Aristo M 36
|Aristo M 36|
The german manufacturer Aristo was more than 100 years known for their mathematical-technical
devices, mainly slide rules. Not before 1972, the rise of electronical pocket calculators
forced them to change their strategy, since it was forseeable, that the days of slide rules
1972 the first Aristo calculator was launched, and in the following years, many further inhouse
developments came onto the marked and especially to the schools.
Although, or maybe since, those calculators were of a very good quality and thus rather
expensive, Aristo did not survive very long on the market, and in 1979 already, the firm had
|... with grey glass cover and original wrapping|
The model M 36 described here in its first version, originates from 1974 from the best
days of Aristo calculators. It was not only visually very appealing and got the
german "Die Gute Industrieform" award, but it was also very well made and "Made in Germany".
The long case (which was quite heavy from the three AA cells inside) layed perfectly in the
hand and on the desk, nothing was shakey or loose, the bright LED display gave a very good
readability and the keyboard with its colorful distinctive and well-shaped keys worked
reliably and much better than many "brand" calculators.
The M 36 was powered by three AA cells or by an external adapter. For changing the
batteries, the case had to be opened by a coin, which led to visible traces on the case. Although
this eliminated the risk of losing the battery cover, this construction was a bit unlucky and the
only weak point of the while calculators.
Inside, the mainboard was shielded and was connected with detachable wires to the two
battery compartements - an expensive detail, which was not found in many other calculators.
As CPU, the Rockwell A 1241 was used; the three LED modules were driven by three ICs by ITT:
two times an XK 1695A (week 36, 1974) and one ITT XK 1696 (week 34, 1974).
The electronic assembly wasn' really contemporary for 1974, since it looked as if it
contained lots of manual work. But visually, it's a pleasure for every electronics freak.
|LED modules with three digits|
The LED display was a bit unusual: Unlike using ready-made LED display lines, the
display used here was made out of three individual LED modules with three digits each. This
leads to two minor spaces in the display, which can be seen here:
|display in full use|
The keyboard was on the back side of the mainboard and worked with double contacts, leading
to mostly bounce-free and reliably usage. Only after more than 30 years now, it can happen
sometimes, that a key slightly bounces, but that's a common thing even on the best vintage
calculators - except HP and Casio. So, no use for worrying.
The calculation functions of the M 36 were rather simple, since it was more or less the
entry model of the whole series. It is only capable of the four standard calculations and
The way, Aristo implemented the memory logics, is quite remarkable: For writing a number
into the memory, you have to press the keys "M" and "+" in that order. Now a dot on the
leftmost digit indicates the filled memory. Every subsequent "M" "+" or "M" "-" sequence
now adds to or subtracts from the memory. Pressing "M" and "=" can recall the memoty and
"M" and "C" will delete it.
The M 36 has got a constant function too, which uses the first keyed-in value as constant:
If you for example enter 5 * 3 =, you will get the result "15". If you now
enter 6 =, you will get 30, since the "6" is now multiplied with the formerly first
keyed-in number "5". For division, it works the same.
You have to admit, that this is not really intutive.
A further speciality is the "X<->Y" key, which replaces the current number with the result
of the last calculation. It is remarkable, since this key is not described on the manual on
the back of the calculator:
|manual on the back|
On the displaying of the results, the M 36 has got another speciality: With a switch, you
can select, if the result is displayed with two fixed decimal places, or as a true floating point
|two fixed decimal places|
|true floating point display|
A minor and rather academical "bug" can be found on this calculator: When you
calculate 1 + 0.000, you get "1.000" as result and not just "1." as expected, which
means, that in this case, the suppressing of unused zero digits does not work. This
is a very common "bug", which can be found on many calculators, but which has no
relevance on your practical work.
|overflow / error|
Made in Germany - this once meant true quality items. Unfortunately this mark had
its price - it just was too expensive to stand against the japanese competition, so that
those fantastic calculators were availably only for a short peroid of time and thus are
|Display||8+1 digit LED|
|Number of keys ||20|
|Functions||+ - * / % M x<->y|
|Entry logic (classification) ||ALG (CC)|
|1 + 0.000 = ||1.000 (the correct value would be 1.)|
|0 / 0 = ||Error |
|Power supply ||3xAA|
|Size||14,9 x 6,0 x 1,7 cm|