HP80 TVM sequence?

[John Garza (3665)]

It seems the HP80 needs the parameters in a certain sequence to get the right answer sometimes. I can't find anything about that in the manual. But all the examples seem to enter the values from left to right on the keyboard. Sometimes if I mix up the order, it gives the wrong answer. I know later business calcs didn't do that - my 12C doesn't care about the order. Is this some 'hidden rule' about the 80?

-John