Computers are everywhere – their presence is certainly more evident with laptops and smartphones, but they are also found in cars, televisions, microwaves, alarm clocks, robotic vacuum cleaners, and other smart devices. Have you ever wondered what goes on inside all these devices to make our lives easier – but, at times, also to complicate them?

For more than 20 years, readers have enjoyed Charles Petzold’s enlightening book about the secrets hidden within computers. Revised for this new era of computing, with smart illustrations and accessible language, this book unravels every mystery. You will discover what lenses, black cats, seesaws, and the "midnight ride of Paul Revere" can tell you about computers – and how human ingenuity and our need to communicate have played a crucial role in the design of every electronic device we use.

This new expanded edition explores more deeply the structure of bits and gates that lie at the core of every smart device – the central processing unit that combines the simplest basic operations to achieve the most complex feats. In addition to the new chapters he has added, Petzold has also created a new website, CodeHiddenLanguage.com, where animated interactive graphics make understanding computers even easier.

From the simple ticking of clocks to the global hum of the Internet, the book "Code" reveals the essence of the digital revolution.

Contents:

• The Two Friends
• Codes and Combinations
• Braille Code and Binary Code
• The Anatomy of a Lens
• Communication in Every Direction
• Logic with Switches
• Telegraphs and Electromechanics
• Electromechanics and Gates
• Our Ten Digits
• Alternative Tens
• Bit by Bit by Bit
• Byte and Hexadecimal System
• From ASCII to Unicode
• Addition with Logic Gates
• How Does It Really Work?
• But What About Subtraction?
• Feedback and Hesitation
• Let’s Build a Clock!
• Assembling Memory
• Automating Arithmetic
• The Arithmetic Logic Unit
• Registers and Buses
• CPU Control Signals
• Loops, Jumps, and Calls
• Peripherals
• The Operating System
• Writing Code
• The Global Brain