Computing Hardware

Chapter 2 presents a kind of computation currently unfamiliar to most, the analog computer. Fifty years ago, they were considered viable competitors to the newer digital computer. Analog computers compute by the use of physical analogs, using, for example, voltages, currents, or shaft positions to represent numbers. They compute using the device properties, not logic. Examples include the balance, a simple device known for millennia; the “Antikythera mechanism,” a complex astronomical calculator from the first century BC; the slide rule; the US Navy’s Mark I fire control computer used for much of the 20th century to aim naval gunfire; and electronic analog computers built in large numbers after World War II. Analog computers can have advantages in ruggedness, simplicity, and reliability but lack the flexibility of digital computers.