Almost....
Softdesk was a DCA product.
When Autodesk bought softdesk, it was then re-branded .....
Ya know, that's what I had thought, too. But I stumbled across my original SDSK8 box yesterday.....the Autodesk logo is prominent, and the fine print says
Autodesk, The Autodesk logo, Softdesk, and AutoCAD are registered in the U.S. Patent Office by Autodesk, Inc. <snipped a bunch of stuff about CAD Overlay> Copyright 1997 Autodesk, Inc.
I do not have the SDSK7 box to check, so all I can narrow it down to is: sometime after ADCADD but before SDSK8, is when Autodesk acquired "the package".