Almost everything I know about computer design I learnt on the internet. Below are listed some of the pages which helped me build my machines:

Relay Computers

Jack Kilby's Relay Computer  Taught me almost everything I needed to get started with computers.

Harry Porter's Relay Computer


Core Memory

Magnetic core memory reborn

Magnetic core memory systems


If I'm honest, probably the majority of what I know came from Wikipedia. It's a good site!