Dr. Dyson was a cybernetics scientist and a high-ranking employee of Cyberdyne Systems Corporation as Director of Special Projects. He was tasked to create a new neural-net processor from two pieces of unknown-sourced advanced technology. The technology actually came from a ten year old crime scene from another Cyberdyne facility (The Terminator's arm and CPU from the first film). Miles worked on the project around the clock with his colleagues at the main Cyberdyne office, where he was one of the few people who were given access to the original Terminator arm and CPU chip. He also worked at his home office. Miles truly believed in the potential of his work as the processor could lead to a revolutionary new brand of automated systems, as well as a more-advanced form of artificial intelligence making other existing computer systems obsolete in comparison. The project eventually reached the point where he nearly completed a prototype of the processor. Had the project been completed and deployed by the nation's military defense network, the processor, named Skynet, would have gained self-awareness and waged a genocidal war on mankind.
This was averted by Sarah Connor however, who wished to stop Skynet's attack before it began using files from another future Terminator to track down Miles at his home. Sarah initially tried to kill him with a CAR-15 sniper rifle but Miles was momentarily distracted by his son, Danny, narrowly evading the shot, which destroyed his monitor. Sarah switched the rifle to full-auto and opened fire again but Miles took cover behind his desk where the bullets, though completely destroying prototype within his computer along with other equipment. With the rifle magazine empty, Sarah advanced on the house with a .45cal side-arm and began shooting at Miles close-range eventually hitting him in the shoulder and cornering him with his wife, and son.
With a gun to his head Miles pleaded with Sarah what she wanted from him. Sarah, in an enraged state, vocally blamed him for everything that was to transpire without any full explanation, only prompting Miles to utter an innocent "...What?" Sarah broke down emotionally and could not bring herself to kill Miles in front of his wife and children when he was not even responsible for anything yet. Sarah's son John and the second Terminator arrived at that moment hoping to stop Sarah from committing murder. John went to his mother while the Terminator administered first-aid to Miles' gunshot wound. Miles then asked his attackers to identify themselves, not expecting the Terminator to cut the flesh from his arm and expose it's robotic nature. Dr. Dyson was speechless at the revelation that this man was actually a machine from the future and identical to the components that brought about his technical achievements at Cyberdyne.
After Miles's wound was partially-healed and the shock of the attack had died down, Sarah and company began to explain Skynet's future and its true effects on humanity. Miles was convinced to quit Cyberdyne and said he would destroy all of his work. However, the Terminator made him realize that as long as the laboratory and technological artifacts at Cyberdyne were intact Skynet could still be created by others following his footsteps. Miles then agreed to go to the Cyberdyne building with the Connors and the Terminator to destroy the entire research, and also sent his family into hiding. Before leaving, Tarissa agreed with Miles that Skynet had to be destroyed above all else and bid him good luck.
Miles initially hoped to enter the building undeterred and destroy the contents of the lab without opposition. But the guard refused due to the late hour of the night and lack of proper paper-work which needed filed prior for access. Instead, the group forced their way in at gun-point and, after Miles helped John gather the advanced technological artifacts of the original Terminator from the high-security lab, began preparing to destroy the entire laboratory itself with a massive polydichloric euthimal bomb. Just as the bomb was ready, multiple SWAT team officers arrived in response to the break in and one unit stormed the building. The team opened fire and Miles's body was riddled with bullet-wounds before he took cover.
Knowing his injuries were fatal, Miles desperately bid the others to escape and stayed behind to trigger the bombs' remote, which would be flipped by a large piece of the Neural Net Processor model in Miles's hand. The SWAT team realized this when they cornered him at gunpoint as he's laying on the ground, and promptly evacuated. Miles slowly succumbed to his injuries with heartfelt and shallowed breathing, losing the strength to hold the model over the trigger. As his lifeless hand dropped the bomb detonated with a massive fireball, destroying the lab and a sizable portion of Cyberdyne Headquarters.