Emphasis on 8. If you are writing code that directly controls hardware, then your software is the abstraction. Hardware is physical and can be quirky. Signals

Emphasis on 8. If you are writing code that directly controls hardware, then your software is the abstraction. Hardware is physical and can be quirky. Signals take real clock time to settle down and your CPU is probably much faster than the transition time. Hardware can and does have bugs just like software. A bad ground pin can make your hardware do “impossible” things. You need to have much more awareness of the context your code runs in the further down the stack you go.