Getting started to Computer embedded systems

Hi everyone, I would like to learn about embedded systems, memory management, computer architecture or what I would need for build smart electronic devices, so maybe I could design and build my own PC, Smarthphone or whatever else with a OS/software supported system

For example, I'm really intrigued with Flash Memory managment, but I don't know where found Info about how Itself works or how to manage them, even more important and intrigued is a tool for simulate them

My dream is, after...

Getting started to Computer embedded systems