Accessing and Installing PathSim

PathSim is a simulator for the simple data path discussed in sections 4.1 - 4.4 of


Computer Organization and Design, 4th ed.
David A. Patterson and John L. Hennessy
Morgan Kaufmann Publishers, 2009


The simulator consists of html with embedded javascript and java and, therefore, is executed from a web page browser. The simulator has been verified for Firefox 5.0 and Internet Explorer running on Windows XP, Vista and 7. For Vista users, you may find that IE 7.0 has an issue with running a Java Applet. Although PathSim works properly with this environment, IE may produce the error message "java.lang.NullPointerException: null pData" when you close IE. Again, the problem is not with PathSim but with IE (others have reported the same error when running other applets).

The simulator presents a graphical depiction of the architecture shown in figure 4.24. This web-based simulator allows its users to enter MIPS assembly code and step-wise execute through the assembled machine code while viewing the values placed on the data lines with each instruction

PathSim, Copyright (C) 2009, is distributed through a ZIP file as free software by the author Dalton R. Hunkins in accordance to the terms and conditions of GNU General Public License. When you extract the files, you will obtain two subfolders DataPathSimulator and SuggestedLabExercises. The simulator is resident in the first subfolder and the name of the main page is PathSim.html. Upon opening the main page in your browser, you should click on the button "About PathSim" appearing in the lower-right corner. This will take you to a discussion on how to use PathSim and also links to three suggested lab exercises.

  Click here to download the zip file PathSim4.zip, which contains the html pages with embedded Javascript and applet (jar) files making up the simulator. The source for the Java applet is available by contacting the author.

Hope you enjoy the simulator. You can contact the author with any questions and, of course, comments are appreciated.

Dalton R. Hunkins, Professor
Computer Science Department
St. Bonaventure University


Date last modified: May 12, 2010

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