NAME
  PEN Function

SYNOPSIS
  PEN(n%)
      o n%    Specifies the information to be returned about light pen status:
              n%    Returns
              --    ---------------------------------------------------------
              0     Whether pen was used since last call (-1 if yes, 0 if no)
              1     The x screen coordinate of the last pen press
              2     The y screen coordinate of the last pen press
              3     The current pen switch status (-1 if down, 0 if up)
              4     The x screen coordinate where the pen last left the screen
              5     The y screen coordinate where the pen last left the screen
              6     The character row of the last pen press
              7     The character column of the last pen press
              8     The character row where the pen last left the screen
              9     The character column where the pen last left the screen

DESCRIPTION
  Returns the status of the light pen.

  Example:
      DO
        P = PEN(3)
        LOCATE 1, 1: PRINT "Pen is ";
        IF P THEN PRINT "down" ELSE PRINT "up  "
        PRINT "X ="; PEN(4), " Y ="; PEN(5); "  "
      LOOP

SEE ALSO
  PEN Statement ON PEN SCREEN Statement Screen Modes