MS-DOS 4.00 (1985)
|Version of MS-DOS|
MS-DOS 4.00 Multitasking Edition is the once hyped future of MS-DOS, that Microsoft shelved in favor of OS/2 and IBM's regular DOS 4.x. It was a parallel project to DOS, never released to the regular consumer market, and Microsoft backtracked to base its next consumer release off of DOS 3.3. It was only released by some OEMs in Europe, which is why it's also referred to as "European DOS 4.0".