"The notion of linking computers together is not new.
In the 1950s and 1960s the U.S. Air Force
established a network of vacuum-tube computers
called SAGE to guard against a Soviet nuclear
attack. In the mid-1980s Digital Equipment
Corporation coined the term "cluster" when it
integrated its mid-range VAX minicomputers into larger systems. Networks of
workstations--generally less powerful than minicomputers but faster than
PCs--soon became common at research institutions. By the early 1990s scientists
began to consider building clusters of PCs, partly because their mass-produced
microprocessors had become so inexpensive. What made the idea even more
appealing was the falling cost of Ethernet, the dominant technology for connecting
computers in local-area networks." More at ScientificAmerican.com.
July 14, 2001