Comparing MS-DOS and DR-DOS

Date: September 1988

Synopsis
I thought Microsoft never tested other OSes?

Snippet
From: pascalm Thu Sep 22 14:42:18 1988 To: billg Cc: aaronr; philba; russw; tomle Subject: RE: DR DOS

Here- follow the three "differences" (between DR and MS DOS) that Aaron has been able to find so far. Except for these differences,the two OSs behave similarly, including undocumented calls.

The bottom line is that, given Aaron's current findings, an application can identify DR DOS. However, most apps usually have no business making calls that will let them decide which DOS (MS or DR) they are running on.

Do you think differently ? ...

Full Exhibit
http://boycottnovell.com/wp-content/uploads/2009/01/px00034_a.pdf