Let's see...
-Nintendo Consoles: GameBoy, GameBoy Pocket, GameBoy Color, GBA, GBA SP, Nintendo DS, DS Lite, DSi XL, Game Cube, NES, Wii, Nintendo 64.
-SEGA: Genesis, Dreamcast, Game Gear, Master System.
-Sony: PS2.
-Microsoft: XBox 360.
So yeah, the true answer is a sh*t ton of consoles.