ABC

A.B.C. is a sentient computer in the Generation 1 continuity family.

A.B.C. is an advanced guidance computer created by the United States military. It was stolen from Rutter U.S. Military Base by the Combaticons and subsequently enhanced by Cybertronian technology. These enhancements unwittingly gave the computer some level of sentience.

Ficiton

Marvel UK comics continuity

Scorponok programmed the A.B.C. to guide a smart missile to zero in on Optimus Prime and destroy him. Getaway was captured by the Decepticons and was being held in their orbiting space ship. He was able to free himself and access the A.B.C. Getaway's interfaced the computer on a direct machine-to-machine level, asking it to stop the missile. The computer coldly reported that that was outside the scope of its programming. With the interface still active, Getaway thoughts turned to how great and noble Prime was when Rev interrupted him saying how he found the escape pod and that they should get out of there.

Later, Optimus Prime, warned of the incoming missile, had fled to unpopulated areas so as to not risk anyone's life but his own. There he took his last stand against the missile but all of his attempts to stop it were to no avail. The missile reached Optimus Prime, but didn't go off. It was disarmed. Getaway guessed that his appeals to A.B.C. had an effect and the computer took the initiative to disarm the device. Optimus Prime was sorry that the newly sentient computer did not have much longer to exist, as Scorponok would surely smash it when he found out it caused his plan to fail. Getaway tried to cheer him up. Prime Bomb!