X-DDOS is a floppy disc and hard disc operating system from the german company Dobbertin Industrie Electronic. It provides 0.7 MB floppy disc formats for B drives and allows to access the [[Dobbertin Harddisc]] HD20. X-DDOS is delivered as a 16 KB EPROM with a lot of software and a manual.
X-DDOS can be used as a rom 7 replacement.