Also good is Ulrich Drepper's "What every programmer should know about memory". It talks about what happens at a very low level from the CPU registers and L1-3 caches to system memory and disk, and how the OS handles it all.
that one should be required reading for any programmer.
Agreed.
There are a few groups around who still keep this kind of spirit alive. Seeing what the guys in the demoscene can to with 64k is truly amazing, but what they do with 4k can blow your mind.