The smallest ever LED RPN calculator


And it's not an HP

About the size of a pack of cigarettes, the Hanimex 276, made in Hong Kong for the Australian Hanimex Company was the smallest ever LED RPN calculator. It was based on the National Semiconductor MM5760 chipset with a calculator forensics number of 8.843762. It sports most of the same functions of the Novus Mathematician except for x^2 and M + x^2, due to the reduced number of keyboard buttons. This particular pristine unit currently resides in the collection of one out our beloved members, who is well know for his addiction to non-HP RPN calculators.

Edited: 12 Feb 2012, 7:25 p.m.


About the same feature set as the HP 35, and IMO very attractive styling, too.

When was it produced?


I can't say for certain, but mid to late 1970s when National Semiconductor was making the chips. There's a whole bunch of other brands that used them, including the Argentinian Microcifra 10 and Taiwanese Prinztronic. Two big differences from the HP-35 is that it only has a 3-level stack and no scientific notation.

Edited: 12 Feb 2012, 10:51 p.m.


This looks remarkably similar to some of the scientific 4-banger designs that have floated around over the years.

- Pauli


I wonder how much it would cost to produce something like that nowadays.


i wonder of Michael Steinmann can replicate an LED HP25C :-)


Good morning!

I don't have that particular calculator (alas...) to take masurements, but if it's the same size than the similar looking Hanimex 202, then the Sinclair Scientific is smaller. In width, thickness, area and volume, but not in length. If that counts.

Funny contest. Usually it goes: Mine is bigger :-) !



You are correct ! I had completely forgotten about the Sinclair Scientific.

The dimensions I measured using a ruler are as follows:

Hanimex 276 : 3-7/8" L X 2-1/2" W X 7/8" T

Sinclair Scientific : 4-3/8" L X 2" W X 3/4" T

That works out to the following areas and volumes:

Hanimex 276 : A = 9.7 in^2 V = 8.5 in^3

Sinclair Scientific : A = 8.8 in^2 V = 6.6 in^3

Also, the Sinclair is 9 grams lighter at 105gm with 4 AAA cells .vs. 114gm for the Hanimex with a 9V battery.

So, I probably should have made the title "the second smallest ever RPN LED calculator."

The Sinclair was far more limited with only a two level stack and no storage memory, although it could handle much larger numbers due its perpetual scientific notation mode. Also, it performs trig operations in radians only and lacks the constant pi for easy conversion from or to degrees. Log operations are base 10 as well.

Edited: 13 Feb 2012, 10:59 a.m.


Hi Michael,

is it smaller than a Commodore Minuteman 6* ?




It's about the same size.


My first ever calculator, well actually my fathers calculator was a Hanimex ESR 1010SN, see : Hanimex ESR1010SN
I have fond memories of that little beastie !! But then my curiosity of electronics took over and I disassembled it, even took the metal lid of the main ceramic chip - needless to say, it didn't work after that :-(



This was a variation on my/my dad's 2nd calculator externals.

The package design & form factor look remarkably like that of the 1975-vintage Casio "Pocket Mini"... in particular
- the on/off switch on the side
- the black display area popping up from the metal faceplate

The std Pocket Mini used a blue-green 8 digit VFD display, as did most Casio calcs of those years.

The Pocket Mini came in a couple of revisions... including a LED version with rounder keys. The common VFD version had rounded-corner square keys pulled into a 'tighter matrix' (i.e, matrix has more substantial border from edge of calc) and had gasketing around the keys.

Casio VFD 4-bangers at the time used Hitachi calc chips.

Bill Wiese
San Jose CA

Edited: 16 Feb 2012, 10:27 p.m.

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