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canopic jug [soylentnews.org] writes:

Software analyst Geoff Chappell was the expert hired by Caldera to dig into the infamous AARD code. Recently he made a review of the discovery, publication, earlier work, personal work, and scale of effort involved in analyzing the AARD code [geoffchappell.com], from a historical perpective. He doesn't adress the ethical or political repercussions of the code. However, being a principal in the analysis, he is able to set the record straight on some technical and legal facts.

The AARD code is from back when MS Windows was still just a graphical shell on top of a text-based disk operating system (DOS) and existed briefly as some XOR-encrypted, self-modifying, deliberately obfuscated machine code and using a variety of undocumented DOS structures and functions. The purpose of the code was to detect competing DOSes, specifically, the then popular DR-DOS, and through up an unnecessary warning when detected.

Some programs and drivers in some pre-release builds of Windows 3.1 include code that tests for execution on MS-DOS and displays a disingenuous error message if Windows is run on some other type of DOS. The message tells of a “Non-fatal error” and advises the user to “contact Windows 3.1 beta support”. Some programs in the released build include the code and the error message, and even execute the code, performing the same tests, but without acting on the result to display the error message.

The code in question has become known widely as the AARD code, named after initials that are found within. Although the AARD code dates from the start of the 1990s, it returned to controversy at the end of the 1990s due to its appearance in a suit at law between Caldera [digitalresearch.biz] and Microsoft [microsoft.com]. Caldera was by then the owner, after Digital Research and Novell, of what had been DR DOS. It has ever since been treated as a smoking gun in analyses of anti-competitive practices by Microsoft.

It is not my intention here to comment on the rights or wrongs that I may or may not perceive in the AARD code’s existence. However, I must declare a financial interest: in 1999 when this note was first published, I was engaged indirectly by Caldera to assist with their understanding of MS-DOS and Microsoft Windows for the suit just mentioned.

What I do intend here is to put on the public record a few points of history.

The AARD code, during its short tenure, was particularly effective in scaring the public away from DR-DOS [geoffchappell.com].

Original Submission