I’ve always been very mechanically minded, although when it comes to electronics and circuits, I’m baffled.
How can pieces of silicon and metal make my computer turn on, to being able to run games and programmes?
In: Technology
The eli5:
Electricity is a force like gravity. Electrons can feel this force, and flow like water.
Wires and circuits are essentially change for the electrons to flow. When they reach a component like a motor they cause it to turn, like a water wheel.
Other components often have mechanical analogs. Transistors can be seen as levers or doorways. Electricity flows against one side, opening or closing it.
A clever arrangenent of these can create situations where flipping one lever closes.or opens others. This allows you to design a setup where a few small changes can alter lots of different things.
Mechanical computers do exist, but are much much larger.
Well a circuit mostly is a conducting line connecting the power supply to whatever is put in as the consumer. But that is boring. It is better to also put in a switch. That switch basically interrupts the conducting line, unless it is closed.
It gets really interesting when you have a switch that does not work by flipping a lever, but a switch that works by electricity (that is where the silicon comes into play, since it has some special properties). Those interupt the conducting line unless a current is fed into the side of the switch. And now you can build a circuit that switches the switch… or only switches the switch if two other switches are switched and so on. So that is basically playing very complex domino…. unless you notice that with two switches that switch each other, you can build a memory retaining thingy.
With two electronic switches you can build a flip flop. A thing that keeps a circuit open once it is opened and closed once it is closed. It is a way to conserve information.
If you put many a flip flops into a row, you got a register. Those flip flops flipping each other makes that register able to count… and do math. It is all really faszinating. You build a few circuits that add or subtract two registers when you flip a switch, and you basically have a calculator. From a calculator to a computer it is only a matter of upscaling. Your keyboard and mouse are the switches you flip and the cpu and graphics card do the calculating, shoveling data from one register (of which a computer has billions) to another.
That’s basically it. Everything else is software (in many different abstraction layers).
Certain materials called conductors or semiconductors can make electrons “flow” at the molecular level. As a very basic example imagine water going through a hose. This doesn’t apply to all electrical circuits but for a basic understanding it is enough. There are different types of electricity, Alternating current (called AC) and direct current ( DC). Basically AC is for stuff you plug into your home using those pronged cords and DC is for batteries. The electric circuits you describe is different from the electricity that powers your house or your oven. Fundamentally it is the same concepts. Electricity is defined as the flow of electrons. They don’t flow differently but for larger things like powering homes resistance is usually bad and for smaller things like microchips or your computer motherboard resistance is necessary because the amount of electricity is so small you don’t want to fry it. Of course electricity on all levels must be regulated to the correct amount. It isn’t just an “amount” to be set to. For example you can’t just pour a certain amount of water into a plumbing system and expect it to work. Pressure and resistance in an electrical circuit must also be regulated. For electronics, which is different than residential electricity or construction electricity, there are a plethora of devices that are used to achieve these things. I’m not gonna lie to you, electricity can be confusing. I myself had only taken an introductory course to electricity and electronics mixed in with more advanced classes. But if you take your time to figure things out, basic problems can boil down to simple arithmetics. I realize my answer might be all over the place so if there’s anything you still want to know that I didn’t say, feel free to message me back and I’ll do my best to explain or hopefully someone else can provide a better answer than me. I love learning the trades so I’d be happy to help you excel in your learning.
Hard to explain to any age, but especially to a five year old. But here is a go.
Complex electronics are built up off of lots of simple components. They are:
Resistor – tries to keep current from flowing.
Capacitor – temporarily stores current
Inductor – also temporally stores current but in a different way.
Diode – allows current to only flow in one direction.
Transistor – think electric valve. Handle gets turned more, it allows more current through.
Take transistors, capacitors, and resistors and put them together in the right way and you create logic circuits. For simplicity we can treat these circuits as working with true and false. Those circuits are:
And – if all inputs are true then output is true.
Or – if any input is true then output is true.
XOR – if one and only one input is true then output is true.
There is a type of math that if you lean it will allow you to use those simple logic circuits to solve higher complexity math problems. It is called Boolean math (aka Boolean logic). Along with grouping multiple trues and falses together to create numbers with more than two possibilities, and you can start doing something real.
So say I want to represent the the number five with only trues and falses (represented as 1 for true and 0 for false). Obviously I need more than one place just like when dealing with normal numbers I need two numbers to represent the number ten. So five would end up being 1 0 1. That represents a true in the four place, zero in the two place, and one in the ones place (4 + 1 = 5).
Ok say you want to add two such numbers. Let’s say add five plus one. Or 1 0 1 + 0 0 1 in binary. You would have a series of logic circuits doing that math.
So first you would add the one columns by xoring them. And the result of that will be the result ones column. In this case 1 xor 1 would equal zero. So the ones column of the result is a one. Then we have to check to see if a one is carried to the twos column. That would be an and between the original ones column. Or 1 and 1 which would be 1. So we have a carry on the twos column. So now I have three numbers in the second column. The carryover 1 + 0 + 0. Same thing but just add two at a time. So first 1 + 0 = 1 xor 0 = 1. Then add that result to the remaining number so 1 xor 0 = 1. So result is 1. So we have 1 in twos column. The carryover is a bit more complicated because you can end up carrying over twice instead of just once. But in our example there is no carryover because 1 + 0 + 0 = 1. Doing the math in the fours column. Gives us 1 1 0 = 4 + 2 +0 = 6.
So just like the electronic components can be grouped to get complex logic circuits, logic circuits can be grouped up to perform complex operations.
Turns out those numbers and logic operations can make up data (what you are dealing with) and instructions (how you want to deal with it). So programs are effectively just that. A bunch of ones and zeros representing data and instructions.
Operating systems are just sets of data and instructions that allow the hardware to do something useful. Programs or apps are data and instructions that work with the operating systems to make the OS useful.
I took a few liberties and shortcuts to try and keep it in the ball park for a five year old.
Basically, a transistor is like a pipe with a valve. there is an input, an output, and then the valve that allows water to flow, or not. As SaiphSDC says, electrical fields are a force that causes electrons to move.
The flow of electricity is essentially atoms passing a spare electron to its neighbor in the same direction, due to this force. Good conductors, such as copper, are very good at allowing this flow. So metal wires are used to create paths for the electrical current to flow. Basically a garden hose.
What is so special about a semiconductor is that it can either conduct, or not, based on a third input. Like a water valve in line with your hose or piping. If you apply an electrical field to the ‘valve’, then it changes the property of the silicon and now the current will flow across it.
Finally, we have two types transistors. One that allows flow by default, and one that is closed by default. If you are clever with how you hook up the valve inputs in series or in parallel, you get these fundamental digital logic blocks that nokvok describes.
From there it’s hard to ELI5. These foundational building blocks allow you to create processing units that will do math for you, or storage elements so that you can write in the data you want to operate on, or read back the results.
The BIOS is special circuitry that controls how the motherboard and everything plugged into it power up, what order they are initialized and the system self-learns all the hardware addresses that the various components and peripherals ‘reside’ at. The BIOS is hardcoded – meaning if you turn power off, it remembers the basic instructions and some of the data it’s learned about. It will run some self tests to look for errors. It will configure clock speeds and timings for various components.
From there, when it’s ready, it looks to the hard drives for boot instructions from the Operating System(s). Once it finds those, the OS software takes over and… well I’m not a computer engineer, so I would butcher explanations from this point on 🙂
But it pretty much comes down to (carefully timed) voltage pulses flying around on wires and flipping billions of switches on or off.
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