Having declared that writing simple programs is the best way to describe, represent and understand the shape and patterns of things in the world, we now need to turn to the contemplation of computing machinery. It is traditional to introduce the subject with reference to the Turing machine. This book will follow that tradition by starting with a step-by-step recipe (algorithm) for such a machine. It is based on a JavaScript simulation written by the author and available on the web as a live demo of an adding machine and a pattern recogniser (https://uelceca.net/JAVASCRIPTS/topturing.htm). The mechanics were described by John L. Casti in Reality Rules: II (1992), a very clear and well-illustrated explanation that forms the basis of the algorithm.