IBM litigation using "software birthmarks"? (watermarks)

Hello all,

in a paper written by Anderson and Petitcolas [1] I read the following sentence:

"When software is written, it contains "birthmarks" such as the order in which registers are pushed and popped, and these were used by IBM in litigation against software pirates who had copied their PC-AT ROM".

The authors cited "Talk on software birthmarks, counsel for IBM Corporation, BCS Technology of Software Protection Special Interest Group, London 1985" for this remark.

Does anybody know which litigation/case was meant by this remark? Any hint where to get more information?

Thank you,
Stefan

[1]: Anderson/Petitcolas, On the Limits of Steganography, IEEE Journal on Selected Areas in Communications 16 (1998), 474, 479.

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#    Stefan Bechtold    stef[_at_]n-bechtold.com    Tuebingen, Germany    #
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