Faced with substantial competition in the DOS
arena, Microsoft released MS-DOS 5.0 in June
1991, which included advanced features similar
to those of DR-DOS 5.0. forcing Digital Research
to responde with DR-DOS 6.0. in September 1991.
DR-DOS 6.0 bundled in SuperStor - on-the-fly
disk compression, to maximize available hard
disk space. It also included an API for
multitasking on CPUs capable of memory
protection, namely the Intel 80286 and newer.
The API was available only to DR-DOS aware
applications, but well-behaved ordinary DOS
applications can also be pre-emptively
multitasked by the bundled task-switcher,
TaskMax. On 286-based systems, allowing only one
process to execute at a time, DOS applications
are suspended to the background to allow others
Microsoft responded with MS-DOS 6.0, which again
matched some features of DR-DOS 6.0.