Hitachi will offer (the size used in the iPod mini) by 2007, according to the company. The density breakthrough represents a refinement in perpendicular recording. Today, hard drives record and store data in a longitudinal fashion, with the read/write heads scanning over a horizontal plane. In perpendicular recording, data bits are aligned vertically, allowing for more data to be squeezed into a defined area, explains ZDNet UK. The hard drives store about 4.5GB per square centimeter using this technology. The technology will allow Hitachi to offer a 20GB microdrive and an 8.9cm drive for desktops that will hold a terabyte. Currently, microdrives top out at 6GB, such as the drive used in Apple's latest iPod mini.