Please make sure you have the latest version of the JDK installed. You can use java -version on the command line to see. Make sure it’s at LEAST 1.9 or 10.0. (Yeah. They changed their version numbering at some point.)

You can install the JRE from this link. Pick the Java SE JDK 11 or 13. Do not get the Java 8 JRE.

I have made changes to both programs to improve usability and fix bugs. Please download and use my versions instead of the ones listed on their respective websites.


Download MARS

This is the MIPS simulator we’ll be using for the first half of the course.

Here’s a newer version that should hopefully fix two bugs: the really delayed MIDI notes, and being unable to stop the program if the sleep syscall (32) is given a large duration.

Running MARS

First, try double-clicking the JAR file. This works for a lot of people.

If it doesn’t, go into your terminal/command line, and do the following:

  1. cd to the directory where you have the JAR file.
  2. run this: java -jar Mars_2201_1025.jar
    • try typing java -jar Mars and then hit the Tab key. It will complete the filename for you.

If you get an error saying this:

java.lang.UnsupportedClassVersionError: Mars has been compiled by a
more recent version of the Java Runtime (class file version 54.0),
this version of the Java Runtime only recognizes class file versions
up to 53.0

Then you need to both install the newest JRE and uninstall the old version of Java.

If you get some other error, please let me know and show me the exact error you get.

Changes to MARS


Download Logisim

This is the new version with the bugs fixed! See the green things in the changes below for what’s new.

Changes to Logisim