This book made me understand pointers. As I read it, I followed along building all the circuits in Logisim [1] from half-adders to latches to multiplexers all the way up to a full CPU.

Many will probably recognize the author, Charles Petzold [2], from his Windows programming books.

[1]: http://www.cburch.com/logisim/

[2]: https://en.wikipedia.org/wiki/Charles_Petzold