Some time ago I talked about one of the first calculators produced in Poland – Elwro 105LN, today it’s time to look at one of its successors.
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Today’s hero, a calculator with the designation EW-116, from the outside very much resembles the aforementioned 105LN model. From the outside, the devices are almost identical, and in fact we can distinguish three main differences – the lack of a rotary switch for changing the number of zeros after the decimal point, instead we have a logo with the model designation, the lack of a movable scale at the display and a slightly different arrangement of buttons, an additional ‘%’ key and separated into two separate keys ‘+’ and ‘=’. The 116 model, as I will call it, was introduced in 1976 and was produced for a year until 1977. Calling it the successor to the 105LN model is a bit of a misnomer, as the device was produced from 1973 to 1978, that is, before as well as after the EW-116, but well, the chaos of the publishing cycle at Elwro is a topic for a completely different article. It is also worth mentioning that there was such a thing as Elwro 112N and Elwro EW-115, which according to numerology are the predecessors of 116, but today they are real white ravens.
The EW-116’s case is made of plastic in two colors, with the darker one having a pleasant-to-touch rough texture. The display cover, like that of the 105LN, is hidden under a flap. Its opening is possible thanks to a button at the right edge of the device, pressing it releases the flap mechanism, which additionally activates an internally placed limit switch, which short-circuits the electrical circuit, thus turning the device on. When the flap is closed, the circuit is disconnected and the calculator turns off. Also noteworthy is the keyboard, which, despite its years, works very well, and the keys have a fairly large stroke. Interestingly, the keys were made by injection molding two plastics in different colors, so their markings are still visible today.
On the back of the case, in addition to the permanently mounted power cord, we find a nameplate. It bears the model designation, the “Mera-Elwro” logo, the serial number, power supply information and the proud inscription “Made in Poland”.
What does the interior hide?
The device can be disassembled in the standard way for Elwro calculators – by unscrewing four screws, two at the back and two underneath. After opening it, we can see the interior, which, compared to the 105LN, is quite minimalistic, not to say poor. We can really only see one IC, the display and the power section.
Although the calculator is based on foreign components, the keyboard is a Polish design, which is, to say the least, made very well.
The calculator’s power supply section is a rather simple circuit based on a transformer produced by the Skierniewice-based Unitra-Zatra factory, a Greatz bridge and an RC filter. At the left edge we can also see the aforementioned limit switch, actuated by the display cover.
Elwro EW-116 is based entirely on only one integrated circuit – HD36290. This is a very popular design from the Japanese company Hitachi used in calculators produced by companies such as SHARP, Privileg, OMRON and CANON. The chip is housed in a 28-pin enclosure, powered by a voltage from 3V to 6V. The chip supports four basic mathematical operations as well as percentages and primes, although the latter function is not 116 used. Unfortunately, HD36290 is not a perfect chip, it has the well-known flaw of “negative zero”, i.e. performing an operation, for example, 1-2+1 you will get the result -0. In addition, you can come across information that in some calculators based on this chip you can perform division by zero. Probably this is a defect of the first series, which was eliminated over time. In my Elwro EW-116 such an operation cannot be performed.
The display on the 116 is in the form of a single VFD bubble with nine seven-segment digits inside. The display for such a number of supported characters has few leads, such a state of affairs is made possible by the use of signal multiplexing.
The display, like the main processor, came from Japan. The difference is that it was manufactured by Futaba, which still exists today, rather than Hitachi. The exact type of display is 9-BT-02A.
On the underside of the motherboard, in addition to the rather neatly arranged tracks, we can see a certain element that does not match the rest, this is the model designation – ELWRO 130.
Despite these difficulties, which prevented the development of production on a wider scale, development work is carried out systematically at “Mera – Elwro” to reduce manufacturing costs, increase functionality and improve the quality of calculators. As a result of these works, designs are being created, in which very significant results have been achieved from the reduction of material and labor intensity, while the functionality of the calculators is increased. The calculator “Elwro 105LN received the quality mark!” In 1976 the first multifunctional calculator in the country, the so-called engineering calculator “Elwro180”, was developed and put into production at “Mera – Elwro”. This is also the year when calculators produced by “Mera – Elwro” will appear in stores in free market sales. These are the EW-116 models and the first pocket calculator of “Mera – Elwro “production, model Elwro 440, which was put into production thanks to the help of “Mera” Unification.
An excerpt from Elwro’s 1977 newsletter.
How is it possible that the Elwro EW-116 calculator has a 130 designation on the motherboard? It’s actually hard to say, in general the subject of the 130 model is quite vague. On the Internet you can come across information that such a calculator was produced, but looking through the official list of Elwro products available in the Wroclaw archive, you will not find it. That is, one can conclude that something like model 130 did not exist, but on the other hand I have a circuit board with such a designation in front of me. Besides, the list from the Wroclaw archive has to be corrected, because the model 131, which was produced, is not there either. Where the truth lies is unknown, but I can give you my theory on the subject. For starters, let’s look at calculators signed with the Elwro logo produced in 1976 to 1977, the production period of the 116 model.
- Elwro 105 LN – from 1973 to 1978,
- Elwro 120 L – from 1974 to 1978,
- Elwro 180 – from 1976 to 1982.
The years 1976 to 1977 were a period when the most famous calculator produced at Elwro, the 144 model and the entire 14x series in general, was not yet available. The first series of mass-produced calculators were the 105 LN and 120 L models, later came a refresh in the form of the EW-116 and 180. In my opinion, the designation on the ‘ELWRO 130′ board is due to experimentation. There was R&D work going on all the time at Elwro, who knows, maybe they initially planned to introduce, for example, models 130, 131 and 134 (131 actually exists) only later decided on the 14x series and designations 140, 141 and 144. But as it was in the times of centrally planned economy – it was important to produce. And so, based on initial assumptions, some amount of PCBs with the designation 130 were produced, and since this model could be structurally compatible with EW-116 it was to it that redundant PCBs with a different designation were packaged.
One model, different execution
Nowadays, when we buy a product from the end of its production period, we can be sure that it is identical to the one produced at the beginning. Making changes to an already-designed model, is not welcome, primarily due to cost. Even if some modifications are made, they tend to be minor and usually caused by technical problems. This is the case today, but the socialism of the 70′s was governed by its own rules.
The Elwro EW-116 calculator presented in this article was so far the only representative of this model in my collection. But recently I have acquired another EW-116. Both devices externally do not differ in anything except the serial number, the design I described earlier with serial number 43296, comes from the end of production, while the acquired copy has the number 1677, also it is a fairly early model.
It gets more interesting when we compare the interiors of the two calculators. Of course, the first thing that strikes the eye is the different type of display. In the older version it was based on nine individual tubes. But that’s not all, there are many more differences.
As in the first device, the VFD tubes here also come from Japan. This time, however, it is an NEC design with the designation LD8051.
The use of single VFD tubes has resulted in a completely different arrangement of paths and components on the motherboard. In addition, you can already see the difference in marking on the laminate here.
In the copy from the early days of production, the marking on the printed circuit is adequate to the model designation. It can be said that this is the kind of board that should be in every piece of Elwro EW-116.
Well, it must be said that it is the second copy of the EW-116 that I acquired that is the real, original one. So is the calculator I described earlier a fake or an accident at work. Rather not, what I saw in the unit from the beginning of production only reinforces my conviction that the case from the 116 model may have contained a motherboard from another, possibly a planned future design of the 130. One must remember that the centrally planned economy was governed by its own laws.
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Sources:
- https://oldcomputer.info/calculator/elwro/list.htm
- https://audiovis.nac.gov.pl/obraz/167705/
- http://www.calcuseum.com/SCRAPBOOK/BONUS/10035/1.htm
- http://www.pdkin.pl/?&idd=9&page=19&id=212
- https://elwro.info.pl/dokumentacja-wyrobow.html
- http://delibra.bg.polsl.pl/Content/29920/BCPS_33790_1977_MERA—biuletyn-prze.pdf