Please refer to the main documentation index for the index file of the main DOC documentation.
You will optionally need the a MEGA65 ROM file, if you wish to use BASIC65, you can download diffs against one original C65 ROM here. If you are a registered MEGA65 owner, you can also download full ROMs.
If you do not have such a file, the MEGA65 contains the free and open-source OpenROM alternative.
Follow the following links to download the latest releases and development builds:
The MEGA65 project maintains an automated build server called builder. Here you can find builds of core, tools, and manual.