When military planners built the Semi-Automatic Ground Environment (SAGE), a computer-based command and control system to thwart potential bombing attacks by the former Soviet Union, they had no idea the project would lay the framework for the Internet Age.
Most people today would be surprised to find that SAGE was a precursor to the Internet. It is commonly acknowledged that the Internet Age began in 1969 when the U.S. Department of Defense implemented the Advanced Research Projects Agency Network (ARPANET), whose purpose was to demonstrate how communications between computers could promote cooperative research among scientists.
But the foundation for ARPANET, and the Internet Age, actually began forming in 1954 with the development of SAGE, said Jim Ray, who worked on the SAGE project as a programmer from 1966 to 1969.
"SAGE laid the foundation for the entire Internet Age," he said. "The Internet is based on a number of inventions made over the years, including the ARPANET, but if you trace them all back as far as they could go, you'll find the earliest patents for things like modems, memories and interactive displays trace back to SAGE."
SAGE emerged as a product of Cold War fears. Twenty-three concrete hardened bunkers across the country (and one in Canada) were linked by a real-time, command and control computer system that would detect Soviet bombers carrying atomic bombs and guide American interceptors to destroy them.
"It was a network system, and it worked interactively with the users and had, in a crude sort of way, all the basic kinds of characteristics of an Internet system," Ray said.
The first of the 23 "Direction Centers" came online in 1959, and comprised two Whirlwind computers. Each center took more than 100 people to operate.
In 1944, the Whirlwind computer originated as a general purpose flight simulator that was part of the Navy's Airplane Stability and Control Analyzer project. The computer was developed at the Massachusetts Institute of Technology (MIT) and marked one of the first applications of magnetic core memory. It also landed MIT professor Jay Forrester in the Inventors' Hall of Fame.
It was nearly dumped by the Defense Department because of cost, but was salvaged by the Air Force to support the SAGE project. A little-known company called IBM built the AN/FSQ-7 computer, a military-grade version of Whirlwind. Each AN/FSQ-7 weighed 250 tons, required a 3,000 kW power supply and needed more than 49,000 vacuum tubes to operate.
In its original form, Whirlwind was an analog computer, but in the late 1940s, Forrester decided converting to digital would allow for more functions than flight simulation. Forrester's bold move resulted in the first real-time, general-purpose digital computer.
Relying on vacuum tubes when building the computer represented something less than a bold initiative, however, and their use rendered the SAGE project pretty much obsolete the day it was activated in 1958 -- although SAGE endured for 25 years until the Air Force ended the SAGE program in 1983.
"It might still be around today if they'd chosen to build it with transistors instead of vacuum tubes," Ray said, noting that at the time, transistors weren't as fast or accurate as vacuum tubes. "They made the judgment that transistors were risky technology, and they decided to avoid the risk. If they'd taken the risk, today we'd be saying, 'Wow, that was a smart decision.' They didn't."
Though the computer was originally built to use vacuum tubes, it could have been rebuilt to use transistors, Ray said.
SAGE was a breakthrough system for many reasons. "It didn't have some of the refinements that [computer systems] had later on, but there were the beginnings of multitasking and a lot of artificial intelligence notions," Ray said, noting that the computers could