Software package for an educational computer system

International Journal of Electrical Engineering Education, Oct 2003 by Grbanovic, Nenad, Djordjevic, Jovan, Nikolic, Bosko

Abstract

Some aspects concerning the realisation of a software package for an educational computer system are considered. First, the rationale behind the development of the educational computer system and software is given. Then the basic characteristics of the educational computer system and typical user features of the software are described. The reasons for the choice of programming environment used in the realisation of the software package are discussed. Finally, the basic elements of the proposed software package are given.

Keywords computer architecture; digital circuits; education; visual simulator

Courses in digital circuits and computer architecture and organisation are the first two courses in the area of computer engineering taken by the students of all departments at the Faculty of Electrical Engineering, University of Belgrade. The first course covers switching functions, combinatorial and sequential switching circuits, methods used to carry out the analyses and syntheses of switching circuits and standard combinatorial and sequential modules such as multiplexers, decoders, arithmetic and logic units, registers, counters, etc. The second course deals with the computer system elements relevant to both the assembly language programmer and the computer system designer, referred to as computer architecture and computer organisation, respectively. The computer architecture elements considered include programmable registers, data types, instruction formats, addressing modes, instruction sets and interrupt mechanisms. The computer organisation elements studied are various techniques applied to design and connect computer system modules using combinatorial and sequential circuits.1

Students attending the course in computer architecture and organisation are faced with the problem of implementing their theoretical knowledge of combinatorial and sequential circuits and concepts of computer architecture and organisation in the design of various computer system modules and their integration into a computer system. A common approach taken to tackle this problem has been to organise practical exercises in the laboratory using a suitable computer system simulator. A survey of the open literature indicates a variety of computer system simulators.2 They have been analysed on the basis of three basic criteria: the simulator should be interactive, with a visual presentation; the computer system should incorporate the majority of topics lectured on in the course; and the simulator should provide presentation of the computer system down to the level of combinatorial and sequential circuits.

Some interesting simulators, such as the Newsport simulator,3 were eliminated since they do not provide a visual presentation. The remaining simulators can be grouped into simulators of systems having simple architectures and organisation, simulators of systems having vary complex organisation, and simulators of systems at the global level. The first group simulates computer systems that include only basic elements of computer architecture and use very simple techniques of computer organisation.4 ESCAPE is an interactive environment with the possibility to simulate two processors with microprogrammed and pipelined organisation and the same set of instructions. The second group deals mainly with the problem of the design and performance analysis of pipeline and multiprocessor systems.5 DLXview is an interactive pipeline simulator, which uses the DLX set of instructions and simulates three versions of the DLX pipeline: basic, scoreboard and Tomasulo. The third group makes it possible to configure systems having a wide range of complexity by linking already simulated modules6 .6 6 HASE includes a set of tools which allows one to configure computer systems by linking in-built modules and to simulate the systems so obtained. As a result of a critical analysis of existing simulators it was concluded that none of them met the above stated requirements. The first group of simulators did not cover all the topics lectured, the second group did not demonstrate basic but very sophisticated issues, and the third group of simulators did not show the system at the level of combinatorial and sequential circuits.

As a solution to the above problem an educational computer system has been devised, a manual for it written, a software package developed and laboratory exercises prepared7 .7 The educational computer system has been devised with the aim of incorporating the computer arcitecture and organisation concepts lectured on in the course. The manual has been written to explain the concepts and to illustrate implementation details. The software package has been developed to simulate the behaviour of the educational computer system, visually present its parts at the level of combinatorial and sequential circuits, and provide various user features. The laboratory exercises have been prepared to demonstrate, using the software package, the concepts implemented in the educational computer system. The features of both the educational computer system and the software package, as well as the organisation of laboratory exercises, are described elswhere7 .7 Some aspects concerning realisation of the software package of the educational computer system are considered in the following section.