Magneto-optical drives (not testable)

Magneto-Optical Discs

Magneto-optical (MO) discs used a combination of magnetic fields and optical technology to read and write data to a 130 mm disc housed in a plastic cartridge. MO discs could be found with capacities up to 9 gigabytes. Some years ago MO discs were popular for data backup because, unlike optical media, the integrity of the data is always checked before it is written to the disc. However, like the DVD, in a modern PACS the vast amount of data needing storage precludes the use of MO discs. Thus MO disks are no longer being used, or even manufactured.