North Central Positronics is a megacorporation in alliance with the Sombra Corporation and LaMerk Industries, and in conflict with the Tet Corporation.
North Central Positronics is a company specializing in the production of robots. It is owned by the Sombra Corporation and was a part of The Imperium thousands of years prior to the beginning of the events of The Dark Tower Series.
During their time in The Imperium they were at the forefront of the Old Ones' technological advances being responsible for the manipulation of the multi-verse and help gave raise to the Old Ones replacing the Beams with technological ones of their own. All their achievements were possible as they discovered how to merge technology and magic together in the Dogans they built, all of which was under Maerlyn's guidance.
The addition of the word "positronics" by Stephen King is likely a reference to Isaac Asimov. Asimov's famous robots had positronic brains.
The Dogan buildings seen within the Dark Tower series and comics were all constructed by this company.