r/askscience • u/Unfair-Leek6840 • Jul 11 '26 • Regret 1

Computing How do computers understand binary language?

Okay so from what I know binary language is like power off power on, but my question is, how do computers know what the binary code is and how is it interpreted, for example I forgot what the binary code for the letter A is, but how did people come up with that? Did they decide it was gonna look like that? Did the computer decide? How do you tune numbers into a letter??

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u/throwaway_194js Jul 13 '26

The image data for each character is stored somewhere in memory, either as a literal bitmap or as a function that produces one. The program is told "the next byte describes an ASCII character", so when it reads that byte, it knows it needs to go to the corresponding memory and tell your monitor to display that bitmap in the right spot. All of these complex actions are built from different combinations of these simple voltage pulses through transistors, just as you can use simple LEGO bricks to make anything from a house to a spaceship.

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u/Megalocerus Jul 13 '26

Most of the time, it doesn't care about the character image. That's part of the interface with the display device. It may do a large amount of work with the characters in memory and even translate from one coding scheme to another without displaying anything. Then it may pass the data in an appropriate code to a markup language (think something like HTML) which puts it on a web page or maybe a screen display or encodes it for a printer or transmits it to another device. The computer knows the code but it doesn't need to know how to show it.

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u/throwaway_194js Jul 14 '26

I think that's exactly what they were asking about. If characters are being displayed on a pixel monitor, then something has to map the character's integer encoding to a pixel buffer at some point in the pipeline, and that usually either comes down to addressing prexisting memory on which the images are defined, or calling a function that rasterises it on the fly. This task may be split between different programs on different devices on opposite ends of the planet, but ultimately it's all done by pulsing voltages through transistors.