Elektronika MK 61 Operating Instructions Manual

“ ELEKTRONIKA

MK 61 ”

M I C R O C A L C U L A T O R

OPERATING INSTRUCTIONS

FOR SCIENTIFIC,

ENGINEERING

AND STATISTICS

CALCULATIONS

Elektronika MK-61 Calculator Operating Instructions

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Table of Contents

Foreword .................................................................................................................................. 3

1. Notice to Owners .............................................................................................................. 4

2. Package Contents .............................................................................................................. 5

3. Safety Instructions ............................................................................................................ 6

4. Micro Calculator Specifications.......................................................................................... 7

5. Keyboard and Switches Description ................................................................................... 8

Latin keyboard layout transcription ....................................................................................... 8

Original Cyrillic keyboard layout ............................................................................................ 9

5.1. Primary functions on the key caps ............................................................................... 10

5.2. Additional symbols for shifted keys ............................................................................. 12

5.3. Additional register indirect commands ........................................................................ 14

6. Entering Data and Displaying Results ............................................................................... 15

7. Modes of Operation and Features ................................................................................... 16

“RUN” Mode ....................................................................................................................... 16

The Register Stack ............................................................................................................... 17

BCD system and Boolean Operations................................................................................... 19

“Programming” Mode ......................................................................................................... 21

Debugging ........................................................................................................................... 22

Indirect addressing revisited ............................................................................................... 23

Loop control........................................................................................................................ 23

8. Calculation functions accuracy ........................................................................................ 24

9. Technical data ................................................................................................................. 25

Average computation times ................................................................................................ 25

Power Supply ...................................................................................................................... 26

Environment considerations................................................................................................ 26

10. Invalid Operations and Overflow ................................................................................. 27

11. Battery Replacement ................................................................................................... 28

12. Storage and Handling .................................................................................................. 30

13. Warranty ..................................................................................................................... 31

14. Literature References .................................................................................................. 32

Elektronika MK-61 Calculator Operating Instructions

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15. Appendix 1 - Test checklist .......................................................................................... 34

16. Appendix 2 - Command Codes ..................................................................................... 35

17. Appendix 3 - Program Examples .................................................................................. 36

Calculating the area of a circle............................................................................................. 36

Using unconditional indirect branching GTO (i) (K, БП) ........................................................ 37

Using conditional indirect branching x<0 (i) (K, x<0) ............................................................ 38

Looping calculations using commands such as DSNZ0 (F, L0) ............................................... 40

Looping calculations using indirect load RCL (i) (K, П→Х)..................................................... 42

18. Appendix 4 - Warranty Card ........................................................................................ 43

19. Appendix 5 - Tear-off Vouchers ................................................................................... 45

Elektronika MK-61 Calculator Operating Instructions

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Foreword

This book is an English translation of the original Russian Elektronika MK-61
Operating Instructions guide, circa 1996. There are other original versions of the
Russian Elektronika MK-61 Operating Instructions guide, showing different
organization and contents. This version was chosen because it was the most recent
version found.

The translation process was initiated by scanning the original paperback guide at 300dpi
grey scale, and later converted to Cyrillic text using the ABBY Fine Reader tool. From
that point forward, the translation was a manual time consuming process, using Google
Translator as the main tool, and occasional assistance from Russian and Ukraine
acquaintances.

Enough care has been taken to be faithful to the original Russian text where possible.
This means that some expressions have retained the Russian tone. For example, a
calculator is designated as micro calculator and sometimes it is referred by its nick
name as MK.

Whenever possible, the original Cyrillic keyboard symbols are retained thru this book.
They are written between parentheses just after the equivalent Latin symbols.

Concerning the decimal separator symbol, despite the comma being used as decimal
separator in the original Russian guide, the MK calculator uses the dot symbol printed
on the decimal separator key. So in this guide the dot symbol was chosen in order to be
consistent with the MK keyboard.

Interestingly, the RPN term never appears in the original text, despite this MK-61 being
a machine that operates as such. Footnotes were added stating that this is indeed a RPN
calculator, though.

To complement the original guide’s information, additional detail was included, based
on Internet literature searches and testing on the physical MK-61 calculator. These
remarks are presented as footnotes references.

Many thanks to all contributors to this small project, namely the good people from the

MoHPC, and special thanks to Sergei Frolov for giving permission to include parts of

his work in this book.

Elektronika MK-61 Calculator Operating Instructions

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1. Notice to Owners

1.1. When you purchase a micro calculator (MK) please check for all of its delivery
contents, namely the MK quality control test, the presence of the warranty card in this
manual, the two tear-off maintenance vouchers in compliance with the MK serial
number and warranty card, the integrity of the seals on the device, and one power
supply unit (PSU).

1.2. Make sure you have a warranty and a detachable coupon signature (stamp) of the
seller, date of sale and shop stamp.

1.3. If the MK needs a repair during the warranty period, use the MK maintenance
vouchers and register the number and date of issue.

1.4. Vouchers for repair are taken by the representative maintenance organization
only after the remedial work intervention.

1.5. Before using the MK, please read this instruction manual.

1.6. If MK was transported in winter conditions or stored in a cold room, please keep
it for 4 hours at room temperature before turning it on.

1.7. A self-adhering protective film is attached to the MK display color filter, but it
can be removed if necessary.

1.8. After turning off the MK, allow a minimum of 30 seconds before switching it on
again.

1.9. For a more detailed acquaintance with the construction and operation of the MK,
use the reference literature listed at the end of the manual.

1.10. The factory is constantly improving the MK, so the product specification may
change and it will not be reported in the manual, without prejudice to the buyer.

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2. Package Contents

2.1. Micro Calculator "Elektronika MK 61”

2.2. Instruction Manual

2.3. Power Supply D2-10M

2.4. Packaging bundle with cardboard inserts, plastic bag, and pouch products.

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3. Safety Instructions

3.1. The power supply calculator can only be opened and repaired by qualified
personnel for such procedures.

3.2. Plugging the power supply to the 220VAC power grid without a calculator
connected to the adapter is prohibited1.

3.3. The use of rechargeable batteries is prohibited.

1

See Chapters 9 and 11 for details .

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4. Micro Calculator Specifications

4.1. Program memory of 105 steps.

4.2. Featured functions:

- Arithmetic (+, ─, ˟, ÷ );

- Direct and inverse trigonometric ( sin, cos, tg, sin

-1

, cos-1, tg

-1

);

- Logarithmic ( lg, ln );

- Calculations ( xy, ex, √x, x2, 1/x )

- Constants ( π )

- Isolation of the decimal (fractional) part of a number, determination of their
absolute magnitude and sign, maximum value between two numbers, inverse of
a number;

- Pseudo-random numbers generation between 0 and 1;

- Convert angular (time) values, expressed in degrees (hours), minutes, and
fractions of a minute, in values expressed in degrees (hours) and fractions of
degrees (hour), and vice-versa;

- Logical bitwise operations for addition, multiplication, xor, and negation.

4.3. Store data in the 15 memory registers RG0-RG9, RGa-RGe and recall them to

read stored data into the stack registers; Stack registers X, Y, Z, T data rotation;
exchange of data between the registers X and Y; clearing the X register and
retrieve the previous value of register X after an operation execution, thru the
register X1.

4.4. Perform operations requiring a single value in register X (ln, sin, among others),

double values operations with numbers in registers X and Y (arithmetic, etc.),
and chain operations.

4.5. Creating, editing and correction programs, commands for direct and indirect

jumps, call to subroutines with handling of up to 5 levels of depth, commands
for direct and indirect unconditional jumps, conditional jumps, looping
commands, indirect entries in registers, indirect branching on the contents of
registers, program counter reset command, start and stop execution in the Run
mode, commands to step through a program, display up to three program code
steps per line with indication of the current address of the program counter.

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5. Keyboard and Switches Description

Latin keyboard layout transcription

Elektronika MK-61 Calculator Operating Instructions

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Original Cyrillic keyboard layout

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5.1. Primary functions on the key caps

The exterior view of the original Russian MK-61 is shown in Fig.1 below.

to , - Numeric keys for data entry into the register X, using digits 0

through 9, plus the decimal point.

, , , - Keys to do arithmetic operations2 (addition, subtraction,

multiplication and division).

2

This is a RPN calculator, therefore it uses postfix notation where the parentheses and the equal keys

are not needed. To do a math operation, first enter the operand(s), then chose the operator.

LED
Display

Angle
Switch
"Radians /
Grads /
Degrees"

Power
Switch
"ON /
/ OFF"

Fig.1. Exterior view of the micro calculator (MK)

Keyboard

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, , , , - From left to right:

The ENTER (В↑) key is used for data entry into stack register X;
The EEX (ВП) key is used to input the exponent of a number;
The CHS (/─/) key change the sign of mantissa or exponent;
The x↔y (↔) key exchange data contents between the registers of X and Y;
The CX key clears the contents of register X.

, - The SST (ШГ→) and BST (ШГ←) keys are used to single-step through a

program.

, - The STO (Х→П) key stores the X register content in one of the

addressable memory registers. The RCL (П→Х) key loads the register X with one of
the addressable memory register’s contents3.

, - In "PROGRAM” mode, the GTO (БП) key specifies an unconditional

jump, while the GSB (ПП) key indicates a call to a subroutine. In "RUN" mode these
keys step through a program.

- In "PROGRAM" mode, the RTN/0 (В/0) key returns from a subroutine, while it

goes to address zero when in the "RUN" mode.

- In “PROGRAM” mode, the R/S (С/П) key is used to stop a program execution

and display the register X contents. In “RUN” mode, it starts or stop a program or a
loop cycle.

, - The F and K keys select the shift functions, whose symbols are printed

above the other MK’s keys in yellow (F) or blue (K) color.

3

The MK-61 has got 15 addressable memory registers (RG0 to RG9, and “RGa” to “RGe) for additional

data storage and to support a number programming features like looping control and indirect branching.

The calculator operations uses a primary memory area: The stack with 4 registers (X, Y, Z, T), plus one
additional register X1 used to automatically save the previous register X value when executing a
command that modifies the register X contents.

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5.2. Additional symbols for shifted keys

, - The F, CF combination cancels the shift key selection.

, - The F, LST x (F, Вх) combination retrieve the previous value of X after an

operation execution.

, ; , - The F, RUN (F, АВТ) combination selects the “RUN” mode,

while F, PRG (А, ПРГ) enters into the "PROGRAM” mode.

, ; , ; , ; ,

These four key combinations x<0, x=0, x≥0, x≠0 gives direct access to the four
corresponding logic conditions.

, ; , ; , ; ,

These four key combinations F, DSNZ0 (F, L0), F, DSNZ1 (F, L1), F, DSNZ2 (F, L2),
F, DSNZ3 (F, L3) allows loop control by using conditional direct branch depending on
the contents of register 0, 1, 2 or 3, respectively.

, - The F, R↓ combination rotates data thru the 4-stack registers.

, ; , ; , ; , ; ,

- From left to right, these five key combinations allow to determine:
The integer part: K, INT (K, [x])
The fractional part of a number: K, FRAC (K, {x})
The absolute magnitude: K, |x|
The sign: K, sign (K,ЗН)
Find the maximum of two numbers: K, max

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, ; , - From left to right:

The combination K, HH.M.S converts from sexagesimal degrees (hours), minutes,
seconds and fractions of seconds, into decimal angular (time) values.

The combination K, HH.M.S converts from decimal angular (time) values into
sexagesimal degrees (hours), minutes, seconds and fractions of seconds.

, ; , - From left to right:

The combination HH.M converts from sexagesimal degrees (hours), minutes, and
fractions of a minute, into decimal angular (time) values.

The combination HH.M converts between decimal angular (time) values into
sexagesimal degrees (hours), minutes, and fractions of a minute.

, ; , ; , ; ,

These four key combinations are used for bitwise logical operations. From left to right:
Multiplication: K, AND
Addition: K, OR
Exclusive or: K, XOR
Negation (one’s complement): K, NOT (K, ИНВ)

, - This key combination K, RND (K, СЧ) generates pseudo random numbers.

, - This key combination K, NOP (K, НОП) invokes a "No Operation".

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5.3. Additional register indirect commands

, - This key combination K + GTO(i) (K, БП) does an unconditional indirect

branch by jumping to an address stored in of one of the registers RG0 to RG9 and RGa
to RGe.

, - This key combination K, X<0 (i) does a conditional indirect jump to the

address stored in one of the registers RG0 to RG9 and RGa to RGe.
Similar operations are carried out under the conditions for indirect branching for the

remaining three commands:

, ; , ; ,

, - This key combination K, GSB(i) (K, ПП) does an indirect call to a

subroutine according to the address stored in one of the registers RG0 to RG9 and RGa
to RGe.

, - This key combination K, RCL(i) (K, П→Х) 4 does an indirect load of

register X with the contents of one of the 15 registers whose number is specified in one
of the registers RG0 to RG9 and RGa to RGe.

, - And of course the indirect store operation is available as well. This key

combination K, STO(i) (K, Х→П) takes the value of register X and does an indirect
store into one memory register referenced by one of the registers RG0 to RG9 and RGa
to RGe.

4

Suppose RG7 contents = 123; we want to load stack Reg. X with the RG7 contents by using indirect
addressing, and we chose RG0 as the pointer. What is the value to assign to RG0?
In this case, store the value 8 into the RG0 in order to retrieve the RG7 contents at the first try. Why?
Because when the instruction executes, first RG0 is modified and decremented by one, before looking
into its indirect pointer value.

This “decrement by one” behavior is only valid for register pointers RG0 to RG3, and applies to all

instructions using them.
However, this “decrement by one” sometimes takes place before the lookup, for example for
instructions like the RCL(i). And for other instructions, like GTO(i), it happens after the lookup.

As for the registers RG4 to RG6, they are first incremented by one before the lookup operation.
However, registers RG7-RG9 and RGa-RGe are modified but the value is not changed during execution.

Registers RG0-RG9, RGa-RGe correspond to modified codes from 0000000 to 0000014 (using leading 0’s)

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6. Entering Data and Displaying Results

6.1. MK numeric system - Decimal. The information is displayed on the 12 digits

luminous discharge type display, sporting a green glow; it has 8-digits for
mantissa, 2-digits for exponent, 1-digit for mantissa sign and another digit for
exponent sign.

6.2. The MK calculation range is: 1˟10

-99

≤ x ≤ 9.9999999˟1099
The results of calculations in the range of 1 ≤ x ≤ 99999999 are displayed in the
natural form, and outside this range are displayed as floating-point numbers.

6.3. The data is introduced in the MK by pressing the appropriate keys. To introduce

fractional numbers, first type the integer part, then the decimal point, and then
the fractional part.

6.4. When you enter a number with exponent, the mantissas is introduced first and

then press the key EEX (ВП) to enter the exponent value.
To change mantissa or exponent signs, press the key /─/ after typing the

values.

6.5. Pressing the key ENTER (В↑) normalizes the inputted number in stack

Reg. X, and a copy of the register X will go into register Y as well5.

6.6. After you enter an eight-digit mantissa number, further pressing additional

number keys does not change the display reading.

5

The 4-register stack lift operation is automatic on the ENTER key execution: The Reg. Y content is also

copied to Reg. T, and the previous Reg. T contents is lost.

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7. Modes of Operation and Features

7.1. The MK works in one of two modes: "RUN" or “PROGRAMMING".

“RUN” Mode

7.2. The "Run" mode is set immediately after switching ON the MK, or after clicking
the key combination , F, RUN (F, АВТ)

7.3. When performing single number operations, first type the numeric argument on the
keyboard, then press the key F and then press the corresponding function.

7.4. Before performing the direct or inverse trigonometric functions, set the switch

RAD / GRD / DEG ( Р / ГРД / Г ) to the desired angles units.

7.5. When converting time (angle) values, the hours (degrees) value is separated from
the value for minutes, seconds and fractions of second by the decimal point. For
example, the following time value:

142.24314 – Represents 142 hours, 24 minutes, and 31.4 seconds6.

7.6. To call a pseudo-random number to be displayed, type in a seed number and press
the keys , , ENTER, K, RND.
When the MK memory is reset, the generated number will be equal to 0.404067.

7.7. When performing double number operations, start by typing the first number on the
keypad, next introduce it with the key ENTER, then type the second number, and

press the button for the desired function. The display will show the result of the
operation.

6

To get this time result, type the decimal value 142.40874 and then choose , 

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The Register Stack

7.8. The MK has got a memory stack with the registers X, Y, Z, T. After switching on
the MK, there is no data in these registers. Entering information into the stack always

occurs through the register X. Pressing the key ENTER will copy the number in
register X into register Y, and Y into Z, and Z into T. In this way, the content of the
register X is preserved7.

7.9. Pressing the key combination , F, R↓, data rotates through the stack:

X → T → Z → Y → X

7.10. When performing single number operations, the MK operates with a number from
register X, and the contents of registers Y, Z, T are not modified.

The operation result is stored back in register X, but a copy of its previous content is
copied into the register X1 – This register X1 saves the previous register X content from
being lost as a result of another operation execution.

In this way, the result of one single number operation remains in register X and its value
is shown in the MK display.

7.11. To check the content register X1 press key the combination , F, LST x
(F, Вх).

It is cleared (or cancel any other operation command) by using the key CX.

7

RPN calculators are not created equal. Each different RPN machine vendor and model behaves in its
specific and unique way. RPN was adopted by HP since the beginning of the slide rule obsolescence with
their HP-35 calculator invention. And since then, HP calculators did evolve with the passing time, and
there are at least three different behaviors handling the stack operations, depending on calculator
models.

What about the MK-61 RPN register stack operations behavior?

Well, running the stack lift test (5, ENTER, CHS, 2, +) mentioned in the  
article by Richard J. Nelson, the result is 7.
This places the MK-61 in the same league as the HP Classics, like the famous HP-25 or HP-65 machines.

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7.12. The four stack registers and the previous X value in register X1 facilitate complex
calculations8.

7.13. To store the register X contents into one of the additional 15 memory registers,
use the key STO (Х→П) and choose the destination register number with one of

the keys to and to .

To load register X with a number from a memory register contents, press key
RCL (П→Х) followed by one of the source register numbers.

7.14. To clear a memory register by writing zero into it, use the key CX followed
by the key STO (Х→П) and choose the destination register address number.

To clear all MK memory registers, simply turn off the calculator9.

8

MK-61 RPN stack manipulation details are beyond the scope here, but let’s see a couple of examples.
The stack Register X is linked to the Display, so its content is always visible. When typing a number, it is
being entered into Register X. There is no need to do an ENTER to execute single number operations.

On the above example, when executing Sin(45), it first copies reg. X contents into Reg. X1, then
calculates the Sin(45) function, and the result is put back into Reg. X.
If we retrieve the previous Reg. X value, it will invoke an automatic stack lift up (X goes into Y, Y into Z, Z
into T, and previous T content is lost), to free up Reg. X to receive the LST x operator result.

On the next example, we pushed 3 numbers into the Y, Z, T stack registers, leaving X=Y. A Multiply
consumes X and Y as operands, leaving the answer in X. During the execution, an automatic stack lift
down was executed (T goes into Z, Z goes into Y) leaving T and Z with identical contents.

9

After switching off the calculator, please allow at least 30 seconds before turning it back on.
See Chapter 1. Notice to Owners.

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BCD system and Boolean Operations

7.15. Numbers in the MK are implemented in a BCD system, so Boolean operations can
be used on them. The binary values for each number and respective
display character are shown in Table 1.

Information in registers

Symbol on the

display

In the decimal

system

In the BCD

system

0

0000 1

0001

2

0010

3

0011 4

0100 5

0101

6

0110

7

0111

8

1000 9

1001 10

1010 11

1011

12

1100

13

1101 14

1110

15

1111

(blank)

Table 1 – BCD system symbol display

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7.16. The output from bitwise logical operations execution is signaled by the presence
of the digit “8” on the leftmost part of the displayed number.

When you enter values in register X and Y for Boolean operations, it is also necessary
to type in a digit other than 0 in the most significant digit of the inputted numbers.

7.17. Example for a bitwise logical addition:
8888888 OR 7770665
Keystrokes:

, , , , , , , ,

, , , , , , , , ,

Please note an extra digit, in this case with the value 1, was typed in to fill the leftmost
position of each number to be evaluated by a Boolean operator.

The result on the vacuum fluorescent display will show a value of10:

Note the digit 8 in the leftmost position of the result – This is the sign of a Boolean
logical operation.

10

These are two numbers having 7-digit with 4-bit each, to be added with the Boolean bitwise OR

operator.

As for the result, we get 7-digits with 4-bit each with the following values: 15, 15, 15, 8, 14, 14, 13

According to the “Table 1 – BCD system symbol display”, we expect to see these symbols on display:

- Three blank characters;

- An “8”

- Two “E”’s

- A “Г”

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“Programming” Mode

7.18. To go into "PROGRAM" mode, press , F, PROG (F, ПРГ).
In this mode, the codes for numbers, operations and commands11 are written into the

MK 105 memory cells, from addresses 00 to 104 12.

7.19. The MK has an internal Program Counter (PC) that changes its content with the
specified jump addresses or recorded in the registers RG0-RG9, RGa-RGe.

7.20. The MK shows the current address of the PC at the rightmost position of the
display13.

7.21. To create complex programs with subroutines, there are commands for direct and
indirect branching, indirect subroutine calls and data storing, and loop controls.
When typing these commands in the program one should specify the branch address
(except for indirect branching commands, which already contains the address).

11

See Appendix 2 - Command Codes

12

In reality step 00 is not available to store any instructions. The first memory address available to store

a command is 01. See the MK-61 behavior below for details.

13

Up to three of the previously entered commands are displayed on the next positions from right (at a
lower PC address) to left (at a higher PC address). The command at the current PC address is located at
the leftmost position of the display. Each command takes 2 digits on the display.

Example to code 1/

2

(a complete program needs to be terminated by a R/S command, though).

Keystrokes Result on the display

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7.22. Addresses branching from 00 to 99 are typed by pressing the corresponding
number keys. Addresses branching from 100 to 104 are used only for direct branching

commands and are typed using the key and one of the keys from to .
The addresses from 00 to 99 are displayed using the appropriate numbers,

but for the addresses from 100 to 104 the two digits used at hundreds and tens positions
are displayed with a “minus" sign. For example, the address 102 is displayed as -2.

7.23. To begin a program at address zero, select the "RUN” mode and reset the Program
Counter to zero by pressing RTN/0 (В/0), and then switch to "PROGRAM” mode.

The display will show the address 00.

7.24. If you want to start a program at any specific address, select the "RUN" mode and
press the key GTO (БП) followed by the required address, and then turn into the

"PROGRAM" mode.

Debugging

7.25. Debugging programs is done in "RUN" mode by pressing key SST (ШГ→).
Typically the required raw data needs to be entered in the appropriate registers, and then

set the start address of the program.

Finally execute the program in single step mode by using the key SST (ШГ→).

Alternatively run the program in automatic mode by using the key R/S (С/П).
In the latter case, the display blinks during the program execution.

WARNING!

When you turn off the MK, programs and data are lost.

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Indirect addressing revisited

7.26. When executing commands for indirect unconditional jump GTO (i)
followed by the address register), modification occurs in the contents of the address
register after the execution of the command, pointing to a new address.

If the command uses the address registers: 14

 RG0-RG3 - their content is decremented by 1;
 RG4-RG5 - their content is increased by 1;
 RG7-RG9 and RGa-RGe – Their content does not change.

7.27. When using the indirect store STO(i) (K, Х→П), modification also
occurs on the contents of addressable register, and writes the contents of register X
into the address that is pointed to by the modified code.

Registers RG0-RG9, RGa-RGe correspond to modified codes15 from 0000000 to

0000014.

7.28. When using the indirect load command RCL(i) (K, П→Х),
modification occurs on the contents of addressable register, and loads register X with
the contents of the address that is pointed to by the modified code.

Loop control

7.29. Computing cycles can be implemented by using the commands DSNZ0
to DSNZ03, as referenced in the register RG0 to RG3, respectively.

For each loop, the content of the address register is subtracted by 1 and test if its content
is equals to 0.

If address register equals 0 then execution continues after the next instruction, otherwise
execution jumps to the specified address.

14

As far as we can tell, the behavior for branching instructions is:

- Indirect addresses for RG0-3, the value is decremented after evaluating the branch address;

- Indirect addresses for RG4-6, the value is incremented before evaluating the branch address;

- Indirect addresses for RG7-e, the value is maintained but the branch address is incremented by 1.

- Conditional and unconditional direct branch, the address value is incremented by one.

15

See Chapter 5.3 – Additional register indirect commands

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8. Calculation functions accuracy

Table 2

Function

Permissible argument values

Maximum relative

error

sin x

10

-99

≤ |x| ≤ 1010

3*10-7

cos x

10

-99

≤ |x| ≤ 1010

3*10-7

tg x

10

-99

≤ |x| ≤ 1010

3*10-7

arc sin x

|x| ≤ 1

3*10-7

arc cos x

|x| ≤ 1

3*10-7

arc tg x

|x| ≤ 9.9999999*10

99

|x| ≥ 1*10

-99

max

y ≠ 0; x ≠ 0

xy

0 < x

1*10-6

ex

|x| < 100 ln 10

1*10-7

x2

|x| < 1050

1*10-7

10x

|x| ≤ 99.999999

4*10-7

1/x

x ≠ 0

1*10-7

√x

0 ≤ x

1*10-7

ln x

0 < x

4*10-7

lg x

0 < x

4*10-7

H H.M

-1*10

-99

≤ |x| < -0.06

1*10-7

H H.M

-0.06 < x ≤ 9,9999999*1099

1*10-7

H H.M.S

-1*10

-99

≤ |x| < -0.06

1*10-7

H H.M.S

-0.06 < x ≤ 9,9999999*1099

1*10-7

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9. Technical data

Average computation times

9.1. Computation16 time for arithmetic, 1/x, √x, and x2 operations: No more than 0.5
seconds.

Average computation time for logarithmic calculations and direct and inverse
trigonometric functions: No more than 2 seconds.

Time calculation for function xy: No more than 3.5 seconds.

16

Elektronika MK-61 hardware details:

New MK-61’s are supplied with operating instructions including the schematic diagram, where we can
identify the main active electronic components.

The Integrated Circuits:

D1: К745ИК1302-2 (K745IK1302-2) - Control Unit for Processor, Display and Keyboard;
D2: К745ИК1303-2 (K745IK1303-2) – One-bit Arithmetic Processor; clock frequency around 100KHz;
D3: К745ИР2-2 (K745IR2-2) - Memory Registers;
D4: К745ИР2-2 (K745IR2-2) - Memory Registers;
D5: К745ГФ3-2 (K745GF3-2) - Clock Generator;
D6: К745ИК1306-2 (K745IK1306-2) - Additional MK-61 features not present on the B3-34 series;

The Vacuum Fluorescent Display:

VL1: ИЛЦ2-12/8Л (ILC2-12/8L or ILZ2-12/8) - Vacuum Fluorescent Display; Filament voltage: 2.15 - 2.9 V
at 20 to 24mA; Brightness: 700 cd/m^2; Number of digits: 12 (8 mantissa + 2 exponent + 2 sign digits);
Size of the digits: 2.4 x 4.3 mm; Color: Green; Lifetime: more than 10000 hours;

The Power Supply Transistors:

VT1: кт361г (KT361G) - PNP Si 250MHz, hfe>50, 35V, 0.05A, 0.15W
VT2: кт315б (KT315B) - NPN Si 250MHz, hfe>50, 20V, 0.1A, 0.15W (schematics wrongly specify it as PNP);
VT3: кт814г (KT814G) - PNP Si 3MHz, hfe>60, 50V, 3A, 10W
VT5: кт315б (KT315G) - NPN Si 250MHz, hfe>50, 35V, 0.1A, 0.15W

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Power Supply

9.2. The MK power supply17 takes three battery cells18 model A-316 "Quantum" or
"Prima", and it can use an external power adapter model D2-10M19 (or similar) to be
connected to an 220VAC (50 ±1Hz) power outlet.

9.3. Power consumption from the three battery cells A316 is less than 0.6 Watt20.

Environment considerations

9.4. Operating temperature from 10 to 35°C at a relative humidity of 50 to 80% and an
atmospheric pressure from 86 to 106 kPa.

9.5. The MK weight (without batteries and power adapter) is less than 250 g.

9.6. The MK physical dimensions are not exceeding 170 x 80 x 38 mm.

9.7. Content of precious metals in the MK: Gold - 0.06455 g, Silver - 0.04274 g

17

The MK-61internal power supply includes a DC-DC converter circuit, taking the 4.5V battery supply to
generate a number of negative output supply voltages for the electronics, consuming between 100mA
and 130mA depending on how many digits are on. The 4.5V battery Positive terminal is used as common
GND (ground).

MK-61 DC-DC converter pin out

Common connection pin:
+BATT/GND (pin9): Connected to Gnd/+5V to IC's.

Input 4.5V battery supply voltage:

-V1 -BATT (pin3): Connected to the Negative terminal of the 4.5V battery.

Output negative supply voltages:

-V2 -15V (pin4): Connected to IC’s logic circuits supply

-V3 -27V (pin7): Connected to the VFD display
~V4: 2.4VAC (pin 1 and 2): Connected to the VFD display filament

18

Western 1.5V type AA LR6 Alkaline or similar battery cells can safely be used as well.

19

Output under normal calculator load of 100mA: 5.2VDC. Output voltage in open circuit: 8.5VDC.

20

Calculator current consumption varies from about 100mA (one digit turned on) to 130mA (12 digits
turned on).

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10. Invalid Operations and Overflow

10.1. Invalid operations include division by 0, elevating 0 or a negative number to any
power, square of a negative number, logarithms of 0 or a negative number, calculation
of direct and inverse trigonometric functions outside its domain, and transfer time
(angular) variables for values in minutes (seconds) larger than 50, results in an error 21
message presented in the vacuum fluorescent display:

10.2. The ERROR signal is also displayed when the calculation result exceeds the value
+9.9999999*1099.

If the result of the calculation is less than 10

-99

, the register X is set to zero.

10.3. After the appearance of an error condition, you can continue to enter numbers and
perform calculations on the MK.

10.4. Using the results of logical operations as an argument in cases where these are
outside the domain of the calculated functions, can lead to incorrect operation and

erratic MK behavior (crashes, infinite loops, incorrect results, etc.).

21

This error message makes sense in English assuming Latin characters. But this is a Russian calculator
where the error message can be wrongly read as Cyrillic text and then it translates to “EGGOG”.

Like MK-52, the MK-61 inherits from the Elektronika B3-34 series. All are famous, and one of the reasons

is related to this “EGGOG” message, as it allows hacking and exploring the “EGGOG” state to great
extent, taking advantage of undocumented “features”. It happens that not every “EGGOG” state is a real

error. One exploit is to manipulate big numbers (larger than 9.9999999x1099).

From number exponents between 100 and 200, the display shows but the numbers
can be manipulated in the registers. They are too large to be displayed, hence the error message.

From exponents above 200 the display can show a . Now we have a “ZGGOG”!

One way to find out where the displayed error is genuine or is a big number, is to do a K, NOP. If the
error message goes away it is a genuine error (like divide by zero), else it will stay on display.

Experts in this calculator series have shared some information on the subject, for instance here:

- How to calculate on the MK B3-34, by Sergei Frolov http://www.leningrad.su/b334/b334doce.htm

- “MK B3-34 Soviet Calculator – Riddle” by Sergei Frolov http://www.leningrad.su/b334/b334e.htm

- “Pseudo-writing mode”, by Gregory Escov http://gregescov.tripod.com/psch.htm

- “The journey of the big numbers”, by Gregory Escov http://gregescov.tripod.com/bignums.htm

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11. Battery Replacement

11.1. When replacing batteries, the MK must be turned off and the external power
adapter disconnected from the outlet.

11.2. Pay attention to the polarity of the batteries to match with the label signs inside the
MK battery compartment (Figure 2).

11.3. Remove the battery compartment cover by sliding it out and insert the three fresh
batteries. Put back the cover and turn on the MK power switch ON (ВКЛ).

The leftmost display digit should light up to show

11.4. If the MK display shows up decimal points, it means that the battery level is low
and it should be replaced.

WARNING

Do not leave dead batteries in the MK in order to avoid damage arising from the
electrolyte leaking – The MK cannot be repaired22 in these conditions.

11.5. When using an external power adapter, first connect it to the MK23, and then plug
the adapter to the 220 VAC power outlet.

To stop using the power adapter, first unplug it from the 220 VAC outlet and then
disconnect it from the MK.

22

Troubleshooting procedures for the most common problems:

- Check the obvious point of failures – Battery leaking, oxidized or corroded battery terminals, broken

power supply wiring, and power switch – Clean it and make sure good continuity is restored.

- Check for normal current consumption – It varies from about 100mA (one digit turned on) to 130mA

(12 digits turned on). If the value is outside this threshold, investigate the DC-DC converter.

- Check the DC-DC power converter output voltages. The IC’s requires -15VDC, and the VFD requires

two voltages (-27VDC and 2.4VAC) - see details on Chapter 9 – Technical Data – Power Supply.
Defective electrolytic capacitors are a common cause for erratic or total operation failure.

23

The reason for this procedure is related to the fact that the Power Adapter model “Elektronika D2­10M" output voltage is not regulated. In open circuit it will present about 8.5VDC, while the calculator
nominal working voltage is only 4.5VDC.
Connecting the Power Adapter to the calculator with 8.5VDC will stress the internal DC-DC converter a
bit, with eventual hardware failures arising from this transitory overvoltage.
However the Power Adapter will present around 5.2VDC for workloads of about 110mA and 4.9VDC at
145mA, meaning that if you follow the above manufacturer recommendation, the calculator will never
see more than 5.2VDC and it will run safely.

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Fig. 2 Install the batteries A-316 24

24

Western 1.5V type AA LR6 Alkaline or similar battery cells can safely be used as well.

Use your thumb to gently press
the protruding rib portion of the
MK battery compartment cover
and carefully slide it up.

Put fresh A-316 batteries into
the battery compartment
according to the label on the
bottom of the compartment, and
then insert the cover into the
slots and slide it into place.

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12. Storage and Handling

12.1. Use the supplied transport packaging to protect the MK from mechanical damage,
dust, moisture, and excessive climatic influences.

12.2 The MK should be stored in a dry heated room at a temperature between 5 and
35°C, and a relative humidity of less than 85%.

The MK should not be exposed to aggressive environments where substances like acids,
alkalis, and others, are present.

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13. Warranty

13.1. The manufacturer guarantees the MK to the technical specifications subject to the
operating rules. Warranty period - 24 months from the date of sale.

13.2. In the absence of guarantee vouchers and coupons sales date and shop stamp, the
MK warranty period is calculated from the date of manufacture of the MK manufacturer.

13.3. During the warranty period, for the first and second repairs use the detachable
coupons. Subsequent repairs are carried out under the act.

13.4. A MK without warranty card or detachable coupons, as well as broken seals, is not
covered under the warranty service.

13.5. MK exchange through sales network help repair facilities and the warranty card
under the rules of the exchange of manufactured goods.

13.6. Address repair facility can be found in the shop where the MK was sold, as well as
at the plant – Manufacturer phone: 2-28-54.

Elektronika MK-61 Calculator Operating Instructions

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Draft version 1.0 – Oct.2014

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14. Literature References

Astanin L. Yu, Daren Yu. - “Using programmable calculators for scientific and
engineering calculations” - Ed.: Energoatomizdat, 1986 - 157 pages (Астанин Л.

Ю. ,Дарений Ю.Д. Применение программируемых микрокалькуляторов для
научных и инженерных расчетов)

Bloch AS, Pavlovsky AI, VV Penkrat – “Programming calculators” - Minsk, 1981 - 192
pages (Блох А.Ш., Павловский А.И., Пенкрат В.В. Программирование на
микрокалькуляторах. - Минск: Выш. шк.)

Boyko A.B. – “Games with the calculator” – Ed.: Znanie, 1987 - 46 pages (Бойко А.Б.
Игры с микрокалькулятором -М.: Знание.1987 -46 с.)

Danilov, ID – “Secrets of the programmable calculator” – Ed.: Nauka, 1986 -160 pages
(Данилов И.Д. - Секреты программируемого микрокалькулятора -М.:Наука,1986 -
160 с.)

Dyakonov V.P. – “Calculation of non-linear and switching devices on programmable
calculators” – Ed. Radio and Communication, 1964, 170 pages (Дьяконов В.П. Расчет

нелинейных и импульсных устройств на программируемых микрокалькуляторах. ­М., Радио и связь,1964 г.-170 с.)

Dyakonov V.P. – “Handbook of calculations on calculators” –Ed.: Science, 1985 - 224
pages (Дьяконов Б.П. Справочник по расчетам на микрокалькуляторах -
М.:Наука,1985 - 224 с.)

Krol G. – “What can my calculator do?” –Ed.: Mir, 1981 -132 pages (Кроль Г. Что
умеет мой микрокалькулятор? -М.:МИр,1981 -132 с.)

“Calculators: Specifications and design characteristics” - EJ Kuznetsov, V.V.Ostetsov,
Minikin YN, Yu.N.Egorova -Ed.: Radio and communication, 1984
128 pages - (Ser. inzhenera.Vyp.40 Public Library) (Микрокалькуляторы:

Технические и конструктивные характеристики. Е.Ю. Кузнецов, В.В.Остецов,

Миникин Ю.Н., Ю.Н.Егорова - М.:Радио и связь,1984 - 128 с. - (сер. Массовая
библиотека инженера.Вып.40) )

V.F.Ochkov, V.H.Hmelyuk – “From a calculator to a personal computer” -Ed.: MEI
1990 - 224 pages (В.Ф.Очков, В.Х.Хмелюк. От микрокалькулятора к
персональному компьютеру. Изд. МЭИ, 1990 - 224 с.)

Elektronika MK-61 Calculator Operating Instructions



Draft version 1.0 – Oct.2014

Please send corrections to Jose Mesquita ([e-mail])

Pukhnachov Y., Danilov N.D. – “Calculators for all” –Ed. Knowledge, 1986 - 192
pages (Пухначев Ю.В., Данилов Н.Д. Микрокалькуляторы для всех. -
М.,Знание,1986 - 192 с.)

Trohimenko Y.K. - “Programming the MK-61 and MK-52” –Ed.: Radio and
communication, 1987 - 209 pages (Трохименко Я.К. Программирование
микрокалькуляторов МК-61 и МК-52. -М.:Радио и связь, 1987 - 209 с.)

Trohimenko Y.K., Lubich F.D. – “Engineering analysis on calculators” - Kiev,
Technology, 1980 - 394 pages (Трохименко Я. К. ,Любич Ф.Д. Инженерные
расчеты на микрокалькуляторах - Киев,Техника, 1980. - 394 с.)

Trohmenko Y.K., Lubich F.D. – “Engineering analysis on programmable calculators” ­Kiev: Technology. 1985 - 328 pages (Трохменко Я.К., Любич Ф.Д., Инженерные
расчет на программируемых микрокалькуляторах - Киев: Техника. 1985 -328 с.)

Trohimenko Y.K., Lubich F.D. – “Radio engineering analysis on calculators” - Ed.:
Radio and communication, 1983 - 206 pages (Трохименко Я. К., Любич Ф.Д.

Радиотехнические расчеты на микрокалькуляторах . М.: Радио и связь, 1983 ­206 с.)

Trohimenko Y.K., Lubich F.D. – “Programming the calculators "Elektronika MK 52"
and Elektronika MK 61"”- Kiev: Technology. 1987 – 208 pages (Трохименко Я.К.,

Любич Ф.Д., Программирование микрокалькуляторов "Электроника МК 52" и

Электроника МК 61" - Киев: Техника.1987 - 208 с)

Chupka A.M. – “Calculation – Engineering operations on programmable calculators” ­Ed.: Machinery, 1968 - 143 pages (Чапка A.M. Расчетно - проектировочные

работы на программируемых микрокалькуляторах - М.: Машиностроение,1968 ­143 с.)

Elektronika MK-61 Calculator Operating Instructions

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15. Appendix 1 - Test checklist

Slide the Switches (ON) "ВКЛ",

(RAD/GRAD/DRG) "Р/ГРД/Г", tap the keys

Digits Lit on Display

1 2 3 4 5 6 7 8 9

10

11

12

1. “ВКЛ” (Power ON)

2.

3.

4.

5.

6. “Г” DEG (sin)

7. “ГРД” GRAD (cos)

8. “Р” RAD (tg, STO 1)

9. (π)

10. (lg, STO 2)

11. (RCL 1)

12. (RCL 2)

.

13. (enter PROG mode)

14. (max)

15. (abs)

16. (STO 3)

17. ( x

y

)

18. (OR)

19. (DSNZ3)

20.

21. (R/S)

22. (exit RUN mode, RTN/0)

23. (R/S) Test executes in less than 5sec.

24. (CHS)

NOTE! To perform the shifted functions printed in yellow (or blue) color, you need to press the

keys (or ) to access those operations.

16. Appendix 2 - Command Codes

1st
digit
code

2nd digit code

0 1 2 3 4 5 6 7 8 9 A B C D E 0 0 1 2 3 4 5 6 7 8

9

.

/-/

EEX

CX

ENTER↑

1

+ - *

/

x↔y

F 10x

F ex

F lg

F ln

F sin-1

F cos-1

F tg-1

F sin

F cos

F tg

2

F ∏

F √

F x2

F 1/x

F xy

F R↓

K

H←H.M

K

H→H.M.S

3

K

H←H.M.S

K |x|

K sign

K

H→H.M

K INT

K

FRAC

K max

K AND

K OR

K XOR

K NOT

K RND

4

STO 0

STO 1

STO 2

STO 3

STO 4

STO 5

STO 6

STO 7

STO 8

STO 9

STO a

STO b

STO c

STO d

STO e

5

R/S

GTO

RTN/0

GSB

K NOP

F x≠0

F

DSNZ2

F x≥0

F

DSNZ3

F

DSNZ1

F x<0

F

DSNZ0

F x=0

6

RCL 0

RCL 1

RCL 2

RCL 3

RCL 4

RCL 5

RCL 6

RCL 7

RCL 8

RCL 9

RCL a

RCL b

RCL c

RCL d

RCL e

7

K

x≠0 (0)

K

x≠0 (1)

K

x≠0 (2)

K

x≠0 (3)

K

x≠0 (4)

K

x≠0 (5)

K

x≠0 (6)

K

x≠0 (7)

K

x≠0 (8)

K

x≠0 (9) K x≠0 (a)

K

x≠0 (b)

K

x≠0 (c)

K

x≠0 (d) K x≠0 (e)

8

K

GTO(0)

K

GTO(1)

K

GTO(2)

K

GTO(3)

K

GTO(4)

K

GTO(5)

K

GTO(6)

K

GTO(7)

K

GTO(8)

K

GTO(9)

K

GTO(a)

K

GTO(b)

K

GTO(c)

K

GTO(d)

K GTO(e)

9

K

x≥0 (0)

K

x≥0 (1)

K

x≥0 (2)

K

x≥0 (3)

K

x≥0 (4)

K

x≥0 (5)

K

x≥0 (6)

K

x≥0 (7)

K

x≥0 (8)

K

x≥0 (9) K x≥0 (a)

K

x≥0 (b)

K

x≥0 (c)

K

x≥0 (d) K x≥0 (e)

A

K

GTO(0)

K

GTO(1)

K

GTO(2)

K

GTO(3)

K

GTO(4)

K

GTO(5)

K

GTO(6)

K

GTO(7)

K

GTO(8)

K

GTO(9)

K

GTO(a)

K

GTO(b)

K

GTO(c)

K

GTO(d)

K GTO(e)

B

K

STO(0)

K

STO(1)

K

STO(2) K STO(3)

K

STO(4)

K

STO(5)

K

STO(6)

K

STO(7)

K

STO(8)

K

STO(9)

K

STO(a)

K

STO(b)

K

STO(c)

K

STO(d)

K

STO(e)

C

K

X<0 (0)

K

X<0 (1)

K

X<0 (2)

K

X<0 (3)

K

X<0 (4)

K

X<0 (5)

K

X<0 (6)

K

X<0 (7)

K

X<0 (8)

K

X<0 (9) K X<0 (a)

K

X<0 (b)

K

X<0 (c)

K

X<0 (d)

K

X<0 (e)

D

K

RCL(0)

K

RCL(1)

K

RCL(2)

K

RCL(3)

K

RCL(4)

K

RCL(5)

K

RCL(6)

K

RCL(7)

K

RCL(8)

K

RCL(9)

K

RCL(a)

K

RCL(b)

K

RCL(c)

K

RCL(d)

K

RCL(e)

E

K

X=0 (0)

K

X=0 (1)

K

X=0 (2)

K

X=0 (3)

K

X=0 (4)

K

X=0 (5)

K

X=0 (6)

K

X=0 (7)

K

X=0 (8)

K

X=0 (9) K X=0 (a)

K

X=0 (b)

K

X=0 (c)

K

X=0 (d)

K

X=0 (e)

17. Appendix 3 - Program Examples

Calculating the area of a circle

 

  





This program assumes that a given value of d is stored in Reg. RG2.

Address

Keys

Codes

Comments

01

62

Load stack register X with the d value from RG2

02

22

Calculation of d2

03

0E

Copy d2 into stack register Y

04

20

Load the π constant

05

12

Calculation of πₓd2

06

04

Input number 4 into stack register X

07

13

Compute the area S

08 50

Stop the program

The command R/S is required to stop the program and display the result;
otherwise the MK will execute all 105 steps of the program.

To calculate S for a particular value of d = 4, it is necessary to perform the following
operations.

Specific procedures to this program:

- Store the number 4 in Reg. RG2: ;

Generic procedures to prepare any program to run:

- While in “RUN” mode, go to address 00 ;

- Enter “PROGRAM” mode and enter the program;

- Go back to "RUN” mode ;

- Reset the program counter to 0 by pressing RTN/0 (/0) and

- Run the program with the R/S (/) key.

Expected result on display: 12.56637.

Elektronika MK-61 Calculator Operating Instructions



Draft version 1.0 – Oct.2014

Please send corrections to Jose Mesquita ([e-mail])

Using unconditional indirect branching GTO (i) (K, БП)

Evaluate the expression: 󰇛  󰇜  

Address

Keys

Codes

01 04

02 0E

03

83

04

21

05

02

06 10

07

84

08 10

09

03

10 12

11

8-

12

11

13

50

Store the numbers 5, 7 and 12 in the registers RG3, RG4, e RGa, respectively. Enter the
program; then go back to “RUN” mode and reset the program counter with RTN/0 (B/0).

During execution of the instruction GTO(3) (K, БП, 3) at address 03, because RG3
contains the value 5, the program jumps to that address 05. The Reg. RG3 is
decremented by 1 after evaluating the branch address 25.

For the next indirect branch, we have number 7 in Reg. RG4 which is increased by 1
before evaluating the branch address, so the program instruction GTO(4) (K, БП, 4) at
address 07 will jump to the address 08.

At last, Reg. RGa will not change the value, so the program instruction GTO(a) (K, БП,
a) at the address 11 will jump to address 13, one address higher than specified in RGa.

25

This MK behavior is bizarre. This example works fine and it is presented here as written in the original

Russian guide. However their explanation seems to be incorrect:

1) Firstly it lists the instruction addresses from 00, when it is obvious that it starts at 01.

2) And then it states that the pointer register RG3 is decremented before evaluating the jump address.

As far as we can tell, the behavior for branching instructions is:

- Indirect addresses for RG0-3, the value is decremented after evaluating the branch address;

- Indirect addresses for RG4-6, the value is incremented before evaluating the branch address;

- Indirect addresses for RG7-e, the value is maintained but the branch address is incremented by 1.

- Conditional and unconditional direct branch, the address value is incremented by one.

Elektronika MK-61 Calculator Operating Instructions



Draft version 1.0 – Oct.2014

Please send corrections to Jose Mesquita ([e-mail])

The above arithmetic expression should give a result of 18.

Using conditional indirect branching x<0 (i) (K, x<0)

Evaluate the expression:   



 



This program assumes that the x value is stored in RG1.
Depending on the expression result, if y<0 then add the value of   to the result, else

add the value of  .

Address

Keys

Codes

01

01

02

09

03

4L

04

09

05

61

06

22

07 12

08

42

09

61

10 02

11 12

12

16

13

62

14 11

15

CL

16

61

17

1E

18 10

19 50

20

61

21

1C

22 10

23 50

Address 01 - 03: Store the branch address for the command (x<0 (i).

Elektronika MK-61 Calculator Operating Instructions

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Address 04 - 14: Evaluation of the expression  



 



.

Address 15: Evaluate the result to check for conditional branching.
Address 16 - 17: Calculation of  .
Address 20 - 21: Calculation of  .
If y> 0, then after the command at 15 the program jumps to address at 20, one address

higher than specified in the pointer register RGb. 26
If < 0, then after command at 15 it executes the next instruction at address 16.

For example, to calculate the value of y for a particular value of x = 4, it is necessary to
perform the following steps:

Go to "PROGRAM” mode at address 00 and enter the program;
Go back to "RUN";

Set the angle switch RAD / GRD / DEG (Р / ГРД / Г) to DEG (Г);
Store the x value = 4 to RG1;
Reset the Program Counter by pressing RTN/0 (В/0);
Expected result: 2836.2007.

26

This example works fine and it is the original one as written in the original Russian guide. However

their explanation seems to be incorrect:

1) Firstly it lists the instruction addresses from 00, when it is obvious that it starts at 01.

2) And then it states that the conditional indirect jump takes the pointer register RGb address as it is (19
in this case, when in reality it should be 20, as the first valid address is 01, not 00).

As far as we can tell, the behavior for branching instructions is:

- Indirect addresses for RG0-3, the value is decremented after evaluating the branch address;

- Indirect addresses for RG4-6, the value is incremented before evaluating the branch address;

- Indirect addresses for RG7-e, the value is maintained but the branch address is incremented by 1.

- Conditional and unconditional direct branch, the address value is incremented by one.

Elektronika MK-61 Calculator Operating Instructions



Draft version 1.0 – Oct.2014

Please send corrections to Jose Mesquita ([e-mail])

Looping calculations using commands such as DSNZ0 (F, L0)

Evaluate the expression:



󰇛 





 󰇜




Program flowchart:

Store X i into RG0

(Address 01)

Load Reg. X from RG0

(Address 02)

Calculation  





 

for X i = 1, ..., 4

(Address 03, ..., 09)

Store summation to RG5

(Addresses 10, 11, 12)

Display contents of RG5 and Stop

(Address 15)

Decrement RG0 and

compare to 0

(Address 13)

RG0≠0

Elektronika MK-61 Calculator Operating Instructions



Draft version 1.0 – Oct.2014

Please send corrections to Jose Mesquita ([e-mail])

Program:

Address

Keys

Codes

01

40

02

60

03 03

04 13

05

1E

06

02

07 12

08 04

09

10

10

27

65

11 10

12

45

13

5Г

14

28

02

15

50

27

Because the program does not initialize the Summation register, we need to do it manually (Store 0

into RG5), or else we get erroneous results when running this program more than once.

28

The original Russian manual lists the addresses starting from 00, which is not correct, because the first
usable address to store instruction codes is 01.
So this example will loop forever if entered as indicated in the original Russian guide (by specifying
DSNZ0 01). They mean the 2nd address when counting from address 00, so the correct address is 02
when counting from 01.

The correct branch address to use is DSNZ0 02 as listed above.

Elektronika MK-61 Calculator Operating Instructions



Draft version 1.0 – Oct.2014

Please send corrections to Jose Mesquita ([e-mail])

Looping calculations using indirect load RCL (i) (K, П→Х)

Evaluate the expression:



󰇛 





 




Address

Keys

Codes

01

43

Store X i into RG0

02

Г3

Indirect load X from a Register pointed
to by RG3. The only purpose is to
decrement the RG3.

03

63

Load X with next x i value to evaluate.

04

5E

Test for the end of the loop.

05

07

If X is not Zero, jump to 08 29

06

65

Else, show the Summation

07 50

And stop

08 03

Evaluating  





 

09

13

…

10

1E

…

11

02

…

12 12

…

13 04

…

14 10

 





  is evaluated

15

65

Load X with previous Summation

16 10

Evaluate the new Summation

17

45

Store Summation in RG5

18

51

Jump to…

19 01

Address 02 30

Before running the program: Set angles to DEG (Г); type xi=4 into X; Clear RG5 31;
Reset with RTN/0 (В/0).

29

The Branch addresses are automatically incremented by one, meaning that we need to specify one
address less than the Target one.
As far as we can tell, the behavior for branching instructions is:

- Indirect addresses for RG0-3, the value is decremented after evaluating the branch address;

- Indirect addresses for RG4-6, the value is incremented before evaluating the branch address;

- Indirect addresses for RG7-e, the value is maintained but the branch address is incremented by 1.

- Conditional and unconditional direct branch, the address value is incremented by one.

30

See previous footnote above.

31

Because the program omits the Summation register initialization.

Elektronika MK-61 Calculator Operating Instructions



Draft version 1.0 – Oct.2014

Please send corrections to Jose Mesquita ([e-mail])

18. Appendix 4 - Warranty Card

WARRANTY CARD

Micro Calculator “Elektronika MK-61”
Serial Number. ____________ Date of Manufacture ________________
Quality Department stamp _____________________________________

Address for claims:

283830, г.Збараж, Тэрнопольской обл.,з-д "Квантор"
ул.Галипкого,56

To be filled by the trade company

Date of sale ___________________ Seller _______________________
Format: d-m-y Signature or stamp

Store stamp _________________________________________________

Included warranty service ______________________________________
Name
___________________________
Repair shop, date, month, year

Warranty Number _____________________________________________

Elektronika MK-61 Calculator Operating Instructions



Draft version 1.0 – Oct.2014

Please send corrections to Jose Mesquita ([e-mail])

Elektronika MK-61 Calculator Operating Instructions



Draft version 1.0 – Oct.2014

Please send corrections to Jose Mesquita ([e-mail])

19. Appendix 5 - Tear-off Vouchers

Expires by using it

(front side)

TEAR-OFF VOUCHER

For warranty repairs during the

warranty period

Micro Calculator “Elektronika MK-61”
Serial Number. ____________ Date of Manufacture ________________
Quality Department stamp _____________________________________

Address for claims:
283830, г.Збараж, Тэрнопольской обл.,з-д "Квантор"
ул.Галипкого,56

To be filled by the trade company

Date of sale ___________________ Seller _______________________
Format: d-m-y Signature or stamp

Store stamp _________________________________________________

Elektronika MK-61 Calculator Operating Instructions



Draft version 1.0 – Oct.2014

Please send corrections to Jose Mesquita ([e-mail])

(Back side)

To be filled the repair shop

Warranty Product number _______________________________________
Repair report. Name and reference number of the replaced part or assembly

in the schematic diagram. Location and nature of defects:
_____________________________________________________________

_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
Repair date ___________________________________________________

Format: d-m-y

Signature of the person who performed the repairs ____________________
Signature of the owner, confirming the repair

______________________________

Repair shop stamp ______________________________________________
Specifying the city

Elektronika MK-61 Calculator Operating Instructions



Draft version 1.0 – Oct.2014

Please send corrections to Jose Mesquita ([e-mail])

Expires by using it

(front side)

TEAR-OFF VOUCHER

For warranty repairs during the

warranty period

Micro Calculator “Elektronika MK-61”
Serial Number. ____________ Date of Manufacture ________________
Quality Department stamp _____________________________________

Address for claims:
283830, г.Збараж, Тэрнопольской обл.,з-д "Квантор"
ул.Галипкого,56

To be filled by the trade company

Date of sale ___________________ Seller _______________________
Format: d-m-y Signature or stamp

Store stamp _________________________________________________

Elektronika MK-61 Calculator Operating Instructions



Draft version 1.0 – Oct.2014

Please send corrections to Jose Mesquita ([e-mail])

(Back side)

To be filled the repair shop

Warranty Product number _______________________________________
Repair report. Name and reference number of the replaced part or assembly

in the schematic diagram. Location and nature of defects:
_____________________________________________________________

_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
Repair date ___________________________________________________

Format: d-m-y

Signature of the person who performed the repairs ____________________
Signature of the owner, confirming the repair

______________________________

Repair shop stamp ______________________________________________
Specifying the city

Circulation 30,000 Orders 2220

Printed by " UKRTIPPROEKT". Eugene Pottier Str., Kiev-57, 252057 Ukraine.

Elektronika MK-61 Calculator Operating Instructions



Draft version 1.0 – Oct.2014

Please send corrections to Jose Mesquita ([e-mail])