FreeDOS

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FreeDOS

FreeDOS (formerly Free-DOS and PD-DOS) is an operating system for IBM PC compatible computers.

As a member of the DOS family, it provides mainly disk access and filesystem through its kernel, and partially memory management, but no GUI.

Unlike Microsoft's MS-DOS system, which has been discontinued and which FreeDOS attempts to be a replacement for, FreeDOS is open source software project licenced under GPL.

It is currently Beta software. However it will reach 1.0 by the beginning of august 2006. http://freedos.sourceforge.net/freedos/files/

FreeDOS supports old hardware like the 1981 vintage IBM PC as well as modern ones up to the Pentium 4 CPU, in addition to embedded computers. Like MS-DOS, it boots from a floppy or hard disk but can also run from ROM. [http://www.freedos.org/freedos/about/ FreeDOS website about

History

The project began 1994-06-28 in response to Microsoft's announcement that it would no longer sell or support MS-DOS. Within a few weeks of Jim Hall posting a manifesto, Pat Villani, Tim Norman, Jim Hall, and others collaborated on a kernel, shell (command.com) and core utilities by pooling code they had written or found available.

Developement has slowed down over the last years, though version 1.0 is expected to come at the end of July 2006.

The FreeDOS web site now redirects to the SourceForge project freedos.sourceforge.net where all project files—releases and sources—are available.

Distribution

FreeDOS does not require license fees or royalties. The only other DOSs that are actively distributed now are DR-DOS and OpenDOS.

Dell Computer offers some of their n-series systems with preinstalled FreeDOS. http://www1.us.dell.com/content/products/compare.aspx/optix_n?c=us&cs=04&l=en&s=bsd The company has come under fire for making the FreeDOS-powered machines no cheaper and more difficult to purchase than identical systems running Windows.http://www.theregister.co.uk/2005/10/06/dell_open_pc/

GRC's SpinRite 6 boot image loads FreeDOS shown at the bottom of the splash screen.

FreeDOS Beta 9 SR2 is available for download in several different formats:

Relation to MS-DOS

FreeDOS is closely related to MS-DOS in that it was begun as a result of Microsoft cancelling MS-DOS, and its main aim is to provide a direct replacement for MS-DOS.

As can be seen below, FreeDOS is mostly compatible with MS-DOS as far as allowing versions of Microsoft Windows to run on it as MS-DOS does.

FreeDOS does have improvements over MS-DOS, mostly involving support of newer standards and technologies that weren't around when MS-DOS was dropped, such as internationalization support, Advanced Power Management/energy saving TSRs, and ASPI. In addition, LBA and the FAT32 file system are supported, whereas some versions of MS-DOS don't support these.

Compatibility

General

Most software written for other DOSes does work fine in FreeDOS. The following types of executables are supported:

Old .COM executables
Standard .EXE 16 bit DOS executables
Borland's 16bit DPMI executables
32bit DPMI executables using DOS extenders like:
- DOS/32A
- Causeway
- DOS/4GW
- GO32/CWSDPMI
- And many others

Further, with use of HX DOS Extender, many Win32 console applications do work in FreeDOS, and some GUIs also, like QEMU, used for the screenshot provided in the Infobox.

Windows 1.0 through 3.xx

FreeDOS operates with 1.0 and 2.0 versions of Windows. 3.x versions are selectively supported: version 3.1 can be run with WIN /S which forces 16-bit 286 mode rather than the preferred 32-bit 386 mode.

Windows 3.11 for Workgroups is not supported with FreeDOS.

Windows 9x and ME

Windows 95, 98 and ME are closely linked to the internals of their respective versions of MS-DOS and do not operate with FreeDOS. A multiboot system with the help of a boot manager like LILO or GRUB works just fine.

Windows NT through XP

None of the Windows NT/2000/XP/2003 versions are based on MSDOS, so they do not operate with FreeDOS. The FreeDOS kernel may be selectively booted by adding an entry to boot.ini.

FreeDOS interacts with ReactOS in a similar manner to Windows NT, 2000, and XP.

FreeDOS-32

FreeDOS-32 is a separate project with different goals. FreeDOS aims to recreate MS-DOS, both features and general limitations. FreeDOS-32 aspires to extend/improve on that base. FreeDOS-32 can be run on top of FreeDOS. It is planned to be a fully 32-bit operation system, therefore providing more memory for the file system, providing better performance, and making obsolete DOS extenders and mode switches needed when 32bit software is running on a 16bit DOS.

Technical details

FAT32 is fully supported (even booting from FAT32). Depending on the BIOS used, as many as four LBA hard disks up to 128 GB or even 2 TB in size are supported. Some BIOSs support LBA but contain bugs for disks bigger than 32 GB. A driver like OnTrack or EzDrive resolves this bug. FreeDOS can also be used with a driver called DOSLFN, which supports long file names (see VFAT), but most (old) programs do NOT support long file names even if the driver is loaded.

There is no planned support for NTFS or ext2 but there are several shareware drivers available for that purpose. To access ext2fs, use the LTOOLS (counterpart to MTOOLS) which can copy data to and from ext2fs drives.

There is no USB driver support inside the FreeDOS projects, but in many cases BIOS-supported USB devices are available for plain FreeDOS. Some external DOS USB drivers (such as USBASPI and USBMASS) for storage devices do work, and FreeDOS run in a Linux DOSEmu window allow any drive to be accessed.

Memory management

The EMM386 memory management program included with FreeDOS provides EMS for old software and supports VCPI, which allows programs and DOS extenders which use DPMI to run. FreeDOS also contains an UDMA driver for faster disk access, which is also compatible with other DOS versions. The LBAcache disk cache stores recently accessed disk data in EMS for faster access and less direct disk access.

The FreeCOM shell—FreeDOS's version of COMMAND.COM—can move portions of itself into XMS freeing up large portions of conventional memory, up to 620 kB. This is useful for DOS programs which only use conventional memory.

FreeDOS compatibility is less than 100% but is sufficient for running normal programs. Most well-written software using standard and documented accesses does work on it, but problems with running Windows do result from Microsoft's intention to prevent their products being run on other DOSes than MS-DOS.

Screenshot

References

External links

DOS on IBM PC compatibles | Free software operating systems | Embedded operating systems

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