1974-1998 [ongoing history of VM family and VP/CSS.] 1977 Initial commercial release of VAX/VMS, later renamed OpenVMS. 1985 October 9, 1985: Announcement of the Intel 80286-based AT&T 6300+ with Simultask, a virtual machine monitor developed by Locus Computing Corporation in collaboration with AT&T, that enabled the direct execution of an Intel 8086 guest operating system under a host Unix System V Release 2 OS. Although the product was marketed with Microsoft MS-DOS as the guest OS, in fact the Virtual Machine could support any realmode operating system or standalone program (such as Microsoft Flight Simulator) that was written using only valid 8086 instructions (not instructions introduced with the 80286).