The total charge in an electrostatic device like SSD/Flash remains about the same, but it's moved around in different microscopic parts inside to represent data

The total charge in an electrostatic device like SSD/Flash remains about the same, but it's moved around in different microscopic parts inside to represent data. In the "floating gate" at the heart of an SSD/Flash cell the 1 or 0 is indeed represented by presence or absence of some quantity of charge, but it's balanced out by charges elsewhere in the device, nearby. In a HDD charge isn't obviously involved; the data is represented by magnetic patterns on the surface of each spinning platter. Ultimately those also represent data by movements of charge, though: charge naturally orbiting around atoms creates the magnetic fields, and the data is represented by the orientation of those orbits. So a drive of either kind full of byte 254 contains about the same charge as one that's zeroed out. They don't have exactly the same mass though, and therefore have slightly different weight, even if they contain identical charge. That's because mass (and weight) doesn't just come from matter. It also comes from the potential energy of different patterns of charge or their orbits, pushing and pulling on each other. It's counter-intuitive that things merely pushing and pulling on each other create mass just by their configuration, and that the mass changes when their configuration changes. But it's true, assuming the theory of relativity is true (it seems to be). That said, the mass created by the configuration of forces is very small indeed. Your SSD or HDD probably changes mass by a very much larger amount in a short time just by existing, giving off or absorbing minute quantities of gases from the air, acquiring dust, and other natural physical changes as the materials age.