Television Interface Adapter

The Television Interface Adapter (TIA) is the adapter or base for the Atari 2600 game console. It was created by Jay Miner.

Atari used improved versions of the TIA for their Atari 400 and Atari 800 calls:

• Color Television Interface Adapter (CTIAAnd,
• George's Television Interface Adapter (GTIA).

Programming for the TIA is very complicated; Limitations such as the absence of a framebuffer and the fact that three pixel cycles equal one CPU cycle make the developer's job more difficult, although they make it an interesting challenge for hobbyist programmers.

TIA functions

The TIA adapter is responsible for rendering the images on the TV and providing access to existing hardware graphics capabilities used to render video game graphics. Due to the cost of memory at the time, the TIA does not have a dedicated VRAM memory, so it only generates one image line at a time. The image is created from data stored in seven registers:

• A background color.
• Two sprites of eight pixels, which make the game function (players) 1 and 2.
• A ball (ball), basically lines of different sizes.
• Two shells (missiles), basically lines of different sizes.

The TIA hardware handles collision detection between these objects and stores the collision bitmaps, which are usually read during the VBLANK period (vertical display list blanking routines). TIA registers allow the programmer to control the position of objects as well as their color. In addition, the TIA is also responsible for generating two sound channels, of which the programmer can control the pitch, volume and type of sound. Finally, the TIA is capable of receiving information from an analog joystick with a potentiometer and its triggers.

Colour Capability

The TIA uses different color palettes depending on the television format used.

For NTSC it has a palette of 128 colors, for PAL it is 104 colors, and for SECAM it is only 8 colors.