Copyright (c) 1979 The Regents of the University of California.
All rights reserved.

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@(#)pxin0.n 5.2 (Berkeley) 04/17/91

.RP Berkeley Pascal PX Implementation Notes

Version 2.0 - January, 1979 .AU William N. Joy\*(Dg .AU M. Kirk McKusick\*(Dd .AI Computer Science Division Department of Electrical Engineering and Computer Science University of California, Berkeley Berkeley, California 94720 .AB

Berkeley Pascal is designed for interactive instructional use and runs on the "VAX 11/780" . The interpreter px executes the Pascal binaries generated by the Pascal translator pi .

The PX Implementation Notes .R describe the general organization of px , detail the various operations of the interpreter, and describe the file input/output structure. Conclusions are given on the viability of an interpreter based approach to language implementation for an instructional environment. .AE

Introduction

These PX Implementation Notes .R have been updated from the original "PDP 11/70" implementation notes to reflect the interpreter that runs on the "VAX 11/780" . These notes consist of four major parts. The first part outlines the general organization of px . Section 2 describes the operations (instructions) of the interpreter while section 3 focuses on input/output related activity. A final section gives conclusions about the viability of an interpreter based approach to language implementation for instruction.

Related Berkeley Pascal documents

The "PXP Implementation Notes" give details of the internals of the execution profiler pxp; parts of the interpreter related to pxp are discussed in section 2.10. A paper describing the syntactic error recovery mechanism used in pi was presented at the ACM Conference on Compiler Construction in Boulder Colorado in August, 1979.

Acknowledgements

This version of px is a "PDP 11/70" to "VAX 11/780" opcode mapping of the original px that was designed and implemented by Ken Thompson, with extensive modifications and additions by William Joy and Charles Haley. Without their work, this P system would never have existed. These notes were first written by William Joy for the "PDP 11/70" implementation. We would also like to thank our faculty advisor Susan L. Graham for her encouragement, her helpful comments and suggestions relating to P and her excellent editorial assistance. .FS \*(dg The financial support of the National Science Foundation under grants MCS74-07644-A03 and MCS78-07291 and of an \s-2IBM\s0 Graduate Fellowship are gratefully acknowledged. .FE .FS \*(dd The financial support of a Howard Hughes Graduate Fellowship is gratefully acknowledged. .FE .bp