GTIA

Over the coming months you'll be hearing more and more about GTIA, the new television interface chip. It is designed to replace the CTIA chip in all ATARIs currently on the market. In fact if you purchased your machine after January 1982, chances are you already have the GTIA installed. The rest of us will probably get a chance to purchase it as an upgrade.

The GTIA provides three additional graphics modes. These modes are variations of the normal Graphics 8 mode you are probably familiar with. The difference is that each pixel is 2 color clocks wide and 1 scan line high. This gives an effective resolution of 80 horizontally and 192 vertically. This is an unusual pixel size, wide and flat. The "pixel" or picture element is the smallest dot that can be manipulated on your television screen. The pixel size varies depending on the graphics mode chosen.

The three new modes are known as modes 9, 10 and 11. Graphics 9 allows 16 different luminances of the same hue (color). Graphics 10 allows 9 different colors and independent luminances. Graphics 11 allows 16 different colors and one luminance.

The additional colors available with GTIA will make some interesting effects possible. We plan to fully explore this new graphics enhancement in future issues.