View source for Elektronika MK-52

{{Short description|Programmable calculator}}
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{{more footnotes|date=August 2016}}
{{original research|date=August 2016}}
{{technical|date=August 2016}}
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[[Image:Elektronika MK-52.JPG|thumb|Elektronika MK-52 programmable calculator]]
[[File:Elektronika mk52.jpg|thumb|Elektronika MK52, Электроника МК-52, calculator; period 1983–1991; ROMː 512 B; RAMː 15 registers; 105 program steps; displayː VFD, 8&nbsp;+&nbsp;2 characters; size: 78&nbsp;×&nbsp;212&nbsp;×&nbsp;35 mm; weight: 250 g, 4 × AA battery]]
[[File:Elektronika MK-52 Calculator PCB.JPG|thumb|Elektronika MK-52 Calculator PCB]]
The '''Elektronika MK-52''' ({{langx|ru|Электро́ника МК-52}}) is an [[Reverse Polish notation|RPN]]-[[programmable calculator]] manufactured in the [[Soviet Union]] from 1983 to 1992 at the Quasar and Kvadr plants in Ukraine.<ref name=":0">{{Cite web|title=Elektronika MK-52|url=https://elektronika.su/en/calculators/elektronika-mk-52/|access-date=2021-07-21|website=elektronika.su|language=en-US}}</ref> It belongs to the third generation of Soviet programmable calculators. Its original selling price was 115 [[Soviet ruble|rubles]].<ref name=":1" />

The MK-52 is a [[Backward compatibility|backwards compatible]] improvement to the [[MK-61|Elektronika MK-61]], the main changes being the addition of an internal [[non-volatile]] [[EEPROM]] module for permanent data storage, a diagnostic slot, and a slot for separately sold ROM modules.<ref>{{Cite web|title=Elektronika MK-61/52|url=https://gtello.pagesperso-orange.fr/elektronika_e.htm|access-date=2021-07-21|website=gtello.pagesperso-orange.fr}}</ref> The [[machine code]] and functionality of the MK-52 and MK-61 calculators were extensions of the earlier MK-54,<ref name=":1">{{cite web |title=Elektronika MK-54 |url=http://www.rskey.org/mk54 |website=R/S Programmable Calculators |publisher=Viktor T. Toth|access-date=1 July 2017}}</ref> [[B3-34]], and [[B3-21]] [[Elektronika]] calculators. The MK-52 is the only calculator known to have internal storage in the form of an EEPROM module. As with many Soviet calculators, the MK-52 has a number of undocumented functions.<ref>{{Cite web|url=http://www.leningrad.su/b334/undocale.htm|title=Undocumented functions of Soviet Calculators|last=Frolov|first=Sergei|website=www.leningrad.su|access-date=2017-02-06}}</ref>                                                                      

In November 1988, the MK-52 went into space on the [[Soyuz TM-7]] spacecraft, where it could have been used as a backup to the onboard computers.<ref name=":0" />

== Architecture ==
The MK-52 has 105 locations of [[Volatile memory|volatile program memory]], an internal EEPROM module (with 512 bytes of memory), and 15 7-byte registers. It uses four AA-size battery cells or can be plugged into a power adapter. It has a relatively dim, ten-digit ИЛЦ2-12/8Л green [[vacuum fluorescent display]];<ref name=":2">{{Cite web |title=Elektronika MK-52: The MK-61 big brother? |url=https://www.hpmuseum.org/forum/thread-2345.html |access-date=2022-10-12 |website=www.hpmuseum.org}}</ref> these ten digits are apportioned into an 8 digit [[Significand|mantissa]] and a 2 digit [[exponent]]. The MK-52 has an expansion port to which various [[Read-only memory|ROM]] modules can be attached. Its system clock speed is approximately 75 kHz (derived from a К745ГФ3-2 four-phase clock generator chip<ref name=":2" />), and it weighs approximately 400 grams.

The MK-52 is the first Soviet micro-calculator with non-volatile memory; this is provided by a КР1601РР1 [[EEPROM]],<ref name=":2" /> with a capacity of 4 kilobits and capable of 10,000 rewrites, ensuring security for programs and working memory when powered off. This memory is capable of storing up to 512 1-byte program words (or the contents of 72 7-byte registers) and exchanging its contents with the calculator's [[Random-access memory|RAM]].

The calculator is fully compatible with the second-generation models (B3-34 and MK-54), using the same command system and machine codes. On average, a program that takes all 105 steps of program memory and 15 registers on the MC-52 will be equivalent in capability to approximately 140-150 steps and 18 registers on the B3-34. Additionally, the MC-52 has an extended set of commands that can allocate integer and fractional parts of numbers, search for absolute and maximum values of numbers, and perform certain logical operations. 

=== ROM ===
In addition, there is an external [[Read-only memory|ROM]] which is a memory expansion unit with stored games and mathematical programs, produced by the manufacturer, that constitute the user library. Manufacturers have produced 4 types of [[Read-only memory|ROM]] cartridges, three of them containing various mathematical functions, and one, the BRP-4, containing game programs:

'''BRP-2 "Astro" (Russian: БРП-2 "Астро")''', with a set of programs for navigational tasks, information about which was published in issue 12, of 1988, of the Russian-language monthly magazine ''[[:ru:Морской сборник|Морском сборнике]]'' (''Marine Digest'');

'''BRP-3 (Russian: БРП-3)''', containing 60 programs for solving mathematical problems. In 1988, 15,200 units of this ROM were manufactured, and were sold at a price of 16 rubles.

'''BRP-4 (Russian: БРП-4)''' was produced in 1989, containing game programs.

'''GRP "Geo"'''.

Another expansion port was used for diagnostics during manufacture; this port could also be used to connect the calculator to external peripherals.

== Basic operations ==
The MK-52 has two main modes of operation: automatic mode and programming mode. General calculations and operations are performed in automatic mode, while programs are fed as input in programming mode. The keystroke sequence {{key press|F|/-/}} switches the MK-52 to automatic mode, while {{key press|F|ВП}} switches it to programming mode.

Manual calculations in automatic mode are in accordance with [[Reverse Polish notation|Reverse Polish Notation]] logic. For example, to evaluate 2+3, the following keystrokes are required: {{key press|2}} + {{key press|В↑}} + {{key press|3}} + {{key press|+}}.

=== [[Bitwise operation|Bitwise]] binary operations ===
The MK-52 is fully capable of performing [[Boolean algebra|Boolean]] operations on [[binary numeral system|binary]] numbers. The following example demonstrates the [[Logical disjunction|OR]] [[logical operation]] on the binary numbers <code>111000</code> and <code>100001</code>:

Binary numbers are input into the calculator as hexadecimal numbers prepended by an <code>8</code>.

First, the operator must divide the numbers into groups of four digits, adding leading zeros if necessary, e.g. splitting <code>111000</code> into groups of four gives <code>0011</code> and <code>1000</code>. The equivalent [[hexadecimal]] values of these two four-digit binary numbers are <code>3</code> and <code>8</code>, respectively, which equal hexadecimal <code>38</code>.

Similarly, <code>100001</code> is equivalent to hexadecimal <code>21</code>.

So, the numbers <code>8.38</code> and <code>8.21</code> are entered into the MK-52 and the OR operation is performed on them. The OR operation is achieved by pressing {{key press|K|/-/}}.

The result displayed should be <code>8.39</code>, which translates into binary <code>0011</code> and <code>1001</code>, and, hence, the binary number <code>111001</code>, which is the result.

The following list details the MK-52's graphical representation of hexadecimal numbers: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, -, L, C, Г, E, (blank). Normal hexadecimal representation is 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F.
== Programming ==
The MK-52's programming commands are typed into the MK-52 in programming mode and are then executed. The MK-52 is fully capable of being programmed to manage memory and to use both [[Causality|conditional]] and [[unconditional branching]].

In programming mode, the screen displays information about the program in memory, represented by two hexadecimal-digit operation codes. For example, if <code>10 01 0E 03</code> is displayed, then this means that <code>0E</code> is stored at program step 00, <code>01</code> is stored at program step 01, <code>10</code> is stored at program step 02, and the machine is prompting for data to be input, to be stored at program step 03.

As an example, the following short program<ref name=":6">{{Cite web |title=Elektronika MK 52 Calculator Programming and Russian Science Fiction|url=http://rtr.bbs.tr/elektronika-mk-52-calculator-programming-and-russian-science-fiction |access-date=2024-08-07 |website=rtr.bbs.tr}}</ref> performs continuous addition to get an idea of the speed of the Elektronika MK 52 calculator:

The keystrokes to enter the program for the Elektronika MK-52 calculator are as follows:

{{key press|F}} {{key press|ПРГ}}<br>
{{key press|В↑}}<br>
{{key press|1}}<br>
{{key press|+}}<br>
{{key press|B/0}}<br>
{{key press|C/П}}<br>
{{key press|F}} {{key press|ABT}}

To execute it:

{{key press|1}}<br>
{{key press|B/0}}<br>
{{key press|C/П}}

To stop it:

{{key press|C/П}} or {{key press|CX}}

Calculator's rough speed can be measured by using a stopwatch, and terminating the program after a specific time elapsed.

=== Saving to EEPROM ===
Before entering a program to [[volatile memory]] with the intention of saving this program to [[EEPROM]] memory, the EEPROM program space to be saved to must be cleared first, which clears the volatile memory as well as the selected area of the EEPROM memory.

Each program step requires 1 [[byte]] of memory and each data register requires 7 bytes of memory.

When clearing, reading, or writing to the EEPROM memory, the address and range are specified by a six-digit number, preceded by a non-zero number, in automatic mode: e.g. <code>1aaaadd</code> specifies that <code>dd</code> bytes are to be stored starting at memory address <code>aaaa</code>. A two-position data/program switch controls whether data (from the registers) or program memory is transferred; a three-position switch is used to select read, write, and clear operations.

== Additional information ==
The Elektronika MK-52 originally sold for 115 [[Soviet ruble|rubles]]. It was produced in a variety of [[wikt:colorway|colorways]], including black and grey, turquoise and blue, white and grey, and orange. As typical for Soviet electronics, technical schematics were provided for the MK-52 when it was purchased, facilitating user modification and repair of the machine.

[[File:MK-52_schematics.png|thumb|right|Elektronika MK-52 schematics]]

=== Error message ===
[[File:Elektronika_MK_52_with_ERROR.jpg|thumb|right|MK-52 displaying ''ЕГГОГ'']]
When an error was encountered on the machine, the display produced a message similar to the English word "error". The word, written in this fashion, cut down on the number of display segments used to display the error message, but this spelling, read as [[Cyrillic script|Cyrillic]], would instead be pronounced "eggog" or "yeggog", depending on the language (the Cyrillic [[е]] is [[Iotation|iotated]] in Russian and Belarusian – and, by extension, in the Russian-derived orthographies created for non-Slavic languages by the Soviet Union – but not in other Slavic languages such as Ukrainian, Bulgarian, or Serbian).

=== Games ===
There is a host of games available for the MK-52. The MK-52's undocumented functions tend to be heavily used in the games due to their ability to make unusual calculations and produce specialized displays. A simple example of the modification of the display is accomplished by the repeated squaring of {{val|1e50}} (and ignoring error messages).

=== Use in outer space ===
In November 1988, the MK-52 went into space on the [[Soyuz TM-7]] spacecraft, where it could have been used to calculate the trajectory of landing in the event of an onboard computer failure.

== Bugs ==
There is currently only 1 known bug in the MK-52: the MAX function returns zero if one of its two arguments is zero.

==References==
{{Reflist}}

== External links ==
* [http://www.rskey.org/detail.asp?manufacturer=Elektronika&model=MK-52 Russian to English translation of the MK-52's keyboard]
* [https://archive.today/20130630093345/http://www.taswegian.com/MOSCOWx/mk-52.html Museum of Soviet Calculators on the Web (MOSCOW)]
* [http://www.leningrad.su/museum/show_calc.php?n=157 Sergei Frolov's "Soviet Calculators Collection"]
* [http://www.rskey.org/detail.asp?manufacturer=Elektronika&model=MK-52 Website detailing programmable calculators]
* [http://members.tripod.com/GregEscov/psch.htm More advanced programming techniques]
* [https://web.archive.org/web/20100726124201/http://www.thimet.de/calccollection/Calculators/Elektronika-MK-61/CmdRef.html Command reference]
* [http://www.alfredklomp.com/mk-61/ Alfred Klomp's page on "Hacking the MK-61"]
* [http://members.tripod.com/GregEscov/bignums.htm More 'EGGOG's]
* [https://web.archive.org/web/20000105134203/http://www.geocities.com/CapeCanaveral/Hall/5525/index.html  Games etc for the MK-52 and compatibles]
* [http://lordbss.pp.ru/pmk.html 250 games for MK-52, MK-61]
* [http://gtello.pagesperso-orange.fr/elektronika_e.htm MK-Compiler] easy programming on the MK-61 and MK-52.
* [http://www.rskey.org/mk54 MK-54]

===Emulators===
* [http://www.emulator3000.org/Calculators3000/Calculators3000.rar Download of an emulator for all Soviet programmable calculators]
* [http://www.emulator3000.org/c3.htm Emulator description page]

==Sources==
[[Category:Elektronika programmable calculators]]