Enhanced Graphics Adapter (EGA)

  The EGA is generally upwardly-compatible with the CGA and the MDA, but
  it has loads of additional features.  It was introduced in 1985 and has
  been popular since about 1986.  It is mostly replaced by VGA and SVGA
  systems.  TECH Help! covers the following EGA and general video topics:

    Video Modes ........... includes EGA modes
    Video Services ........ INT 10H video services

    Video Memory Layouts .. accessing EGA video memory

    EGA 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

    EGA I/O Ports ......... I/O port addresses; video controller registers
    EGA Switch Settings ... those pesky switches at the rear of the adaptor
    EGA Pin Outs .......... connectors on EGA cards

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

  The EGA supports 25- and 43-line text modes and graphics modes up to
  640x350 with 16 colors.  You can redefine fonts and remap the color
  palette.  It is upwardly-compatible with CGA.  VGA, and SuperVGA are all 
  upwardly-compatible with EGA, supporting all of its modes, I/O ports, and
  BIOS variables.

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

█▌Testing for an EGA▐█
  To see if you are running on an EGA, use INT 10H 12H BL=10H.  If on
  return,  BL>4 then the EGA BIOS is not present, so you must be running
  on a CGA or MDA.

See Also: CGA
          Video Memory Layouts