GRC | Security Now! Episode Archive
How a Computer Works series:
Let's Design a Computer (part 1) #233
Steve does a very good job of explaining (relatively) technical topics in plain english, and he does so without any visual aids. That being said, I'd recommend listening to the "Design A Computer" series with a piece of paper so you can draw what he describes.
(Note: I am listening to the latest Security Now as I write this.)