What’s Inside Your Computer? A Simple Guide to Digital Devices
I know you use computers, because whatever type of device you’re reading this on, it’s some type of computer. We’ve gotten so accustomed to them that we have stopped being amazed by them. I have several friends — of varying ages — who prefer not to use digital devices anymore than absolutely necessary, and let me tell you, computing technology is not just a kids’ game, and not all kids feel comfortable with it. What seems like magic is really electricity at work. The flow of electricity makes everything happen.
I want to demystify some of that for you. Today I’m going to explain how inputs to computers become actions, the role electricity plays in videos and email and your banking app, and why we nerds are obsessed with 1’s and 0’s.
All Digital Devices Speak the Same Language (essentially)
All digital devices – computers, smartphones, tablets, smart home devices – function through a cycle of input, processing, output. No matter how simple or complex, devices must receive data (input), make sense of it (processing), and deliver a response (output).
For a computer, input could be typing on a keyboard, the CPU does the processing, and the output is the words that appear on the screen or monitor. If you’re using a smartphone or tablet, you tap on an app for input, the phone processes the command that it associates with that tap, and the output is the app opening. Let’s go off the beaten path and take a look at a smart home device. A motion sensor detects movement, which is the input. The system processes the security alert, and the output is turning on a light.
Once you realize that this is the circle of digital life, it’ll help you grasp how technology functions across different devices. It can also be a great troubleshooting help. Knowing what’s supposed to happen in what order can help you identify what the problem is by knowing where the failure happens.
The Role of Electricity in Enabling Communication Between Computer Components
Not only do we have devices talking to each other, but in order for that to happen, we also have to have components within the devices talking to each other. Electricity powers every action in a device. It’s electricity that allows components to send and receive data. Electricity carries signals between hardware components.
Devices use binary signals, which represent an “on” state or an “off” state. I’ll get deeper into that in just a bit, but it’s the foundation of all digital processing. All input devices – keyboard, touchscreen microphone – convert a user action into electrical signals. Processors interpret those signals and determine how the device should respond. Memory and storage hold the data before sending it on to the next phase. Output devices like screens, speakers, and monitors receive all the processed signals and deliver the results back to the user.
Here’s An Example
When you press a key on a computer keyboard, it closes a tiny circuit inside the keyboard. When we say a circuit is closed, we mean that before the key is pressed, the circuit is open – it’s like two ends of a wire that don’t touch. Closing the circuit by pressing the key means that something comes in and forms a bridge between the two not-touching ends and creates a complete loop. Electricity will flow through it.
With that closed circuit, the key press generates an electrical pulse that travels through circuits on the motherboard to the Central Processing Unit (CPU). The CPU translates the pulse into a letter, number, or character, which then shows up on the screen as an output.
Why Do We Want to Know That?
We all have some experience with how quickly an action affects electrical flow. You flip a light switch and the light comes on. You don’t have to wait minutes, or even seconds – it’s instantaneous. That’s how quickly devices respond to the electrical impulses generated by our taps, touches, and movement. It can also help explain why some devices need more power. High-performance gaming PC’s suck up a lot of juice compared to your camera doorbell.
What Was That About 1’s and 0’s?
Let’s start by talking about spigots – you know, the thing that connects to your house and lets you put a hose to it and you can water your yard? When we were building our house, I picked one of those up and looked into it. Now, I had already been working in technology for a good while, so I knew that “0” means off and “1” means on. That is, “0” means no flow, “1” means flow. Looking into that spigot, I got a flash of inspiration. Turning the faucet, the spigot closed, and I saw the gate as a 0; no water was going to flow. Turning it the other way, all the way open, I saw the sideways view of that gate, and it appeared as a |, just an up-and-down line, and the water would flow just as fast as the diameter of the pipe would let it. So the 0 of the closed gate is “no flow,” and the | of the open gate is “flow.” What a great object lesson!
Don’t get confused by “open gates” which let electricity flow with “open circuits” which don’t. They’re not the same. The open gate is like – well, a gate. When it’s open, the whole herd can go through it. Remember that an open circuit means there’s something that isn’t touching that should be. It’s “open” because it’s “not complete.”
When we read a computer program’s code, we don’t see 1’s and 0’s, we see words. There’s a program, either a compiler, or an interpreter, depending on the programming language, that will translate those words into the 1’s and 0’s that the computer can use to open and close the electrical gates. So, at the most basic heart of it all, it really is all 1’s and 0’s.
Turning Computer Inputs into Electrical Signals
In order to explain this journey, I have to talk about analog signals. Analog signals are continuous. They represent real-world data like sound waves, temperature, and pressure. Think of the sound of someone’s voice as they speak into a microphone, or when you press a touch screen, the varying pressure you can use to do different things.
The Role of ADCs
Digital devices deal with digital signals – 1’s and 0’s – rather than analog signals. Those analog signals have to be converted into the digital signals in order for a computing device to be able to process the signals. We need a helper, and that helper is an Analog-to-Digital Converter (ADC). ADCs may be built into the input device, they may be built into the processor, or they may live on a chip between the input device and the processor. There are so many factors that determine where the ADC should be, and those factors are figured up by the hardware engineers. The ADC has the job of detecting analog inputs, like sound waves or motion, there’s an intermediary that generates an electrical signal from the waves, and an ADC takes that signal and converts it to digital data.
The Role of Transducers
What’s a transducer? So glad you asked! A transducer is any device that converts energy in one form into energy in another form. See where we’re going? Transducers in digital devices convert physical inputs like sound, pressure, and motion, into electrical signal. Microphones, touchscreens, and accelerometers (the thing that knows when you’ve turn your phone sideways to watch a video) are all transducers.
When the transducer has converted the input into an electrical signal, the signal can flow through circuits to the proceessor. The processor “interprets” the signal to decide what to do with it. That means that it reads the signals coming in and uses instructions coded in its architecture to decide how to handle the incoming stuff. After that, it sends the response to an output device like a screen, a speaker, or some other kind of device.
Brains and Boxes and Buses – Oh My!
Brains
The CPU is the brain of the device, because it handles all of the processing tasks. It takes raw electrical signals (the binary 1’s and 0’s) and interprets them as meaningful actions. Everything that happens goes through the CPU. The CPU always follows the same cycle: fetch, decode, execute. Inside the CPU, the binary signals control tiny transistors that turn on and off to do the calculating stuff. Here’s where the mind-blowing happens: this happens billions of times a second.
Boxes
Storage boxes, that is. Random Access Memory (RAM) is short-term memory. It’s where stuff is stored (hence, the boxes metaphor) for execution or for waiting for execution. It’s much faster for the CPU to read data from RAM than from long-term storage. When you open an app or a program, the app loads data into RAM so that the CPU can grab it quickly. It’s the box of stuff on your desk that pertains to the project you’re working on right now. If you put it all back where it came from, every time you need it, you have to go and get it again. Unlike a physical box of stuff, though, RAM gets cleared out when the device gets turned off or rebooted.
Buses
Buses are pathways made of material that can conduct electricity, and they’re embedded in the circuit board that the holds all the system components (the motherboard). They work more like highways than vehicles. Think of a narrow road, wide enough for only one vehicle at a time. That was the norm at one time. The first improvement was widening the path, from 8 bits to 16, then to 32, then to 64. It was like going from 1 lane to 2, then to 4, then to 8 — but still only in one direction. There had to be one highway in one direction and another in the other.
One of the most significant advances was introducing bidirectional data movement, in which the same bus can handle data in both directions at the same time! Sending signals from the input component to the processor and then out to an output device is much faster now than in the early days of computers.
Your Turn
Obviously, this was an simplified explanation of how the box of electricity in your hand (or on your lap or on your desk or on your wall) works. Even so, knowing what’s at the heart of your devices, isn’t it amazing the stuff they can do for us? Consider that number of billions of times a transistor opens or closes each second. Now remember this – even though it can be frustrating when they don’t work exactly perfectly, isn’t it mind-blowing that they ever work at all?
Drop me a comment below – what would you like to explore further? Or, do you have a funny story about computers we need to hear? Bring it!
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