Why binary?

Now let’s have a look at why computers use binary anyway. Let’s start by thinking about the most simple use case: computers need to store data. Now if a computer worked in denary, then for each digit, it would need to be able to store one of at least 10 different possibilities. At the hardware level, that would mean using some electronic component that could be in any of 10 different states, to represent the 10 digits from 0 to 9.Such components do exist – In fact there are components that can represent an almost infinite number of states – but they are unwieldy and complicated to use in electronic circuits.A much simpler component would be one that has only two states – on and off, for instance. A component like this is called a switch.Let’s have a look at how a switch can be used to store binary numbers. Shown below a simple circuit. You don’t need to understand exactly what is going on, but notice that at the top, the multimeter shows a reading of 1 volt. That is a 1.We want to be able to change the state of this circuit using a simple component, so we add in a switch. With the switch in place, the circuit state can be controlled by flipping the switch.When the switch is in the “on” position, a 1 is shown on multimeter. When the switch is flipped to the “off” position, a 0 is shown on the multimeter. So we have represented the numbers 1 and 0 using a simple switch.If we want more digits, we just need to add in more circuits, and we can represent as large a binary number as we need. We just need one switch for every digit we want to represent.The switches used in modern computers are so cheap and so small that you can literally get billions of them on a single circuit board. We’ll look at that in the next step.