67/97 card read bug on the HP41

[Ángel Martin]

If I recall correctly this is the reason why buffers should not have empty registers, or at least that their "last" register (footer) should not be zero. This you told me a few years ago, when I was working on the 41Z project - remember?

So I'd assume this is a limitation of the Card Reader, regardless of whether 67/97 cards or 41 cards are used... but this is just a conjecture.