last case is performed in order to eliminate vibrations on the spring that are not a result of a repositioning of its corresponding robotic arm the non volatile memories 211 u02dc 214 231 u02dc 234 of pca 39 s 201 u02dc 204 221 u02dc 224 may be electrically programmable read only memory eprom devices electrically erasable and programmable read only memory eeprom devices or flash electrically erasable and programmable read only memory flash eeprom devices since flash eeprom devices do not generally support erasure of single bits but require that all bits of the device be erased at the same time it is desirable when using this kind of non volatile memory to increment counts stored therein without having to erase any bits one way to do this is using a simple u201c tick u201d scheme wherein n bits are allocated to facilitate counting to n i e one bit per count using this scheme the n bits are initially erased so that they all indicate a u201c 0 u201d logic state and each time the count is incremented one of the n bits is changed to indicate a u201c 1 u201d logic state fig1 illustrates as an example a flow diagram of a method used for performing optional power down tasks in conjunction with the preventive maintenance method described in reference to fig1 in 310 a power down.