Yes. They are real.
You need the relevant operating system and a wheel that will take a disc rotor .
Playstation
Microsoft Disc Operating System
The disk drive doesn't. The operating system determines that there are no files on the disk.
A disc operating System (DOS) which was marketed as MSDOS (MicroSoft Disc Operating System). It enabled the open platform, IBM Personal Computer, to be operated by typing in simple commands.
Operating System disk will have a option to repair your O/S, do this to prevent data loss.
A recovery disc is a CD or DVD used to restore the operating system of a computer to working or factory conditions.
DOS meaning Disc Operating System
Use a boot disc or a Linux LiveCD such as Knoppix
Answer is in english: Ans: DOS is the abbreviation of "Disc Operating System"
Simply because an updated version is there to replace an older version. Keeping the older version on the disc may cause conflicts with the operating system and peripherals. Removing the redundant version also saves on disc space.