If for example I clear the contents of my SD card with command dd if=/dev/zero of=/dev/sdX , I'm guessing this completely wipes (sets to zero) every single content on the card? partitions, file system, data etc.
Now what I can't understand is, when I will plug this device into a computer again afterwards, Linux or Windows, I am able to write to it again. How does the OS know what type of device this is if everything is wiped?
There are different types of flash memory and I'm guessing they need specific drivers to write to them depending on what type, so how does the OS know what type?
Can it be that there is a small part of the flash memory which was not overwritten which contains data explaining what type of memory it is?