It has been a full two-and-a-half years now since we first saw the game-playing TASBot (short for tool-assisted speedrun robot) take full control of a Super Mario World cartridge. In that time, you would think we would have gotten tired of seeing the machine mangle classic games using nothing but data sent through the controller ports on actual gaming hardware.

Then last week’s Summer Games Done Quick speedrunning marathon came along, and on Saturday, TASBot showed off its newfound ability to beat Super Mario Bros. 3 in less than a second (the marathon run had some padding, so it’s actually visible to the audience). Our jaws were on the floor once again. There must be some sort of trick. How in the world is this possible?

Exploiting a decades-old hardware bug

The graphical glitches here are a result of some bits of memory that SMB3 fails to initialize at the beginning of the game.

TASBot’s newest bit of game-breaking magic relies on the vagaries of the NES’ DPCM (differential pulse code modulation) sound channel. This one-bit data stream was used to play extremely basic audio samples in select games, including Super Mario Bros. 3.