The Retrode project would not have been possible without the many excellent console-related tech sites out there. On this page, I will list a few that I found particularly useful. Please note that I do not own these sites and I am not responsible for their contents.
Retrode hardware / USB / FAT16
Microsoft’s FAT16/FAT32 specification
SNES
SNES Controller/Mouse Protocol by Raphaël Assenat
SEGA
SEGA Genesis/Mega Drive cartridge pinout
N64
Excellent description of the N64 cartridge access protocol
GB/GBA/GBC
Excellent GB tech repository with MBC substitute circuits and all
GB cartridge header description
GB memory manager (MBC5) in detail