clear also reassigns the
gfx globals to
display(5) respectively, and moves the text cursor to row 25 (top of the screen).
clear method is defined in
clear changes all eight display modes back to their default modes, it makes no sense to set up some other display type (for example a TileDisplay) that you want to use and then call clear. Doing so would just switch off the display you had set up. Moreover,
clear does not clear non-standard displays; it only turns them off.
As a result of the above, in most programs
clear should be called very early in the program, and certainly before you start setting up any displays.