MK-DOS was one of the most widespread operating systems for Elektronika BK personal computers, developed by Mikhail Korolev and Dmitriy Butyrskiy from 1993.

Like ANDOS, the system provided full compatibility for all models, emulating the BK-0010 environments on the more modern BK-0011 and BK-0011M machines.

All program requests to a magnetic tape (if they were made through proper ROM functions) were redirected to the disk.

[1] Starting from version 3.0 the system also supported mounting disk images as logical drives.

It did not support file fragmentation (like the file system used with RT-11) and required frequent spatial reallocation to maintain optimum contiguous free space (RT-11 users would use the 'SQUEEZE' command, which worked the same way as the *COMPACT command on Acorn's DFS for the BBC Micro).