I'm pretty sure (but please correct me if I'm wrong!) in the 4th generation (e.g. SNES, Sega Genesis) assembly for whatever chip the console had was still the most common development language(s) and by the 7th generation (e.g. Xbox360) games were mostly written in C++, but I'm not sure when the switch happened.
What was the first game console to ship with an official C development SDK?