The Ravenscar-compliant hardware run-time (Ravenhart) kernel

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2004.Includes bibliographical references (leaves 69-71).Real-time embedded systems are increasingly becoming the foundation of control systems in both the aerospace and automotive worlds. This class of systems has to meet three requirements: strict timing constraints on operational behavior, limited resource availability, and stringent certification standards. The heart of any embedded system is its run-time system (RTS), which provides resource management, task creation and deletion, and manages inter-task communication. The traditional Ada RTS does not provide deterministic behavior. In order to meet the requirement of a minimal, deterministic RTS, a formal model based on the Ravenscar profile of Ada95 was developed by Professor Kristina Lundqvist in 2000. This formal model forms the basis of the work carried out in this thesis. This thesis aims to leverage the reliability and efficiency of programmable hardware to implement a run-time kernel called RavenHaRT. The kernel was designed to support Ravenscar compliant Ada95 code and provides task creation, task scheduling and inter-task communication capabilities. The timing properties embedded in the formal model are captured in terms of kernel performance within the hardware. The kernel was implemented using a Xilinx Virtex-II Pro FPGA. The results from testing demonstrate that the hardware kernel has the expected behavior and can interface correctly with software code.by Anna Silbovitz.S.M

THE CHOICE OF COMPUTER LANGUAGES FOR USE IN SAFETY-CRITICAL SYSTEMS

The paper reviews the choice of computer language for use in safety-critical systems. The advice given reflects both civil and military requirements. A comparison is made between assembly-level languages, the language C, CORAL 66, Pascal, Modula-2 and Ada. It is concluded that a well defined sub-language is essential for use in safety-critical projects, and a guide is provided for project managers and designers on the characteristics which such a subset should possess