DanBoris' Tech Blog - Attract Mode

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The next thing I want to talk about is the attract mode, which is the mode the game is in when it’s not being played, designed to “attract” new players. Most of the schematics for this section I have posted already, so I will just describe how attract effects each section. The attract signal is generated by the game control circuit and is fed as both an active high and active low signal to various other circuits in the game.

 

In the paddle circuit, /ATTRACT holds the preset pin of flip-flop H3 low, which holds pin 6 low and thus the output of NAND gate G3 high, which prevents the paddles from being displayed.

 

While in attract mode the ball will bounce continuously around the screen bouncing off not just the top and bottom of the screen, but of the sides. The vertical ball control works pretty much the same as in play mode, but the ATTRACT signal hold the A5 and B5 flip-flops cleared which is equivalent to the ball having hit the top part of the paddle. This keeps the ball moving vertically at its sharpest angle.

 

In the horizontal direction when the ball goes off either side of the screen the /MISS signal goes low as usual, but the /ATTRACT signal on the input of NAND gate E1 prevents the MISSED from going low, which prevents the score from incrementing. The /MISS signal will trigger timer G4 which brings the signal SC high and reverse the balls direction through NAND gate C1, but unlike in play mode, the /ATTRACT signal will prevent the horizontal ball counter from being cleared so it will always be displayed. I neglected to show this particular gate in the Ball Horizontal Counter circuit, so here it is.

 

 

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