The pre-electric world ?
Around 1840 electricity started to change the way people lived. messages from the electric telegraph (pp. 24-25) begun to replace letters broug by horse or ship, and electric power followed soon after. But machines to help people communicate with each other, control things, and do calculations have existed for a long time. In these simple machines lie the beginnings of some basic ideas used in electronics-principles like logic, amplification, and memory. The machines worked slowly and cost a lot to build and run. Many broke down-their ropes, levers, or wheels wore out in time. Communication devices were primitive. At night, you could signal "yes" or "no" by lighting or not lighting a fire. This idea of a code based on just two possibilities lives on today at the heart of every digital electronic system.