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Калькулятор
B3-34
1980-85
Casio
fx-48
1979

Elektronika MK26

Brief History
At the Angstrem factory known for later calculators equipped with LCD display started production of the B3-26 model in 1977. The used new integrated circuit in addition to features of the earlier models, allowed exchange of registers, change sign and provides a four-key memory. After launching the manufacturing of liquid crystal display calculators, the Billur plant in Azerbaijan continued production of B3-26 and later its predecessor, the MK 26 by the first half of 1990s. This example is made in 1991, but with exception of re-drawed circuits, it is completely identical to these manufactured in the first days...
Manufacturer:Биллур (Billur) (USSR)
Mfg. date:1986-91
Size:8×14×2,7 cm
Weight (ready for operate):n.a.
Type:four-function
Capacity:8 digits (input/display)
8 digits (internal precision)
Operating logic:semi-arithmetic (Rockwell)
CPU:Billur K145IP11A
Registers:2 standard (with saving the pending operation)
1 constant (with saving the pending operation)
1 memory (with aritmetic)
Features:%calculation with percent +/-change sign (direct entry of negative numbers) RVexchange registers (X-Y) Ffloating-point notation Sqrsquare root
Display:9 digit VFD (IB-28A)
Power:4×AA-type battery
6V adaptor

MK26

Inside of the MK26
Detailed Description

Interesting features

This machine uses K145IP11A chip, which has some interesting features:

Square root of a negative number causes no errors.

Constant-handling mechanism is similar to one used by Rockwell calculators. The previous stored function is executed when the =, or any arithmetic function key (+, -, , ) has pressed. The latter results to the desired operation was stored for further constant calculations.

With using the exchange key the contents of the Y register is displayed, which can be cleared and overwritten by keying in the new value.

Overflow caused all decimal commas lights up. To clear the error, press the C.

The machine computes multiply and divide operations with floating point, but adding and subtracting dont suppresses meaningless zeroes at the decimal places: 1 + 2.00 = results 3.00. 2 5 + 0.6 = shows 1.0.

After clearing registers with C, the /-/ sign change key can be used before entering the number: C /-/ 3 results -3.

The memory-arithmetic keys causes adding (?+) or subtracting (?-) the X register to/from the memory register, without changing the stored calculation.

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