67/97 card read bug on the HP41

[hth]

I came across some comments in the Time module source code about the 67/97 card read bug. The Time module works around it by ensuring there are no null registers inside the alarm buffer.

Does anyone know more about it? Was it ever fixed? Why would 67/97 cards cause this effect, I suppose that 41 cards does not? Is it related to the translation process somehow?