Hi,
I'm afraid it's not quite THAT easy :-(

Yes, it works OK as long as the value you add to the accumulator is 1 but what about when you want to add 2? Well, then A goes 0, 2, 4, 6....252, 254, 1 which means that B won't increment.

And what about adding a value larger than 255?

Of course it can be done in PBP but it involves a little bit more.

/Henrik.