Logisim

Abstract

Logisim enables students in introductory courses to design and simulate logic circuits. The program's design emphasizes simplicity of use, with a secondary goal of enabling design of sophisticated circuits. This motivates a two-tiered system, where users can move to the second tier by selecting a menu option.Users draw circuits of logic gates using the toolbox model popular in drawing programs. The circuit automatically propagates circuit values through the circuit; by selecting the appropriate tool, users can toggle switches to see how the circuit behaves in other situations. In the advanced tier, the user can treat circuits as black boxes within larger circuits, enabling the simulation of hierarchical designs. The author has successfully drawn and tested a simple 8 bit CPU using the program.The program has proven useful in a variety of introductory courses, from a nonmajors survey course to a sophomore-level systems course. Students find Logisim simple to follow, and find the laboratories designed around it useful in reinforcing the circuit concepts from class.In this article, we identify and compare a variety of systems similar to Logisim, we explore Logisim's features in detail, and we examine its use in class assignments.