A report in the November issue of LSN discussed the limited market penetration of the optical data storage technologies. Recently, accounts of the merits of optical disk technology have begun to give way to descriptions of developments which promise improved performance from the more traditional magnetic storage media. Both media are examined in detail by Charles Goldstein of the Lister Hill Center for Biomedical Communications in his chapter “Computer-Based Information Storage Technologies” in the most recent issue of the Annual Review of Information Science and Technology (Volume 19, 1984).
A promising development in magnetic storage is that of perpendicular recording. The recording surface is thicker than that used in traditional longitudinal recording media, and thus supports the perpendicular or vertical writing of data. This results in denser data storage per inch and overcomes the possibility of data being corrupted during reading—a problem with the usual magnetic storage media. Data densities of over 240,000 bpi (bits per inch) can be achieved with perpendicular recording techniques and it is thought that densities could be increased as high as 500,000 bpi. In comparison, the data storage capacity on longitudinally recorded tape is 24,000 bpi.
Floppy disk technology is also being improved. In laboratory settings, regular floppy disk recording technology is being used in small (3 1/2 inch) floppy disks being developed by Sony. The disks, encased in rigid plastic jackets, have a theoretical capacity of 1 million characters; in practice, the densities are likely to be 300,000 characters. Even greater storage capacities are expected of small floppy disks which use the perpendicular recording approach. Sony and Toshiba have developed prototype units capable of storing up to 5 million characters on 3 1/2 inch floppy disks. These are expected to be brought to the market in 1985.
