Abstract: A physiological monitor has a sensor port configured to attach and communicate with a sensor. A processor board is in communications with the sensor port and has a board digital signal processor (DSP). Firmware residing on the processor board is executable by the board DSP so as to calculate physiological parameters in response to a sensor signal received from the sensor. Upgrade tools are individually attachable to the sensor port in lieu of the sensor so as to designate to the processor board which of the physiological parameters, if any, to calculate when the sensor is attached to the sensor port.