From a New York Times obit by Katie Hafner headlined “David Walden, Computer Scientist at Dawn of Internet, Dies at 79”:

David Walden, a computer scientist who helped develop a machine that would evolve to become the backbone of the internet for decades, died at his home in East Sandwich, Mass.

In 1969, Mr. Walden was part of a small team of talented young engineers whose mission was to build the Interface Message Processor. Its function was to switch data among computers linked to the nascent Arpanet, the precursor to the internet. The first I.M.P. was installed that year at the University of California, Los Angeles. The I.M.P.s would be crucial to the internet until the Arpanet was decommissioned in 1989.