I’m researching good resources to explain to students how CPUs work. I came across a book called “But How Do It Know? – The Basic Principles of Computers for Everyone”, which seems to cover the subject really well, with more specific detail than most other resources (which offer over-simplified descriptions of “Fetch-Decode-Execute” cycles making it difficult to appreciate what’s really happening inside the CPU).
The book talks through a conceptual processor, the Scott CPU. Some people have created emulations of the Scott CPU, including this one created in an Excel spreadsheet. Now, I’ve seen some amazing things done in Excel, but this one is unbelievable. Watch the video and be amazed as it churns through assembly code and lights up bus lines and registers to show the instructions being executed.