EKBM Elektronika B3-08

This machine was manufactured in October 1975, takes 9V (8 batteries, or transformer), and uses eight individual tubes for its display, plus a 9th tube for error indication. See the section below for a full description of the display. The keyboard is laid out in typical business-machine functionality - that is, the + and = key are combined. The small switch at the top of the keyboard is 0/2/4, probably a switch for the number of decimal places to display.

It really does look this squat, in the flesh!

It is quite blocky, and heavy - certainly not the sort of thing you'd want to carry around all day. Rather than compact, the general impression is squat. But I like this machine a lot - the large display and interesting battery configuration make it quite unusual.

Power

The power connector. The small center hole is for a screw.

Display

This machine has quite an unusual display. Each digit is formed from a single tube, containing a 7-segment + decimal digit. There are eight tubes for number display, and one extra!

Note the unusual extra digit, shown up-close in the insert!

There are several interesting points to note about the display of this machine. The most obvious oddity is the extra display digit inserted sideways at the top right of the display. The picture shows this area circled, and in close-up in the insert. It is obviously a full digit, but my guess is that parts of this digit were used to indicate overflow, error, etc. This is the only known machine to use this odd method.

The second oddity is the extremely shoddy nature of the workmanship. Well, not so odd, perhaps - but in this case, it is particularly evident in the uneven alignment of the display digits. This machine would never have been fun to use!

Viktor the Repairman

"Well, germanium was used in semiconductors before silicon came into widespread use. It is still being used in low-noise applications; for instance, if you ever build a crystal receiver these days, chances are you'd be using a 1N34 germanium diode as its detector. However, in the overwhelming majority of applications it has been replaced with silicon, which has much better overall characteristics (except for noise.) One way to detect a germanium semiconductor junction is by measuring its "forward bias" voltage. This is a simple measurement that can be made with just about every digital multimeter out there. For a silicon junction this voltage is typically 600-700 mV; for a germanium junction it's much lower, usually under 200 mV. Unfortunately, this measurement cannot be made reliably when the device you're measuring is in a circuit, because the test current may flow through other components as well, which means that your reading will be less than the actual forward bias voltage. This is why I said that I *think* those transistors are germanium power transistors; without desoldering them, I cannot tell for sure. In any case, I'll make note of their model numbers and do some digging. I may still be able to find some reference materials on vintage Russian transistors and identify the type. Here's another interesting tidbit: I don't know to what extent it applies to these Russky calculators though. You probably know that the spacing between the pins of a standard dual-in-line package (DIP) chip in the Western world is 0.1", or 2.54mm. Now imagine this: some genius in Moscow or wherever decided that 2.54 is such a non-metric number... and of what consequence is 0.04mm? So he made the East Bloc standard to be 2.5mm instead. This is not a big problem with small chips, like typical 14 or 16 pin TTL chips; with 8 pins to one side, the actual difference between the distances measured from the first to the last pin is only 7x0.04 = 0.28mm. But then, they began to manufacture larger chips in Eastern Europe, like the infamous East German clones of the Z80 microprocessor. (Infamous because they matched a ZiLog batch down to the last microcode bug, making it clear that they were made from stolen production masks.) These chips have 40 pins, or 20 to one side; the difference now between Western and Eastern chips was 19x0.04 = 0.76mm. This is actually a quite significant difference; it meant that an East German Z80 no longer fit into Western circuit boards or vice versa, at least not without some serious bending of the poor chip's legs. It also didn't fit into Western-made chip sockets; unfortunately, although I am sure they manufactured a few, I have never actually seen any East Bloc chip sockets, certainly not any with the 2.5mm spacing... To further compound the problem, precisely because of this some East European countries, such as Hungary, refused to follow this silly standard and continued to use the Western 2.54mm spacing instead. To date, I haven't seen any DIP chips in the Russian machines that I have, but I am sure there are quite a few out there. It'd be interesting to measure the spacing between the pins... "

- Viktor T. Toth