VDM Verlag Jop: A Java Optimized Processor for Embedded Real-Time Systems

This thesis presents a Java processor designed for time-predictable execution of real-time tasks. JOP (Java Optimized Processor) is the implementation of the Java virtual machine in hardware. JOP is intended for applications in embedded real-time systems and the primary implementation technology is in a field programmable gate array. This research demonstrates that a hardware implementation of the Java virtual machine results in a small design for resource-constrained devices. Architectural advancements in modern processor designs increase average performance with features such as pipelines, caches and branch prediction. However, these features complicate worst-case execution time (WCET) analysis and lead to very conservative WCET estimates. This thesis tackles this problem from the architectural perspective - by introducing a processor architecture in which simpler and more accurate WCET analysis is more important than average case performance. The proposed processor and the Java real-time profile have been used with success to implement several commercial real-time applications.