As the article points out, it was included only in the beta release. IIRC an explanation for this that I read was that the beta release was given to outside te

As the article points out, it was included only in the beta release. IIRC an explanation for this that I read was that the beta release was given to outside testers and journalists writing about it in computer magazines. Some of those journalists would try to run it on DR DOS, get the intimidating error message and be very helpful in spreading the rumor that it doesn't work properly on DR DOS. The final release would work of course and not have a "smoking gun" in it, but the rumor is out there. The later part obviously failed by only disabling, but not removing the code. On the other hand of the spectrum you have explanations like the one on Larry Osterman's blog, that this was all for compatibility, because early Windows and the DOS underneath would have to interoperate closely and Microsoft would take the blame if anything didn't work properly[1]. Which by the way is also the reason for gems like [2], which could also be re-interpreted as trying to weed out MS DOS clones. Of course, the first one is only hearsay because I can't track down the source right now, and BOTH statements are from people who also have a stake here, but on opposing sides, so please take both with a grain of salt. It is not necessary that one side is blatantly lying (or falsely accusing). There can easily be truth to both here, with the "compatibility checks" done for semi valid engineering reasons while also having the desired side effect that management wants of making the competition look bad. [1] https://docs.microsoft.com/en-us/archive/blogs/larryosterman/aardvarks-in-your-code https://docs.microsoft.com/en-us/archive/blogs/larryosterman... [2] https://news.ycombinator.com/item?id=20315453 https://news.ycombinator.com/item?id=20315453