From a young age, Nelson was tinkering with electronics, aided and abetted by his father who was a physicist that had become an engineer.
From his first few days of High School, Stewart displayed his talents for hacking the international telephone trunk lines,[1] along with an uncanny skill for picking combination locks, although this was always done as innocent entertainment.
Nelson enrolled at MIT in 1963 and quickly became known for hooking up the AI Lab's PDP-1 (and later the PDP-6) to the telephone network, making him one of the first phreakers.
Nelson was hired by Ed Fredkin's Information International Inc. at the urging of Marvin Minsky to work on PDP-7 programs at the MIT Computer Science and Artificial Intelligence Laboratory.
He was influential in LISP, the assembly instructions for the Digital Equipment Corporation PDP, and a number of other systems.