Using digital logic circuit simulation to build demonstrations of IT concepts

Abstract

This paper describes using an open source, freely available logic simulation package to build visualizations to teach IT concepts. The first visualization is of an XOR based, symmetric encryption/decryption process. While it is not the actual process used in modern encryption, it illustrates concepts that are used in encryption/decryption and are often used in IT, particularly in computer and Internet technology to protect files and secure transactions. While actual encryption would be over a much larger word size and use several passes in the encryption process, this tool clearly illustrates the basics of the process. A second visualization shows Hexadecimal numbers with their binary and decimal counterparts. These are important concepts in understanding how bit patterns can represent many different things within a computer. The flexibility of these visualizations is shown by a small circuit addition that can add ASCII characters to this display. Building these visualizations could be done with many different software tools; however, using a logic simulator for some visualizations has the advantages of being easy and also providing insight into the logic of the process that are being visualized.