Vintage Rare USSR Soviet Calculator Programmable Elektronika MK 52. The Elektronika MK-52 (Russian: ??????????? ??-52) was an RPN-programmable calculator manufactured in the Soviet Union during the years 1983 to 1992. Its original selling price was 115 rubles. The functionality of the MK-52 was identical to that of the Elektronika MK-61, except that the MK-52 had an internal non-volatile EEPROM memory module for permanent data storage, a diagnostic slot, and a slot for ROM modules. The programming language and functionality of the MK-52 and MK-61 calculators were extensions of the earlier MK-54, the 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 had a number of undocumented functions. The MK-52 was used as a backup to onboard computers of the Soyuz spacecraft during the Soyuz TM-7 mission to the Mir space station. Will be shipped from Europe by Air Mail International priority mail. Thanks for looking I will ship to Worldwide. PayPal or Paypal eCheck.