Elektronika MK-52

The Elektronika MK-52 (Russian: Электро́ника МК-52) is RPN-programmable calculator which was manufactured in the Soviet Union during the years 1983 to 1992.

The functionality of the MK-52 is identical to that of the MK-61, except the MK-52 has an internal non-volatile EEPROM memory module, for permanent data storage, diagnostic slot, and slot for ROM modules. Programming language and functionality of MK-52 and MK-61 are extensions of the MK-54, the B3-34 and B3-21 Elektronika calculators. It is the only known calculator to have internal storage in the form of an EEPROM module. All Soviet calculators are renowned for having a very large number of undocumented functions.

The MK-52 has 105 steps of volatile program memory, an internal EEPROM module (with 512 bytes of memory) and 15 memory registers. It functions using either four AA-size battery cells or a wall plug. It has a relatively dim, ten-digit (8 digit mantissa, 2 digit exponent) green vacuum fluorescent display. The MK-52 has an expansion port to which various ROM (Read-only memory) modules may be attached. Its system clock speed is approximately 455 kHz (derived from a ceramic resonator), its weight is approximately 0.4 kilograms and its original selling price was 115 Roubles.

The MK-52 was used as a backup to the onboard computers of the Soyuz spacecraft on the Soyuz TM-7 mission to the Mir space station.