A paper system architecture

For disassembling, I could do with a refresher on assembling, and decided to leave yet another trail. Like with operating system concepts, a paper system (a simplified system) is extremely re-useful for grounding the basics, and gives me the benefit of having to consider my word choice such that I can not fly over the subject. My refresher will be thoroughly kinesthetic and emergent.

A paper system of a microcomputer: a small computer with a microprocessor as its central processing unit (CPU), memory, and minimal input/output (I/O) circuitry mounted on a single printed circuit board:

Many microcomputers (when equipped with a keyboard and screen for input and output) are also personal computers (in the generic sense).