out in this manner the overall set of conditions for deciding whether to store a u201c final u201d pwm output value would be intended to allow the fan supervisor control algorithm to interact favorably with limitations of the non volatile memory subsystem it will be understood however that these u201c storing u201d conditions are not directly material to the functions of controlling the successful operation of the fan speed when using the fan supervisor control algorithm of the present invention in an alternative mode of the invention it also can be used to allow for instances in which the printer 39 s operation does not allow sufficient time at a given operating point e g printing idle etc for the fan supervisor control algorithm to come to a final pwm output value solution when that circumstance occurs each intermediate output value can be stored in memory and subsequently used as a starting point the next time the printer enters that particular operating point in this manner the fan supervisor control algorithm may converge to a final pwm output value solution for each operating mode despite frequent changes between modes this type of operational control of an actual device can effectively use the present invention for many types of devices.