Operating system focused on disk-based file operations
This article is about disk operating systems in the broadest sense. For the disk operating system used by IBM PC compatibles, seeDOS. For IBM mainframe operating systems, seeDOS/360 and successors.
The term is now historical, as most if not all operating systems for general-purpose computers now require direct-access storage devices as secondary storage.
In the early 1960s, as disk drives became larger and more affordable, various mainframe and minicomputer vendors introduced disk operating systems and modified existing operating systems to use disks.
Hard disks and floppy disk drives require software to manage rapid access to block storage of sequential and other data. For most microcomputers, a disk drive of any kind was an optional peripheral. Systems could be used with a tape drive or booted without a storage device at all. The disk operating system component of the operating system was only needed when a disk drive was used.
By the time IBM announced theSystem/360 mainframes, the concept of a disk operating system was well established. Although IBM did offerBasic Programming Support (BPS/360) and TOS/360 for small systems, they were out of the mainstream and most customers used either DOS/360 or OS/360.
Most home and personal computers of the late 1970s and 1980s used a disk operating system, most often with "DOS" in the name and simply referred to as "DOS" in the context of its user community. For example,CBM DOS,Atari DOS,TRS-DOS,Apple DOS,Apple ProDOS, andMS-DOS.CP/M is also a disk operating system, despite not having "DOS" in the name.[1]
Commodore DOS is on 8-bitCommodore computers such as theCommodore 64. Unlike most other DOS systems, it is integrated into the disk drives, not loaded into the computer's own memory.
Atari DOS is used by theAtari 8-bit computers. The Atari OS only offers low-level disk-access, so an extra layer called DOS can be booted from a floppy for higher level functions such as filesystems.[2] Third-party replacements for Atari DOS includeDOS XL,SpartaDOS,MyDOS,TurboDOS, andTop-DOS.
MSX-DOS is for theMSX computer standard. The initial version, released in 1984, is MS-DOS 1.0 ported toZ80. 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 usingBASIC extended commands.
Disc Filing System (DFS) is an optional component for the AcornBBC Micro, as a kit with a disk controller chip, a ROM chip, and a few logic chips, to be installed inside the computer.
Some disk operating systems are the operating systems for the entire computer system.
TheBurroughs (now Unisys)Master Control Program[3] (MCP) for theB5000 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 IBM Basic Operating System/360[6] (BOS/360),Disk Operating System/360[7] (DOS/360) andOperating System/360[8] (OS/360) are standard for all but the smallestSystem/360 installations; the360/67 also has Control Program-67 /Cambridge Monitor System[9] (CP-67/CMS) and Time Sharing System/360[10] (TSS/360). BOS is gone, CP-67/CMS has evolved intoz/VM, DOS has evolved intoz/VSE, OS has evolved intoz/OS and TSS/360 evolved into TSS/370 PRPQ, which is now gone.
TRSDOS is the operating system for theTRS-80 line of computers from Tandy.[11]
MS-DOS forIBM PC compatibles withIntelx86 CPUs.86-DOS was modeled onCP/M, and then was adapted as the basis forMicrosoft'sMS-DOS. It was rebranded by IBM asPC DOS until 1993. Various compatible systems were later produced by different organizations, starting withDR-DOS in 1988.
