There are some documents you should read if you plan to dev on genny

► Technical documentation

You want to be serious abou Genny development ? Read these docs!

sega2f
The doc you MUST have!
Get it, read it, print it and have it near you when you dev, it's the genny bible!
Thanks to Nemesis, it's no longer a corrupted Word 2.0 file but a HTML

Services manuals
All these documents came from a join effort between Sega16, Spritesmind and some others forums members.
They are just GOLD so if you like them, be thanksfull to all of these great guys !
MD1 maintenance manual revA part 1 (A4)
MD1 maintenance manual revA part 2 (A3)
Sega Mega Drive 2 VA0 1 of 2 A4
Sega Mega Drive 2 VA0 2 of 2 A3
Sega Gen 2 & MD2 Supplement A4
Sega Gen2 & MD2 Supp VA1 1 of 2 A4
Sega Gen2 & MD2 Supp VA1 2 of 2 A3
Sega IC Specifications (Genesis VA7, MegaDrive PAL VA6.5 and Mega/Sega CD)
spec_6Buttons_pad_rev2
spec_6Buttons_stick
spec_sega_mouse
spec_sega_tap
spec_sms_converterII
Mega CD 1 of 2 A4
Mega CD 2 of 2 A3
Mega CD 2 Service Manual 1 of 2 A4
Mega CD 2 Service Manual 2 of 2 A3
Mega CD 2 Supplement 1 of 2 A4
Mega CD 2 Supplement 2 of 2 A3
Mega CD 2 Additional Information A4
Sega 32X 1 of 2 A4
Sega 32X 2 of 2 A3
Sega Saturn (PAL) No.013-1 issued june 1995 part 1 A4 size
Sega Saturn (PAL) No.013-1 issued june 1995 part 2 of 2 A3 size
For SMS/GG files, see SMS Power of course

Accolade useful documents
These documents below comes from RetroJunkie, an ASSEMbler forum member, which get a load of Accolade stuff
Genesis Software Development Manual [Version 2.0]
Genesis Sound Software Manual
Software Production Specifications for Mega Drive 6-Button Control

Other
SEGA Genesis II VA3 Service Manual

► Dev notes

Hacking NHL 94
How I added 6 buttons support to NHL 94.
This log could help you to do the same for any other games.

Eclipse Genesis IDE
This is my guide to use Eclipse as IDE.
I personnaly use it with Stef's dev kit (<0.6) but I'm pretty sure you can use it with XGCC or even SGCC.
All you need is to use makefile ;)

collide
Essay on collision detect, general and genny optimized

► Hardware notes

MegaCD nightmare
I received my MegaCD in a very bad condition.
I'm trying to repair it so a lot of pictures of the inside