In episode 5 of Quantum Consciousness, Justin Riddle answers the question, what is a digital computer? An understanding of how digital computers work is essential to discussing consciousness. Fundamental to the digital computer is the creation of solid states within a universe teeming with quantum fluctuations. Topics for today: Alan Turing's model of a computer, David Marr's three levels of analysis of information processing, the creation and maintenance of solid-states, how digital computation highlights the measurement principle of quantum mechanics, logic gates within central processing units, de-mystifying computer software, and the limitations of automation.