> The processor (AMD or Intel) does not support 16 bit protected mode > applications while running in 64 bit mode so you need an emulator to > run 16 bit under 64 bit. > I should have said 16 bit real mode and virtual 8086 modes are not supported but protected is. Support for Virtual 8086 mode is not available in x86-64 Long Mode, although it is still present on 64-bit capable processors running in 32-bit protected mode. The removal of this sub-mode means that 16-bit compatibility must be rewritten or removed from 64-bit operating systems. For example, DOS and 16-bit Windows application support is not present in x64 editions of Windows, necessitating the use of 3rd party emulation software such as DOSBox. http://en.wikipedia.org/wiki/Virtual_8086_mode#64-bit_support John
