Graphical effects taking advantage of the way
raster scan video works. (Drawing the screen in lines starting at the top right.) Done by changing the contents of the
video memory or graphics
registers as the screen is drawn, to do weird stuff like displaying more colours onscreen than a machine is capable of through changing the
palette register, or vertical
scaling by moving an image about as the screen is drawn. Examples being
copper bars, the fake
transparencies in
Gunstar Heroes and the roads in many an 8 or 16-bit
racing game. Very popular with
demo coders
The raster in Axeley is so kewl that it convinced two people (possibly more) to buy a SNES
See also: raster interrupts