Building an AND Gate

In the last lesson I gave you the setup. This time, I’m handing you the tools and stepping back — you’re going to build the next gate yourself.

Here’s the trick. The N at the front of NAND is doing all the work. NAND literally means not AND — it’s an AND gate with its output flipped. That’s the only thing standing between a NAND and a regular AND.

So if a NAND is just an AND with its output flipped, then to get an AND back, all I’d need to do is flip the NAND’s output one more time. And I just spent the last lesson learning how to flip a signal — that’s a NOT gate.

The editor below has two inputs (A and B), one output (Y), and a palette with just NAND and NOT. No AND available — you have to build one. Try it.

Your task

Build a circuit that turns the two inputs into an AND gate. The output Y should be on only when both A and B are on. You have NAND and NOT available.

Interactive circuit builder — visual interaction required. The current circuit’s truth table is shown to the right of the canvas.

Palette

NAND

NOT

A

B

Y

Drag a gate from the palette. Click ports to wire.Reset

Live

updating

A	B	Y
0	0	0
0	1	0
1	0	0
1	1	0

Target

A	B	Y
0	0	0
0	1	0
1	0	0
1	1	1

Wire it up to match the target.

Stuck? Show a hint

Notice what I didn’t have to add: a new kind of part. The whole circuit was built from NANDs (one of them, technically) and the NOT I built last lesson — which itself was built from a NAND. So really? Everything you just made is NAND gates wired in clever ways. This will be true for every gate, every register, every memory cell, and every CPU you’ll ever see.

Next, you’ll build an OR gate. It’s slightly trickier, because the symmetry isn’t as obvious. But the trick will turn out to be just as elegant.