Tandy Graphics Adapter

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Tandy Graphics Adapter
Release date 1984; 40 years ago (1984)
Cards
Entry-level Tandy Video I
High-end Tandy Video II
History
Predecessor Color Graphics Adapter
Successor Video Graphics Adapter
File:Tandy 1000 rl 1.jpg
Tandy 1000 RL computer with a Tandy Video II display
File:Screen color test PCjr 16colors 160x200.png
Sample image of simulated Tandy 16-color screen at 160x—200

Tandy Graphics Adapter (TGA) is a computer display standard for an IBM PC compatible video adapter that improved on IBM's Color Graphics Adapter (CGA) technology. Whereas CGA could display only four colors at a time at a screen resolution of 320×200 pixels, a TGA adapter could display up to 16 colors.

IBM premiered the new video adapter in the PCjr home computer it announced in 1983. At that time, the company called the adapter the Video Gate Array (not to be confused with the later Video Graphics Array standard), or CGA Plus. The adapter incorporated the Motorola 6845, an integrated circuit for controlling video.

The PCjr was not popular, but the Tandy 1000 family of home computers were compatible with its video standard and Texas Instruments SN76489-based enhanced sound, and sold well. With built-in joystick ports the 1000 was the best platform for IBM PC-compatible games before the VGA era, and the combination of its graphics and sound became known as "Tandy compatible";[1][2] 28 of 66 games that Computer Gaming World tested in 1989 supported Tandy graphics.[3] The later Tandy 1000 SL and TL models were equipped with an enhanced version of the CGA Plus adapter, capable of displaying 16 colors at an improved resolution of 640x200.[4]

Output capabilities

Tandy Video I, TGA, TCGA, or ECGA

Pre-SL systems have this type of video.[5]

CGA compatible modes:

  • 160×100 16 color mode
  • 320x200 in 4 colors from a 16 color hardware palette. Pixel aspect ratio of 1:1.2.
  • 640×200 in 2 colors. Pixel aspect ratio of 1:2.4
  • 40×25 with 8×8 pixel font text mode(effective resolution of 320×200)
  • 80×25 with 8×8 pixel font text mode(effective resolution of 640×200)

In addition to the CGA modes, it offers:

  • 160x200 with 16 colors
  • 320x200 with 16 colors
  • 640x200 with 4 colors

Tandy Video II or ETGA

The video on the SL's, TL's, and RL's is known as Tandy Video II or ETGA.[5] It offers all the same modes as Tandy Video I, plus one more non-CGA mode:

  • 640x200 with 16 colors

Palette

Full CGA 16-color palette
black
#000000		 0 gray
#555555		 8
red
#AA0000		 4 light red
#FF5555		 12
brown
#AA5500		 6 yellow
#FFFF55		 14
green
#00AA00		 2 light green
#55FF55		 10
cyan
#00AAAA		 3 light cyan
#55FFFF		 11
blue
#0000AA		 1 light blue
#5555FF		 9
magenta
#AA00AA		 5 light magenta
#FF55FF		 13
light gray
#AAAAAA		 7 white (high intensity)
#FFFFFF		 15

The full 16 color CGA color palette was available. Some games detected the Tandy hardware and displayed enhanced graphics in Tandy mode while selecting CGA mode, while others specifically offered the option to select "Tandy" graphics.

See also

References

  1. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  2. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  3. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  4. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  5. ↑ 5.0 5.1 II.B.5. What is this weird video Tandy has?, Tandy 1000-series FAQ (Version 2.52 / October 25, 2005)
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