NES reference guide
From Nesdev wiki
The nes reference guide is the section of the wiki were you will find all major hardware reference divided by categories in their simplest form. From this list, you can drill down to a more specific section of the selected category. <br\><br\>
- Every major category containing many sub section have a printer friendly link beside their name.
- The wiki will use a wide range of well known acronym to make your reading shorter and simpler. If some acronym are still new to you, especially if you're just starting nes development, you can refer at any time to the nes terms glossary.