the largest store in the central unit, mainframe is the premier shop for all things electronic. owned by BIOS itself, mainframe has the latest in all technology far before any of the other surrounding shops stack their shelves with it. prices here are high, but the things sold here are worth every last penny. computing technology, robots, entertainment, and even transportation are displayed on every floor, and the building itself is tall enough to be accessible from all three street levels. the bottom-most floors are for repairs, and the farther up, the more expensive the goods - until you get to the top floor, which is exclusive to those that are given invitation to browse its merchandise.