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Score hold out

Entry posted by Guest August 17, 2005

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The next portion of the score circuit we will look at is what I call the “hold-out” generator. The output of this circuit goes to the enable input of the seven segment decoder chip we discussed earlier. When the enable signal is low, all the outputs of the decoder are turned off. So the scores can only be displayed when the output of this circuit is high. The easiest way to describe how this circuit works is to show it graphically. If we take every point on the screen, feed the horizontal and vertical values into this circuit and plot the output what get this:

You will notice that the black areas line up with where the scores in Pong get displayed. No matter what happens after this, the scores can only appear in these two areas.