No$GBA, also known as No Cash GBA, is an emulator for the Gameboy Advance and the Nintendo DS systems. It originally was created to work only on Windows computers, but a Mac version is also available from a different distributor. The Mac version is possible due to Wine wrapping, a process that involves a developer turning a Windows application into a Mac application by wrapping it in the special software so the Mac OS can open it. In order to use No$GBA for Mac you need at least Mac OS X 10.5.
Go to the No$GBA download Mac website (see Resources).
Select "Click Here to Start Download from Media Fire" and wait for the file to download.
Click on the "No$GBA.zip" file that mounts on your desktop. A new file will open.
Drag the "No$GBA" application into your application's folder. Double-click on the "No$GBA" application to open it.
You need backups of GBA and NDS roms that you already own in order to play them on No$GBA. Using game roms you don't own is illegal.