The original name of Softdisk's diskmagazine for the IBM PC and compatibles. IBM made occasional rumblings about suing over this name for infringement of its "Big Blue" nickname, but was stymied by the fact that they didn't actually have any registered trademarks to this term dating back before 1986, when BBD began publication. Nevertheless, the name was changed to On Disk Monthly later.
Originally, this publication was marketed as "The Magazine On Disk for IBM PC / PCjr and Compatibles", as the PCjr was believed to be a possible up-and-coming home computer. Mention of the PCjr was soon dropped as this model died a rapid death, though it remained necessary for a while to support the Tandy 1000, which was designed with some of the worse features of the PCjr.
Issue #3 of Big Blue Disk included a pair of 3D glasses, for viewing a graphical demo program included on that issue. The glasses were purchased from Eclipse Comics, which had surplus glasses left over from 3D comic book projects from their past.