

What do flashlights, the British invasion, black cats, and seesaws have to do with computers? In CODE, they show us the ingenious ways we manipulate language and invent new means of communicating with each other. And through CODE, we see how this ingenuity and our very human compulsion to communicate have driven the technological innovations of the past two centuries. Using everyday objects and familiar language systems such as Braille and Morse code, author Charles Petzold weaves an illuminating narrative for anyone who’s ever wondered about the secret inner life of computers and other smart machines. It’s a cleverly illustrated and eminently comprehensible story—and along the way, you’ll discover you’ve gained a real context for understanding today’s world of PCs, digital media, and the Internet. No matter what your level of technical savvy, CODE will charm you—and perhaps even awaken the technophile within.
A glimpse inside

Petzold frames the story of computers as fundamentally about communication. He draws parallels between language, signals, and codes—like Morse and Braille—to show that computers are extensions of humanity’s drive to encode, transmit, and process information. By grounding digital technology in familiar systems, Petzold makes the leap from everyday communication to binary logic feel natural and intuitive.
The book meticulously traces how simple on-off switches (relays, light bulbs, telegraph keys) can be combined to create logical operations. Petzold walks readers through the construction of basic logic gates and circuits, demonstrating how complex computation emerges from the humble binary state. This hands-on, bottom-up approach demystifies how hardware can 'think' using nothing but electricity and clever arrangement.
Ratings at a glance
- 1Communication as the Root of Computing
- 2From Switches to Circuits: Building Blocks of Logic
- 3Binary: The Language of Machines
- 4Layering Abstraction: From Hardware to Software
- 5Demystifying the 'Magic' of Computers
