This is NOT a shallow subject. What are you MOST interested in learning about? For general knowledge, you can find out a lot on Wikipedia, but for more in-depth knowledge, that requires extensive study. I've been working professionally with this stuff for 30+ years, and am still clueless about a lot of it! Consider that I have been factory trained by IBM, Compaq, AT&T, Sun, Apple, and others, and have been a systems-level software engineer for most of those 30 years, and am currently Senior Systems Engineer for a tier-one mobile phone manufacturer!