Elektronika B3-11

Gold Medal of Exhibition of National Economic Achievement, 1974

Though marked as a gold-medal winner of 1974, this calculator seems to have appeared during 1976 (although an earlier origin is probable). There are two variants, both labeled B3-11.

Epos 73 and 73A

There are two variants of the B3-11, curiously labeled "Epos 73" and "Epos 73A". Though identical in appearance, the earlier Epos 73 model (1977) has 4 ICs and computing logic like the B3-02 (i.e.: leading zeroes are not removed, calculator has fixed comma). The Epos 73A (1978) has a single K145IP11 IC, and has "modern" computing logic. On the Epos 73, the keys [C] and [CK] have identical function, whereas on the 73A the keys [C] and [CK] are different ([C] is all reset, [CK] is correct entry). Curiously, there is another machine called the Epos 73A (Soviet machines, in general, have avoided duplication of model numbering/naming, implying a centralized register of model names).

The mortality rate of the B3-11 appears to be quite high; of the three in my collection to date, none of them work correctly! One, in particular, likes to have power applied for several minutes before working, whilst the others function intermittantly. A good thump usually helps these machines :)

Display window and flip-up cover are missing. In the unit shown here, the display area is missing the green plastic view window, and the flip-up cover which would have protected the entire display area. The two slots on the sides of the display were guide areas for the edges of this display cover. The small black button to the bottom right of the display is a power interrupt (there is no other power switch on the calculator). When the display cover was closed, it also interrupted the power (this design was also used in several early western calculators, including the Sanyo ICC-804D). To open the cover and turn on the calculator, one would push the black button. The picture shows on the left side the screw which fastened the flip-up cover. There is a fold-up foot on the back, towards the top, which will let the calculator sit on the desktop at a 10 degree slope. On the foot (on Epos 73A variants) there is room for a hand-engraved price. Although the manually scractched prices on my machines appear to read 325 and 500, this is an anomolously high price for a machine at the time. The display tube consists of eight 7-segment digits, with decimals. A sign/error display at far left can be just seen in the picture (directly under the 2nd and 3rd grille hole).

© Sergei Frolov Almost exactly as I thought it would appear!

Internal circuitry. The latest date is 09/78.

Profile. Note the screw which held the display cover, and the foot on the back in stowed position.

Early Variant

© Thomas Brockmeier An early version of the B3-11. Note the styling differences. I find it rather curious that all the machines I have seen so far have large letters/numbers on their body (usually in white, as above).