https://lwn.net/Articles/250967/ - 'What every programmer should know about memory' is a very in-depth series of articles mostly about RAM, but also CPU Cache and general performance. While it is 10 years old, memory technology hasn't kept up with CPU speeds, and it is often a bottleneck - perhaps making the articles even more relevant today.
http://paulgraham.com/articles.html - I feel like every reader of Hacker News must have come across this at some point, but it's still worth bringing up. Paul Graham writes about start-ups, LISP, about technology in general, and sometimes about society.