Brand: Aristo
Model: M 85 S
Type: Scientific calculator
Picture: Aristo M 85 S
Batteries: AA x 3
Lifetime: Introduced: 1975
Terminated: 1978
Notes: This scientific calculator by Aristo is a beauty. It has a very solid case with a removable transparent lid. Take the lid off and this beauty of a calculator is revealed. The lid can conveniently be snapped on the back of the calculator. Small bumps on the lid should protect it from scratching.

A first look at it might give the impression that this is a simple plain calculator with only basic functionality but of course it isn’t.

Very similar to the Aristo M 76 but with an extra row of keys, brackets, inverse goniometric functions, angle conversions and the factorial function.

When entering numbers they appear from left to right. Results are always in scientific notation. So, when for instance dividing 1 by 10, the displayed result is "1        - 1".

Errors are indicated by displaying ". .0.0.".

The calculator has mixed accuracy. Most regular function have 8 digit precision. More advanced functions have 5 digit precision.

One peculiarity. When a non-zero value is present in the calculator this is indicated by a "n" symbol using the top three elements of the digit to the left of the location where the exponent might be visible. When a result ends up with a negative exponent, this combines into a symbol that looks like "degrees", in other words a little "o". Takes some getting used to.

There is no battery compartment visible at the back of this beauty. Instead there is a little notch at the bottom to enable lifting the calculator out of its back cover. There you can insert or replace the three AA batteries. Contrary to what one would expect, both batteries face the same way. Everything of this calculator seems to be designed with aesthetics in mind.

A brief manual of the calculator’s functions is printed on the back.

The calculator accepts Alcaline batteries but also NiCd batteries. Aristo sold their own NiCd batteries under number Aristo 6773. The NiCd batteries can be charged using the Aristo 6773 battery charger.

According to a X-Number World article I once read (no longer linkable), the German brand Aristo only entered the calculator market in 1972 and left it due to heavy competition in 1978.


A power adapter.
A NiCd battery charger (Aristo 6773).