`git clone https://bitbucket.org/delan/matrix86.git`, then `make run`. The author has graciously checked in the compiled version at matrix86.img; if you want to recompile it, you'll need nasm installed.

If you don't have qemu installed locally (such that it complains about not being able to open a graphical window), you can run `qemu-system-i386 -curses matrix86.img` to make it run in your terminal. Press Esc 2 (Meta-2) and type "quit" when done.