R1 and XCON at DEC
An expert system began configuring orders for VAX computers on Digital Equipment's production line, not in a laboratory but in daily work.
Why it matters
The first expert system that made money turned the field from a research pursuit into a commercial one.
John McDermott wrote it at Carnegie Mellon in the OPS5 rule language. It grew from about 750 rules to 2500; by 1986 it had processed 80,000 orders at 95 to 98 percent accuracy and, by DEC's estimate, saved some 25 million dollars a year. By 1985 corporate spending on expert systems passed a billion dollars a year. Maintaining the rule base turned out to cost more than writing it.