Complex real-time systems need databases to support concurrent data access and provide well-defined interfaces between software modules. However, conventional database systems and prior real-time database systems do not provide the performance or predictability needed by high-speed, hard real-time applications. To address this need, we have designed, implemented, and evaluated an object-oriented software system called MDARTS (Multiprocessor Database Architecture for Real-Time Systems). MDARTS avoids the client-server overhead of most prior real-time database systems and object-oriented real-time systems by moving transaction execution into application tasks. By eliminating these sources of overhead and focusing on basic data management services for hard real-time systems (data sharing, serializable transactions, and multiprocessor support), our MDARTS prototype provides guarant..