Operating Systems: Software to facilitate running programs on some hardware. But how is operating system software different from other complicated systems such as compilers, editors, integrated development environments, etc.

Operating system code is event driven; that is, o.s. code executes in response to events rather than being executed directly the way a compiler is.

Approach 1: Could study the general concepts that most operating systems have in common. That is, abstract away many of the details.

Approach 2: Examine general concepts, but then probe how they are implemented in a real operating system.

We will attempt to take the second approach.

What real OS? Until recently, details (e.g., source code) of Windows, not available.

Linux source available is available, and a good deal of examination and explication of its structure.

Both are committed to be robust, production operating systems.

This goal tends to make a full understanding of how various components work together quite opaque.