After a memory clear, during powerup, setup parameters receive default values. Calculations are made in some settings that rely on calculations made in other settings. If any of those calculations involve division, protections must be made to prevent divide by zero errors.

The top three lines window does a lot of periodic low priority functions. One of those functions is to update a persistent footage totalizer. The Footage totalizer is stored in feet, which requires conversion from counts, which requires division, which requires a constant that gets calculated after a memory clear on power-up.

There is a bit of timing involved as to which thing happens first, the calculations for the constant or the calculations that require the constant. It is unclear how this problem has not shown up until now, at least ten years since the footage totalizer was added.

The software has been modified to delay the footage totalizer calculations until they can be safely performed.