Learn how computers add numbers and build a 4 bit adder circuit

Let's build a circuit that adds numbers! Binary addition is even easier than decimal addition since you don't have to know how to add numbers larger than 1.

You can get all the components used in this video from any online electronic components distributor for a few dollars.

Complete parts list:
2x 74LS86 (Quad two-input XOR gate)
2x 74LS08 (Quad two-input AND gate)
1x 74LS32 (Quad two-input OR gate)
2x 4-position DIP switch
5x LEDs
1x Solderless breadboard
22 gauge wire
USB charger and cable or some other 5v power source

[BuckeyeStormsProductions]

One of the most concise explanations I have seen.

[wolverine]

Teacher: No calculators allowed for this test.
Me: Okay

[aaronk]

Ben, I wish you were my teacher when I was studying computer science... This is an absolutely amazing, simple, and fun explanation.

[tinytonymaloney]

I would love to go back 40 years (101000) and re-learn all this, what a brilliant project. I last did this stuff in 1982 at college. Watching these videos just brings it back. 👍👍👍

[WannabeSpaceman]

I wish I had some spare cash to give you because you've managed to teach me everything I've wanted to know about computers from the semiconductor level up to this; more so than the computational college courses I've actually taken.

This is more computer science than how to use computers, which is what I went into computer studies for in the first place.

[SiddhantVerma-tpgt]

Man in my whole engineering course I haven't seen any thing as practical as u have shown me. We can draw a lot of circuits on paper but when doing practically people nowadays hardly have any knowledge pertaining the subject. 👍👍

[daveb]

How do I build a intel core i7 using this method? Can you use legal size paper clips if you don't have wires?

[TheBigBigBlues]

The way you teach with physical examples after the theory is exactly how my brain learns best. Thank you for doing these brilliant videos.

[BeniRoseMusic]

I love this stuff! It's amazing to me that even this close to the metal, there's still a layer of abstraction using ICs with pre-built logic gates. It's amazing to me that people figured out how to build these logic gates with vacuum tubes, and later transistors. No wonder they used to take up entire rooms! And then less than a century later we have these things in the millions on a microscopic scale doing arithmetic so fast that it can be abstracted into a high definition video streaming over the internet for millions to see!

[tubular]

That’s insane! I always thought computers were like intelligent pieces of magical technology (not really but that’s what it felt like) and now I understand that what you’re ‘computing’ is really just an electrical representation of the math! As in, it’s just physics, and the math existed there already before we created any circuits or put any electricity through them. It’s so cool to think that it’s actual such a tangible thing, and that it actually works with using electricity and some intelligent placement of a few specific materials. Fantastic video!

[Deshammanideep]

so cool.. I just understood how computer understands numbers.. your one video explained more than my 22 years of learning... thank you from deepest heart....

[HighStakesDanny]

I was confused, but I can see how very smart people figured this out over the years. Thanks.

[pesto]

Where were you when I was learning this stuff back in the 90's??!?! AMAZING explanation and so easy to get... Thx.

[Standbackforscience]

There are _so_ many videos on youtube claiming to explain how binary adding works in a computer, but this is only one that actually does it. Thank you!

[MrHyde-fusr]

"I've got these four little dipswitches"
What'd you call me?

[TomPauls]

Wow! This brought back memories. I remember my training to fix old mainframes in the early 70's. The amazing thing is computers only know how to add or shift. Seeing how they do the different math functions was just amazing. Fun thing is finding what circuit element was "on strike" when a failure occurs.

[BuckeyeStormsProductions]

I found an app that allows simulation of logic circuits, and used your explanation here to build an adder. Your explanation, and then putting into practice, if only in a virtual environment, really helped me grasp the concept. I am going to follow your other explanations, and build/test other logic circuits. Ultimately, I may add all the components into a virtual machine, like you built a real machine. Maybe, sometime down the line, I will build real hardware. I showed my wife the virtual logic circuit, and was able to explain the workings to her, although her interest may have been feigned. They say you really know something when you can teach it to someone else. I think you also know you are a good teacher when your students can teach others. By that logic, you are a good teacher. Thank you!

[craig]

Thanks for the video! Very inspirational to find out that he didn't finish college either and managed to still do what he loves. I failed at my first attempt at college as well, taking computer science as well, and have been stuck at a job I hate for 20 years, dreaming of what might have become. Just recently returned to my passion as a hobby and to see if I've still got the brains for it. To find people like Ben Eater really sparks my thirst for more knowledge, something I thought was dead in me. I forgot what it was like when it was fun to learn. Will be either buying a kit or donating when I can. I love this content! Thanks Ben!

[HalawaAlantabli]

Many thanks from Egypt.. you have really awesome planned and organized method in exploring your materials let any one understand.. many of peoples can say some of that theoretically but few can apply like you..

[diligenthawk]

Can we just appreciate how neat and clean his circuit looks! Mine always looks like a catacomb of wires!😂