Electronika MK-52


Technically speaking, MK-52 was not a computer, but an advanced calculator though it has many similarities with early computers. The MK-52, often described as one of the last Soviet-designed calculators because the later models were based on Japanese models. This is the only calculator in the world that offers permanent storage in the form of an internal EEPROM module. Most newer calculators offer permanent storage in the form of non-volatile (CMOS) memory. The contents of program and data memory (and often, even the contents of the calculator's display) are preserved when the unit is turned off. In contrast, programs and data stored on

the MK-52 are lost when the calculator is powered down; however, it is possible to copy both programs and data, up to 512 bytes in total, to internal storage.

The internal EEPROM is organized as 1024 4-bit nibbles. Each program step requires 1 byte of memory; each register requires 7 bytes. The D-P switch controls whether data or program memory is transferred; another three-position switch is used to select read, write, and clear operations.

MK-52 equipped with special-purpose ROM modules was used in Russian space program as a backup in case of an on-board computer failure.