Elektronika MK-61

Keyboard

Keys (from L to R, top to bottom, in this format: key function|F-shifted function|K-shifted function) where aa=two-digit address, r=register (0-e), (r)=contents of register (0-e)

Key                      F,Key                  K,Key

F
step forward             if x<0 goto aa         if x<0 goto r
step backward            if x=0 goto aa         if x=0 goto r  
gosub return             if x>=0 goto aa        if x>=0 goto r
run or eop               if x!=0 goto aa        if x!=0 goto r

K
pop r to x               inc r0, goto aa        dec r, pop to x
push x to r              inc r1, goto aa        dec x, push to r
goto aa                  inc r2, goto aa        goto (r)
gosub aa PRG, sst AUTO   inc r3, goto aa        gosub (r)

7                        sin                    integer part
8                        cos                    fractional part
9                        tan                    put max of x,y in x
-                        square root
/                        inverse

4                        arcsin                 abs
5                        arccos                 sign (plus/minus 1)
6                        arctan                 convert to HH.MM
plus                     pi                     convert from HH.MM
x                        square

1                        exp
2                        log
3                        ln                     convert to HH.MMSS
swap x,y                 x^y                    convert from HH.MMSS
ENTER                    Last x                 Random

0                        10^x                   NOP
.                        Roll stack down        AND
CHS                      AUTo (run) mode        OR
EEX                      PRG (prog) mode        XOR
CLx                      CL flags               INV (NOT)

Ok, now for two explanations: bit-wise (logic) operations and prograhexadecimal The logic is in hexadecimal, the display showing hexadecimal digits like this:
DISPLAY:DIGITS

0:0000  1:0001  2:0010  3:0011
4:0100  5:0101  6:0110  7:0111
8:1000  9:1001  -:1010  L:1011
C:1100  T:1101  E:1110  _:1111

where -,L,C,T,E are approximations to what is shown on the display, the last one "_" being a "blank" digit display, corresponding to the keys a,b,c,d,e and x the times key, respectively.

To perform bit-wise operations, prepend the desired hexadecimal with "8." An example is the best explanation. Assume you want to OR 111000 with 100100, the result being, we know, 111100. Here is the procedure: convert to hexadecimal, thus (00)11 1000 is 38 and (00)10 0100 is 24. Then type 8.38 ENTER 8.24 K OR (above /-/ or CHS key). You should see 8.3c or 8.(0011)(1100). This is 00111100, the answer.

Programming

The MK-61 has a lot of unusual keys, many related to programming. To gain an understanding of this keyboard, study the chart above and visit Greg Escov's detailed Description of the MK-61 Keyboard.

As stated, the MK-61 has 105 program steps. The interesting point is that step #105 is, in fact, the same as step #0. So one is able to write a "round-walking" code.

For programming, let me give an example: To go to programming mode, press F PRG (the key right to the left of the red one). Pressing F AUTo (looks like ABT, to the left of the PRG key) takes you back to auto (run) mode. In programming mode, the display shows four two-digit numbers. The last (right-most) number is the address following the address containing the left-most number (ie: it is the next free memory location for programming. The next two numbers show the PREVIOUS two address contents, for convenience. For example, the display 05 0L 13 10 means that 05 is in memory location 9, while location 8 contains 0L and location 7 holds 13. Programs run from low numbers to high, therefore on the display from right to left. So, in the example, if the calculator somehow reached location 7 it would run 13 (division), then 0L (CHS) and then put the number 5 on the stack.

A simple program: if a number is even, divide by two, else add one. In AUTo (run) mode, press GTO (key below L2) and then 0 0. This takes you to memory location 00, where you will start programming. Now enter PRG mode, and press these keys: ENTER (which is above red key), swap (beneath + key), 2, (you should see on the display 02 14 0E 03), divide, K, fractional part (above 8), F, x=0 (display should show 5E 35 13 06), 1, 1, F, Roll down (decimal key), 2 (display shows 02 25 11 09), divide, eop (this means end-of-program key, looks like C/Pi), F, Roll down (display will now show 25 50 13 12), 1, +, eop (display shows 50 10 01 15), and finally press F AUTo to get out of program mode. Now, press GTO 00, enter an integer, and press RUN (upper right-most key).

The program should run a second, and if it was an even # like 4, it should show half of it (2), and if an odd # like 5, it should show one plus the # (6). That is it. You can single step through the program by pressing PP (the key below L3) in AUTo mode.

Viktor writes... "There are 105 programmable locations. The last is hex "-4" (104 decimal), which can be entered from the keyboard as .4 (e.g., BP .4 takes you to this program address.) In actuality, the program counter can run all the way to 159 (_9), with 55 (105-159) of these 'extra' steps. Steps 105-111 (-5-L1) correspond with steps 00-06 (the first of fifteen 7-byte registers that hold program code; the other 15-register block is the 15 data registers.) Steps 112-159 (L2-_9) correspond with steps 00-47 but after L9, (from C0-_9, 40 steps) program contents are no longer displayed. Still, by entering code into these locations, I was able to determine the mapping (on my MK-52, but I have no reason to believe that it's different on the MK-61.) I presume that the mapping is also very similar on the B3-34 (which has only 14 registers in each bank, corresponding with 98 program steps instead of 105.)"

Jump addresses are actually correct with the B3-34 (and MK-52, MK-61). With the B3-21, you still need to add 1 to the least significant digit of the jump address (i.e., to jump to location 15, you need a jump address of 16) but that's a peculiarity of that machine's architecture.

Some interesting information about the MK-61 can be found on Viktor Toth's fine page http://www.vttoth.com/calcs/mk61.htm. Or how about an X-Ray view of the MK-61? Visit http://www.petergof.com/x-ray/calcs/mk61.htm

Many books and magazines presented programs for the MK-61 and equivalent machines, and games were especially popular. Some very interesting things could be done with this machine, and you should definitely spend some time investigating...

The journey of the big numbers
^{by Gregory Escov}
About the various "big numbers" that you can get on your MK-54 compatible calculators - that is, the numbers that can not be displayed properly and, according to documentation, can not even exist. But, as you see, there's quite a lot of stuff you can do with bignums...

Pseudo-Writing Mode
^{by Gregory Escov}
... here I'll describe a rather special mode that you could get your calculator in. That mode seems ideally suited for the creation of strange hexadecimal strings. And besides, its very existence is quite unbelievable... unless you try for yourself!

Eggog!

"The funniest thing about MK-61 was its spelling of "Error". It went like: So not a ERROR but it cut down lines.-in russian it got pronounced not [error] but [eggog], rather funny. I got so used to it that occasionally mis-speak "error" myself. "

- Alex Klimov

An analysis of the serial numbers during the 1989-1990 period incidcate that approximately 2,250 of these calculators were being manufactured per month.

This is a rough machine-translation of the page at http://www.vspu.ac.ru/~ua/ivk32.htm. The original authors retain the copyright of this material. I must admit to not having obtained permission to include this translation or the images on this site - because I have been unable to find a way to contact the original author(s). I do hope they don't mind.
Thanks to Sergei Frolov for assistance with the translation!

Measuring - computer complex IVK-3/TO

© http://www.vspu.ac.ru/~ua/ivk32.htm

Knowing algorithm of spent measurement or researches, the pupil himself makes and enters the program in the microcalculator, on which then and the researches on a nature or in laboratory are fulfilled. From our point of view, the creation of such mobile educational measuring system on the basis of the programmed microcalculator from a position of optimal sufficiency and economic feasibility is justified in spite of the fact that there are also portable small-sized computers types Notebook.

The measuring - computer complex IVK-3/TO does not require(demand) even of knowledge of elementary operations on a PC, but allows, except for the direct purpose of measurement of this or that parameter, to explicate algorithmic culture of the pupils.

IVK-3/TO has a self-contained supply from 3 galvanic cells on 1,5 In or 3 accumulators. It also can feed through the external power supply with an output voltage 5 In from an alternating-current mains with power 42 In and 220 In. Its power consumption about 2 W.

Without external converters the complex immediately meters:

• Fixed and alternating voltage from 0,01 up to 50 In;
• Frequency from 0,1 up to 1000 Hz;
• Time slices from 0,01 up to 100 with.

© http://www.vspu.ac.ru/~ua/ivk32.htm

For measurement of such parameters as temperature, damp, pressure, expenditure of air or gas, illuminance, noise, acid of the environment, radio-activity, magnetic intensity, earthing resistor or isolation and others the external converters connected to plugs of the instrument - complex are used.

As it is visible from appearance IVK-3/TO, the display and keyboard of the microcalculator quit on the upper panel. On the front panel the switches of a sort of operations of the complex are output.

Let's consider them on the right - on the left:

At the released first key the complex on the first and second channel meters power, and at pushed - frequency. At the pushed second key (irrespective of a rule(situation) by first) the complex meters time slices. The third key - "start-up" - "stop". At measurement of power or frequency in the hand-held mode on this key "start-up" is pushed once, and at measurement of time the time slice by the first pressing "start-up" and second - "stop" is set.

The hand-held mode of measurement of power and frequency is fulfilled at the released fourth key, and at pushed - power and frequency are metered in an automode in 20 seconds.

The fifth button is used very seldom. If there was any failure at measurements, that the interface to place(install) in an initial state, is pushed this key.

On an oblique part of the upper panel two switches (snap switch) are placed(installed): If the switch 1 is in such rule(situation) as in a figure, "the channel 1", and if in an opposite direction, "the channel 2" is switched on. The plug 3 is used at measurement of time intervals with the help of external commutators, and 4 - for connection of the external network power supply.