Code: The Hidden Language of Computer Hardware and Software
Code: The Hidden Language of Computer Hardware and Software (1999) is a book by Charles Petzold that seeks to teach how personal computers work at a hardware and software level. In the preface to the 2000 softcover edition, Petzold wrote that his goal was for readers to understand how computers work at a concrete level that "just might even rival that of electrical engineers and programmers".

The idea of writing the book came to him in 1987 while writing a column called "PC Tutor" for PC Magazine.

Content 
Petzold begins Code by discussing older technologies like Morse code, Braille, and Boolean logic, which he uses to explain vacuum tubes, transistors, and integrated circuits. He noted that "very smart people" had to go down the "dead ends" of mechanical computers and decimal computing before reaching a scalable solution—namely, the electronic, binary computer with a von Neumann architecture. The book also covers more recent developments, including topics like floating point math, operating systems, and ASCII.

The book focuses on "pre-networked computers" and does not cover concepts like distributed computing because Petzold thought that it would not be as useful for "most people using the Internet", his intended audience. Specifically, he said in an interview that his "main hope" in writing Code was to impart upon his readers a "really good feeling for what a bit is, and how bits are combined to convey information".

Reception 
Software engineer and blogger Jeff Atwood described Code as a "love letter to the computer".

See also 
 Bit
 Computer memory
 History of computing hardware

References  

1999 non-fiction books
Computer books
Computer science books
Computer programming books
History of computing hardware
American non-fiction books