KeyRus was a DOS-based TSR device driver for keyboard and display, written by the Donetsk student and hacker Dmitry Gurtyak in 1989. It was widely distributed in the USSR and outside of the country free of charge. The last version of KeyRus was released in 1994, not long before Gurtyak suddenly died. Later versions of KeyRus utilized an original font compression technique - the bitmaps were stored in memory being packed and unpacked just before loading into the graphics adapter. This allowed KeyRus to occupy a minimum of the limited DOS memory space.