Mar 152011

Every couple of years, I pull out a particular book that’s been sitting on my bookshelf for the past decade, read it, and am suddenly refilled with the passion of computers and computing science. This book is Code: The Hidden Language of Computer Hardware and Software, authored by Charles Petzold.

This book is perfect for those who never did an EE or CS degree at university, and want to know exactly how and why computers work. I’m sure a lot of DBAs fall into this category! Petzold takes us on a wonderful journey, on how communication is encoded into our lives, and focussing particularly on digital codes – binary.  Starting with the most simple concepts (communicating simple messages with flashlights and Morse code over short range), new concepts are introduced in simple, logical steps. From the flashlights, electricity is introduced, and a telegraph system is designed.

From Morse code, we are introduced to Braille and to UPC barcodes, all tied together with the theme of binary logic – the information can be coded by a series of ones and zeroes.

The book slowly builds up these concepts in an easy to follow fashion, using telegraph relays to build logic gates, through to a machine that can add two binary numbers, and finally culminates in a design for a theoretical general purpose, programmable computer.

From there, the concept of a transistor is introduced, the Intel 8080 and the Motorola 68000 CPUs are examined in detail, and it’s then a whirlwind of fast logical steps from machine code, to assembly, to higher level languages, operating systems and file systems (with a reasonably detailed look at CP/M). Finally, modern (well, 1999) graphical operating systems are examined, along with how various types of information are stored – graphics formats, sound formats, video, and HTML.

The book doesn’t go into networking protocols (except for a brief couple of paragraphs on modems), but it is easy to extrapolate how computers can talk to one another from the previous concepts.

All along the way, Petzold sprinkles in the history of computing, and the entire story is woven in a very engaging tone. Every time I read this book, I’m reawakened to the beauty and underlying simplicity (underlying – there’s nothing simple about 10 million transistor processors!) of computing.

Highly recommended!