Electrical Engineering
      and Computer Sciences

Electrical Engineering and Computer Sciences


UC Berkeley


2009 Research Summary

Ptolemy Project

View Current Project Information

Edward A. Lee, Hugo Andrade1, Christopher Brooks, Dai Bui, Yasemin Demir, Thomas Huining Feng, Shanna-Shaye Forbes, Man-Kit Leung, Ben Lickly, Isaac Liu, Thomas Mandl2, Slobodan Matic, Eleftherios Matsikoudis, Hiren Patel, Bert Rodiers, Mary Stewart, Yang Zhao and Jia Zou

Center for Hybrid and Embedded Software Systems, National Science Foundation 0720882, National Science Foundation 0720841, Army Research Office W911NF-07-2-0019, Air Force Office of Scientific Research FA9550-06-0312, Air Force Research Lab FA8750-08-2-0001, California MICRO, Agilent Technologies, Robert Bosch GmBH, HSBC, Lockheed-Martin, National Instruments and Toyota

The Ptolemy Project studies modeling, simulation, and design of concurrent, real-time, embedded systems. The focus is on assembly of concurrent components [1]. The key underlying principle in the project is the use of well-defined models of computation that govern the interaction between components. A major problem area being addressed is the use of heterogeneous mixtures of models of computation. Current research thrusts include:

  • Precision-timed (PRET) machines [2]: This effort reintroduces timing into the core abstractions of computing, beginning with instruction set architectures, using configurable hardware as an experimental platform;
  • Real-time software: Models of computation with time and concurrency, metaprogramming techniques, code generation and optimization, domain-specific languages, schedulability analysis, and programming of sensor networks;
  • Distributed computing [3]: Models of computation based on distributed discrete events, backtracking techniques, lifecycle management, unreliable networks, and modeling of sensor networks;
  • Understandable concurrency: This effort focuses on models of concurrency in software that are more understandable and analyzable than the prevailing abstractions based on threads, and more suitable for implementation on multicore architectures;
  • Systems of systems: This effort focuses on modeling and design of large scale systems, those that include networking, database, grid computing, and information subsystems;
  • Abstract semantics: Domain polymorphism, behavioral type systems, meta-modeling of semantics, comparative models of computation; and
  • Hybrid systems: Blended continuous and discrete dynamics, models of time, operational semantics, and language design.

Figure 1
Figure 1: The Ptolemy Project is named after Claudius Ptolemaeus, the second century Greek astronomer, mathematician, and geographer.

J. Eker, J. W. Janneck, E. A. Lee, J. Liu, X. Liu, J. Ludvig, S. Neuendorffer, S. Sachs, and Y. Xiong, "Taming Heterogeneity--the Ptolemy Approach," Proceedings of the IEEE, January 2003, Vol. 91, Issue 1, pp. 127-144.
S. Edwards and E. A. Lee, The Case for the Precision Timed (PRET) Machine, UC Berkeley EECS Department Technical Report No. UCB/EECS 2006/149, November 2006.
Y. Zhao, J. Liu, and E. A. Lee, "A Programming Model for Time-Synchronized Distributed Real-Time Systems," Proceedings of the 13th IEEE Real-Time and Embedded Technology and Applications Symposium (RTAS 07), Bellevue, WA, April 2007.

1National Instruments
2Robert Bosch GmBH