The Computer Graphics Screen

Remember the SCREEN statement:

SCREEN 12

This sets up the graphics hardware and selects mode 12. Selecting mode 12 is like selecting a sheet of graph paper. When you select mode 12 you get:

• A range of X from 0 to 639.
• A range of Y from 0 to 479.
• 16 possible colors for pixels.

(Don't memorize these numbers. But look at them to understand get some idea of what you can do.)

With 640 columns and 480 rows you have 640 times 480 squares on the graph paper. Or, there are 640 * 480 = 307,200 pixels on the graphics screen. If you had actual graph paper with this many columns and rows, the squares on the paper would be very small.