Super FX 2

The Super FX 2 runs while the SNES is running, but the SNES must halt the Super FX 2 to read the results of the Super FX 2's calculations. For this reason it is not considered a parallel processor. This is more than just a pedantic observation, since such definitions effect import and export between countries. As for effects of system performance, the chip gets halted every 1 to 4 cycles of the SNES' 65C816 CPU; meaning that, at best, the whole operation can only deliver slightly less than 20 frames per second. The chip can be overclocked for improved frame rate but this is of course is an unofficial hack that could damage the chip, game, and SNES (no commercial games run the chip above 21.477 MHz). Another limitation is 192 horizontal lines of resolution. The SNES displays 256x224 creating an 8 pixel wide boarder above and below that the chip cannot access. The SNES still can, so, some games fill this area with regular 2D graphics. The SNES also has 512x448 mode, which would require very creative solutions to include Super FX 2 effects.