Quote Originally Posted by kythe
This simply isn't true. As Nihil noted, if it were true, disks would produce errors all the time, as they'd not be able to tell what data is current and which is old.

Among others: DBAN.
Well that is why there is a fat table this directs the computer where to see the data. So when people do quick formats all that is deleted is the fat table the data is still there but the directory isnt, until the data is completely written over it can still be seen. Im not an expert at hard drives but I do remember what I was taught back in my college days.

I also understand it that even after a full format the magnetic charge only formats to all zeros and if the magnetic charge isnt at full charge there would still be evedence of the ones, making it somewhat readable. True this may be very old information and hard drives have changed but I thought it was worth noting.