F
- Direct
- Select F shift for the next key.
- F
- — No second F function.
- K
- — No K function.
Вкл
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ПРОГРАММИРУЕМЫЙ МИКРОКАЛЬКУЛЯТОР
ЭЛЕКТРОНИКА
OPERATING GUIDE ENGLISH
Elektronika MK-61
A quick reference for the programmable scientific calculator. Key names below use English, with the Cyrillic originals alongside them where useful.
01 Getting started
The MK-61 uses Reverse Polish Notation (RPN). Enter the numbers first, then the operation. There is no equals key.
Calculate 2 + 3
2→ENTER→3→+
Display: 5
ENTER (В↑) copies X to Y and lifts the four-level X / Y / Z / T stack. X is what you see on the display. Binary operations use Y and X; unary operations use X alone.
CLX (СХ) clears X; ↔ swaps X and Y. Use . for decimals, /−/ to change the sign, and EEX (ВП) to enter a power of ten.
02 Yellow and blue legends
Press the F key before a yellow label. Press K before a blue label. Then press the physical key below that printed legend. The key itself still performs its ordinary function when no shift is used.
Square root of 9
9→F→√= 3
Sine of 30 degrees
3→0→F→sin≈ 0.5
The complete reference below lists the ordinary, F and K actions of every physical key, including the advanced programme commands.
03 Angles and number display
Set the three-position switch before trigonometry: Р / RAD for radians; ГРД / GRAD for gradians; Г / DEG for degrees. The default in this app is degrees.
Results can use scientific notation, with a mantissa and a signed exponent. The original machine sometimes shows a small rounding difference: sin(30°) can appear as 0.50000002.
04 Memory registers
Save the displayed X value with STO (Х→П) followed by a register key. Recover it with RCL (П→Х) and the same register key.
Save 7 in register 0 and recall it
7→STO→0
CLX→RCL→0= 7
Registers 0–9 and lettered registers a–e are available. The tiny a b c d inscriptions beneath the last four bottom-row keys are register identifiers, not separate keys.
05 A first programme
The MK-61 stores keystrokes as programme steps. To store and run an example that calculates 2 + 3:
- Press F then PRGM (ПРГ) to enter programming.
- Enter 2 ENTER 3 +.
- Press R/S (С/П) to end the programme.
- Press F then RUN (АВТ) to return to calculation mode.
- Press RTN (В/О) to return to the start, then R/S to run. The result is 5.
For single-step execution in RUN mode, press ПП (GSB) once per stored instruction. For this example, reset with RTN and press GSB five times: the displayed results progress through 2, 2, 3, 5, 5. SST / BST (ШГ→ / ШГ←) navigate stored programme addresses without executing instructions. R/S runs until the next stop. In PRGM mode, the GSB key instead stores a subroutine call. Direct and indirect branches, loops, and subroutines have also been tested.
06 Full 30-key function reference
Every button is shown in its physical row. Direct means press the key alone. F and K describe the yellow and blue functions printed above it. A dash means that shift has no separately assigned function for that key.
In programmes, a direct branch takes an explicit target address. An indirect operation reads its target or register selection from a memory register. For the four conditional tests, a true condition continues to the next instruction; a false condition takes the branch. Direct branches resume at the instruction after the displayed address, so take care with the MK-61’s unusual address convention. DSNZ means “decrement and skip when zero”; it is used for counted loops.
ROW 1 · Top row · programme control
ШГ→ / SST
- Direct
- Advance the programme address by one, displaying codes in PRGM mode. This does not execute the stored instruction; use ПП / GSB for single-step execution in RUN mode.
- F
- x<0: continue to the next instruction if X is negative; otherwise jump.
- K
- x<0(i): continue if X is negative; otherwise jump to the indirect address.
ШГ← / BST
- Direct
- Move the programme address back by one without executing an instruction.
- F
- x=0: continue if X is zero; otherwise jump.
- K
- x=0(i): continue if X is zero; otherwise jump to the indirect address.
В/О / RTN
- Direct
- In RUN mode, reset the programme counter to its start; return from a subroutine in programme execution.
- F
- x≥0: continue if X is nonnegative; otherwise jump.
- K
- x≥0(i): continue if X is nonnegative; otherwise jump to the indirect address.
С/П / R/S
- Direct
- Start or stop the current programme; act as a stop instruction inside a programme.
- F
- x≠0: continue if X is nonzero; otherwise jump.
- K
- x≠0(i): continue if X is nonzero; otherwise jump to the indirect address.
ROW 2 · Second row · memory and branching
K
- Direct
- Select K shift for the next key.
- F
- — No F function.
- K
- — No second K function.
П→X / RCL
- Direct
- Recall a numbered or lettered memory register into X.
- F
- L0 / DSNZ0: decrement register 0 for loop control and branch while nonzero.
- K
- RCL(i): recall from a memory register selected indirectly.
X→П / STO
- Direct
- Store X into a numbered or lettered memory register.
- F
- L1 / DSNZ1: register 1 loop control, decrement and test.
- K
- STO(i): store X in a register selected indirectly.
БП / GTO
- Direct
- Go directly to a specified programme address.
- F
- L2 / DSNZ2: register 2 loop control, decrement and test.
- K
- GTO(i): go to the address held in a register.
ПП / GSB
- Direct
- In RUN mode, execute one stored programme instruction (single-step debugging). In PRGM mode, enter a GSB subroutine-call instruction followed by its address.
- F
- L3 / DSNZ3: register 3 loop control, decrement and test.
- K
- GSB(i): call the subroutine address held in a register.
ROW 3 · Digits 7–9 · trig and arithmetic
7
- Direct
- Enter digit 7 into X.
- F
- sin: sine of X in the selected angle unit.
- K
- INT / [x]: integer part of X.
8
- Direct
- Enter digit 8 into X.
- F
- cos: cosine of X in the selected angle unit.
- K
- FRAC / {x}: fractional part of X.
9
- Direct
- Enter digit 9 into X.
- F
- tan / tg: tangent of X in the selected angle unit.
- K
- MAX: return the larger of X and Y.
−
- Direct
- Subtract X from Y (Y − X).
- F
- √: square root of X.
- K
- — No K function.
÷
- Direct
- Divide Y by X (Y ÷ X).
- F
- 1/x: reciprocal of X.
- K
- — No K function.
ROW 4 · Digits 4–6 · inverse trig
4
- Direct
- Enter digit 4 into X.
- F
- sin⁻¹: arcsine; answer in the selected angle unit.
- K
- |x|: absolute value of X.
5
- Direct
- Enter digit 5 into X.
- F
- cos⁻¹: arccosine; answer in the selected angle unit.
- K
- SGN / ЗН: sign of X (−1, 0 or 1).
6
- Direct
- Enter digit 6 into X.
- F
- tan⁻¹: arctangent; answer in the selected angle unit.
- K
- H→H.M: convert decimal hours/degrees to hours/degrees and minutes.
+
- Direct
- Add X to Y (Y + X).
- F
- π: place pi in X.
- K
- H←H.M: convert hours/degrees and minutes to decimal units.
×
- Direct
- Multiply Y by X.
- F
- x²: square X.
- K
- — No K function.
ROW 5 · Digits 1–3 · exponentials
1
- Direct
- Enter digit 1 into X.
- F
- eˣ: exponential of X.
- K
- — No K function.
2
- Direct
- Enter digit 2 into X.
- F
- lg / log: base-10 logarithm of X.
- K
- — No K function.
3
- Direct
- Enter digit 3 into X.
- F
- ln: natural logarithm of X.
- K
- H→H.M.S: decimal-to-degrees/minutes/seconds conversion.
↔
- Direct
- Exchange X and Y without arithmetic.
- F
- xʸ: raise Y to the power X.
- K
- H←H.M.S: degrees/minutes/seconds to decimal conversion.
В↑ / ENTER
- Direct
- Lift the RPN stack, copying X into Y.
- F
- LST X / Вx: recall the previous X value.
- K
- RND / СЧ: generate a pseudo-random value.
ROW 6 · Bottom row · numeric entry and logic
0
- Direct
- Enter digit 0 into X.
- F
- 10ˣ: raise 10 to the power X.
- K
- NOP / НОП: no-operation command for programmes.
.
- Direct
- Insert the decimal point in the current number.
- F
- R↓: rotate the four-level stack downward.
- K
- AND / ∧: bitwise logical AND on calculator data.
/−/ / CHS
- Direct
- Change the sign of a number or its exponent during entry.
- F
- RUN / АВТ: switch from programming to calculator RUN mode.
- K
- OR / ∨: bitwise logical OR.
ВП / EEX
- Direct
- Begin entry of a signed base-10 exponent.
- F
- PRGM / ПРГ: enter programme editing mode.
- K
- XOR / ⊕: bitwise exclusive OR.
СX / CLX
- Direct
- Clear the displayed X register.
- F
- CF: cancel an accidental shift/function prefix.
- K
- NOT / ИНВ: bitwise logical inversion.
Indirect addressing and programme instructions are advanced features. The reference describes the MK-61 instruction set; some uncommon operations have not been individually verified in this browser port. The original machine uses a green vacuum fluorescent display, not conventional LEDs.
07 This browser version
Click or tap ЭЛЕКТРОНИКА on the front to change between Cyrillic and English key legends. This does not change the calculation or the English guide.
Keyboard shortcuts: 0–9, decimal point, + − * /, Enter (ENTER), F and K (shifts), and Escape (CLX when face-up). While reading this guide, Escape turns the calculator face up.
The switch on the left pauses the emulator; switching it back on resumes the existing state. Save state downloads the machine state; Load state restores it; Reset clears the machine after confirmation. These controls are here, at the end of the guide, to keep the calculator face uncluttered.
Unlike a restored physical MK-61, this is an accelerated microcode port. Some unusual hardware behaviour and timing may differ.
Saved state and reset
Save a copy of the calculator’s entire state, restore a previously saved copy, or reset its programme and registers. Reset always asks for confirmation.
Ready
МК-61 · REFERENCETAP MK 61 ABOVE TO RETURN