Proceedings of the 2001 Winter Simulation Conference B. A. Peters, J. S. Smith, D. J. Medeiros, and M. W. Rohrer, eds.

A CROWD OF LITTLE MAN : VISUAL SIMULATOR TEACHING TOOLS

William Yurcik Hugh Osborne

Department of Applied Computer Science School of Computing & Mathematics Illinois State University University of Huddersfield Normal, IL 61790, U.S.A. Queensgate, Huddersfield, HD1 3DH, U.K.

ABSTRACT complex to understand; and (C) cryptically documented. This makes executing laboratory experiments for students a This paper describes the use of a particular type of com- challenge requiring extensive preparation and the result may puter simulator as a tool for teaching computer architec- be skills and knowledge not transferable to other machines. ture. The Little Man Computer (LMC) paradigm was de- Third, computer architecture is intimidating to most veloped by Stuart Madnick of MIT in the 1960s and has students – while students may have a high level computer stood the test of time as a conceptual device that helps stu- literacy of software applications, languages, and peripher- dents understand the basics of how a computer works. als, many have incomplete, unrealistic, and sometimes pro- With the success of the LMC paradigm, LMC simulators foundly strange conceptions of how a computer works un- have also proliferated. We compare and contrast the cur- derneath the cover. Thus, most students are reluctant to rent crowd of LMC simulators highlighting visual features. figuratively or literally open the computer cover for dis- We found unexpected insights since despite starting with covery, scared of the binary can-of-worms they do not un- the same paradigm with the same goals, each implementa- derstand. tion is distinct with different strengths and weaknesses. It Lastly, students are crowded with marketing informa- is our intention that interested educators will find this a tion about computers from advertisements on television, useful starting point or useful reference for incorporating radio, and magazines. Since students are not informed simulation into their courses. consumers understanding computer architecture there are two effects: (1) empty or misleading information crowds 1 INTRODUCTION out useful facts about computer architectures, and (2) stu- dents acquire a false sense of competence due to familiar- The value of teaching computer architecture and assembly ity with computer marketing hype. language programming is an old debate that continues to All is not lost however. Recent textbooks, web re- resurface as outside pressures on educational institutions sources, supplementing traditional lectures with active learn- press for market-driven skills based on high-level abstrac- ing experiences, and the sharing of distributed expertise tion. We feel that concrete and rigorous low-level educa- have empowered educators with new tools and increased the tional experiences are necessary as a foundation before opportunity for student learning of computer architecture building toward higher-level abstraction. Dr. C. Ravis- (Cassel et al. 2001; Yehezkel, Yurcik, and Pearson 2001). hankar, Professor of Computer Science/University of Cali- This paper describes the use of visual computer simula- fornia-Riverside says it clearly, “Information hiding is all tors as teaching tools for computer architecture. Detractors very good, but students need to have some information be- state that simulation is not as good as the real thing. We fore they can start hiding it.” agree – simulation can be better than the real thing! For in- Computer architecture is also maligned because it is a stance, programming can be one of the difficult topic to teach. First, a wide range of skills and de- most user unfriendly human-computer interactions – a com- tails need to mastered – ranging from transistor implemen- puter simulator can make assembly lan