To clear the screen.
n is one of the following values:
Value of n - Effect
0 : Clears the screen of all text and graphics1 : Clears only the graphics viewport
2 : Clears only the text window
If the graphics viewport is active, CLS without argument clears only the viewport. If the graphics viewport is inactive, CLS clears the text window.
If the screen is in graphics mode, the entire screen buffer is cleared to background color.
The screen may also be cleared by pressing CTRL-HOME, or by changing the screen mode with the SCREEN or WIDTH statements.
CLS returns the cursor to the upper-left corner of the screen, and sets the last point referenced to the center of the screen.
If the VIEW statement has been used, CLS clears only the last viewport specified.
This clears the screen.