Course · Computer science
Computer science.
How a machine of switches sorts, searches, keeps secrets and learns, from bits and logic gates to machine learning.
The course, unit by unit
Units
10 units · 41 lessons · about 17 hours
Jump to a unit 10
Unit 1 · 4 lessons
Bits and data
Bits and bytes, counting in base 2 and base 16, and how a computer stores colour, pictures and text as numbers.
Unit 2 · 4 lessons
Logic gates
AND, OR, NOT and XOR, truth tables, and how a few gates add two numbers, up to a processor's arithmetic unit.
Unit 3 · 4 lessons
How a computer runs a program
A toy eight-bit processor, one tick at a time: memory, instructions that are numbers, the fetch–execute cycle, and loops.
Unit 4 · 4 lessons
Algorithms and efficiency
Comparing algorithms without a stopwatch: four ways to sort, searching by halving, and big-O notation.
Unit 5 · 4 lessons
Graphs and networks
Nodes and edges: the bridges of Königsberg, the shortest route through a network, packets, and PageRank.
Unit 6 · 5 lessons
Information and codes
How much information a message holds: surprise in bits, entropy, the limit of compression, and codes that repair errors.
Unit 7 · 4 lessons
Cryptography
The mathematics of secrets: modular arithmetic, primes, key length, and agreeing on a key over a channel everyone hears.
Unit 8 · 4 lessons
Computability
What it means to compute: a Turing machine, a question no program can always answer, and the Game of Life.
Unit 9 · 4 lessons
Machine learning
A computer that learns from examples: a line fitted to data, a neuron, training a network, and how a language model writes.
Unit 10 · 4 lessons
Computing in the real world
Earlier Units at work: ray tracing, a pole balanced by feedback, a robot arm, and a quantum computer that searches.