MDOS

MDOS may refer to:


 * Micropolis MDOS, an operating system for Intel 8080 machines
 * Motorola Disk Operating System for the M6800 based EXORciser development system in the 1970s
 * Motorola Disk Operating System, also the underlying basis of the QDOS operating system of the Fairlight CMI digital sampling synthesizer series
 * MIDAS (operating system) (originally named MDOS, and also known as M-DOS or My DOS), an 8-bit operating system for 8080/Z80, developed by Microsoft's Marc McDonald in 1979
 * Myarc Disk Operating System (aka MDOS), an operating system emulating the TI-99/4A for the Geneve 9640 in 1987
 * MS-DOS 4.0 (multitasking), a multitasking operating system
 * Multitasking DOS sub-system in IBM OS/2, e.g. C:\OS2\MDOS\
 * Multiuser DOS (aka DR MDOS), a DOS- and CP/M compatible 32-bit protected mode operating system for 386 machines developed by Digital Research / Novell in the 1990s
 * Multiuser DOS Federation, an industry alliance in the 1990s