It’s all in the marketing, because every major player in Japan Inc, and half a dozen leading US disk drive and media companies have been stumbling over themselves in their rush to develop a reliable and cost-effective erasable optical technology, but Tandy Corp deserves the headlines for spotting that the way to promote the technology was to enable it to record music on disks that can be used in existing Compact Disk players as well as offering it for data storage: the Fort Worth, Texas company is talking about having a consumer Compact Disk recorder on the market within 18 months to two years at $500, and the promise was good for a $2.625 jump in its share price to $45.75.