Ken Shirriff has been working hard lately. In two great reads, he presented details from the classic CPUs 6502 and 8085. Basically, what he does is that he picks apart the overflow flag of the 6502 and the ALU of the 8085 in very, very, very great detail. For the 6502, he actually shows the wires and junctions on the silicon.
All the information comes from the Visual 6502 project, but the interpretation and explanation is all Ken’s. Great read, and nice to see that a full CPU really only consists of the basic components everyone can grasp.