Free Software for DOS
Operating Systems / Shells

9 Dec 2005

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DR-DOS and OpenDOS 7.01 / 7.02 / 7.03 — The Digital Research-Novell-Caldera-Lineo DOSes, now free.

* * * * *

[updated 2005-06-22]

DR-DOS, direct descendant of Digital Research's CP/M, the first OS for microcomputers, has been upgraded and expanded to compete very well against other DOSes for the PC. Variants of it can handle large FAT32 multi-partition hard disks, networking and more. And it works with Windows 3.x!

A very brief (and possibly confusing) business history: Digital Research developed DR-DOS up to v6.0, then sold it to Novell, Inc., which renamed it Novell DOS, and then developed it up to v7. The next owner, Caldera Systems (now part of The SCO Group, Inc.) renamed it OpenDOS and released v7.01 and v7.02. Ownership next passed to Lineo (originally Caldera Thin Clients, and now Metrowerks), which changed the name OpenDOS 7.02 to DR-DOS 7.02, and then released v7.03. The current owner, DRDOS, Inc. (formerly Devicelogics, Inc.) sells bootable and embedded variants of v7.03 and of its own v8.x.

Novell Caldera Lineo DRDOS, Inc.
DR-DOS 6 Novell DOS 6

Novell DOS 7 OpenDOS 7.01

OpenDOS 7.02 DR-DOS 7.02

DR-DOS 7.03 DR-DOS 7.03

DR-DOS 8.x 

The Caldera-Lineo versions 7.01 / 7.02 / 7.03 are available at the download sites listed below, and are free for private, non-commercial use. FAT32 & LFN drivers, and other OS and PNW support files, are also available. For antique collectors, there is CP/M 2.2.

OpenDOS 7.01 is available in two basic bundles: In a complete package with Personal NetWare (PNW), and in the Lite package without PNW. Each bundle is available in a package of single files for installing from HD or CD, as 1.2MB diskette images, as 720K diskette images, and as 1.44MB diskette images – a total of eight packages:

OpenDOS 7.01, HD or CD installer
OpenDOS Lite 7.01, HD or CD installer
OpenDOS 7.01, 1.2MB diskette images
OpenDOS Lite 7.01, 1.2MB diskette images
OpenDOS 7.01, 720K diskette images
OpenDOS Lite 7.01, 720K diskette images
OpenDOS 7.01, 1.44MB diskette images
OpenDOS Lite 7.01, 1.44MB diskette images
DR-DOS 7.02 is available ten ways:
DR-DOS 7.02, HD or CD installer
DR-DOS Lite 7.02, HD or CD installer
DR-DOS 7.02, 1.2MB diskette images
DR-DOS Lite 7.02, 1.2MB diskette images
DR-DOS 7.02, 720K diskette images
DR-DOS Lite 7.02, 720K diskette images
DR-DOS 7.02, 1.44MB diskette images
DR-DOS Lite 7.02, 1.44MB diskette images
Separate 1.44MB diskette image files (5)
Separate 1.44MB diskette image files (3)
DR-DOS 7.03 is available three ways:
DR-DOS 7.03, HD or CD installer
DR-DOS 7.03, separate 1.44MB diskette image files (5)
DR-DOS 7.03 Lite, separate 1.44MB diskette image files (3)
Download sites
Planet Mirror
The Horde Project
University of Bayreuth
Free Software Network

Florian Xaver's Club Dr-DOS has tools, info and links to even more DOSes.

Christoph Fuchs's Unofficial DR-DOS Resources has the complete DR-DOS documentation library, other info and tools.

The new Digital Research.

Enhanced DR-DOS — Updated, open source derivative of the Digital Research-Novell-Caldera OS.

* * * *

[added 2004-10-29, updated 2005-08-03]

Enhanced DR-DOS is based on Caldera OpenDOS 7.01, with integrated modern features: LBA disk, FAT32 & LFN support, better memory management, & more. This is the only member of the DR-DOS / OpenDOS family that is still in development. Requires OpenDOS 7.01, which it patches.

Author: Udo Kuhnt, Germany (2005).

2005-03-06: Stable v7.01.07.
2005-07-04: Second work-in-progress (WIP) v7.01.08.

Go to The DR-DOS/OpenDOS Enhancement Project for complete info & downloads.

OpenDOS 7.02-4 — DOS under DOSEMU and Linux.


[added 2004-12-19, updated 2005-06-23]

This variant of OpenDOS 7.02 provides a full DOS under Caldera OpenLinux with DOSEMU, which it configures. It should work easily with other flavors and relatives of Red Hat Linux (OpenLinux was one), and later DOSEMU. Distribution files are HD images that contain gzipped .cpio files.

Author: Caldera Thin Clients, Inc. (1999).


DR-DOS 7.04/7.05 — A DR-DOS that manages FAT32 & LBA hard drives.


[added 2005-06-22]

DR-DOS 7.04/7.05 was developed by Ontrack Data Recovery in 1999 for use on bootable diskettes, to read FAT32 and LBA hard drives without loading external drivers. The files have been used by Ontrack and by Seagate Technology with hard drive diagnostic and recovery tools, and by IBM with installer tools.

DR-DOS 7.04/7.05 is not a complete OS, but consists only of the three kernel files. The double version number reflects the differing file IDs: IBMBIO.COM and IBMDOS.COM are labeled internally as 7.04; COMMAND.COM is labeled as both 7.04 and 7.05, but is reported on bootup and by VER as 7.05 only.

Despite the limited original purpose, the files can be installed on a system hard drive as part of a complete OS: Doing so is as simple as overwriting a DR-DOS 7.03 installation with the new files.

Caution: There may be incompatibilities between the 7.04/7.05 kernel and some external programs. When two or more hard disks are in use, drive letter assignments might change. Test well! (And think about going to Enhanced DR-DOS or FreeDOS instead, with the same disk handling, better system integration and other new features).

Download (80K).

Bug: The RENAME command does not work. But help is available – A fix for the RENAME bug in OEM DR-DOS 7.04/7.05 is an online HTML page that contains a documented DEBUG patch for IBMDOS.COM, as well as other info on DR-DOS 7.04/7.05.

[updated 2005-12-08]

Author: Michal H. Tyc, Poland / BTTR Software, Germany (2003).

More in these pages from BTTR Software.

FreeDOS — Free MS-DOS clone with many improvements.

* * * *

[updated 2004-12-18]

"The to create a free implementation of MS-DOS" that "Works on old hardware, in DOS emulators, and in embedded systems." Some components can be plugged into any DOS. With many new and enhanced functions, and an impressive array of addons, this DOS is worth serious attention.

Authors: The many contributors to the FreeDOS Project, founded and coordinated by Jim Hall.

2004-11-30: Beta 9 Service Release #1.

Go to the Files page for downloads.

Go to The FreeDOS Project for support programs, news and links to related sites.

Linux users: See DOSEMU, further down this page, for a variant of this OS.

Also worth visiting is FreeDOS-32, a project "to provide a heavily modularized framework to enable features that legacy DOS systems don't have, like 32-bit flat memory model, optimized I/O, support for many file systems, compatibility layers, support for modern standards..."

Still-breathing, major commercial DOSes — Not freeware, but stuff that many people come here searching for.

IBM PC DOS 2000 (PC DOS 7 with Y2K fix) is still available and is worth considering, if you are willing to pay for a 16-bit DOS. Take a look at its feature set, at IBM's DOS & REXX page. If you already have PC DOS 7, get the free Y2K fix, in any of 14 languages, at the Y2K Fixpak page.

MS-DOS is no longer sold or supported by MS. Also, MS has apparently shut down its ftp site, once a source of free updates, supplements, etc. Try a search for anything you need, from vendors of older software, and from ftp sites that still have support files online.


Also see the Unix >> DOS page.

4DOS and 4OS2 — Enhanced command processor replacements for DOS and for OS/2.

* * * * *

[added 2004-10-29, updated 2005-08-03]

The well known 4DOS and 40S2, replacements for the DOS, and for the OS/2 command.cmd, are now freeware. Both of them contain all of the commands of the files they replace, plus many more. A few examples, from the docs:

4DOS and 4OS2 also have powerful batch processing, and many other capabilities. If you need to know more before you download either one, get the 4DOS Introduction and Installation Guide intro.txt (71K), or the Reference Manual (pdf file, zipped, 1.5MB).

Publisher: JP Software (2002, 2003).

4DOS v7.50, for any DOS 3.1 or later (Windows installer – but it can be unzipped for manual installation):
Download 4dos750.exe (1.3MB)
or, go to the directory: and download everything that's in it.

40S2 v3.04, for OS/2 2.1 or later, including Warp:
Download (523K).

4DOS.HLP: An expanded replacement for the one in 4DOS v7.50.
Author: Charles Dye / Freeware, FreeDOS and 4DOS-related stuff.
2005-07-18 release.
Download (401K).
More in these pages from Charles Dye.

Connect (CN, IBM Handshaker) — Integrated shell with impressive Norton Commander-style file manager.

* * * *

[added 1998-10-29, updated 2004-11-09]

Among freeware programs, Connect is truly in a class of its own. Connect is not just a file manager – but a multi-component programming environment and general shell. Connect can function as a nearly complete "desktop" environment. It sports a text mode, mouse- & menu-driven, multiple document ("Borland") interface. The various components share a common clipboard (even the configuration text boxes have clipboard support). Screenshot.

Connect incorporates several noteworthy units that should interest the non-programmer:

See the included READMEEN.HTM for an English overview of features. For a more in-depth evaluation of Connect see the OFM Paradigm page at Softpanorama.

Install notes: Unzip with create directories option. Modify cn.bat to point to Connect directory, adjust default archive and other settings as necessary. Installed files require about 6MB.

Disadvantages: Some configuration settings are nested deep within menus and may be difficult to locate during the initial learning phase. Many readers will not benefit from the help files because they are composed in Russian only.

Tips: Investigate the interface with the mouse – there are many context sensitive areas. Press both left and right mouse buttons when attempting to use drag and drop copy in file manager (and editor). Many file manager setting dialogs (e.g., display options, archive settings) are accessed through a right button pop up menu in file manager (same for the terminal). To view DBF files select a dbf file and invoke the VIEW command.

Here's another review.

Authors: Ian Balter, Ukraine; Dima Orlov, Israel (2002).

2002-09-16: v7.5. See docs for version history (in Russian).

Download (1.4MB).

For support files, source and info in English and Russian, go to the CONNECT files at Kiarchive, http, or ftp, and to Dima Orlov's CONNECT program support page (which also has an OS/2 version).

Mi-Shell (MSH) — Configurable and programmable Norton Commander-like shell.


[added 2004-12-17, updated 2005-12-08]

This large program can be run in one of two basic ways: "Out of the box" as an expanded Norton-style shell, or user-configured by means of scripts (ASCII files) and substitution of components. Mi-Shell starts up using a default script, CONFIG.MSH, which is itself a program, written in the MSH script language, that sets parameters for shell functions. CONFIG.MSH also calls up other, external programs that perform many functions. User-configuration can consist of changing the operation of internal functions, or replacing the default external programs, or both.

Some default support programs that can be changed by the user: On opening, Mi-Shell looks for the Berkeley Utilities, and will use some of them for standard functions. File / directory comparison tool is Delta. File editor is the standalone MWE (this one is included). Mi-Shell has many other functions, and many possibilities for expansion through use of the scripting language.

Author: Jean Michel, France (1997). Distributed by OPENetwork.

1997-08-17: v2.2. Formerly paid commercial software, now in the public domain and completely free.

Download (196K).

Go to Mi-Shell, The Programmable Shell at OPENetwork for a longer introduction, with screenshots.


These can coexist with DOS/Win9x on the same partition.

BasicLinux (BL3) — A small Linux with Internet support.


[added 2000-10-15, updated 2005-08-03]

This newer Linux distro was designed to run on minimal hardware, yet it includes TCP/IP networking capabilities (ppp/plip/ethernet/slattach), an adequate set of networking applications (web browser, ftp, telnet, fetchmail, router/firewall), and other tools (Pico text editor, bash, and several unix tools).

BasicLinux runs in a 4MB RAM device giving it a degree of quickness even on slower 386es. Although many ramdisk-based Linux distributions are designed to be booted from floppies, the distribution files for BasicLinux (~2MB) can be unzipped to a hard disk directory and Linux can be booted immediately from the DOS prompt. Although you can also boot from pre-prepared floppies (2 req.), a HD boot will obviously be quicker (e.g., about 80 sec. from boot command to login prompt on my 386sx/20 w/8MB RAM, which is fast compared to floppy-only Linux distros). Because it runs in a ramdisk, BasicLinux is a fairly safe distribution to use for learning and experimenting; however, it does permit mounting (and modification) of other drives and was not designed for tutorial purposes (e.g., lacks man pages). A package is available for installing to a dedicated Linux partition.

As distributed, BasicLinux provides only about 800K free space in the 4MB ramdisk but an additional 4MB ramdisk can be created if you have 16MB+ RAM. You can mount other drives in order to permanently save work from the ramdisk, but you'll need to be comfortable with creating mount points and mounting devices. The DOS version of BL3 boots from DOS on a hard drive, runs in a loop file, and requires a 386+ CPU, 3MB RAM, and a DOS (including Win 9x/MS-DOS 7). The Floppy version runs in a ramdisk, from two diskettes, and requires a 386+ CPU, 12MB RAM, two 1.44MB diskettes (or one 2.88MB?). BasicLinux is derived from Slackware 3.5 and Linux kernel 2.2.16.

Author: Steven Darnold, New Zealand (2004).

2004-03-09: v3.32.

DOS version
Floppy version

Go to the BasicLinux home page for more info, related software and http downloads.

If you know which files you need, go direct to the BasicLinux ftp site.

ZipSlack — Small Linux distribution, part of Slackware package, still in development.


[added 07-22-01, updated 2005-12-08]

Not really small, but a reliable package that is worth considering. From the publisher:
ZipSlack is a special edition of Slackware Linux that can be installed onto any FAT (or FAT32) filesystem with about 100 MB of free space. It uses the UMSDOS filesystem and contains most of the programs you will need. This means that you do not need to repartition your hard disk if you already have DOS or Windows installed. ZipSlack installs into a directory on your DOS filesystem. It can also be installed to and booted from a Zip disk.
This distribution is ideal for people who don't have a lot of hard disk space, do not have a fast Internet connection to download the entire distribution, or who want a Linux distribution they can carry around on a Zip disk.

Requires about 107MB allocated disk space, 80386+, 8-16MB RAM.

2005-09-15: Slackware v10.2, with Linux kernels 2.4.31 and 2.6.13.

Go to The Slackware Linux Project for more info. Go to Get Slack, to find a list of download sites. Look in a site for a directory something like /linux/distributions/slackware/slackware-10.2/zipslack/.

For purchase of CDs and books, go to the Slackware Store

Pygmy Linux — Small Linux distribution.


[added 1999-09-26, updated 2004-10-29]

From the docs:
... Pygmy is UMSDOS based... co-exists peacefully with DOS/Win95, 98 on the same partition. ...minimal configuration is i486, 8 MB RAM and approximately 25 MB of disk space... internet ready... supports connection via ...modem and ...LAN... allows installation of Slackware, Redhat and Debian packages.

Other features: Based on Slackware 7.1. SVGALIB graphic browser in package. Released under GPL.

Author: Peter Psota, Czech Republic (2002).

2002-10-05: v0.92. Last version – development has ended, author's website is shut down.

Download (13.2MB).


DOSEMU — Provides DOS system emulation under Linux.

* * * * *

[added 2000-03-06, updated 2005-06-23]

"DOSEMU is a PC Emulator application that allows Linux to run a DOS operating system in a virtual x86 machine. This allows you to run many DOS applications." Requires some native DOS files (e.g.,, io.sys/, msdos.sys/ Compatible with many DOSes, but see the specialized dosemu-freedos at SourceForge, and OpenDOS 7.02-4 on this page.

Capabilities include:

Authors: DOSEMU Team (2004).

2004-07-11: v1.2.2, stable release.
2005-05-19: v1.3.2, development version, not final.

Get the latest official releases of DOSEMU and dosemu-freedos at DOSEMU Stable Code.

Get development versions at DOSEMU: Bleeding Edge.

For latest info, go to

LTOOLS (formerly LREAD) — Command line tools read/write Linux ext2 filesystem from DOS/Windows.


[added 2001-08-05, updated 2005-08-03]

All the following functions are included in a single (111K) executable (individual functions can be called with included batch files):

Tools can be called from DOS, or from a DOS box under Win9x/NT+. Run on one machine, or over the Internet or any other network.

Author: Werner Zimmermann, Germany (2005). Suggested by Jon-Egil Korsvold.

2005-06-08: v6.10.

Download (2.1MB).

Go to the LTOOLS Page for lots more info & news.

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©1994-2004, Richard L. Green.
This Edition ©2004-2005, Richard L. Green and Short.Stop.