These are .tap tape images, generated by running the cassettes on a normal audioplayer, then using Jim Battle's dpwav2tap program ( adapted for 64 bits systems) From the fileheader : ======================== DOS.D is the Datapoint Corporation Disk Operating System for the 1800, 5500, 6600 processors, and the 932X/937X disk drives or the Storage Module Disk (939X). ======================== Contents are DOS.D 2.6, the update for 2.6.1, and various utlity's. Also the datashare software is present. All is untested, as I lack the appropriate hardware. Some files had dropouts, so user beware... jos.dreesen@greenmail.ch November 2023