I can explain to a 35 years old in tech. A modern generalist CPU is made of many smaller, simpler, specialized CPUs : there's a whole orchestra inside. Amongs

I can explain to a 35 years old in tech. A modern generalist CPU is made of many smaller, simpler, specialized CPUs : there's a whole orchestra inside. Amongst those smaller CPUs, there's a master : it'll see to decoding of instruction, sending jobs to the various CPU units, and fetching the results of said jobs. That master is running a program, executing ... microcode ! And of course, if there is a program, there are bugs. CPUs have bugs since CPUs were invented. Microcode itself was present in early CPUs, (say, the Z80), but hardcoded. Nowadays, microcode can be uploaded to a CPU to fix bugs.