For someone starting up into embedded systems this book is excellent. For an experienced developer this book makes for a nice bedtime read. The hardware overview is something that all software developers should understand but many don't take the time. Who needs an RTOS ? In todays fragmented embedded world, where we have 8051's at one end, and StrongArms or Power PC's at the other end of the spectrum, David Simon does a good job of presenting the available options. Table 5-1, "Characteristics of Various Software Architectures" is worth the price of the book. My only real complaint is that on the cover of the book the word 'kernel' has been spelled as 'kernal'.