One bit of memory
Two NAND gates wired into each other hold an answer after the input goes away. The smallest memory there is, and the reason a switch stops bouncing.
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Digital logic and memory
Build logic from individual gates, then make a bit persist, count and move through a register.
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What you will build
2 projects, built step by step
4 lessons in 2 chapters, about 4 hours on a simulated breadboard. Free, in your browser, every step checked by the simulator.
Eight outputs from three wires
A 74HC595 driven by a clock and a switch, with no processor anywhere. Load a pattern by hand, watch it march, and find out what the latch is for.
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Chapter by chapter
Each lesson opens when the one before it is done, and each chapter ends in a project.
Chapter 1
Decisions and state
Combine gates, then cross-couple them so a circuit remembers one bit.
- Open145 XP
Gates, as real chips
AND, XOR and NOT with two buttons and three lamps. Fill in the truth tables by pressing, and find out what a real chip has that the symbol does not.
0 of 6 steps
- ProjectLocked290 XP
One bit of memory
Two NAND gates wired into each other hold an answer after the input goes away. The smallest memory there is, and the reason a switch stops bouncing.
0 of 6 steps
Chapter 2
Count and shift
Turn stored bits into a counter, then clock a byte through a real register.
- Locked145 XP
Flip-flops that count
A D flip-flop wired to toggle halves a clock. Four of them in a chain count in binary, and the lamps spell out the number.
0 of 6 steps
- ProjectLocked290 XP
Eight outputs from three wires
A 74HC595 driven by a clock and a switch, with no processor anywhere. Load a pattern by hand, watch it march, and find out what the latch is for.
0 of 6 steps
Syllabus
Every lesson in the course
All 4 lessons, in order, each with what it covers. Any of them opens in the editor right away.
Decisions and state
- Gates, as real chipsAND, XOR and NOT with two buttons and three lamps. Fill in the truth tables by pressing, and find out what a real chip has that the symbol does not.
- One bit of memoryTwo NAND gates wired into each other hold an answer after the input goes away. The smallest memory there is, and the reason a switch stops bouncing.
Count and shift
- Flip-flops that countA D flip-flop wired to toggle halves a clock. Four of them in a chain count in binary, and the lamps spell out the number.
- Eight outputs from three wiresA 74HC595 driven by a clock and a switch, with no processor anywhere. Load a pattern by hand, watch it march, and find out what the latch is for.
Keep going
The next course on your track
Digital logic and memory is part of the electrical track, a ladder of courses from zero to expert.
Transistors and op-amps for real
Intermediate, after Electronics basics: the diode curve, biasing a BJT, common-emitter gain, the MOSFET as switch and resistor, op-amp gain both ways, comparators with hysteresis and split supplies.
Open the next courseElectrical track
Current and voltage you can see, then transistors, op-amps, filters, power and PCBs. Every circuit runs in a real circuit simulator in your browser.
See every course on the trackKits
Build it on your bench too
Every lesson runs in the simulator with nothing to buy. When you want the real thing, these kits have the parts.
Logic Lab Kit
Gates, a NAND chip, two flip-flops and a shift register, with no processor at all.
Open the kitFind your kit
Pick the starter kit you own and run every lesson in its manual with the same parts on the same pins.
See every kitQuestions
About Digital logic and memory
Is Digital logic and memory free?
Yes. All 4 lessons of Digital logic and memory are free and run in your browser, with nothing to install and no parts to buy before you start.
Do I need any parts?
No. Every circuit is built on a simulated breadboard, and the simulator checks each step as you go. When you want to build it for real, the same parts and wiring work on a real bench.
How long does Digital logic and memory take?
About 4 hours: 4 lessons in 2 chapters, each one a few short steps. Your progress is kept, so you can stop after any lesson and pick up where you left off.
What will I build?
Each chapter ends in a project that puts it together: One bit of memory and Eight outputs from three wires.
Where do I start?
With "Gates, as real chips", and each lesson builds on the one before it. New to circuits? Electronics basics is the course that starts from zero.