Discover what is really inside your computer! Astound your enemies with your intimate knowledge of the x86 cache hierarchy! Amuse your friends with your deft application of memory-mapped I/O! Push your BIOS to its limits, and serve up EFI for dessert! In this course, we will discuss the essential components of a modern computer, from registers to RAM, from cache to keyboards. We will describe the basics of how all of these work, and how they interact to give you the ability to use Facebook. We will also explore what actually happens from when you press the power button to when you see the OS logo. If you want to write your own operating system or build your own computer, this course will help you take the first steps. Or if you want to know which pieces you can pull off the motherboard without an explosion, this is the course for you.