Hello, all: I was able to get my hands on the two DOS 1.0 disks. So, I spent a few minutes with Sourcer and a good hex editor in search of the DR copyright notice. I didn't find it. Maybe I misunderstood the timing of the message, but I thought that the 1.0 version of DOS contained copyright information from Digital Research and when IBM found out, they compelled MS to expunge it, resulting in the 1.1 version.