Turn this toggle on when you want QuickBASIC to
  - Run your program at full speed
  - Record the last 20 lines of program code executed
    before a program stops
 
You can then step backward and forward through the 20 lines
of code recorded by History On by pressing SHIFT+F8 or
SHIFT+F10 to review branching and other program actions.
 
Tip: Use History On together with breakpoints to review any
     group of 20 consecutive statements in your program.