Classic Computer Magazine Archive COMPUTE! ISSUE 55 / DECEMBER 1984 / PAGE 10

Atari Attract Mode

I own an Atari 1200XL. So far, I have programmed two games in BASIC, but there is one problem I haven't solved. After about 8–10 minutes of play, the screen starts to change colors. Is there any way to get around this annoyance? Also, I heard that Atari has a contest for amateur programmers. Have you heard anything about this?

John Hnat

The Atari computers incorporate the color shifting to protect the screen from damage. Normally, you have nothing to worry about, since TV images change constantly, but theoretically an image could burn itself into the phosphor if left displayed unchanged for a long period of time. Back in the early days of Atari computers, rumors about this problem were seized upon by the public and blown all out of proportion. To allay fears, all Atari machines have this color shifting protection built-in. If the keyboard has not been touched for 8.5 minutes, all the colors cycle at a reduced brightness. This constant color shift prevents any one image from burning into the TV screen. However, we have never seen a documented case of a home computer damaging a television due to long exposure. Incidentally, the color shifting is called attract mode, named after the way arcade games will play automatically to attract customers.

Every four seconds, memory location 77 is incremented by one. When it reaches 128, attract mode starts. To prevent attract mode, POKE 77,0 periodically. If you want to preserve the intention of attract mode, perform this POKE only when the player makes some action, as in moving the joystick. If you are playing a game that does not disable attract mode, you can press any key to stop the color shifting. Sometimes a keystroke interferes with a program, but you can often press the inverse video key (which doesn't generate an ATASCII keystroke) twice to cancel attract mode while a program is running.

The Atari Program Exchange (APX), which has been recently discontinued, was a potpourri of user-written programs. You would send your program for consideration. If it was good enough, Atari would market your game through the APX catalog. There were also quarterly prizes in several categories for the best programs received, and the famous Atari Star award was given once a year for the best program overall. The prize money ($25,000) gave the first Atari Star winner Fernando Herrera the impetus needed to start his own software company, First Star Software. IBM has started a similar mail-order service for the PC and PCjr, called Personally Developed Software.