Hitachi Ltd announced a 5 diameter optomagnetic disk with a storage capacity per disk side of 1Gb three times the capacity of current disks. Transfer rate is 4Mbytes per second. The advance was achieved through the use of mark-edge recording mode; control of the high-precision recording wavelength, through suppression of heat interference and development of a thermal interrupt mode; and setting of optimal optical power for recording, by several trial writes at different optical power settings. Hitachi is supporting one standard for optical disks, joined by NEC Corp, Fujitsu Ltd and Hewlett-Packard, while Sony Corp and IBM Japan Ltd support a different standard. A decision on an international standard for optical disks is expected in late 1993, from the International Standards Organisation.
