Bubble memory

Bubble memory uses magnetic fields within the ICs. The scheme is popular in computers, because a large amount of data stored in a small physical volume.A single bubble is a small magnetic field around 0.002 millimeters across. Logic highs and lows correspond to existence or absence, respectively, of the bubble. The IC contains a ferromagnetic film which behaves as a reprogrammable permanent magnet on which the bubbles are stored

                                                      Figure--Cross-sectional view of a bubble-memory IC.


Magnetic bubbles don’t disappear when power is removed from IC. Bubbles are moved easily by electrical signals. An advantage of bubble memory is that it is a nonvolatile,RAM is one which does not require a backup battery. Another asset is which data can be moved from place to place in large quantity. This process is called as block memory  transfer.