A fluid ejection device including a plurality of primitives each having a same set of addresses and including a plurality of fluid chambers, each fluid chamber corresponding to a different address of the set of addresses and including a firing mechanism. Input logic receives a series of fire pulse groups, each fire pulse group corresponding to an address of the set of addresses and including warming data having an enable value or a disable value and a series of firing bits, each firing bit corresponding to a different primitive and having a firing value or a non-firing value. For each firing bit of each fire pulse group, when the warming data has the enable value, activation logic provides a warming pulse to the firing mechanism of the fluid chamber corresponding to the firing bit when the firing bit has the non-firing value.