Pac-Man has a bug in it that prevents it from being completely finished. This bug occurs at the 256th board, where it will cause an overflow in the the 8-bit byte distinct values. As a result, the final board is unplayable, with the right half replaced by a series of garbled symbols and letters.
How do you do this glitch?Edit
It's extremely hard to do this glitch unless you have extreme patience and dedication. You have to play up to the 256th board which can take up to 6 hours of non-stop playing. You can also use an emulator and skip to it.
Why does this glitch happen?Edit
While probably not the first game to suffer from a kill screen, Pac-Man's is possibly the most famous. Pac-Man's level counter was a single 8-bit byte, and could therefore store only 256 distinct values because in binary, the highest number you can store with 8 1s is 255, add 1 and it becomes 0000000 or 0. Players who reached the 256th board would in fact overflow this counter and end up playing board zero — something the fruit counter's logic was not designed to handle. The fruit counter said "Okay, take the level number, and subtract one and then draw a fruit. Now is the level number zero? If no, repeat. If yes, start." The problem is, 0 - 1 = 255. So 256 fruits are drawn. Causing the drawing routine to show glitch symbols since it is tying to take other data as graphics. The final board was unbeatable, with the right half replaced by a series of garbled symbols and letters. With most of the dots are gone, the game still thinks "Okay, the number of dots pac-man ate isn't enough, keep going." (directly from Wikipedia and other sites)
How can I prevent this glitch? Edit
You can't with normal arcade machine versions. Some versions, however, have a board reset after completing the 255th board, meaning you start again at the first board with your score staying the same as you left it before the reset. This allows you to continue with the game without being attacked by the bug. However, this is assuming that you would actually WANT to complete the game, and not encounter the glitch. Donhodges.com also has a fix for the glitch.
So what does this mean for me? Edit
- It means you can only get about 3,333,360 points. It means you can't play this game forever.