Fujitsu and Sony have unveiled the latest upgrade to the Magneto Optical (MO) rewritable optical disc in Hanover. The two companies are showing prototypes of new drives and discs that can hold up to 2.3GB of data - almost double the current highest capacity disk. The new 2.3G format is expected to go on sale by the fourth quarter of this year and is targeted for use as a backup for commercial systems, such as telephone switches and automated teller machines (ATMs), and for backup video and other applications that use large volumes of data, the companies said in a statement. Drives for the new format include support for the Media ID copy protection system and are compatible with the previous 3.5-inch MO formats from 1.3GB down to the original 128MB discs. Introduction of the format means increased competition in the high-capacity removable media market, especially for DVD-based formats and Iomega's Jaz, which currently dominate the market over 2GB. First generation DVD-R and DVD-RAM discs will hold 2.6GB of data per side with second-generation versions of the same format storing up to 4.7GB. Jaz cartridges hold 2GB of data. Below 2GB, competition will come from existing 1.3GB MO discs and other formats including the immensely popular write-once and rewritable CD-R and CD-RW formats, and the recently-announced Double Density CD. Expected on the market from April, the Sony-developed DD-CD can store up to 1.3GB of data. The two companies said they have already received support for the 2.3GB MO standard from Olympus and Konica for the drives and Teijin, Hitachi, Mitsubishi and Ritek for the media.