Atari Attracts

Phil Griffin


Issue 1

Dec 82/Jan 83

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One of the many excellent features included in the ATARI Computers is the automatic screen protection systems called the "ATTRACT MODE". This system initiates a continuous rotation of colours on the screen as protection against "burn through" which may occur when a colour is displayed for too long without change. The computer monitors the use of the keyboard and will automatically enter the "ATTRACT MODE" if no keys have been depressed in the previous 9 minutes (9. 01 to be precise). As soon as the keyboard is used, the "ATTRACT MODE" is disabled and the original screen colours return.

You may have found that some games, which use only paddles or joysticks, enter into the "ATTRACT MODE" automatically after 9 minutes use. With a little bit of "peeking" and "pokeing" you can discover what causes the "ATTRACT MODE" to begin and, hopefully, how to temporarily disable it while you play your game.

The first thing you need to know is that the memory location which governs whether the "ATTRACT MODE" will be activated or not is location 77. By "peeking" into this location, you can see what is happening during the 9 minutes before the system comes into operation. The following short program should do the trick.

10 PRINT PEEK (77): GOTO 10

This program forms an endless loop which will repeatedly print the contents of location 77. On running, you will see that the contents of this location gradually increase in steps of 1 from 0. If you sat and watched for long enough, you would eventually see something strange happen to the sequence of numbers. To speed things up a little you can add an extra line to the program and run it again to watch the results.

5 POKE 77, 125

This line inserts a value of 125 into location 77 and on running you will see that the values displayed start at 125 and not 0 as previously. This value will gradually increase until 127 is displayed. The next number shown will be 254 and at this point the "ATTRACT MODE" will be activated.

You can see from this that if location 77 contains a value of 127 or less, then the "ATTRACT MODE" will remain inoperative. The ideal situation from a game - playing point of view would be to place a 0 in this location as of ten as possible or at least every 9 minutes. This can be done by including an instruction POKE 77, 0 in a frequently used part of the program (e.g a "movement" or "fire" routine). This will ensure that the attract mode remains inoperative during the course of the game.

As a matter of interest, this is precisely what happens when a key is depressed. If you run the program again and then press a key you will see that the value shown will immediately change to 0 and gradually increase as before. Any subsequent pressing of keys will have the same effect.

If you want to use the "ATTRACT MODE" during one of your own programs this is easily done by issuing the instruction POKE 77,254. The system can then be disabled at the appropriate point by a POKE 77, 0 instruction.