Commodore Plus 4 - Page 168

186 Some Programming Techniques
Example: 10 INPUT "PROJECT HAME";P$
SO PRINT CHR$(147);"A REPORT ON ";P$
Instead of using the CHR$ code for the CLEAR key, you can type the opening
quote, press the CLEAR key (with SHIFT), and then type the rest of the PRINT
message. The CLEAR key appears in quotes as a reversed heart.
20 PRINT "E2IA REPORT ON ";P$
You can use the SCNCLR command in a program line to clear the screen
during program execution. SCNCLR has no parameters.
Example: 10 INPUT "PROJECT NAME";P$
15 SCNCLR
20 PRINT "A REPORT ON ";P$
Clearing Graphic Mode Screens
To clear a graphic mode screen while you are in a graphic mode, use SCNCLR.
When you issue SCNCLR in a graphic mode, only the graphic mode screen is
cleared. When you issue a SCNCLR command in a text mode, the text screen is
cleared, but the graphic mode screen is not cleared. When you issue a SCNCLR in
a split-screen graphics mode, both the text and graphics mode screens are cleared.
If you are just issuing the GRAPHIC command to enter a graphic mode, clear
the graphic mode screen by adding a ,1 to the end of the GRAPHIC command
(e.g., GRAPHIC 2,1).
You can clear the text screen in a split-screen graphic mode screen by pressing
the CLEAR key (with SHIFT), but this is not the best way to clear this area.
When you press CLEAR, the cursor goes to the cursor-home position—the very
top of the screen, which is not visible in split-screen mode. You have to cursor
back manually to the text window at the bottom of the screen. It is much simpler
just to scroll the text out of the text window by pressing the cursor down key five
times. If you do a lot of work in a split-screen mode, you could set a screen
window consisting of the bottom five (text) lines of the screen. Then, a SCNCLR
command or the CLEAR key would clear only the window and leave the cursor at
the top left of the text area of the screen.
Using the Escape Key Functions to Control the Screen
The Plus/4 has 17 ESCape functions that you can use to edit or otherwise control
the screen. These functions, which are explained in subsequent sections, include
the following types of operations: