Mr Viral
With its recent switch to a different kernel, SvarDOS moves from being a distro of FreeDOS to greater independence.
Until recently, the the SvarDOS project was essentially a distribution of FreeDOS. SvarDOS cut FreeDOS down into something that would run on even an 8086 or 8088 PC. SvarDOS came as four 360kB floppy images, or a single 1.4MB disk image, and didn’t need a 386-class CPU or a CD-ROM drive.
In 2024, though, somes changes have been afoot – perhaps prompted by Microsoft open sourcing MS-DOS 4 back in April. No, SvarDOS hasn’t switched to the MS-DOS kernel (With good reason: IBM’s PC DOS 4 was not one of the classic releases. In fact, DOS 4 was famously one of the most memory-hungry version of DOS ever released.)
SvarDOS is perfectly able to run MS Word 6 for DOS, even in graphics mode with WYSIWYG – click to enlarge
We reported in 2022 on the more relevant information that the usage terms covering CP/M and its derivatives has been relaxed. Specifically, the license now grants:
This is relevant because DR-DOS is a derivative of CP/M – specifically of CP/M-86. Most of DR-DOS remains proprietary, but way back in 1996, Caldera announced it would open source its DOS. It released the kernel and a few core utilities, and while it later changed its mind and shut the project down, the internet never forgets and the source code is still available. It got picked up and developed by the DR-DOS/OpenDOS Enhancement Project.
Sadly, project lead Udo Kuhnt stopped working on it around 2011, but in recent years another developer, EC Masloch, has continued work on what’s now known as the EDRDOS kernel, including simplifying the toolchain needed to build it. In late 2023, Bernd Böckmann created a SvarDOS package for the EDRDOS kernel. Back in July, the SvarDOS developers made it the default kernel.
It’s been on our to-do list ever since, but since it’s now what online retro-computing enthusiasts call #DOScember, we thought it was time.
Although the main SvarDOS download page has a CD-style ISO file as well as floppy images, watch out: the default ISO is as small, and as limited, as the single-floppy image. If you want to try it in a VM, or a newer PC with an optical drive, head for the SvarDOS repository page, where you’ll find a much more comprehensive 321MB file called SV-REPO.ISO. This has a much richer package selection, although the default install remains just as tiny.
We last looked at FreeDOS when version 1.3 came out back in 2022, and we may well revisit it soon as version 1.4 is approaching. At the time, we were very impressed to see FreeDOS automagically pick up that it was in a VM, install a network card driver, and get online.
However, there is one significant new feature which probably won’t be in the new release: you still can’t run Microsoft Windows 3.1 on FreeDOS without some advanced tweaking. DR-DOS, on the other hand, ran Windows 3.1 perfectly – despite Microsoft’s efforts to fake it failing, known to history as the AARD code.
The SvarDOS setup program is a lot more basic than FreeDOS, and so is the default configuration, but if you know how to configure it, it can do pretty much anything its better-known rival will. One of the packages in the repo is a packet driver for the AMD PCnet Fast III Ethernet adaptor, which handily is the same model of NIC that VirtualBox emulates by default. The online help tells you how to install and enable it, but trying to remember this exactly enough after we’d rebooted proved a bit much. Good news: the instructions are also online, and all we had to do was install a single package, run the resulting command, and presto, SvarDOS was online. This is particularly handy, as once you’re online, the SvarDOS package manager can fetch packages directly.
It’s DOS. Who will ever need more than 640kB? But SvarDOS leaves a lot of that free for use – click to enlarge
It took some time doing some very 20th century fiddling with config files, but an hour or so later we had successfully installed the FreeDOS text editor fdedit, plus the DOSKEY command-line history tool, and used them to configure the JEMM 386 memory manager. Then, we enabled the built-in CD-ROM drivers, added the LBACACHE disk cache, the CTMOUSE mouse driver, and a few other essentials… and set the whole lot to load into upper memory blocks. The result was a whopping 625kB of free conventional memory. Early in this vulture’s career, he made good money from his expertise optimizing DOS memory. It may not sound like much, but 640,224 bytes free is a lot for DOS, and that includes a network stack. The fact that it took next to no configuration other than changing DEVICE= to DEVICEHIGH= or inserting LH before some commands is very impressive.
We gave the VM a 2GB virtual drive, and it automatically partitioned and formatted it as one big FAT32 volume. Even with the additional tools we installed, it only took about 6MB of disk. The repo has over 400 packages, including tools to access OS/2 HPFS and Windows NTFS drives, plus USB drivers, development tools, editors, games, and more. If that’s not enough, there’s also the FreeDOS-repo, an online collection of totally legal DOS freeware – no dodgy abandonware here. The SvarDOS repo has a copy of the Dillo web browser and the wget file-download tool, to help you get them onto your DOS box.
DOS is a harsh contrast to 21st OSes. FreeDOS tries to automate things and make them easy; SvarDOS, not so much. Alongside our existing DOS skills, we needed to learn new commands, such as:
pkgnet search editor ← searches the repository for packages containing the word “editor”.
pkgnet pull fdedit ← downloads the “fedit” package.
pkg install fdedit ← installs the “fdedit” package – note the different command.
pkgnet checkup ← looks for updates for any installed packages.
pkg upgrade tree ← after you download it, installs the updated version of the “tree” command.
Most packages installed into their own directories, rather than into C:SVARDOS, and the packaging tool doesn’t add them to the path, or insert them into CONFIG.SYS or AUTOEXEC.BAT or anything fancy like that. Even so, this is pretty advanced stuff by DOS standards. We were especially impressed that it can check online for updates. SvarDOS has a rolling release model, and the snapshot we installed was built in September, so a few things needed to be updated.
In the SvarDOS package repo, you will find FreeDOS bits like its text editor – click to enlarge
50 years ago, CP/M started the microcomputer revolution
The many derivatives of the CP/M operating system
FreeDOS puts out first new version in six years
Eighteen year old server trumped by functional 486 fleet!
There are holes here and there. There is no tool included that can check or repair a FAT32 drive; although FreeDOS’s dosfsck is in the repo, it needs DPMI – and when we installed and loaded the CWSDPMI package to provide that, dosfsck crashed our VM. So, incidentally, did the Dillo web browser. You are going to have to get your hands dirty, but we found it nostalgic fun.
(Saying that, SvarDOS’s ability to run Windows 3.x is currently more of a theoretical capability than a practical one. You will need to do some work with memory management to get it running. In our testing, Windows for Workgroups 3.11 installed without a hitch, but it hung on launch. Also, of course, Windows is not in any way abandonware.)
Back in the DOS era, we preferred DR-DOS – or Novell DOS as it was later known – to the “real thing” from Microsoft. Sadly, Caldera only released the source for a few core tools. Now, SvarDOS supplements updated versions of those components with a whole selection of others, to recreate a mostly-complete DOS-compatible OS. It’s a very different beast from FreeDOS, and needs a lot more manual configuration, but now it has its own kernel. As a result, in places it’s now more Microsoft-compatible than FreeDOS. We think it deserves some more attention. ®
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