SYSTEM DESIGN AND IMPLEMENTATION OF BGRAF2.

BGRAF2 is a real-time interactive 2D graphics language. Its supporting system contends with an unusual combination of features: timing, events, parallelism, image manipulation, user interaction and procedural structures. This combination creates within the system many unpredictable interrelated tasks competing for execution. A BGRAF2 program is compiled into an object module consisting of a sequence of pure code blocks, tasks, and a set of data blocks. The real-time environment is a hierarchical structure, where the highest level is a Scheduler, and the next level is composed of the object module and five additional processors: Graphics Processor, Control Processor, Input-Output Processor, Real-Time Processor and Memory Manager. The Scheduler is an abstract monitor responsible for scheduling tasks in accordance with a multi-level priority from a multi-queue scheme.