A reimplementation of the missing parts needed to run MS-DOS 2.0 (MBR, DBR, DOS BIOS, FORMAT, FDISK).
Done mostly for fun, and because AFAIK there was no freely redistributable drop-in replacement of the closed-source IBMBIO.COM (IO.SYS).
Allows to actually run and install MS-DOS 2.0 on a PC.
Includes support for 3.5" floppy disks and a single hard disk partition of size up to whooping 20 MiB.
Also includes the CON, PRN, AUX and CLOCK$ device drivers.
Works best on a PC with 640 KiB of RAM :-D