MS-DOS 4.0 was a
multitasking release of
MS-DOS developed by
Microsoft based on MS-DOS 3.1. Lack of interest from
OEMs, particularly
IBM, led to it being released only in a scaled-back form. It is sometimes referred to as
European MS-DOS 4.0, as it was primarily used there. It should not be confused with
PC DOS 4.00 or
MS-DOS 4.01 and later, which did not contain the multi-tasking features.