A logic board is the Apple Macintosh equivalent of a motherboard. The term "logic board" was coined back in the 1980s, when the compact Macs at the time had two separate circuit boards, the Logic Board, containing all of the computer's "logic" circuitry (processor, RAM, etc.), and the analog board, containing all of the hardware necessary to drive the built-in display and to power the rest of the computer's components. The term "logic board" stuck over the years of Macintosh manufacturing, even in the non-all-in-one Macs. A longtime practice for Apple when an existing model was upgraded was to offer a 'logic board upgrade' where a user could bring their computer into an Apple dealer and have the old logic board replaced with the new one, along with other upgrades necessary to bring their computer in line with the new model's specs. The old logic board would be kept by the dealer as a trade in.
