A microdrive is originally a miniaturized hard disk in the format of a CompactFlash-Card developed by IBM. The first generation of microdrives had a capacity of 340 MB. This version was already used by the NASA. The next generation were available with a capacity of 512 MB and 1 GB. Microdrives have a magnetic memory with a high capacity and a disc-diameter of 1 inch. These small hard disks can be easily destroyed by vibrations and too low air pressure.