The optical storage side of the Japanese camera company’s Nikon Precision Inc in Belmont, California has found the answer to the problem that causes erasable magneto-optical disk drives to take twice as long to write as to read. The delay is caused by the need for a separate erase cycle before the write, and it means that write transfer speeds are only 50% of the rated read speed. The company’s answer is a technique it calls Direct Overwrite, which uses Nikon’s Light Intensity Modulation to vary the intensity of the laser – presumably between that required to generate enough heat to erase and that required for a write, and plans to offer it in 5.25 drives that store 2.6Gb. The company claims a read and write transfer rate approahing 4M-bytes per second. The drives will be fully read- and write-compatible with the several million 1.3Gb 5.25 magneto-optical platters in use worldwide. Nikon and Hitachi Maxel Ltd are jointly working on production of the medium. Nikon’s approach to Direct Overwrite has been submitted to the International Standards Organisation and Nikon expects it to become a worldwide standard. Initial samples will be available in the first quarter next year. Target markets include professional graphics development and jukebox-oriented work.
