Disk Doctor (similar to Norton Disk Doctor) was one of my system utilities for MSX (April 1991). Source was mixed C (2,098 lines) and Z80 assembler (1,173 lines) code and was using Kirill's Churukanov's «United C LIBrary» (UCLIB). Executable can be downloaded from here, no warranties though.

bd.zip,оригинал

Eugeny Brychkov, Inventor's Corner