Adler 80 C

Adler 80 C
Adler 80 C

The german business machines manufacturer Triumph-Adler from Nürnberg, Germany distributed in the 1970ies several pocket calculators, probably licensed products, under the names "Adler" and "Triumph".

From that era, the mid 1970ies, the Adler 80 C presented here originates. It is a very elegant, flat but rugged pocket calculator with only basic calculation capabilities. As the inventory number indicates, those calculators were used for ambitious and representative purposes as in banks. And by the way, the shop "Finkenzeller", who sold this calculator was a quite well-known shop in Munich.

back side
back side


The case construction and design are pretty unusual: The square-edged case, which is slightly convex on the upper and lower side is surrounded on the sides and on the back by an aluminium cover. If this cover is slided in top direction, you can access the battery compartment, which holds either four AAA cells or an 4.8V NiCD accu. This rechargable cell can be charged via a 2.5mm jack on the lower side of the case.

back side with removed cover
back side with removed cover

As usual on these old calculators, the rechargable block is a weak point here, too: It is sealed pretty well, but when it is completely discharged, for example after a long storage time, it loses almost all of its capacity and leaks. Although because of the good sealing, only a very small amount of electrolyte can get into the battery compartment, it is still enough to corrode the contacts.

The accu block is made by Varta, one of the most famous german battery makers that time and offers the (from todays' point of view ridiculously low) capacity of only 90mAh. For comparison, modern NiMH AAA cells today already extend the 1000mAh barrier.

Inside the accu block, there are four 1.2V cells, connected in a row. You can easily imagine the mess inside, when all of them leak.


opened accu
opened accu


The construction of the 80 C is pretty modern, the CPU and external componenty use way less room, that on calculators, which are just one or two years older. Due to the small size of that pocket calculator and the resulting squeeze inside, it is very difficult to see the CPU without desoldering the keyboard.

CPU view - as good as possible
CPU view - as good as possible


The flat VFD tube with its row of contacts on the broadside were cutting edge technology that time and also perfecly readable, bright and room-saving the same time. Compared with a LED display of 1975, you can see the worlds laying inbetween.

display view, sideways
display view, sideways

The keyboard is of a rather simple quality: The keys don't offer a click point and if you press them, you never know for sure, if they work or not. The "x"-key already stopped working most of the time. This bad keyboard is a pity, since the rest of the calculator is of a much higher quality and deserves a better keyboard.

inside view
inside view

Calculation capabilities

The calculation capabilities of the C 80 are rather simple, but sufficient for financial usage: Apart from the usual four basic calculating functions, it has got a percentage automatics and a constants function for all four calculating functions.

This calculator adds and subtracts with a so-called "commercial" calculating system, which reminds a bit of the reverse polnish notation (RPN): To add two numbers, you have to press the "+" key after the second number, too, for example 2 + 3 + , which results in "5".
Subtraction works the same way, except, that the first number has to be followed by a "+" keystroke. For calculating 5-2, you have to enter 5 + 2 - to get the result of "3".
If you had entered 5 - 2 = instead, the "2" would have stayed in the display; if you had entered 5 - 2 - , you would have calculated (-5)-2 instead, resulting in "-7".

From todays' point of view, this entry logic seems quite confising, but it originates from the mechanical calculating machines, which were use the past decades and made the switch from them to a pocket calculator quite easy.

A word about the overflow logics: When a result extends the display range of 8 digits, it is shown with an "C" (or "E" on negative numbers) in front. The rest of the number has to be multiplied by 10^8.
If you for example get an result of E1.2345678, it means, that the true result is in the range of -1234567890 to -1234567899. The last (ninth) digit is lost and cannot be restored. If you press the "CI" key, the overflow lock is removed and you can go on calculating, but you have to keep in mind, that the number in the display has to be multiplied by 10^8.


The Adler C 80 was a contemporary office calculator in 1975, whose entry logic and calculation power resembles of mechanical calculating machines. For switchers, this was ideal, but for beginners, there were better and more suitable pocket calculators on the market.

Technical data

Model80 C
Display8+1 digit VFD
Number of keys 19
Functions+ - * / %
Entry logic (classificationALG ((BCCC))
1 + 0.000 = 1.
0 / 0 = Error
Power supply 4xAAA
Size12,0 x 7,4 x 2,1 cm
Serial Number67.503.267

Links TA 80C, EC 21/21B (en) (Short description)
Uni Greifswald: Adler 80 C (de) (Short overview of the Adler 80 C)
Vintage Technology: Adler 80 C (en) (Very informative description of the 80 C) Adler 80 C (Spanisch short description)