the DS itself has a magnet inside just for triggering sleep mode.
No, that magnet is there to provide a magnetic field against which the magnetic field produced by current running through the wire coil in the right hand speaker can push and pull, thus causing the speaker surface to move. The fact that said magnetic field is also used to detect when the system is closed is just a clever bit of engineering.
Interestingly enough, the same principle is used by the electric motors that cause hard disk drives to spin.
It boils down to this: Yes, moving a magnetic storage medium through a strong magnetic field can cause data loss (nothing happens if the field and the device are not moving relative to one another), but weak magnetic fields like those produced by refrigerator magnets and other everyday objects do not extend nearly far enough to affect anything that is not almost touching the magnet. Furthermore, limited magnetic shielding can be included in the design of the storage device. There are plenty of portable devices such as the original iPod that use magnetic storage without suffering unacceptable rates of data loss.
Any magnetic storage device will be susceptible to strong magnetic fields, but if the benefit is a 50x or more increase in capacity, we'll learn to live with it.
QUOTE(Bladexdsl @ May 11 2010, 02:57 AM) than why does every computer on earth use them than and how come external hard drives sell good these days?
