We started in 1995 with the A-100 and introduced the meanwhile well-known bus system with UNBOXED pin headers. The reason for the unboxed was to keep the price as low as possible (at that time the boxed headers were significantly more expensive). So there was no need to pay attention to the polarity of the "nose" of the IDC connectors because it was not necessary. In the meantime some manufacturers introduced BOXED pin headers.

Since that we pay attention that the polarity of the bus connectors of all A-100 modules is correct (i.e. pin "1" = red wire / nose = right when red wire is at the bottom). But these bus boards may cause problems with older A-100 modules because the user may be urged to plug in the cable in the reverse direction. And we have to point out that not only A-100 modules are affected but also modules from other manufacturers. E.g. Livewire, Plan B, Jomox, Cwejman, MFB and other manufactures also offered modules with "wrong" polarity of the nose.

In retrospect we agree that it was the wrong decision to use unboxed pin headers. But at that time it was a very small project and we tried to keep the costs as low as possible (the boxed pin headers were much more expensive at that time). We really did not expect such a success of the A-100 and that I would have discuss this issue problem 20 years later because of problems with second source manufacturers of the bus boards. If we could we would turn the wheel of time back to 1995 and use boxed male connectors from the beginning. But if we now introduce keyed male connectors at the bus boards there is a 50% chance that the polarity is wrong for older modules.

That's why we decided not to introduce keyed male connectors because this would cause probably much more troubles than solutions. And funny enough there exist two different versions of bus boards with boxed headers ! Most manufacturers use the version with the gap (for the nose of the bus connector) at the right side. But I've seen also a few bus boards with the opposite polarity. And the problems occured not until bus boards were offered from other companies who specified the bus boards as A-100 compatible what is not correct. They would be only A-100 compatible without boxes. I hope this explains why we decided not to switch to bus boards with boxed headers. It's not a monetary problem (the boxed headers are not much more expensive in the meantime) but a technical problems with older modules.

Nevertheless we decided to change over to boxed pin headers during the year 2019 because this kind of bus connectors established as a kind of standard on the market. But we will add a corresponding warning notice to each system which is equipped with the new boxed headers.