Turing Machine Tape

This animation compares two Turing machine tapes side-by-side to show that a head can only stay on the same cell twice in a row if it hits a left-end wall, which only exists on the "textbook" (one-way) tape. It demonstrates that while left moves are blocked at the boundary on the top tape, the bottom "slides" (two-way) tape allows the head to move freely past that point.