Elektronika MK 60 calculator: my summer gift from Russia

[jebem]

I had friends visiting family in Moscow during the summer.

And then they asked me about what I would like to have as a gift from there.
Well, my answer was simple:
Go to a street market and bring me a Russian pocket calculator! The older, the better.

Apparently shopping in street markets can be tricky and be very time consuming.
If you go to the central areas the asking prices is too high, then you spend hours commuting to reach the ones where the prices are lower and by the time you arrive there the fair is closing and most seller are gone.
So they spent a couple of days touring around. I felt a little bit guilty for steeling quality time from them, but hey, they asked!

And here it is.
It was dirty with marks of glue, has a few dents and the keys are scratched.

But is works nicely, as long as the environment light is strong enough to enable the solar panel.
The pouch is unusual but nice and soft.

This specimen was made in USSR on Sept-1988 (IX 88 on the back cover) and the official price was 45 Rubles.








Seven segment 8 digits LCD display, with 3 indicators on the right. From to to bottom:
"П" - Memory in use ( Память = Memory)
"_" - Minus signal
"Е" - Error




The factory seal is in place. It just takes a little steam to be removed without damage.



(to be continued)

[jebem]

Time to dismantling the machine.
This just requires to remove two screws on the back cover.
And another six to release the PCA and display/solar panel.





There is a white ink hand written label with a unknown number: 808039.
The serial number in the back cover is also 6 digits, but it is different: 847948



The SoC is a Russian КБ145ВХ3-2 made in 1988 week 08.
The 20µF/6.3V paper electrolytic capacitor was made in 1988 week 06.

This SoC operates from 1.5Volt nominal (with a minimum of 1.2V and a maximum of 1.8V), supplied by a 4 element solar panel, and consumes around 25µA.
This SoC contains 10,000 transistors to support a 5405 bits ROM microcode, RAM registers, ALU, keyboard scan, display decoding and control, synchronization unit and power supply.

I measured the solar panel under strong warm light (60 Watt at 40cm distance) and got 1.42Volt.
All four elements generates about the same voltage of 0.355 Volt.
This is a little lower than expected but it happens that the capacitor is dry and has resistance leaking, so it is pulling down the power supply a little.

A uncommon design choice by today's standard was to use two АЛ102Г yellow LED diodes to protect the SoC from over-voltage.

The schema can be downloaded from here.

[rprosperi]

(11-24-2015 07:15 PM)jebem Wrote:  I had friends visiting family in Moscow during the summer.

And then they asked me about what I would like to have as a gift from there.
Well, my answer was simple:
Go to a street market and bring me a Russian pocket calculator! The older, the better.

As usual, nicely documented.

Also, I must say you have your friends much better trained than I do. I've asked similar favors in the past, and upon returning, they ask "What was it you wanted me to find again? Old what? "

[jebem]

(11-24-2015 08:55 PM)rprosperi Wrote:  Also, I must say you have your friends much better trained than I do. I've asked similar favors in the past, and upon returning, they ask "What was it you wanted me to find again? Old what? "

Yeah, usually the same thing happens with me when asking favors.
But in this case I helped to pay the flight tickets in executive class using my miles program (I travel a lot around the world - although not as frequently as Geoff Quickfall ).

[Massimo Gnerucci]

(11-26-2015 10:05 AM)jebem Wrote:  flight tickets in execute class

I think I'll pass this, thank you! ;)

[jebem]

(11-26-2015 01:51 PM)Massimo Gnerucci Wrote:  

(11-26-2015 10:05 AM)jebem Wrote:  flight tickets in execute class

I think I'll pass this, thank you!

Me too... This damn orthographic corrector has got its own will.
Thanks!