The book itself is pretty straight forward, taking the reader through the development of the 2600, then into a selection of games that illustrate certain aspects of the market and finally wrapping up with a bit about the end of the Atari-era in 1983/84.
When released in 1977, the 2600 was not the first console or even the first to use cartridges -- that honour probably goes to the long-forgotten Fairchild F VCS and Magnavox Odyssey systems -- but it was the first to find widespread popularity. Part of this popularity was the price: when personal computers like the Apple 2 or Commodore PET sold for around $1300 (U.S.), the 2600 when for about $200. This price was barely above the cost of manufacturing the system -- with the intent to make the profit on game sales -- a then-uncommon strategy for computers, but now standard for game consoles. In order to get the system down to that price a number of compromises had to be made from reducing on-board memory down to a mere 128 bytes of RAM (personal computers of this era had 2-4KB of memory) and a low-cost (the MOS 6507 at $25 dollars as opposed to $200 for similar chips) processor. Where they did spend money was on the developing the TIA (Television Interface Adaptor) chip that was going to provide graphics and sound for the system. This was an early design by Jay Minor and Joe Decuir. Jay Minor went on to develop other chips for Atari including those for the Atari 800/400 personal computers and later designed the Amiga computer system. Because of the lack of memory, TIA couldn't hold a full screen's-worth of data, instead it worked line by line in colour cycles (roughly analogous to a pixel). Sound was equally primitive, as one developer discovered, "[it missed] most of the Chromatic scale." meaning that it was difficult to re-create familiar Western tunes.
So even against the standards of mid-70's personal computers, the 2600 was quite primitive. However, over its lifespan developers found ways to at first, work within the constraints of the system, and by the late 1970's discovered ways to get around the limitations. While the TIA was simple, it also was flexible. A case in point was the "draw and forget" nature of its graphics meant that after it it had drawn something, it wouldn't complain if you told it to draw something again at a different position. For a system that was designed to play games like Pong, with maybe three things moving on the screen, this meant the system could be "tricked" into doing a lot more than what it was designed to do.
Games and Times
It wasn't until about 1980 -- four years after its arrival -- that some of of the more visually interesting games appeared. Part of this is probably due to the rivalry between Atari and Activision, a company started by ex-Atari developers. Activision was born when several Atari programmers realized they where being paid about a $20,000 dollar salary for work that was earning Atari millions. Activision and the companies that followed became the first third-party developers, something Atari had not expected to happen and it's probably this more than anything that caused them problems later. Later console makers assumed there would be third party developers, but made sure they created approved content through various legal and technical steps that Atari did not have available at the time.
End of an Era
Two licenced games PacMan, and Star Wars: The Empire Strikes Back are examined as examples of licencing familiar characters to home video games. PacMan did poorly for a number of technical reasons -- simply the 2600 was not really designed for that kind of game -- and and unrealistic development schedule. The Empire Strikes Back, also released in 1982, did much better and is still held up as a one of the better licensed games, probably because there was time given for proper development. Unfortunately there was a third licenced game released in 1982: E.T. the Extra-Terrestrial which gave rise to the rumour of a landfill in New Mexico being filled with un-sold E.T. cartridges - which is partly true according to the book. While Atari still exists as a brand-name, 1983 saw the end their dominance and the arrival of Nintendo who would benefit from Atari's experience.
Racing the Beam looks at the development of the 2600 and some of the games that illustrate certain events in the history. There is a lot of technical material here that could be gleaned from Atari fan sites, but this book condenses it down to about 150 pages that capture a lot of why the 2600 and Atari where important in creating the home video game industry. There's a great quote on the back cover by one-time Atarian Chris Crawford that sums the book's purpose up nicely, "game designers should study this book for the same reason that modern generals study the military campaigns of Alexander and Caesar: the technology is completely different but the principles are the same."