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munching squares

munching squares: n. A display hack dating back to the PDP-1
   (ca. 1962, reportedly discovered by Jackson Wright), which employs
   a trivial computation (repeatedly plotting the graph Y = X XOR T
   for successive values of T --- see HAKMEM items 146--148) to
   produce an impressive display of moving and growing squares that
   devour the screen.  The initial value of T is treated as a
   parameter, which, when well-chosen, can produce amazing effects.
   Some of these, later (re)discovered on the LISP machine, have been
   christened `munching triangles' (try AND for XOR and toggling
   points instead of plotting them), `munching w's', and `munching
   mazes'.  More generally, suppose a graphics program produces an
   impressive and ever-changing display of some basic form, foo, on a
   display terminal, and does it using a relatively simple program;
   then the program (or the resulting display) is likely to be
   referred to as `munching foos'.  [This is a good example of the
   use of the word foo as a metasyntactic variable.]