How Computers Work

Most people who use computers professionally have a gap somewhere in the middle. They know their language and they know roughly what electricity is, and between those two points is a region of vagueness containing the words register, cache, kernel and packet. The gap is rarely a problem, right up until it is — and then it is the reason a bug makes no sense, or a performance decision gets made by superstition.

This course closes it. It is Crash Course Computer Science in order, which builds the machine from the bottom: a switch becomes a logic gate, gates become arithmetic, arithmetic plus memory becomes a processor, a processor plus instructions becomes something you can program. Nothing is assumed and nothing is skipped, and by the fourth module you can trace a line of code down to electrons without any step being magic.

The order is the whole value. Each episode is about eleven minutes and each one genuinely uses the last, which is why watching three consecutive episodes teaches far more than watching three interesting ones. It is also why this works as a course and not merely as a playlist.

The later modules cover the parts you interact with daily and understand least — operating systems, file systems, and then networks and the internet as a stack of layers rather than a single thing. About four hours in the core sequence, in eleven-minute pieces, which makes it unusually easy to finish. The optional lessons go a great deal deeper on the three topics that most reward it — how a processor physically works, what an operating system is actually doing, and how networks stack up into the internet — and take the pool to around fifty-six hours. It pairs well with the programming courses here: take it before if you like knowing why things work, or after if you would rather see the machinery once the code is familiar.