; An overview on the PC graphics standards
; IAVS script created on 1.5.1995
; Last updated on 7.5.1995

.TITLE The PC Graphics Standards
.TITLE An Overview from ~CGA~ to ~Super-VGA~
.TITLE Created using the ~InstantAccess~ Viewer System

.CPIC COVER.PCX
.DSM PCGRAPH.MOD


; ========================================================================
.ART Introduction

Hi!

... and welcome to a brief overview on the PC graphics standards. This
document contains information on the following display adapters:

        þ  Monochrome Display Adapter (MDA)
        þ  Color Graphics Adapter (CGA)
        þ  Hercules Graphics Card (HGC)
        þ  Enhanced Graphics Adapter (EGA)
        þ  Video Graphics Array (VGA)
        þ  Super-VGA


; ========================================================================
.SUB Monochrome Display Adapters

.ART Monochrome Display Adapter

.M1 ~The ~Monochrome Display Adapter~ (MDA) was introduced back in 1981 when the
first IBM PC was presented to the public. The capabilities of the MDA aren't
very impressive in comparison to VGA and Super-VGA cards that are common
nowadays. Monochrome text with 25 lines and 80 columns is all the MDA is
capable of.

.ART Hercules Graphics Card

.M1 ~The ~Hercules Graphics Card~ (HGC) was released one year after the introduction
of the IBM PC. The manufacturer of this card was not IBM but a company named
Hercules. The HGC is completely compatible with IBM's MDA but exceeds it in
features: The HGC can display monochrome graphics with a resolution of 720x348
dots. This feature ensured the HGC and its numerous clones a long period of
success.

.ENDSUB


; ========================================================================
.SUB Color Display Adapters

.ART Color Graphics Adapter
.PIC CGA.PCX

.M1 ~The ~Color Graphics Adapter~ (CGA) was introduced by IBM at the same time as
the Monochrome Display Adapter (MDA), back in 1981 when the first IBM PC was
presented to the public.

The CGA display adapter features the same text mode as the MDA card, namely
25 lines by 80 columns. The difference between the CGA card and the MDA card
is that the CGA card can display that text mode with 16 colors. The price that
had to be paid for the color display capability of the CGA card is a dot
matrix resolution that is much lower than the resolution of an MDA card.

The lower text resolution also affects the graphics resolution of the CGA
card. The CGA card features two graphics modes: 320x200 with 4 colors and
620x200 with 2 colors. Both resolutions are lower than the resolution of the
HGC card.


.ART Enhanced Graphics Adapter

.M1 ~The ~Enhanced Graphics Adapter~ (EGA) was released in 1985 and was a techno-
logical break-through in comparison to the CGA card:

þ Thanks to a higher display resolution the quality of the character dot
matrix on the EGA display almost reaches the quality of an MDA card.

þ The graphics resolutions include a new high-resolution mode with 640x350
dots in addition to the old 320x200 and 640x200 modes. All modes can be
displayed with 16 colors.


.ART Video Graphics Array
.PIC VGA.PCX

.M1 ~The ~Video Graphics Array~ (VGA) was introduced in 1987 at the same time as
IBM's first PS/2 computers. VGA succeeded in further improving the EGA
technology. The most important changes in comparison to EGA are:

  þ Graphics mode 320x200 with 256 colors
  þ Graphics mode 640x480 with 16 colors
  þ Changeover from digital to analog display signals
  þ Free color-selection from a palette consisting of over 256'000 colors


.ART Super-VGA

.M1 ~The term ~Super-VGA~ comprises all display adapters with features that go
beyond the VGA standard. Common Super-VGA graphics modes are:

  þ 640x480
  þ 800x600
  þ 1024x768
  þ 1280x1024

(with 256, 32768, 65536 or 16.7 million colors each)

The main problem with this new magnificence of colors and resolutions was that
there was no standard on how the new modes were to be implemented. However,
.M1 ~this problem was recognized and led to the foundation of the ~Video Electronic
.M1 Standard Association~ (VESA). Soon after the VESA had been founded, it published
a standard which would be known as the Video BIOS Extension (VBE) or just as
the VESA standard. The VESA standard defined a uniform system (a so called
interface) by which programs are able to access the Super-VGA modes on any
VESA compliant Super-VGA display adapter.


.ENDSUB