Similar to Windows 3.x, VDMs can let you run many DOS applications at one time if you use the EMM386 /MULTI option. Digital Research / Novell was working on a similar system since 1991 under the codename "Vladivar" (originally a device driver KRNL386.SYS and not part of EMM386). It was made for the next version of DR DOS, released as Novell DOS 7 in 1994, but it was also used in their "Star Trek" project, which they stopped working on before finishing.