ICONPAGE, ICONPMAX, and ICONPUSE (System Variable)

and  are nonnegative integer read-write system variables. is initialized to zero whenever a program begins, and always contains a value betwen 0 and  inclusive. is a boolean read-write system variable.

When a negative value is assigned to, it takes on the value   instead; when any other value is assigned to it, it takes on the value rounded down to the nearest integer.

When a negative value is assigned to, it takes on the value  ; when a number greater than   is assigned to it, it takes on the value  ; otherwise, it takes on the value rounded down to the nearest integer.

If  is , a small upward-pointing button and a small downward-pointing button appear at the bottom of the touchscreen near the right side (just to the left of where the four 'icons' appear). When the user taps the 'up' button,  gets decremented (unless decrementing will give it a negative value), and when the user taps the 'down' button,   gets incremented (unless incrementing will give it a value greater than  ). The up and down buttons have the same auto-repeat as the keyboard (the 'tap' must remain in the button: if the stylus is dragged away, the auto-repeat will stop, and if it is dragged back, the auto-repeat will not resume). Note that the up and down buttons will not disappear with  (and neither will the icons), and if   is   and   is zero, these two buttons are visible, and change their appearances when tapped, but are absolutely useless.

Note that the subsystem comprised of these three system variables and two buttons is independent from the subsystem for the icons, which uses the  and   commands. The four icons displayed on the right are not automatically updated whenever  changes its value. To implement 'pages' of icons, the value of  must be checked regularly, and the four icon spaces updated accordingly with   and. And it is not possible to do this while the system is waiting for user input while executing an  or   command;   will continue to get updated as the user taps the up and down buttons, but it is impossible for the program to update the icons until the user finishes typing and the  /  command is ended.