The CPU Chief is a one binome in a senior command position of the CPU defense force directly under Dot Matrix and Phong. He is also in charge of general security of the Principal Office and the Archives. The Chief apparently is lower ranked than the CPU Senior Chief.
The Chief was in charge of security outside the Principal Office during a scheduled system upgrade. The building's shields went up to prepare for the upgrade and the Chief was given orders by Dot to have his troops go to dispersed format. They maintained a security perimeter around the Principal Office during the procedure. Their forces did not know that Megabyte and Hexadecimal had faked the upgrade and taken control of the Principal Office. The Chief received a simple distress signal from inside from Dot. He immediately contacted Enzo Matrix at Dot's Diner to see if he had heard from his sister. Enzo hadn't and the Chief issued a curfew for Mainframe until further notice. (Infected)
The Chief was on watch duty in the Principal Office a week later. He was monitoring the security cameras when Megabyte's ABC fleet attacked the Principal Office to steel the Core Energy. The Chief quickly scrambled the CPU fleet into the air. Phong tried to contact Bob but lost communications, however the Chief was able to contact Dot and warn her. A Game Cube landed in the city during the battle and the Game was corrupted by the release of the Core Energy. The Chief had never seen anything like it. Once the Game was over, the Chief and Dot had organized a CPU platoon to defend Bob from a very angry defeated Megabyte.(Bad Bob)
Later that year, Hexadecimal broke into the system Archives and infected the system paint program. The Chief alerted Dot to the crisis, telling her that Hex had also destroyed the entire Archive security system and kidnapped all the guards. (Painted Windows)
During a disappearance crisis the Chief was seen at Dot's Diner informing the Senior Chief that another disappearance had occurred. Bob over heard their conversation and asked what was going on. The Senior Chief filled Bob in on the situation, and the Chief told him that the most recent disappearance was Al's Waiter. Bob went to level 31 to assist in the investigation. (Trust No One)
At the end of the same year, Mainframe came under attack from the Web. The Chief helped Bob coordinate the CPU fleet to defend the city during the Web War. One of the fighter pilots got scared and shot a Web Probe. The others scattered and quickly fled toward the Web Portal to call on the attack drones. The Chief told Bob what had happened and ordered the fleet to try and stop the probes before they got to the portal. (Web World Wars)