The implementation of the attributed recursive descent architecture in VAX-11/780 microcode

ABSTRACT

This paper describes a case study in the implementation of a special purpose architecture on a particular microprogrammable engine. The host engine used is the VAX-11/780; the target architecture is one tailored for implementing recursive descent translators. The paper describes the mapping of the target resources onto the host machine including a discussion of the issues involved in interfacing with the normal VAX environment. The architecture specification does not mandate the exact bit-level representation of the target architecture instructions allowing a more efficient emulator to be constructed. Many of the important design decisions involve choosing instruction representations to effectively utilize the host engine. The paper concludes with discussion of the considerable shortcomings of this approach, of the suitability of the VAX-11/780 as an underlying engine for the target architecture, and of the implications of the study for universal host machines.

References

1. 1.D.M. Abrahamson "A Fast Entry Path into User Microcode on the VAX-11/780," IEEE Micro, vol.3, no.6, December, 1983, pp.40-43.
2. 2.Digital Equipment Corporation KA780 Central Processor Technical Description, Digital Equipment Corporation. Maynard, Massachusettes, 1979.
3. 3.Digital Equipment Corporation VAX Architecture Handbook, Digital Equipment Corporation, Maynard, Massachusettes, 1981.
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7. 7.J.L. Linn Formal Semantics of the Attributed Recursive Descent Architecture, University of Southwestern Louisiana Technical Report, 1984.
8. 8.J.L. Linn The Implementation of the Attributed Recursive Descent Architecture in VAX-11/780 Microcode University of Southwestern Louisiana Technical Report, 1984.
9. 9.Y.N. Part "Introduction to the VAX-11/780 Microarchitecture," Digital Equipment Corporation, internal technical report, still in preparation.
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Index Terms

• Computer systems organization

  • Architectures

    • Serial architectures

• Hardware

  • Electronic design automation

    • Methodologies for EDA

  • Integrated circuits

    • Logic circuits

      • Arithmetic and datapath circuits

      • Design modules and hierarchy