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To SET a dot (turn a dot ON) or UNSET a dot (turn a dot OFF) you must know how to find the correct bit in the character memory that you have to set to a 1. In other words, you have to find the character you need to change, the row of the character, and which bit of the row that you have to change. You need a formula to calculate this.

We will use X and Y to stand for the horizontal and vertical positions of a dot, The dot where X=0 and Y=0 is at the upper-left of the display. Dots to the right have higher X values, and the dots toward the bottom have higher Y values. The best way to use bit mapping is to arrange the bit map display something like this:

Each dot will have an X and a Y coordinate. With this format it is easy to control any dot on the screen.

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This page has been created by Sami Rautiainen.
Read the small print. Last updated May 12, 2002.