clear screen -- erases the text window

clear screen
*** requires ncurses support compiled in ***
See Documentation/Advanced for info. 

clear screen erases the text window (the window where the output of print appears).
It must be issued at least once, before some advanced screen-commands (e.g. print at or inkey$) may be called; this requirement is due to some limititations of the curses-library, which is used by yab for some commands.

clear screen 
print "Please press a key : "
a$=inkey$ 
print a$ 

The clear screen command is essential here; if it would be omitted, yab would issue an error ("need to call 'clear screen' first") while trying to execute the inkey$-function.

Start this program in a terminal.