Cyberdyne reverse engineered its CPU and created a powerful new microprocessor for weapons systems, becoming a major contractor for the US military.
Cyberdyne eventually developed Skynet, a network of supercomputers that employed artificial intelligence in order to replace human beings as commercial and military aircraft pilots,
and for the control of other military systems, including nuclear missiles. The system went online on August 4, 1997. On August 29, 1997, Skynet became self-aware. In a panic,
its creators attempted to shut it down, but Skynet retaliated by launching a nuclear attack against Russia,
knowing that the Russian counterattack would eliminate its enemies in the United States, initiating an indeterminately long period of global warfare.
The battle pitted humans against Cyberdyne machines, which developed ever-increasing capabilities. Although the company was presumably shut down or destroyed,
the event was later known as Judgment Day.
Source: Terminator Wiki