Disk operating system

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A disk operating system (DOS) is a computer operating system that resides on and can use a disk storage device, such as a floppy disk, hard disk drive, or optical disc. A disk operating system provides a file system for organizing, reading, and writing files on the storage disk, and a means for loading and running programs stored on that disk. Strictly speaking, this definition does not include any other functionality, so it does not apply to more complex OSes, such as Microsoft Windows, and is more appropriately used only for older generations of operating systems.^{[citation needed][1]}

Disk operating systems for mainframes, minicomputers, microprocessors, and home computers are usually loaded from the disks as part of the boot process.

Early computers predate disk drives, floppy disks, or modern

A disk operating system is usually loaded from a disk, but there are exceptions, such as Commodore's disk drives for the Commodore 64 and VIC-20 which contain the DOS in ROM. AmigaDOS also mostly resides in ROM, as a part of a Kickstart firmware (a few select versions are also loaded from disk).

• Commodore DOS is on 8-bit Commodore computers such as the Commodore 64. Unlike most other DOS systems, it is integrated into the disk drives, not loaded into the computer's own memory.
• Top-DOS
  .
• MSX-DOS is for the MSX computer standard. The initial version, released in 1984, is MS-DOS 1.0 ported to Z80. In 1988, version 2 has facilities such as subdirectories, memory management, and environment strings. The MSX-DOS kernel resides in ROM (built-in on the disk controller) so basic file access capacity is available even without the command interpreter, by using BASIC extended commands.
• Disc Filing System (DFS) is an optional component for the Acorn BBC Micro, as a kit with a disk controller chip, a ROM chip, and a few logic chips, to be installed inside the computer.
• Advanced Disc Filing System (ADFS) is a successor to Acorn's DFS.
• AMSDOS is for the Amstrad CPC computers.
• GDOS and G+DOS is for the +D and DISCiPLE disk interfaces for the ZX Spectrum.

Some disk operating systems are the operating systems for the entire computer system.

• The
  B5000
  originally runs from a drum, but starting with the B5500 it runs from a disk. It is the basis for the MCP on the B6500, B7500, and successors.
• The SIPROS, Chippewa Operating System (COS), SCOPE, MACE and KRONOS operating systems^[5] on the Control Data Corporation (CDC) 6000 series and 7600 are all disk operating systems. KRONOS became NOS and SCOPE became NOS/BE.
• The
  GE (later Honeywell and Groupe Bull) 600 family of mainframe computers
  (it later became GCOS).
• The IBM Basic Operating System/360
  z/VSE, OS has evolved into z/OS
  and TSS/360 evolved into TSS/370 PRPQ, which is now gone.
• The
  EXEC 8 operating system for the 1108, which has evolved into OS 2200 for the Unisys ClearPath Dorado Series
  .
• The DOS-11 operating system for DEC PDP-11 minicomputers.
• CP/M is a disk operating system, as the main or alternate operating system for numerous microcomputers of the 1970s and 1980s.
• ProDOS
  .
• TRSDOS is the operating system for the TRS-80 line of computers from Tandy.^[12]
• IBM PC compatibles with Intel x86 CPUs. 86-DOS was modeled on CP/M, and then was adapted as the basis for Microsoft's MS-DOS. It was rebranded by IBM as PC DOS until 1993. Various compatible systems were later produced by different organizations, starting with DR-DOS
  in 1988.

• Live CD