WINED3D FOR WINDOWS
WineD3D For Windows is a DirectX 1-11 to OpenGL wrapper based on WineD3D, which is an almost full implementation of DirectX used in Wine.
Even if Windows supports DirectX natively, using WineD3D can enhance backwards compatibility with older games, especially on Windows 8 and newer that don't support 16 bit screen modes. Another possible use is to emulate unsupported versions of DirectX, or porting DirectX applications to OpenGL without having to rewrite the rendering code.
DOSBOXÂ
DOSBox is a DOS-emulator that uses the SDL-library which makes DOSBox very easy to port to different platforms. DOSBox has already been ported to many different platforms, such as Windows, BeOS, Linux, MacOS X.
DOSBox also emulates CPU:286/386 realmode/protected mode, Directory FileSystem/XMS/EMS, Tandy/Hercules/CGA/EGA/VGA/VESA graphics, a SoundBlaster/Gravis Ultra Sound card for excellent sound compatibility with older games.
You can "re-live" the good old days with the help of DOSBox, it can run plenty of the old classics that don't run on your new computer!
DOSBox is totally free of charge and Open Source.
86Box
86Box is a low level x86 emulator that runs older operating systems and software designed for IBM PC systems and compatibles from 1981 through fairly recent system designs based on the PCI bus.
Features:
PCem
PCem is an IBM PC emulator for Windows and Linux that specializes in running old operating systems and software that are designed for IBM PC compatibles. Originally developed as an IBM PC XT emulator, it later added support for other IBM PC compatible computers as well.