Elwro 151 – The last evolution of the 144 model

A little bit of calculators were produced in socialist Poland. There were models dedicated to the ordinary Kowalski, scientific designs for professors, printing for accountants or pocket calculators for school children. The basic and probably one of the most popular models was the Elwro 144, a classic base design, on which quite a few other calculators produced by the Elwro plant in Wroclaw were based. Today I would like to tell you about the latest evolution of the 144 model, the Elwro 151 calculator. 

Elwro 151 in its full glory

The first look at the Elwro 151 and it is immediately clear that it is a derivative of the classic 144 model. From the outside, the two models differ little. The casing is identical, and the differences can only be seen in the keyboard, or rather, in the shape of the keys. Here they are slightly more “sharp”, compared to the rounded keys in older designs. These types of keys can also be found in other calculators from the late Elwro years, including the 183, 184 and 190 models.

The 151 inherited its method of operation from the original in addition to its housing. A potential user could perform four basic operations along with primes and percentages. In addition, the calculator also had a memory.  


It gets interesting when you look at the nameplate. You can see there the marking “TYPE ELWRO 144”, but this is not really anything strange. It’s very common to see this type of erroneous marking, and it’s on a great many different models from this Wroclaw-based company. Who knows, maybe in the 1970s, when the 144 debuted, such quantities of rear panels were produced that it was even included in the 1990 design.

Breeze of the West

Calculator when unfolded

What would my article be without a look inside the described design. The 151 is opened similarly to other Elwro designs by unscrewing the back panel and two screws on the bottom of the device, after this procedure it can be disassembled into two parts connected by tapes connecting the main board to the keyboard.

After opening the calculator you can feel a kind of “whiff of the West”. Usually, the motherboard laminate was made in a light or dark brown color, similar to that of the keyboard PCB. Here, however, it is white in color, to be honest, this is the first time I’ve seen a laminate of this color made in Poland, by Toral’s Torun plant. Also surprising are the previously mentioned tapes connecting the motherboard and keyboard. Classically this connection was made with ordinary wires, but here we have tapes made of plastic with traces applied. Interesting, given the fact that the motherboard was not adapted to such a solution and the manufacturer had to use an additional board with connectors.

Other than that, the distribution of components is quite classic, similar to that found in other Elwro calculators. There are still a few differences, but we will deal with them when discussing the individual components of today’s hero.

Motherboard of the device

As I have already mentioned, the motherboard, in terms of component layout, resembles laminates from other Elwro calculators. The device was based on a single Polish-made chip, a classic example of Calculator on Chip solution. There are quite a few transistors around the chip, along with associated resistors. Thanks to them, it is possible to operate the VFD lamp acting as a display.   

Czechoslovakian KC307 transistors

The transistors used in the calculator have the designation KC307. They are PNP-type elements manufactured by the Tesla Elektronicke plant in the former Czechoslovakia. 

Elwro 151 Brain

At the heart of the Elwro 151 is the MC14007 chip, manufactured in the first week of 1990, at CEMI’s Warsaw plant. This design is an evolution of the MC74007 chip, which was used in the 144, among others. In fact, the two chips are identical in terms of logic, it’s just that in the late 80′ CEMI changed the naming system and so the MC74007 became the MC14007 chip.

The chip supports eight functions: +, -, *, /, %, 1/x, x2, x1, so the Elwro 151 does not use all its capabilities. Besides, the chip can control not only a VFD lamp, but also an ordinary LED display.

The MC74007, or later MC14007, was one of the first widely produced chips designed for use in calculators. The MC74005 chip had been developed earlier, but it was a much simpler design. The creation of the MC74007 is a bit of a mystery, since it is likely that the documentation for the chip, on which the Polish design was based, was obtained by CEMI not entirely legally. This is mentioned, among others, by engineer Zbigniew Galganski. 

I came to work at Elwro in 1972 after studying at Gdansk University of Technology. I passed my apprenticeship with A. Urbanek in designing boards for Odra 1305.

In 1972/3 I chose my first interesting topic. It was the design of integrated circuit logic for a 4 action calculator It was an overdue assignment from CEMI that no one wanted to take on. Together with my colleague Matuszewski (I don’t remember his name) in a few months we designed such a calculator, built a model and developed documentation of the logic structure of such an IC.

The calculator was entirely our idea, it was in fact a 4-bit processor with an architecture and software we invented. It performed the functions of addition, subtraction, division and floating-point multiplication, as well as square root. It supported a keyboard and a display. I remember T. Kultys suspecting us of cheating and looking for a hidden chip in the model. In those days, such a project was judged unworkable at Elwro. The model was based on TTL circuits and fixed memory from Riada where the information was encoded by the way of sewing wires through ferrite cores. The logic of the IC was organized on the basis of regular fixed memory matrix structures which was supposed to simplify the topology of the IC. With such a design we went to CEMI.

There it turned out that CEMI was already carrying out its own project to copy the structure of an existing IC. We were asked to help analyze the logic structure of that chip. CEMI had already drawn out the logic diagram but had trouble understanding how it worked. We got the schematics and after two weeks we already knew the answers to the questions that stopped CEMI. Knowing how it worked was essential for developing tests. In this way we contributed to the start of production of the first “Polish” calculator on an integrated circuit. Elwro mass-produced this calculator as the ELWRO 144. Our project turned out to be late and did not provide the same assurance of success as a circuit copied from a working model.

It is puzzling that the company had ready-made circuit diagrams, but the personnel working there did not understand them. Could it be that CEMI, not CEMI, was the creator of them?

Calculator display

The device’s display is formed by an eight-position VFD lamp. It is a Soviet classic with the designation IV-18, found in masses of equipment of the era. In addition to the 7-segment digits, the display also has two special characters – a dot and a minus. The bubble has relatively few leads, as all the same segments have been combined, so its control is multiplexed.

Power section

It must be admitted that the power supply section is quite modest, here we have only a transformer, semiconductor diodes and a few resistors and capacitors. In addition, a small fuse watches over the whole thing. 

Motherboard and keyboard connection

Let’s take a closer look at the ribbon connecting the motherboard to the keyboard. I must admit that this is a very interesting and unprecedented solution for Elwro hardware. Who knows, maybe my copy 151 comes from a test batch that tested plastic-made tapes instead of wires, because you can see that the main laminate was rather adapted to the latter solution. Here, an additional board with connectors for the tapes had to be added in the production process.

Marking on the laminate

Although the calculator model described today is the Elwro 151, there was another designation on the motherboard – ELWRO 144/C. However, there is nothing surprising about this, as it is indeed an evolution of the 144 model, and besides, there has always been a mess of designations in the equipment of this Wroclaw-based manufacturer.

VFD lamp during operation

Well Elwro 151 is an interesting device, but still stuck in the Gierko era. We have a few innovations here – a slightly more modern transformer, an early version of FFC tapes, but it’s not enough to be competitive in the early 90′, when Poland broke out from under the yoke of communism and equipment from Western manufacturers started coming into the country. Going into the topic of Elwro and the 1990s, one must also ask the question, could the company have survived the time of transformation? I’ll leave my own considerations to myself for now, because that’s a topic for other material, but I think another excerpt from the memoirs of the aforementioned engineer Zbigniew Galganski can be recalled here. 

In the photograph you can see the Elwro plant in 1974. Any attempt to take a picture of the company, could have ended with the intervention of the Industrial Guard, but the author, Japanese-born Makino Watanabe, may not have known about this fact. (https://elwrowcy.pl/strona5.html)

I was laid off from Elwro in 1990. I recall those times as a period of very romantic, creative work. We were building new things, getting ahead of the times, shortening the distance to the West. My only regret is that I was not able to reward the work of the people who made up my team. And they deserved it. I naively thought that I would reward them for their efforts from implementation awards, from patent shares. Unfortunately, this was the wrong policy. Today I know that we should have talked to the top about patents, then the cash would have been there. At the time, however, I was naive and oriented more technically than business-wise. 

Today I observe relations in various factories and come to the conclusion that Elwro was not such a bad company. There were procedures (a little oversized), there was quality control (a little too formalized), there were technologies (a little underdeveloped) Above all, there were great people on whom the company was based.

It’s a shame about Elwro. The company became a victim of the transformation that Poland was deliberately applied (it was more of a hostile takeover than a liberation). The goal was to destroy or take over the Polish economy, after all it is a huge market. Billions can be made, in a market as large as Poland’s. Banks, industry, commerce were taken over by “privatizers” who then got lucrative jobs in these seized companies.

Today Poland has a typical colonial economy. Cheap Polish labor works for foreign owners, a classic of colonialism. The rest don’t work and a million have left the country for bread. This is a drama for the country. Tough luck, the wheels of history grind inexorably. It is a pity that Poland did not follow the path of controlled opening to the West. China did so and today is an economic powerhouse. Remember China started from an economic collapse after Mao’s idiotic Cultural Revolution.

Well working at Elwro was a cool experience, great people, there is something to remember. The reason for the collapse of Elwro (leaving aside the main reason which was the planned liquidation of Polish industry) was the classic evolution of the company over time. Elwro was created by a group of young active and dynamic people who, given favorable conditions (there was cash and permission), took on great romantic challenges. They accomplished great things, developed mainframe computers taking care of compatibility with the prototypes (unlike Karpinski). This policy brought Elwro great success. However, a bit of an incumbent elite was formed after a while, which decided the further directions of Elwro’s development.

Such a stage is called the aging of the company. After this stage comes the twilight of splendor because the elites simply get older, become more comfortable, more conservative. According to the logic of the times, the colleagues from the big computers probably missed the coming era of microcomputers, which completely changed the way the economy was computerized. Elwro should have switched to production based on microcomputer technologies.

Unfortunately, the truth is that even if such attempts had been made in time and with positive results, Elwro would also have been closed down, for political reasons. The Polish market was to be supplied entirely by the products of our friends. And this is what happened, not only in Poland. It’s a classic of colonization, or globalization as it’s called today.


  • http://www.calcuseum.com/SCRAPBOOK/BONUS/79168/1.htm
  • https://archive.sundby.com/mirror/oldcomputer.info/calculator/elwro/list.htm
  • http://www.calcuseum.com/SCRAPBOOK/BONUS/33133/1.htm
  • https://web.archive.org/web/20191006232047/http://legendy-prl.pl/kalkulator_elwro_151.html
  • http://retrokolekcja.pl/Uklady_kalkulatorowe.php
  • http://www.elwrowcy.pl/strona65.html
  • http://www.elenota.pl/datasheet-pdf/125959/Tesla/KC237?sid=f16f8770a6c7212f8bf818dd9e660b25
  • http://www.elenota.pl/datasheet-pdf/59917/CEMI/MC14007?sid=5dbec146ba507b0b66842b504c3a78e2
  • https://elwrowcy.pl/strona5.html

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