Open Architecture Computer (OAC) designed and developed by ADA, combines the functions of earlier mission computer, display processor, video switching unit, mission preparation and retrieval unit. It is designed based on open system interfaces standards, which provides interoperability, scalability, and portability. OAC drives three multi-function displays, HUD and the helmet-mounted display. This open architecture design will allow the designers to continuously adapt and upgrade Tejas to meet the challenges of modern warfare.