Download Ruby 2.4 for Windows here. Alternatively, if you have Windows 10 you can get Bash on Ubuntu on Windows and then use the Linux instructions. Directions for other systems here.
If you want to work in a virtual Linux environment on your Windows computer, you can use a virtual machine. First, you have to download VirtualBox from https://www.virtualbox.org/ and install it. Then download the Linux VM image file CMSC330.zip, and open it with VirtualBox. This Linux image have Ruby, OCaml, and emacs installed. You can install other tools if you want.
Linux VM Image (CMSC330.zip, 2.8GB) (Linux admin user name: cs, password: cmsc330!)
PythonTutor for Ruby - An interactive, web-based visual debugger for Ruby programs
The Pragmatic Programmer's Guide - "The Pickaxe Book" is a more comprehensive overview of Ruby. It's an online version of the first edition of a printed Ruby book. The only thing to keep in mind is that it covers Ruby 1.6, while you can buy the newest printed version which covers the Ruby 1.9 and 2.0. We probably won't do anything for this course where the difference between versions. There's a lot of information here which you won't need- the most relevant sections are the first fourteen listed (the first up through "Basic Input and Output"), then "When Trouble Strkes", "Ruby and Its World", and "The Ruby Language" and "Classes and Objects". These last two are good summary references for the language.
Ruby documentation - A list from ruby-lang.org of Ruby reference manuals, online sources of Ruby information (some of the ones which will probably be more useful are mentioned specifically below), and Ruby articles. If you want to buy a printed book about Ruby several are listed.
Ruby User's Guide - An English translation of a book written by the designer of the language. More of a language reference than a tutorial.
Previous required texts for CMSC 330 have chapters on relevant topics covered in this course. If the lecture notes are insufficient, look for these books. They should be available in the university library.
Concepts of Programming Languages (Seventh Edition) by R. Sebesta, Addison Wesley (2006) (ISBN 0-321-33025-0).
Programming Languages: Design and Implementation (Fourth Edition) by T. Pratt and M. Zelkowitz, Prentice Hall (2001) (ISBN 0-13-027678-2).