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Sunday 6 May 2018 at 01:40
Speaking specifically about NINE BALL I found the following post listed a long time ago on the RGP newsgroup:
"...the other (myth, IMO) that "rumor has it there were 60 revisions of software and it never worked properly on location" (paraphrasing from Gary Flower's book Pinball Lure of the Silverbal...
Source: http://pinside.com/pinball/forum/topic/stern-mpu-200-how-to-know-the-software-version#post-4381500