Editing Virtual DOS machine (section)

===Absence in x64 and AArch64 architectures===
In an [[x86-64]] CPU, [[virtual 8086 mode]] is available as a sub-mode only in its legacy mode (for running 16- and 32-bit operating systems), not in the native 64-bit [[long mode]].<ref name="Intel_2013_Arch-Ref"/> NTVDM is not supported on x86-64 editions of Windows,<ref name="Klein_2008"/> including DOS programs,<ref name="Microsoft_2007_Limitations"/> because NTVDM uses VM86 CPU mode instead of the Local Descriptor Table in order to enable 16‑bits segment required for addressing.<ref name="modify_ldt"/> NTVDM is also unavailable on [[AArch64]] (or ARM64) versions of Windows (such as [[Windows RT]]), because Microsoft did not release a full emulator for this incompatible instruction set like it did on previous incompatible architectures.

{{anchor|x64alt}}While NTVDM is not supported on x86-64 and AArch64 versions of Windows, they can still be run using [[virtualization]] software, such as [[Windows XP Mode]] in non-home versions of [[Windows 7]] or [[VMware Workstation]]. Other methods include using [[ReactOS]]-derived NTVDM,<ref name="dosEx64"/> or OTVDM (WineVDM), a 16-bit Windows interpreter based on [[MAME]]'s i386 emulation and the 16-bit portion of the popular Windows compatibility layer, [[Wine (software)|Wine]] (see the section on WineVDM below).<ref name="Otvdm"/>