Eli5; Where exactly do our pictures go when deleted from phone?
In: Technology
Data on a phone is stored in “flash” memory. That’s memory made up of specialized transistors. They have a “floating gate” which can have charges trapped on them or not, indicating a 1 or a 0. Since the charges are trapped, they remain there even when your phone is powered off.
When you tell your phone to delete something, it marks those memory bits as “unused”. When it wants to write something new into that location, the memory controller has to do some work, because flash memory has some specific requirements.
The controller will copy all of the “in use” memory locations in that block/page to temporary storage in RAM, erase the whole block/page, and then write back the saved data to the flash memory. Then it can also store the new data.
At the point that the block/page is erased, your old photo that you had deleted is truly gone. The charges on the floating gates which contained the information have been removed.
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