The M5 Repository uses the Mercurial (a.k.a hg) revision control system.
The documentation on Mercurial's website and the hg-book are both excellent resources for learning about the revision control system. We promise that it is worth taking 30 minutes to read some of the documentation to get you started. You may even decide that you really like hg and want to use it in your own projects. We do!
We also highly encourage you to read about Mercurial Queues (MQ) as they're a great way to follow the changes that occur in the repository while keeping your own changes separate. A good introduction is also included in chapter 12 of the hg book http://hgbook.red-bean.com/hgbookch12.html.
The patchbomb extension is a great way to share patches with other users. It adds the hg email command which allows you to send a set of changesets (or mq patches) to the m5 developer's mailing list!
To quickly get started, you can get a copy of the m5sim.org repository for your use by using the following command
% hg clone http://repo.m5sim.org/m5
To see what files are modified from the last committed revision
% hg status
To see diffs of the outstanding changes
% hg diff