*Lawrence Roberts, far left, with other internet pioneers, from left, Robert Kahn, Vinton Cerf and Tim Berners-Lee, at a conference in Spain in 2002. Dr. Roberts insisted that engineers look for practical uses for the Arpanet, the precursor to the internet. Credit Carlos Alvarez/Getty Images*
In late 1966, a 29-year-old computer scientist drew a series of abstract figures on tracing paper and a quadrille pad. Some resembled a game of cat’s cradle; others looked like heavenly constellations; still others like dress patterns.
Those curious drawings were the earliest topological maps of what we now know as the internet. The doodler, Lawrence G. Roberts, died on Dec. 26 at his home in Redwood City, Calif. He was 81.
The cause was a heart attack, said his son Pasha.
As a manager at the Pentagon’s Advanced Research Projects Agency, or ARPA, Dr. Roberts designed much of the Arpanet — the internet’s precursor — and oversaw its implementation in 1969.
Dr. Roberts called upon a circle of colleagues who shared his interest in computer networking for help in creating the technical underpinnings of the Arpanet, integrating and refining many ideas for how data should flow.
Dr. Roberts was considered the decisive force behind packet switching, the technology that breaks data into discrete bundles that are then sent along various paths around a network and reassembled at their destination. He decided to use packet switching as the underlying technology of the Arpanet; it remains central to the function of the internet.