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What kind of data is stored in the RAM when it is fresh out of manufacture? Apart from certain basic instructions (if yes, what are they), are there numbers stored as well or are most of the memory cells just empty?

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RAM is cleared after each power cycle. The power-up value of cells depends on the technology.

  • Static RAM content is usually random (there is no preference between 0 and 1, but the same chip may present similar patterns after each power-up).

  • Dynamic RAM has the value corresponding to empty capacitors in the RAM array, which usually corresponds to ones, but there is no guarantee. Dynamic RAM can retain data for several seconds when unpowered (very dependant on temperature) : One cannot assume a known state at power-up and recent DRAM (DDR3, DDR4...) need complex initialization sequences where the RAM controller stores and checks some values like FFFF/0000/AAAA/5555, ...)

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Memory cells are just electronic components whose voltage is used to store information: you can think of it as high voltage meaning a binary 1 and low voltage meaning a binary 0. Everything that is stored is either binary 1s or binary 0s.

As such, there isn't really any such thing as "empty" and, as far as RAM goes, there isn't really any voltage if the memory isn't connected to some kind of power source.

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  • $\begingroup$ Oh. So what you mean to say is, an instruction such as 'LOAD' becomes the load instruction only when the RAM is connected to a power source? How does that work? Is there some pre written data that gets activated when connected to a source? $\endgroup$ – noorav Mar 15 at 20:30
  • $\begingroup$ "LOAD" is something the CPU does. I suggest you read a bit about how memories actually work. Your impression of how they work isn't very close to what actually happens, so your specific questions don't make a lot of sense: it's a bit like the fictional professor-student conversation I wrote in this answer. Please don't take this as an insult: you're not being stupid or anything; it's just that your mental model of the situation isn't right and the way to move forward is to completely replace the model, not to try to fix the individual bugs. $\endgroup$ – David Richerby Mar 15 at 20:37
  • $\begingroup$ Could you please provide me with some sources? Perhaps something that you used for your understanding on how memories work? I'd appreciate it. $\endgroup$ – noorav Mar 15 at 20:39
  • $\begingroup$ It's probably worth reading the Wikipedia Random-access memory article, up to "Memory cell", and then the articles on memory cells and flip-flops. At first, skim past anything that's too technical for you to follow; later go back and look up the bits that look interesting or useful. For more detail, a textbook on computer architecture (for the bigger picture) or digital electronics (for lower-level implementation) would be... $\endgroup$ – David Richerby Mar 15 at 20:50
  • $\begingroup$ ... helpful. Or look for online lecture notes for university courses with names like those. Googling for "how does computer memory work?" looks like it gives some good information, too. $\endgroup$ – David Richerby Mar 15 at 20:51

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