MUNCHING SQUARES

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 .]