Baymax's chips are special chips designed to be placed in Baymax in order to provide the robot his programming.
The original chip, a healthcare chip, was created by Tadashi Hamada in order to house Baymax's personality, memories, and needs to make him the ideal healthcare robot. It is a green-colored chip with an icon of a smiling doctor and a sticker with the name of its creator on it. As long as this chip is present, any additional chips installed into Baymax will only enhance Baymax's abilities but the base personality will remain.
While in the portal, Baymax removes the chip before being deactivated by Hiro. Later, Hiro discovers the chip clenched in Baymax's rocket fist while attending the San Fransokyo Institute of Technology, giving him the ability to rebuild Baymax's body and using the chip to revive Baymax within the new body.
A second chip was also created by Hiro Hamada that contains data on various martial arts styles, granting Baymax the ability to fight with these moves. This chip was red with a skull-and-crossbones drawing on it. As opposed to Tadashi's chip, which made Baymax peaceful, the fighting chip causes Baymax to become an aggressive, single-minded killing machine if the green chip isn't present. This personality surfaced when Hiro removed the green chip and ordered Baymax to terminate Yokai, which the formerly pacifist robot carried out without question. However, Honey Lemon found the chip and reinserted it back into Baymax, restoring the robot to its peaceful, nursing personality.