DOSBox

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DOSBox is an emulator which creates a DOS-like environment intended for running MS-DOS-based PC computer games which may not run properly on newer PCs and may not run at all on non-IBM PC compatibles (e.g. Macintosh). It also allows such games to be run on other operating systems that do not normally support DOS programs. DOSBox is open source and available for many operating systems, such as Linux, FreeBSD, Windows, Mac OS X, OS/2 and BeOS. Recently, it has even been ported to the GP2X [1] device.

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Features

DOSBox is a full CPU emulator, not just a compatibility layer like dosemu or the VDMs of Windows and OS/2, which rely on virtualization capabilities of the 386 family processors. It requires neither an x86 CPU nor a copy of MS-DOS or any other DOS to run, and it can run games that require the CPU to be in real mode or protected mode.
- Dynamic CPU core: On systems which have the i386 instruction set, dynamic instruction translation is used. On systems which are not x86 compatible, full emulation occurs, resulting in a significant slowdown. A 1.6 GHz PowerPC G4 system is capable of coming close to emulating a 50 MHz 486 system with the standard emulated hardware; whereas this same speed can be achieved on a "slower" Pentium II era x86 system.
Graphics emulation: Text mode, Hercules, CGA (including composite and 160x100x16 tweaked modes), EGA, VGA (including Mode X and other tweaks), VESA and full S3 Trio 64 emulation.
Sound emulation: Adlib, PC speaker, Tandy, Sound Blaster, Creative CMS/GameBlaster, Disney Soundsource, Gravis Ultrasound, and MPU-401.
Network emulation: Modem simulation over TCP/IP, allowing for DOS modem games to be played over the internet. IPX network tunneling, which allows for old IPX Dos multiplayer games to be played over the internet. Finally, Win32 builds support direct serial port access.
It contains its own internal DOS-like shell, rather than being a fully virtual PC emulator like Bochs.

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Issues

As with most programs that emulate systems, DOSBox requires substantially more computing (particularly processor) power than the original systems, greatly affected by what software the user is running in the emulated system at the time. Moreover, DOS programs that run in protected mode, which include most games released after 1995, may not perform as well as in other emulators such as VMWare or Virtual PC, since those programs mostly virtualize the processor instead of emulating it like DOSBox. Even simple programs run slowly on the current version of the GP2X port of DOSBox.

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