The Cyberdyne Systems Model 101 Series 800 Version 2.4 Terminator, once referred to as "Uncle Bob" by John Connor, was sent from the future to arrive in Acton, California on June 8, 1995. Its mission was to protect the young John Connor, which it successfully completed.
To protect his younger self in the past, John Connor had this Terminator reprogrammed and sent back to 1995 via the time displacement sphere. Upon arrival, it encountered a group of bikers on a bar, stealing one's clothing, injuring various bikers and took the bar owner's sunglasses, a Colt Series 70/Detonics 1911 Hybrid pistol and Model 1887 Winchester lever-action shotgun from a bartender, along with a Harley-Davidson_Fat_Boy as his personal vehicle.
The T-800 then tracked down John Connor in a shopping mall. Following a short fight of hand-to-hand combat with the T-1000 (sent by Skynet to kill Connor), a lengthy chase ensued with the T-1000 chasing John through the channels of the LA river system, but the T-800 and John managed to escape the T-1000. Connor questioned the Terminator about itself and who sent it. The Terminator answered that it is a cybernetic organism, having living tissue over its metal endoskeleton. It told John that it was his future self who sent it to protect him.
John and the Terminator go to the Pescadero State Hospital to help free John's mother, Sarah, who was also trying to escape from there as well. The Terminator later told John and his mother that it has the ability to learn. In the Extended-Release version of the film, however, the three go to a garage and Sarah tried to kill the Terminator by smashing its CPU, but she was stopped by John, who felt that it was needed. Later on, John started teaching some things to it in an effort to help it "blend in" with humans better (some of the things he taught the Terminator included the euphemistic phrase "Hasta la vista, baby!"). When Sarah asked it how Skynet was created, it answered that Miles Dyson was the most directly responsible person. It also explained that Skynet became self-aware after its creation, and began to deny human authority.
group later encountered Dyson, but did not kill him. The Terminator explained him the consequences of his research. The three, along with Dyson, attempted to destroy the Cyberdyne building to prevent Skynet from being created. They were soon approached by the police. John, Sarah, and the Terminator escaped the building while Dyson blew up the building with himself inside.
The three were encountered again by the T-1000. The Terminator succeeded in destroying it when it fell into molten steel. Afterward, John drops the CPU and the arm of the first Terminator into the hot liquid. Since the Terminator had a computer chip in it, it also planned to destroy itself to prevent its technology from being discovered by others to create Skynet. John begged it not to be destroyed, but it had to fulfill its mission. When John cried, the Terminator understood why, but could not cry itself because it was a machine. It hugged John for the first and very last time, and having finally earned Sarah's respect, shook her hand offered to a brother warrior. As it is lowered into the steel below, the Warrior of Steel-in-Flesh gave John an encouraging thumbs up before sacrificing its life for humanity's future. The machine also renewed Sarah's hope in humanity as she mused that if a machine could learn to value human life, then so could humans.
