There are different articles about principles of automatics, computers…
The first one-“Preliminary Automatics Course” is a flagship. It’s big like Gulliver. The main advantage is a virtual laboratory. You test all you can read! Other such courses are rarely equipped with this tool!
The other articles are Lilliputians next to the first.  The used animation enables easy subject understanding.
I am thinking about the next ones. It’s nice to return to it during
Notes
1. Previous name of “Preliminary Automatics Course” was a “PID control with laboratory”
2. “Preliminary Automatics Course” in polish language–>click
p,s. There are photos of my bike trips in every article. It’s nice to reminisce during dark raining days.