Learn How Computers Work on a Breadboard

Do you understand how computers work? Not a vague recollection that there are ones and zeros involved, but a true understanding of the fundamentals, like how a processor counts and how data flows into and out of registers. Everything in our modern digital world sits atop those principles, but most people — even very tech-savvy people — don’t know how they work. The best way to learn is through hands-on experience, which is why 3DSage made this video and simple breadboard computer as a crash course.

Digital computers are all built on a single component, which is the transistor. You can combine transistors to create logic gates, which enable the Boolean logic that makes everything from addition to modern triple-A gaming possible. You can also use logic gates to “remember” set states, which is how you get memory for your ones and zeros — though that is volatile memory and requires constant power.

In his video, 3DSage explains how to get to that point on a breadboard in just minutes and it all starts with a 555 timer. That regulates the timing of each cycle, which you may recognize as your processor’s clock speed. In this case, it is just much, much more leisurely.

Before you get to counting on your breadboard computer, you should understand how binary counting works in the first place. 3DSage designed some very helpful 3D-printable models you can make to grasp that concept through tangible interaction, so it isn’t just an abstract and nebulous idea. On the breadboard, 3DSage uses a 74161 4-bit binary counter IC (Integrated Circuit) chip to do the same thing in a tidy digital package. With its four bits, it can count from 0 to 15 — advancing at the clock speed of the 555 timer — and displays the current value across four LEDs.

In the next section, 3DSage combines three concepts: “writing” code, storing that code in RAM, and running that code. He uses a CDP1824 IC for RAM, DIP switches to enter the code at each location denoted by the counter, and a set of seven LEDs to indicate the results. Four of those LEDs are blue and represent the data at that location, while the other three are yellow and represent the opcode (Operation Code) at that same location. The opcode can, for example, stop the program at the current point or jump to another.

Finally, 3DSage demonstrates how to do something with all of that by adding a speaker and playing notes at certain points in the program. And if you still aren’t convinced that this is a real computer, 3DSage threw in binary adder ICs for basic arithmetic.

To go from the breadboard to a more permanent solution, 3DSage designed a custom PCB and 3D-printable enclosure for those circuits. If your goal is to truly understand how computers work, we think that is a great place to start.