International Telemetering Conference Proceedings / October 25-28, 1993 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Functional integration and validation of complex systems in an operational environment, prior to delivery or installation, can be expensive. Real-time simulation, in a lab environment, can replace hardware subsystems to provide the interfaces necessary to validate and or integrate the test article. The test article can be hardware, software or firmware. Multitasking simulations can provide modeling of subsystems and environmental sensor data for complex system integration. The simulation presented provides the capability to integrate 1553 remote terminals and provide validation of 1553 bus controller software.