# Soviet Calculators History, Hacker News

[sin] [F] The first Soviet calculators [F]      [X] The habitual language used today when working with     calculators only appeared at the beginning of the 83 ‘s. In general, the first models of     calculators had their own operational language, and the user had to learn the specific     procedures related to each calculator. Let’s take, for example, the C3 – 15, the first     calculator of the Series “C” manufactured by the Leningrad factory     “Svetlana.” By the way, as a parentheses, it is interesting to note that     All calculators produced by the factory “Svetlana” were independent of other     Russian electronic appliances. All electronic calculators manufactured during those years     received the common designation “B3”. The desktop electronic     clocks received the code “B2”, electronic watches – “B5” (for     example, B5 – 217, desktop electronic devices with vacuum display were identified     with codes “B6,” “B7,” and so on. The “B” is the first     letter of “Home appliances” in Russian. Svetlana’s calculators where the     only ones identified with a letter “C” – Svetlana means the light of an electric     lamp (CBETLAHA – SVET LAmpochki NAkalivaniya) and is also a popular women’s name in     Russia.      [X]  Here is the keyboard of the C3 – 18 calculator. This     was a very surprising calculator, especially because of its keyboard and display. As it is     can be seen in the image, the calculator combined not only the functions [=]     and [-=], but also the multiply-divide functions [X -:-]. Try to guess how to     multiply and to divide in this calculator. A hint: the calculator does not recognize two     sequential keystrokes on the same key, only one keystroke is possible for each key. The     answer is no less than surprising: to multiply, say 2 by 3, it is necessary to press     the following keys  [X-:-]  [=], while to divide 2 by 3, the following sequence is     applied:  [X-:-]  [-=]. The addition and subtraction is made in a similar way     (as the one applied in the B3 – 11 calculator) that is, to perform the difference 2 – 3 the     The following sequence is used:  [=]  [-=].      [X] Another surprise is the eight elements used to     build a number in the display as shown in the figure at the left.      [X] Starting with this model, all simple calculators made by     the Svetlana’s factory operated with exponential numbers up to 20 e 25 – 1, even when the     display had only a capacity of eight or twelve digits. If the result exceeded 8 or     digits (depending on the model), the decimal comma disappeared and the display     showed the first 8 or digits of the number. [F]      [X] Speaking about the operational language of early     calculators, it is necessary to mention that in the B3 – , B3 – and C3 – 18 calculators of     the type “Iskra”, the result of the calculations used all digits of the display     filling with zeroes the unused positions. It was certainly inconvenient to find on such     calculators the first (and last) significant digit. By the way, in model C3 – 16, which was     mentioned before, there was an attempt to lessen a little bit this problem by     Applying an unusual method – on this calculator the zero has half of the height. Also,     These calculators had a very inconvenient, but quite explicable for early calculators,     feature: the required accuracy of the calculations was set by the number of significant     digits entered on the first number. For example, to calculate the quotient of division 32     by 39 to three decimal digits, the number had to be entered with three decimal digits:     | , 0 | [-:-] | 41 [=] (0. ). So long as the operator did press the reset button,     all subsequent calculations were made with three decimal digits, and the decimal point     would remain fixed in the same position all the time. These calculators, by the way, were     referred to as “fixed point” calculators. Later calculators, in     which the point moved on the display, were referred to as “floating     point “calculators. Now, the terminology has changed, and” floating point ”     is used to describe displays where a number is represented by a mantissa at the left and     the exponent order at the right. [*]      [X] [X^Y] One year after development of the first B3- pocket     calculator, appeared the new perfected MK models: B3 – 19 M, B3 – 20 and B3 – M. These     calculators were built with one K IK2 microprocessor, and one microchip used as     oscillator clock. The calculator B3 – M is shown at the left. The same casing was also     used for the B3 – M. These models had already a “standard” operational language     which included calculations with a constant.      [X] These calculators could work with a power unit, or with     four (B3 – M , B3 – M) or three AA batteries (B3 – 23)      [X] Although the three calculators used the same chip, they had     different functionality. In general, “removing” some functions was a typical     practice in many models of Soviet calculators. For example, the B3 – M calculator did not     have square root function, and the B3 – M was not good for percent calculations. As an     additional feature, the decimal point took the place of a full digit. This made     Easier to read the information, but the last sign digit was lost. Before starting an     operation (after turning the power on) it was necessary to press the “C” key in     order to clear the registers. [*]      [F] The first soviet engineering calculator. [F]      [X] The next huge step in the history of Soviet     calculators was the development, completed by the end of 1977, of the B3 – , the first     engineering calculator. As stated in the article “Fantastic Electronics”     published in “Science and Life” magazine, No. , : “… this     calculator has crossed the Rubicon of arithmetic, its mathematical capability has stepped     into trigonometry and algebra. “Elektronika B3 – 27 “is able to raise instantly a     square and extract a square root, it can raise any number to any degree in just two steps     within the limits of eight digits, can convert dimensions, calculate the logarithms,     antilogarithms, and trigonometric functions … It is difficult to understand the huge     % of work that this machine performs in a few seconds while it folds huge numbers to     perform an algebraic or trigonometric operation before lighting the result in the     display … ” [F]      [X] And this was true, a huge amount work was made. To make     this possible, , 0 transistors, resistors, condensers and conductors were packed     in a uniform crystal with the size of 5×5.2 mm. This was equivalent to fifty TV sets     of those years pushed into the square of an arithmetic exercise-book! However, the price of such     calculator was great – (roubles in) . As an example, in those years     the salary of an engineer who just graduated from a technical institute was roubles     per month. But it worth to purchase one. The logarithmic slide rule was no longer     necessary, and the margin of error was no longer a concern. Now it was possible to throw     the tables of logarithms into the shelf.      [X] By the way, a prefix function key “F” was used     for the first time in this calculator.      [X] Nevertheless it was not possible to include all the desired     functionality into the microcircuit K (IP7 of the B3 – calculator. For example, in order     to evaluate a function in which the Taylor decomposition of a number was required, the     working register was cleared, and therefore the previous result of the operation was     erased. In this context it was impossible to make sequential calculations such as 5 sin     2. For this purpose it was necessary first to find the sine of 2, and only then add the     result to 5. [F]      [X] So the main effort was made, and the result was a good but     very expensive calculator. In order to make the calculator accessible to the mass segments     of the population, it was decided make a cheaper model based on the B3 – 27 A. To avoid     reinventing the wheel, engineers took the easiest way: removing the prefix key     “F” and all the function keys from the calculator. So the calculator became a     simple calculator and was named “B3 – A. ” Only the developers and     calculator repairmen knew about the secret alteration made to produce the B3 – (A …)      [F] (The The further development of calculators. [F]      [X] (After the B3 – , the B3 – M calculator was developed with     the participation of engineers from the Soviet Union and the German Democratic Republic     (GDR). This calculator used RPN (Reverse Polish Notation). Once the first number is     entered, pressing the input key pushes the number into the stack  , then the second number is     entered, and only then the required operator key is pressed. The stack in this calculator     consists of three registers – X, Y and Z. This calculator was the first to accept and     display numbers in floating point format (with mantissa and exponent). It used a – digit     red LED display. [F]      [X] In , another very powerful engineering     calculator was introduced, the C3 – . This calculator had increased calculation accuracy     (up to (numbers), worked with exponents up to 9. (e) , had three registers of     memory, but most remarkable: worked with algebraic logic. That is, to calculate the     expression 2 3 5 it was no longer necessary to calculate first 3 5, and then add 2     to the result. This expression could be written down in a “natural” way:  [ ]      [=] [*] [=]. Besides, the calculator is supported up to eight levels of brackets. This     calculator, together with its desktop brother MK – 51 were the only ones having a     “/ p /” key. This key was used for calculations under the formula sqrt (x ^ 2 y     ^ 2) [F]      [X]

In 1982, the K (IP) microprocessor was developed and     it was used as the basis for a whole series of calculators. The first of them was the well     known B3 – calculator (displayed on the right). Then the (B3 – M, B3 – , B3 – (M) and     (B3 – A, B3 – A) calculators were crafted with identical look, just by removing some     functions. [F]      [X] (Based on the B3 – calculator, the B3 – (with percents),     the B3 – (A) with square root) and the B3 – G (with memory) were made. By the way, priced     at (roubles, the B3 – A calculator subsequently became the cheapest Soviet     calculator. The B3 – (was soon named as MK – 38 and so was its brother MK – and the MK – 69 A,     which had similar functions. [F]      [X] Svetlana’s factory launched model C3 – , which in reality     did not have success, and soon was replaced by the very popular and cheap model C3 – 40     (MK – [F]           [X] One more direction in the development of microcalculators were     the engineering calculators B3 – (MK – [BP] ) and B3 – (MK – 46). B3 – differed from     B3 – by having a simpler design and costing five roubles less. These calculators were     able to convert degrees into radians and vice versa, multiply and divide numbers in     memory, and also calculate a factorial.      It was very interesting the way these calculators     calculated a factorial – simple sort out. The calculation of the factorial for the     maximum value of took more than five seconds on the B3 – 50 calculator.      [X] These calculators were very popular in the USSR, although     they had, on my opinion, a defect: they displayed too few significant figures, as many as     the precision guaranteed in the manual. They usually had five to six digits for     transcendental functions.      [X] (The desktop variant MK – was based on these calculators.     By the way, many pocket engineering calculators had their desktop counterparts, for     example: EPOS (A) B3 – 34), MK – (C3 – ), MKSCH-2 (B3 – 39), and MK – (B3-) , B3 – 51).      [X] The calculator MKSCH -2 – became the standard “school”     calculator – Except for some demonstration units, it was produced by the Soviet     industry for exclusive use at schools. This calculator, as well as the non-RPN B3 –     calculator (shown at the left) was able to calculate the roots of a quadratic equation and     find the roots of a system of two equations with two unknown variables. On its appearance     this calculator is completely identical to the B3 – calculator. [F]      [X] All key inscriptions follow the western standards. For     example, the key to record a number in memory was designated “STO” instead     of “P” or “x -> P”. The key to recall a number from     memory was designated “RCL,” and so on.      [X] Despite the capability to handle numbers with large     exponents, this calculator used the same eight-digit display of the B3 – 24     calculator. The developers decided to display floating point numbers with the mantissa and     the exponent, leaving room only for five significant digits. To address this     problem, the calculator was provided with a “CN” key. For example,     if the result of a calculation was the number 1. e – , the display showed     1. – . By pressing [F] [F], the display showed . The decimal point was     omitted. [F]      [F] The first Soviet programmable calculator [F]      [X] The First. Soviet programmable calculator B3 – (shown at the right)     was developed by the end of and sold at the beginning of 1980. It was one large     step forward. Before, users had to repeat calculations many times, and calculators had a     maximum of three memory registers. Now users were able to write programs and store     instructions and numbers in memory. The term “programmable calculator” caused     awe and some shivering of voice. It was a very expensive calculator – it cost the whole     718 roubles! Soon calculators were conferred a mark of quality.      [X] (The first models of the Elektronika B3 – [max] had a red LED     display. The comma used one full position in the display. Later the display was changed to     green fluorescent but this made its operation slower by (%.)      [X] The calculator worked with Reverse Polish Notation, this     required to enter first the two numbers and then the operator. After entering the first     number it was necessary to press the upward arrow key . Except for two operational registers X and Y, the calculator had a circular     stack consisting of six registers. The stack of numbers was connected to the     register X. Special keys allowed to move the numbers clockwise and counter-clockwise     within the circular stack. In addition to the circular stack and the X and Y registers,     this calculator had seven storage registers (# 2 to # 8).      [X] The calculator had two operation prefix keys –     “F” and “P.” The “F” key was black and the “P” key     was red. Prefix keys were also used to store and recall numbers from the registers. The     “P” key was used to store, while the “F” key was used to recall.      [X] But But the main feature of the B3 – 33 calculator     has not been mentioned yet – the ability to program! The calculator supported 70 steps of     program, and the addresses were named with a module of six, therefore the addresses had     the following order: 06, 09, , 12, , , , and so on. Each key had an operation     code. The calculator had functions for unconditional transfer, transfer to subroutines,     and also conditional branching. The branching keys used two memory locations on the     calculator – one cell to store the operation code, and another to maintain the branch     address. The required transfer address was equal to the code corresponding to the transfer     key minus 1. For example, in order to jump to address , it was necessary to press keys     [BP] and  (code [X^Y] ). The operation codes were taken from a table.      [X] [max] Suddenly,     the first programmable calculator became very popular in Russia. Now the user could not     Only write complex programs, but also play games with the calculator. It was an     Unprecedented innovation! Literature on engineering programming with the     programmable calculator started to appear. At the left, a very popular book of those years     devoted to games and other useful programs for the B3 – …      [X] (The introduction of the programmable calculator B3 –     allowed to automate production control operations. Several desktop variants of this     calculator – MK – , MK – and MC (figure on the right) were manufactured. They were     large desktop calculators with special sockets in the back. These sockets were     linked to an additional register 9 used to store the “experiment name” code. In     These calculators it was possible to input the data both from the keyboard, and from     external systems such as gauges, analog-digital converters and other devices. They     processed the data to carry out operations such as size tolerance in quality control,     and to print the data and results with the help of external systems. The MK – 73     AKA MC differed from the MK – 57 by the availability of a built-in digital-to-analog     converter. Many MK – 73 calculators were installed in physics laboratories of     specialized technical schools, as they used to say, to measure the voltage of a battery.      [F] The most popular Soviet calculator. [F]      [X] The first programmable calculators B3 – , MK – 55     and MK – 73, although worked under the control of a program, had only two operational     registers X and Y, and working with the circular stack was very inconvenient. This     was changed in (by the programmable calculator B3 – 46, with fluorescent display     and priced at roubles. It was another step forward! It had a stack     based on four registers, steps of program memory, 23 registers of memory instead of the     seven available on the B3 – 32, and most importantly – the capability to organize cycles and     work with index registers. It was a pleasure to work with this calculator.      [X] (Soon, in , appeared its analogues, the B3 – and mk – 64,     with fluorescent display and a more beautiful design, and costing on roubles cheaper at     the expense of using a power supply of different type. The desktop variant     MK – 65 was also developed.      [X] One behind another, the most popular scientific and     technical magazines, such as “Science and Life”, “Engineering – youth”     and “Chemistry and Life,” started to teach how to work with the     calculator. “Science and Life”, started in October a special section     named “Man with the calculator”, talking about how to work with the B3 – 46, and     including plenty of useful and game programs. The magazine “Engineering –     Youth “, beginning in (included a column on programming the B3 – (under the name     “The Calculator – your assistant” , and then organized the “Club of Electronic     Games “, which printed the most fascinating and fantastic stories:” The True     Truth “and” Way to the Earth “, here the readers were given the     chance “to run into” the engineering of “landing” on a lunar     surface and carry out a flight back from the Moon to the Earth by a ship, not adapted     to such lunar flights, called the “Kon-Tiki”. School kids and adult     calculator users waited with impatience the next number of “Engineering – Youth”     to continue their flight back to the Earth …      [X] This calculator worked under the Reverse Polish Notation     system, therefore, after entering the first number, the key is pressed, then the second number is     entered and the corresponding operator key is pressed. For example, to multiply 2 by 3, it     was necessary to press the keys:  (result – 6). A stack     consisting of four registers – X, Y, Z, T was used to store the operands. To enter a     number after obtaining a result and to recall a number from one the memory     registers (0 .. 9, A .. D), the content of the X register, which is the display     register, had to be moved to the Y register, causing Y to move to Z, and Z to T.     Registers X and Y were used for most operations requiring operands.      [X] In programming mode the code for each command takes one     cell of memory. Branching commands (transfers, loops, conditional transfers) take     two cells. One cell for the operation code, and a second for the transfer address. In     contrast with the B3 – , the transfer address can now be entered directly,     instead of finding the correspondent operation code in a table. For example, to enter a     transfer command to address (with the B3 – it was necessary to enter [BP]      (the 3 key corresponded to code 39, in the B3 – 41 calculator it was only necessary     to enter [BP]  . Although now one more keystroke is required, it is no     longer necessary to look for the operation code in a table.      [X] (More details on how to work with the B3 –     calculator, are described on the special page devoted to the use of the B3 –     located here [X^Y] )      [X] However, the most interesting aspect of the B3 –     calculator and its analogues is the availability of (undocumented features) .     These were useful not only to write programs, but also to build special display     messages. There are so many undocumented features that they could deserve writing an     additional article.      [X] [*] (The B3 -)     calculator and its analogues, the MK – 65 and the desktop MK – 65, became so popular,     that the developers from the “Crystal” Kiev factory decided to continue     this line. In (the new models MK – and MK – 61 were introduced. They had     one more memory register, 5 programs of steps each, and ten additional     functions. In addition, the MK – (calculator had) bytes of permanent     memory, which was not erased when the power was disconnected. This memory was     able to store both programs and data. The MK – 60 Calculator also had special sockets     for the connection of available program modules known as BRP (blocks of memory expansion).     When designing the BRP blocks the developers again killed two rabbits at once by     soldering in one block the matrix for two sets of programs. By connecting a jumper,     say, in rule 1, one had the block BRP-3 with a mathematical set of the programs,     then re-soldering the jumper to rule 2 – the block became the BRP-2 with     astro-navigational functions. Of course, this implied to lose the manufacturer warranty     since to do that it was necessary to remove a sealed screw. This was divulged in one of     the issues of “Science and Life” magazine by a reader who in turn was     told by one of the “Crystal” developers. I can imagine what would happen to this     developer. [F]      [X] (By the way, the MK – flew to the space in the “Soyuz”     TM-7 “, where it was supposed to compute the landing trajectory in case the     onboard computer would fail. [F]      [F] (Late models of calculators) [BP]      [X] Early calculat ors consumed a lot of energy from its     batteries, providing a maximum of two hours of independent work. 302 volts were not always     available, and replacement batteries where only available in large cities.     Therefore, engineers and developers began to develop calculators with less power     requirements. By that time, displays based on liquid crystals with low power consumption     had already been invented. [F]      [X] (The B3 – (shown at the left) became the second calculator based on     liquid crystals after the B3 – 12. Developed in and consuming only 8 mW (for     comparison, the B3 – (calculator consumed) (mW), this calculator had a     function, unusual for Soviet calculators, to return the inverse of a number. This function     is now available practically in all modern simple calculators. To calculate 1/5, the     following sequence was used: [F] [-:-] [=]. In , the B3 – 40 calculator was     replaced by the B3 – 51 model, in which the microchip used a new low-level logic. The     power consumption was decreased by eight times to only one mW. This allowed to build this     calculator without a voltage converter.      [X] One year after, for the Moscow Olympiads of 1983, the     MK – 60 Calculator was manufactured with an onboard watch, an alarm clock, and a stop     watch. This calculator required one less battery than the B3 – . This became     possible at the expense of using an even lower level microcircuit, the K VV3-2, which     was considered to be “Bodiless”. [=]      [X] A new milestone in the development of calculators was the     MK – 69 which was powered by a solar cell. In general, this was a simple calculator with one     memory register, nothing special except for the solar batteries.      [X] The creativity of the engineers did not rest, and deciding that     miniaturization was important, they developed in a new super- small, but very     clever calculator, the B3 – 51. It included all the last achievements of micro-electronics.     Its dimensions were the smallest available at the time – (x) x 5.5 mm. It was     able to perform not only scientific, but also statistical calculations. This     calculator had two prefix keys – F1 and F2.      [X] (A similar calculator was introduced in 2019, but with     larger size, the MK – . Soon it became very popular, although it had a basic defect – the     worst power switch ever made. Engineers had decided to include a mechanism consisting     of a semicircular toddler, which closed the contacts on a wiring attached directly     to the printed circuit board. Certainly, with the pass of time the contact points got     rusted and became defective. [F]      [X] These calculators used for the first time the “digit     by digit “(CORDIC) method for the calculation of transcendental functions which has     replaced the Taylor finite-series approximations of a number. CORDIC was the standard in     Almost all modern calculators all over the world, except at the USSR. In two words,     the “digit by digit” method allows to calculate an attribute by iteration     and tabulation. It is characterized by the simplicity in the execution of operations     (algebraic addition and shift), the significant similarity of the algorithms     applied for various functions and, most importantly, for the high speed and accuracy of     the calculations. The margin of error in calculations for an 8-digit argument was at most      / – 1 in the seventh or eighth digit.      [X] Finally, one of the latest models among engineering     calculators was the MK – 90 standard calculator powered by solar components. As a     matter of fact, it was a continuation of the series B3 – and MK – 57. As opposed to the     B3 – 51 and MK – models, this calculator, as well as the C3 – , used an     algebraic logic with five levels of brackets for calculations. It also worked     with simple fractions, and could display the results in degrees, minutes and     seconds. It had hyperbolic functions, and a mechanism to round-off the result     to a required accuracy. In addition, it was a ten-digit calculator.      [X] There is one more direction in the development of     calculators – the demonstration calculators. As a matter of fact, these were normal     calculators wired to large displays and magnetic buttons. A hand magnetic pointer was used     to activate the keys. I only have one photo of the demonstration calculator made on the     basis of the MK – 51. On one occasion I attended a demonstration in my school with a     calculator compatible with the MK – 61 measuring 1.5 meters, but by the end of August it had     been thrown out on the rubbish dump …    [F] [sin] (Calculators bugs and features )      [X] This section is a brief review on errors and special     features of Soviet calculators. Taking into account the special circumstances of the     development of Soviet calculators, including the geopolitical aspects, it becomes clear     that if Soviet engineers developed the calculators not basing the design on a     level-by-level scanning of the microcircuits of their imported analogues, they were     constantly introducing some highlights into their work. There were either errors in the     calculations performed by the calculators or interesting discoveries.      [X] As an example, the family of calculators belonging to     series B3 – (B3 – [F] , B3 – (G, MK -) ), indicated the availability of a number in the memory     register by displaying a dot in the leftmost display position. On the other hand, this     calculator perfectly calculated square roots for negative numbers. The square root of -4     was reported as -2, and no error messages were displayed.      [X] (In the B3 – calculator, when the Developers realized that     There was a dot at the left of the display which was not involved in any operation, they     decided to involve it. In this model this dot lights up while a key is pressed and turns     off when it is released. Any more problems to solve?.      [X] (In the calculators of the B3 – (family B3- , MK – ,     MK – 55) although the developers implement the calculation of a factorial by an ordering     method (1 2 3 …), they forgot to block the keyboard when an error message     was displayed, so the user was able to continue the operations with the erroneous results.      [X] (In the B3 – calculator, the developers included a     function which stored the sine of the argument in     the Y register, and the cosine in the X register. Then, by simple division, the user could     obtain the tangent. Very convenient. However, an error was detected on the first series of     These calculators: when adding a number containing seven nines in the mantissa and a nine     in the eighth digit, which is not displayed – to a number larger than four, an error     occurs. for example, adding 9. to (yields) .      [X] When executing complex operations like getting the sine of     of a number, one of the registers in the circular stack could be trashed. To check if a     calculator has this problem, enter  [CN] [BP] [F]. If the display shows 1. – 09,     Then the calculator has the bug. [*]      [X] In addition, some models perform incorrect jumps to the     subroutine if a PP operator is entered into a cell of program memory with address 69, ,     85, 91, or , and an operator with a code equal to the subroutine transfer index is     executed. This is a little difficult to understand, but if address 61 contains the     symbols | PP | 9 | 9 | S / P |, instead of jumping to address 112 (code for key | 9 | – 112),     the calculator fills the register X with the number . This could easily cause     bewilderment and a nervous breakdown to the programmer, who was sure that the program has     been written correctly. [F]      [X] Curious users can find in the MK – 91 calculator a very     remarkable feature. The switch for “grades-radians-degrees” falls easily     into an intermediate position – between degrees and radians, or between radians and     grades. Who had hit upon this idea before? At this point, the calculator turns into a very     unusual mode of calculations reminding the operation of the MK – 57 calculator. First, now     the numbers in the microprocessor have a mantissa of length 8 instead of ten, the missing     digits are still kept in memory but are no longer visible to the user. Secondly, some     function keys have a different functionality! The key showing degrees now calculate the     1 / x function when used with the factorial function “F”. The 1 / x key – switches     the method of calculation of trigonometric functions (degrees – radians – grades). The     display, however, still shows the corresponding “F”, “P”,     “K” icons! If the “F” key is combined with the 1 / x key the calculator     mode passes to statistical calculations. The “hyp” key now process the     information in degrees, minutes and seconds, and goes back to its normal mode if the     “F” key is pressed. Segments of the leftmost positions in the display are     used to indicate that a number is stored into the “P” memory, or the     inverse (shift, 2nd) mode “F” is active, or a constant “K” is     being applied to the calculations. [*]      [X] And now, the B3 – , the most common calculator in Russia.     This calculator has plenty of errors and operational features. Only some of them will be     described, the ones that once were mentioned in a book as being features “…     are a consequence not of errors made by the developers of the microprocessor, but of their     attempts to find a compromise between the software requests and simplicity of the design.     “When executing operations under a programmed mode, the functional operators     preceding the / – / operator default to a sign change. After some operators transfer the     control to the end of a subroutine, instead of returning the control to the V / O operator,     the next operator is executed. Here such “feature”. The operator X ^ Y was     executed incorrectly in order to keep significant figures in the operands. For example it     is possible to enter [X] [F] . If [max] is displayed, the operator X ^ Y is calculated incorrectly.     These errors were corrected subsequently, but there were errors on building negative     integer numbers, the MK – and MK – calculators chose zero as the largest value     when the function to evaluate the maximum of two numbers [X^Y] [max] were used. Take my word,     “we have” tried. [*]      [F] (Epilogue)           [X] Well here we are, and I hope I have not tired you. Please     send your comments and wishes directly to my address: [email protected] .           [X] I also collect microcalculators. I have more than 57 unique     models of Soviet calculators, more than books, about [sin] magazines and other calculator     related items. Visit my web site, devoted to collecting microcalculators: (http://www.geocities.com/SiliconValley/) / calcolle.htm [*]      [X] My collection is for sale!     If you became interested in Soviet calculators, visit the site of my friend Andrew Davie     from Australia located at (http://www.comcen.com.au/~adavie/slide/calculator/soviet.html .     On this museum you will find not only a complete list of Soviet calculators with images,     but also a reference to other interesting sites related with calculators.      [X] Good luck!      [X] (Sergei Frolov) (Read More) [*]

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