This game technically has no end; the player will be given new boards to clear as long as he or she retains at least one life. However, due to a glitch in the game, the right side of the 256th board is a garbled mess of text and symbols rendering the level unplayable. This bug, known as a “kill screen” occurs because of a bug in the subroutine that draws the fruit at the bottom of the screen that indicate the current level. Normally, at most seven fruits are displayed, regardless of the current screen, but since the level number is stored in a single byte, level 256 (100h) rolls over to 0h in the subroutine, and 256 fruit are drawn, corrupting the bottom of the screen and the entire right half of the maze. Enthusiasts refer to this as the “Final Level,” the “Split-Screen Level,” or simply as the ending.
[ on the Pac-Man split screen level, via Wikipedia ]
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