The form factor used by most PC motherboards in the early 1990s. The original motherboard for the PC-AT measured 12in by 13in. Baby AT motherboards are a little smaller, 8.5in by 11in. This term is commonly used in computing and information technology contexts, where its meaning is defined by established technical standards and industry usage. It is commonly encountered in computing and information technology, where its behaviour and usage are defined by formal standards or widely accepted industry practice.
