Fundamentals
The physical foundation: the transistor as a voltage-controlled switch, the four values a wire can carry (0, 1, Z, X), and why every CMOS gate is a complementary pull-up and pull-down pair.
The transistorA switch you control with a voltageEverything in this course is built from one part: a voltage-controlled switch.The build, name, reuse ladderThe one move this whole course repeatsEvery level of digital design uses the same move: build a thing from smaller things, verify it, name it, then reuse it as a single block.Signals: 0, 1, Z, XThe four values a wire can carryWires can carry more than just 0 and 1. Learn what floating (Z) and contention (X) mean and why mixing them up causes real bugs.Complementary CMOSWhy gates use both NMOS and PMOSEvery gate in this course is built from a PMOS pull-up network and a complementary NMOS pull-down network. Understanding this skeleton makes every gate obvious.Designing gates from truth tablesA repeatable method for any static CMOS gateGiven any truth table, you can mechanically derive the pull-down and pull-up transistor networks. Series transistors enforce AND conditions; parallel transistors enforce OR conditions.Wires, nets, and junctionsHow signals travel and branch through a circuitA net is everything electrically connected. Wires cross without joining unless a junction dot is present. Branching a signal to many gates is safe; driving a net from two sources is not.