screen attributes

VGA I/O Ports ......... I/O port addresses; video controller registers
VGA Pin Outs .......... connectors on VGA cards

Font Definition Data .. layout of binary data that defines a font
.CPI Font Files ....... the DOS interface for EGA font definition

It supports 25-, 43-, and 50-line text modes and graphics modes up to
640x400 with 256 colors.  You can redefine fonts and remap the color

In text mode, video memory begins at b800:0.  In graphics modes 0dH-10H,
video memory is at a000:0 (see Video Memory Layouts).

  Testing for a VGA  
To see if you are running on a VGA, use INT 10H 1bH.  If that fails, see
EGA, CGA, or MDA for fall-back tests.

See Also: CGA
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Video Graphics Array (VGA)