ELI5. If a computer is made up of preprogrammed circuits, then how does it display anything on its screen, even if that particular thing hasn’t been preprogrammed in its circuits?
In: Technology
Answering this requires a few steps:
*Preprogrammed circuits can give different results, because they transform data they were given into something else.*
Those preprogrammed circuits don’t simply give you 1 result all the time, they can take an Input, a chunk of data stored electronically, and the circuit physically alters it into different data, giving out a different chunk of data called an Output. All that certain preprogrammed circuit does is take one or more Inputs, and transforms them into the Output.
Example: One such circuit can add 2 numbers in binary. 2 chunks of 1s and 0s representing the 2 numbers are sent to the circuit, and the circuit gives the result. This is all happening through tricky layouts and physics, the circuit doesn’t need to “understand” that it’s adding, or that what it was given are numbers.
How does this give you images on the screen?
*Your display is given chunks of data that are simply long lists of numbers, each representing one pixel, the display has circuits built in that turn those numbers into electric signals that light up specific parts of the screen in specific colors in different degrees, according to the numbers.*
How does this chunk of data get sent?
This is the part not explicitly asked in the question, but I believe is a key piece to understand what’s going on.
Computers can really only do one thing: handling data. They can handle single pieces of data, they can put pieces of data together, they can split data into smaller pieces, etc. Processors are just really complicated chips that have many preprogrammed circuits, and what some of those circuits do is forward data to specific circuits, so this way, the processor can be “told” what you want it to do with the data you give to it, by giving it an Instruction Code(this is just a number, therefore a simple chunk of data, that will make the other chunk of data you actually want to work with “flow” into the specific circuit you want). You want to add 2 numbers? You use the code number for adding, and put the number you want afterwards. You do the same with the second number. You want to multiply them, you use the code for multiplication and then your number. The Outputs of the circuits are stored in Memory, and can be used to do work with afterwards.
Since computers have been a thing, computer scientists and programmers have worked on creating layers of programs that contain sets of the above instructions detailed above in ways that they create more complex pieces of data. Programming Languages were created this way, so people can write specific human readable words that then get translated into a list of commands for the Processor to execute.
*Some of these layers deal with translating specific commands into specific numbers on the lists that then get sent over the cable to the display.*
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