Apple's biggest Advantage in the technology industry

Since the computer technology industry is changing ever so quickly, one has to wonder how Apple has made it through the decades and stayed a major competitor in the consumer market. The past 10 years have showed that Steve Jobs had a rare gift of understanding the whole computer industry perfectly. His/ Alan Kay's idea that a good software company should also make its own hardware, is being slowly copied and accepted by other companies that didn't think so, such as Microsoft(Microsoft Surface) and Google( Nexus 7). There are several other examples of how Steve Job's computing Philosophy has been vindicated such as the success of the iPhone, the iPod, etc.

One thing that really stood out for me was this:

"I've always wanted to own and control the primary technology in everything we do." Steve Jobs

BusinessWeek online, October 12, 2004

It seems Apple has always been situated strategically in the Technology industry, such that recent tech successes such as Google with its search, Facebook and Twitter with their social networking revolution, haven't threatened its core business. While several other companies such as Microsoft, Yahoo and RIM have suffered seriously in recent years.

And it also seems that the philosophy has been carried on to the next management team:

“We believe in the simple, not the complex. We believe that we need to own and control the primary technologies behind the products we make, and participate only in markets where we can make a significant contribution.” Tim Cook

I have just one question, Is there any book or article about tech companies and their primary technologies?