Development programs?

[uglybuddy6]

I think the Dev kits where only used by Sega and other company that produced legitimate games, must homebrew is created on a computer with the help of a development library like KallistiOS. The dev kits to my understanding where only a step in the middle between a PC and a Dreamcast cause most if not all the code for the game was produced on a PC. Some body please correct me if i am wrong.