Employment of concrete models to enhance comprehension has been a common approach in teaching abstract subjects such as physics and mathematics. In computer programming, concrete models are still a novelty. Recently there have been plausible attempts to employ models to enhance programming comprehension. In this book, new concrete model called Memory/Mselle Transfer Language (MTL) (invented by Dr. Leonard J. Mselle) is consistently employed to enable the learner and the instructor to reason about his/her code from machine semantics. Such reverse playing is designed to reduce ambiguity and hence facilitate comprehension. Furthermore, in this book, issues are organized and presented in a way that will enable the learner to feel that he/she is “working the machine” and the machine has no influence on what goes wrong on the code.