Aboard the Constitution, the Navy's oldest commissioned warship, the Navy's oldest officer on active duty retired last week. In 1943 Grace Murray Hopper, then an associate professor of mathematics at Vassar College, joined the reserves, and while developing an early computer program, coined one of computerese's most useful terms when she found a moth in the machine. "From then on," she recalled, "whenever anything went wrong with a computer, we said it had bugs in it." After the war, told she was too old for active duty, she went to work on UNIVAC, the first large commercial computer, and created COBOL, the breakthrough computer language that made the machines accessible to non-mathematicians. She was recalled to active duty in 1967 at age 60. Now 79 and a rear admiral, Hopper is philosophical about the Navy's early slight. "It's just as well to be told you're too old at 40," she says. "Then you're over it."