A multi-color roofshooter type thermal ink jet printhead includes a common heater substrate having at least two arrays of heating elements and a corresponding number of elongated feed slots, each heater array being located adjacent its corresponding feed slot. A common channel substrate is layered above a heater substrate and includes arrays of nozzles corresponding in number to the arrays of heating elements, each nozzle array communicating with one of the feed slots on the heater substrate. Each nozzle array is isolated from an adjacent nozzle array and each nozzle of each nozzle array is aligned above a respective heating element of a corresponding heater array. Each of the heater arrays is individually addressed and driven by switching circuitry located on the heater substrate adjacent to its corresponding heater array. The switching circuitry can be active driver matrices corresponding in number to the arrays of heating elements. The locations of the driver matrices preferably alternate with locations of the feed slots. With this construction, multi-color printheads can be efficiently arranged on a single wafer, so that silicon real estate is conserved. The switching circuitry can also be used to address an array of heating elements in a mono-color thermal inkjet printhead. In a preferred embodiment, inputs of the switching circuitry extend from sides of the switching circuitry whereby distances between adjacent feed slots are minimized.