The 2.8-inch DataDisk was a magnetic floppy disk, introduced by Smith Corona for use in their Personal Word Processor (PWP) word-processing systems introduced in 1986. The PWP range fell between an electric typewriter and and personal computer, and allowed users to do word-processing without having to buy a complete computer system. Several other manufacturers introduced similar machines around the same time, such as the Magnavox Videowriter and the Brother WP-55, but these machines opted for the 3.5-inch microfloppy (except for the Amstrad PCW range in the UK that used the 3-inch Compact Floppy disk).
The disk was based on the Mitsumi Quick Disk format (as were Nintendo Famicom disk cards) and the disks were manufactured by Mitsumi and rebranded by Smith Corona. The disks used a 2.8-inch disk inside an approximately 3-inch housing and could store about 100 KB (100,000 characters) of information, the equivalent of about 50 pages of text. Due to the way the software worked, each disk could hold up to 20 documents, 10 on each side. The 3.5-inch double-sided microfloppy could by contrast store over 7 times this much.
Unlike the 3.5-inch floppy disk, DataDisks needed to be turned over to use the other side of the disk, and used breakout tabs for write protection (rather than a sliding tab) for each side. They also did not have a protective shutter for the disk, and needed to be kept in their jackets to avoid dust.
DataDisks continued to be used into the 1990s, and a 1991 review refers to the process of using the drive as ‘slow (and strangely noisy) and expensive’. Perhaps because of their non-standard nature, the disks were more expensive than 3.5-inch floppy disks despite their much more limited capacity.
Finding a working PWP or Mitsumi Quick Disk drive is difficult, and even if you can get one working (you’ll almost certainly need to replace the drive belt), reading data from the disks is likely to be very difficult due to bit rot.
Dimension (outer casing): 78.1 mm x 75.9 mm x 3 mm
Capacity: 100 KB