The disc operating system VDOS was developped by the german company Vortex.
VDOS was supplied on an EPROM, and was released in 3 versions:
- VDOS 1.0
- VDOS 2.0
- VDOS 2.11
Further there were German and English versions of this ROMs.
The VDOS ROM also contained a machine language monitor.
VDOS supported as first DOS the Vortex format, which become a standard format later on.
- Vortex Vdos 2.0 Manual (pdf) (also describes how to upgrade from VDOS 1.0 to 2.0)