Computers are often divided into two types: digital or analog. The fundamental difference between digital and it is generally accepted that analog computers contain information processing. In a digital computer, information is presented in discrete-form elements and the computer goes through a series of discrete states. In an analog computer, information is presented continuously in sizes and the computer processes the information continuously. AND considers this a valuable distinction as long as it is understood that way in the distinction was made on a symbolic level and not on a physical level Understanding the computer. Treated as strict physical descriptions, the digital and analog functions would be very confusing. Alan Turing makes the point about discrete-state machines well.