Like how do they turn the electricity running through them into actual 1’s and 0’s and show all of that on my screen?
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At the lowest level, computers are made up of transistors, which are basically switches that can be switched on or off. When they get switched on, voltage passes through, and the output of the switch becomes ‘high voltage’ or a ‘1’. When they’re off, no voltage passes through, and the output of the switch is ‘low voltage’ or a ‘0’. The key thing to remember here is that unlike a light switch which needs to be physically turned on or off, transistors are turned on or off by voltage.
At the next higher level up, you have logic gates which are transistors hooked up together such that the output from one transistors turns another transistor on or off. Depending on what 1’s and 0’s you input, you will get 1’s and 0’s at the output according to some logic. For example, for a multi-input AND gate, you input a bunch of 1’s and 0’s, and the output will be a ‘1’ if all of the inputs are all 1’s and a ‘0’ otherwise.
At the next higher level up, you have a switch that controls which logic gate gets used and which 1’s and 0’s to feed into its input. So for example, you want to use your multi-input AND gate from the previous level to check 5 different inputs to see if they’re all 1’s. So this switch would turn on the power to your multi-input AND gate, turn off the power to all the other logic gates, and turn on the switches to the data pathways to allow the 5 different inputs to reach your multi-input AND gate. For example, if your 5 different inputs that you’re checking are in address #’s 3, 12, 19, 22, and 27, then the switch will turn on the access switches to those 5 addresses and turn off the access switches to all the other addresses.
So how does this become useable information? Well, the designer of the computer will include a table that tells users what pattern of 1’s and 0’s they should send to this switch in order to do different things, and what the resulting output means in human terms. This is called an Instruction Set Architecture. So for this example, it would tell you which pattern of 1’s and 0’s to send to the switch to turn the multi-input AND gate on and everything else off, and which pattern of 1’s and 0’s to send to make sure it pulls the inputs from the addresses that you want.
Software programmers will write software that does this for you, and also convert the output into a form that you can understand (for example a number on a screen or something). The screen works in a similar manner – the designer of the screen will have a table that tells users what pattern of 1’s and 0’s to send to the screen in order to turn on different pixels, and these pixels create an image on the screen.
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