Possible Aurora FN-1000 Bug


I have noticed a possible bug in the FN-1000's "multiply by 12" function. There may be a defect in the stack enabling process.

I say "possible bug" because I am not sure exactly what is happening. I have encountered the bug during the following calculation:

{[(650 - 10) * 12] - 300} / 12

with keystrokes:

650 [ENTER] 10 [-] [12*] 300 [-] [12/]

Following the second [-] in the keystrokes above, the display shows "-300". If I explicitly key in the 12 rather than using the special functions, I do not encounter the problem. I am new to this calculator and have never had a 12C, so I may be doing something wrong.

I don't know if the purchase price of approximately $12 is related to this issue. :)



I experimented with my FN-1000, and I think I see the problem here. When you hit [12*], x (the number displayed) gets multiplied by 12, and that value is stored in the n (number of payments) register. The result of that multiplication is also displayed in x, but it gets deleted (not pushed up the stack) when you hit another digit. If you then hit a math operation button, it uses your new x and whatever was in y before.

I think the bottom line is: the [12*] and [12/] keys were not meant as general purpose mult and div by 12; rather, they are used to enter month-oriented values into the n and i registers. However, It appears that you can make the number "stick" if you hit [ENTER] after the [12*] or [12/].

I think you can get your calculation to work the way you expect if you simply add a strategic [enter] after your [12*]. I.e., your calculation should be:

650 [ENTER] 10 [-] [12*] [ENTER] 300 [-] [12/]

I experimented with my HP-12C, and it seems to work this same way. Note that another case where RPN calculators display numbers that aren't really x-values is with statistics, with the sigma+ key. The number shown (after sigma+ is hit) is the index of the data value just summed. However, this index is not available for calculation unless you hit [ENTER] first.

Hope this helps.


Larry .. I agree ... could have not said it better myself!


One thing I forgot to ask in my earlier post: Where did you get the FN-1000 for $12? Was this from an internet auction? The only retail price I've seen is $24.95 at Fry's in Tempe AZ.




I want to thank everybody for the responses. I'm glad to hear the calc works the way it's supposed to work. I picked the FN-1000 up at Fry's in West Phoenix at I-17 & Thunderbird.

Other observations:

I am generally rather impressed with the unit. The keys have no tactile feedback, but they are good keys otherwise. It did become quite apparent to me why tactile feedback is a more significant feature for single line RPN calculators than for EOS algebraic calculators. On RPN, you tend to press the same key in repeat sequences with the tactile feedback indicating the number of key presses. Probably the most common example is 3 Enters. Repeated sequences are difficult to keep track of on the Aurora especially if you're not watching the display to see if the key registered. Once again, note that the keys work, just the termination of key travel is the only physical indication that contact has been made.

[On AOS algebraic calculators, tactile feedback is important for repeated parenthesis presses, but when I use EOS, I find that I am more likely to be watching the display and if entry is incorrect the calculator will alert me after the fact.]

The Autrora's display is very good with large bold numbers, similar in size to the HP-20S, larger than numbers on the HP-15C, which I presume are the same size as on the 12C. And of course, the Enter key is in the wrong place.

[Anyway, glad I said POSSIBLE bug. :) ]

Even if it is largely a clone of the HP, the differences in implementation vs. HP models make it fun to use. And you can't beat the price with a postfix.

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