Thursday, December 4, 2008

DOSBox

 

DOSBox is an emulator which simulates an IBM PC compatible computer running MS-DOS. It is intended especially for use with old computer games. Released under the terms of the GNU General Public License, DOSBox is free software.

DOSBox is a command-line program, configured either by a set of command-line arguments or by editing a plain text configuration file. For ease of use, several graphical front-ends have been developed by the user community.

DOSBox is a full CPU emulator, capable of running DOS programs that require the CPU to be in either real mode or protected mode. Other similar programs, such as dosemu or VDMs for Windows and OS/2, provide compatibility layers and rely on virtualization capabilities of the 386 family processors. Since DOSBox can emulate its CPU by interpretation, it is independent of its host CPU. However, on systems which provide the i386 instruction set, the option to use dynamic instruction translation is available in DOSBox. Though this setting is less accurate and reliable, it is faster than interpretive CPU emulation.

DOSBox is capable of emulating many types of graphics and sound hardware. Graphics emulation includes text mode, Hercules, CGA (including composite and 160x100x16 tweaked modes), Tandy, EGA, VGA (including Mode X and other tweaks), VESA, and full S3 Trio 64 emulation. Sound hardware that can be emulated includes the PC speaker, AdLib, Gravis Ultrasound, Tandy, Creative Music System/GameBlaster, Sound Blaster 1.x/2.0/Pro/16, MPU-401, and Disney Sound Source. (MT-32/CM-32L emulation is included in unofficial builds, but not in the official source code repository due to need for copyrighted ROM images.)

A popular feature of DOSBox is its ability to capture screenshots and record gameplay footage. The video is compressed using the Zip Motion Block Video codec. In its uncompressed state the footage is almost an exact replica of the actual program. The video recording feature was added in version 0.65. In earlier versions, one had to rely on custom modifications and Fraps to record video, but the quality and emulator performance was generally very poor. To capture a screenshot, the default key combination is CTRL+F5, and video is CTRL+ALT+F5. Under Linux however, CTRL+ALT+F5 is usually a shortcut for the console terminal screen which means you'll most likely need to change the combination by accessing DOSBox build-in keymapper via CTRL+F1. To stop a video recording, you press the same key combination again.

A component that differentiates DOSBox from other emulators is its ability to simulate peer-to-peer or Internet/Intranet networking. This includes modem simulation over TCP/IP, allowing for DOS modem games to be played over modern LANs or the Internet, and IPX network tunneling, which allows for old IPX DOS multiplayer games to be played as UDP/IP over modern LANs or the Internet. Win32 and Linux specific builds support direct serial port access.

DOSBox contains its own internal DOS-like shell, rather than being a fully virtual PC emulator like Bochs. This means that DOSBox can be used without owning a license to any real DOS operating system. Most commands that are typically used in installer batch files are supported, but many of the more advanced commands of later MS-DOS versions (e.g. post-Windows 98 DOS shells) are not. In addition to its internal shell, DOSBox also supports running image files of games and software originally intended to start without any operating system.

DOSBox is capable of timing-compatible implementation of the serial ports, and can run older hardware and software dependent on such; however, some USB devices that are supported by the host OS can act as a replacement for older serial port devices when using the emulator.

While there is nothing in principle that prevents the running of non-game DOS programs in DOSBox, the DOSBox project has a policy of not adding features that are of no use for DOS games. Also, there is no support for the emulation of post-80486 CPU features. Some unofficial CVS versions contain experimental patches that add support for these elements.

Download DOSBox 0.72 here.

Official site: www.dosbox.com/