When Pac-Man Met Turing > The Game Runs on an Emulated 6502 CPU

As I read the newest papers about DNA-based computing, I had to confront a rather unpleasant truth. Despite being a geneticist who also majored in computer science, I was struggling to bridge two concepts—the universal Turing machine, the very essence of computing, and the von Neumann architecture, the basis of most modern CPUs. I had written C++ code to emulate the machine described in Turing's 1936 paper, and could use it to decide, say, if a word was a palindrome. But I couldn't see how such a machine—with its one-dimensional tape memory and ability to look at only one symbol on that tape at a time-could behave like a billion-transistor processor with hardware features such as an arithmetic logic unit (ALU), program counter, and instruction register.