The programming language Pascal Plus [1][2] has emerged from refinement of a number of experimental notations developed for large-scale sequential and concurrent applications in the early 1970s. The language can be used to construct simulation models for any concurrent system and to implement such systems on either single processors, or multiprocessors with shared memory. The language is also useful for general purpose programming as it supports Pascal as a sub-set.
The main purpose of this project, together with a related development contract [3], is to make Pascal Plus widely available as a tool to aid research in all areas of computing. This entails the development of a portable compiler kit and specific high quality compilers for three of the leading main frames in UK universities (DEC, CDC and IBM).
All four systems have recently been aligned with the ISO Pascal Standard and both the portable and CDC systems are available for distribution. The development of the IBM and DEC compilers will be completed shortly as part of a new project.
For further information contact: Dr D W Bustard, Dept of Computer Science.
1. J.Welsh and D.W.Bustard, Pascal Plus - Another Language for Modular Programming, in Software - Practice and Experience. Vol. 9, pp 947-957, 1979.
2. D.W.Bustard and J.Welsh., A Tutorial Guide to Pascal Plus, Department of Computer Science, Queen's University, Belfast, 1982.
3. J.Welsh and D.W.Bustard, Portable Pascal Plus, in Proceedings of Pascal Experiences Conference. Gothenburg, Sweden, June 1980.
The objective of this project, which is funded through the EMR (q.v.) Contract mechanism, is to produce a compiler-interpreter system to allow Pascal Plus to be easily implemented on a variety of computers.
A pre-release version of the portable-plus system was completed in 1980 and has still been installed on a range of different processors including LSI/PDP 11 s (running RT-11 and RSX-11), Vax (running VMS), Z80 (running CP/M) and Motorola 68000.
Experience gained from this work led to the production of a revised system which is now available for distribution. In the new system Pascal-plus is aligned with the ISO Pascal Standard, keeping the full Pascal language as a pure sub-set [2]. The alignment produced a significant expansion in the size of the compiler which was counter-acted by splitting it into two passes. Also for ease of portability the compiler is now coded in standard Pascal rather than Pascal-plus.
Enhancements due for release in December 1983 include a model p-code to assembly language translator [3][4] and a program development tool that assists with both the preparation of a program text and the detection and correction of compilation and logical errors [5].
1. J.Welsh and D.W.Bustard, Portable Pascal-plus, in Proceedings of Pascal Experiences Conference, Gothenburg, Sweden, June 1980.
2. D.W.Bustard and J.Welsh, A Tutorial Guide to Pascal-plus, Department of Computer Science, Queen's University, Belfast, 1982.
3. R.Orr, A Naive Pascal-plus P-code to Assembly Language Translator, Department of Computer Science, Queen's University, Belfast, 1982.
4. A.Rammasubu, A Study of the Optimisation of Portable Object Code, MSc Dissertation, Department of Computer Science, Queens's University, Belfast, 1982.
5. R.M.S.Young, A Pascal-plus Compiler for an Interactive Environment, MSc Dissertation, Department of Computer Science, Queen's University, Belfast, 1981.
The investigator is interested in several aspects of parallelism, in both systems and applications programming. In the former he is concerned with operating systems problems, such as distribution and protection. In the latter he is concerned with the use of parallelism in the design of systems and with how a parallel design may have to be transformed into an implementation with a different process structure.
This grant provided funds for the investigator to make several short study visits to a number of centres in the UK and USA to examine current ideas on parallelism.
The investigator visited the University of Southern California (Professor Brinch Hansen: Edison and Highly Concurrent Languages), the Argonne National Laboratory (Dr Boyle: Program Transformations; Dr Dritz: Parallelism in PL10, Carnegie-Mellon University (Professors Wulf and Jones: Programming Multiprocessor Systems; Dr Joseph: Communication Systems) and the Massachusetts Institute of Technology (Professor Liskov: Distributed Computing). Reports of the visits are available from R M McKeag.
