Digital Logic Design
Logic design lives in waveforms, not in prose. These topics drive real inputs through gates, latches and counters, and show the outputs settle.
Start from the beginning →8 topics you can watch now, 16 still to come.
Foundations
Why a computer is built out of two voltages, and the handful of gates that is all you get.
- Why Digital, and Why BinaryStart here. Send one value down a noisy wire as a level and as a bit, and only one of them survives.
- Logic Gates and Truth TablesSeven gates, seven truth tables — and the proof that you only ever needed one of them.
- Positive and negative logic
- Fan-in, fan-out and propagation delay
Number systems
Every value a circuit holds is a pattern of bits you chose.
- Counting in Any BaseWatch the column weights re-scale from 1000-100-10-1 to 8-4-2-1, and hex stops being a separate system.
- Signed Numbers and Two's ComplementThree ways to write −5, and only one of them lets the adder you already built be correct.
- BCD and Gray code
- Floating point representation
Combinational logic
Output depends only on input, right now, with no memory.
- Boolean Algebra and De Morgan's LawsFour lines of algebra turn a three-gate circuit into a piece of wire — and De Morgan drawn as two schematics.
- K-map SimplificationGroup the ones and watch variables cancel. Includes the wrap-around groups everybody misses.
- Adders and Carry PropagationFollow the carry across four stages one gate delay at a time, and see exactly why lookahead exists.
- Multiplexers and DecodersMove the select lines and watch the route move — then wire a truth table into the data inputs.
- Quine-McCluskey
- Comparators and parity generators
Sequential logic
Add a clock and a feedback path, and the circuit can remember.
- SR, JK, D and T flip-flops
- Setup and hold timing
- Registers and shift registers
- Synchronous counters
State machines
Designing behaviour as states first, then as a circuit.
- Moore vs Mealy
- State diagram to circuit
- State minimisation
Memory and logic families
How a bit is physically stored, and what that costs.
- ROM, PLA and PAL
- SRAM vs DRAM cells
- TTL and CMOS