Liam on Linux

My occasional project to resurrect DR-DOS and make something vaguely useful from it continues, and in the spirit of "release early, release often", I thought that someone somewhere might enjoy having a look at some of my work-in-progress snapshots.

So while there is nothing vastly new here, building a bootable DOS VM is not completely trivial without what is now some very old knowledge, so I thought these might help someone.

The story so far...

In the OpenDOS Enhancement Project, Udo Kuhnt took Caldera's FOSS release of DR-DOS 7.01 (which they had renamed OpenDOS) and added in FAT32 support and some other things. Caldera spin-off Lineo (later DeviceLogics) implemented these in later, closed-source versions of DOS, but they were not officially FOSS. They also used bits of FreeDOS and were later withdrawn. DeviceLogics has since gone out of business.

Udo's disk images are on Archive.org but they aren't bootable. I've made bootable images you can download. I have a bootable VM of DR-DOS 7.01-08 but I need to clean it up and give it some spit and polish. I also added back the ViewMax GUI from DR-DOS 6.

Meantime, what I have uploaded here are three Zip-compressed VirtualBox VDI files. A VDI is the hard disk of a VirtualBox VM. These contain FAT16 hard disks.

• DR-DOS 6 with ViewMax;


• DR-DOS 7.01 with ViewMax added back in from the above & very basic memory optimisation;


• The later withdrawn DR-DOS 8.

The quick way to use them:

1. Download the image.


2. Run VirtualBox. Create a new VM. Call it (e.g.) "DR-DOS 6". You must have "DOS" in the name for Virtualbox to correctly configure the new VM for DOS! Otherwise you must manually do that part.


3. When you get to the "create or add hard disk stage", stop!


4. Switch to the file manager. Unzip the file. Put it in the newly-created VM's directory.


5. Go back to VirtualBox. Pick "add an existing hard disk". Browse to the file you just moved into place. Click it, and click "Add".


6. Now you're back at the "choose a disk" dialog. Pick the newly-added one.


7. Finish VM setup.

Now you can start the new DOS VM and enjoy.

While I was off work with a dislocated shoulder, I spent some time dabbling with DR-DOS. It's an OS I've long been fond of. What I was aiming to create were images that could make a bootable DR-DOS USB key and VM image.

The OS that made the PC great was MS-DOS, an adaptation of SCP QDOS, which broadly speaking was reverse-engineered from Digital Research's CP/M (itself now FOSS). Much later, DR responded with DR-DOS -- a cut-down version of Concurrent CP/M-86, without the multitasking but with near-perfect MS-DOS compatibility.

The first version was 3.41, basically a response to MS-DOS 3.3. DR-DOS added large disk support -- i.e. multiple FAT16 partitions of >32MB. MS-DOS 4 added little more except a graphical shell, DOSShell. DR-DOS 5 added support for mapping upper memory blocks and loading TSRs into them, and a graphical shell, ViewMax, a cut-down version of PC GEM. MS responded with much the same in MS-DOS 5. DR responded with DR-DOS 6, which bundled disk compression, and ViewMax 2. MS DOS 6 bundled disk compression too. Novell bought DR and responded with Novell DOS 7, which added peer-to-peer networking via Netware Lite -- but ViewMax 3 wasn't ready and was dropped. Most people were using Windows 3 on top of it by then anyway.

Microsoft's response was Windows for Workgroups, with peer-to-peer networking built into Windows, and then Windows 95, which built-in MS-DOS 7 too. And that was about it for DR-DOS. Novell spun its DOS and Linux division off as Caldera, which released DR-DOS 7.01 as open source. It then changed its mind and closed-sourced DR DOS 7.02 and the handful of later versions. The DOS business was spun off again as Lineo, which made subsequent releases, went broke and sold off DR-DOS again. It made it to DR DOS 8, but that was partly built from FreeDOS source code and was later withdrawn when this was demonstrated.

The history of DR-DOS after 7.02 is confused and confusing. Most of the Novell sources were lost, along with updates and fixes Novell made. Backups of some were later rediscovered  and the fixes incorporated, and it gained FAT32 and LBA support, but it's not freeware.

So DR-DOS 7.01 remained the latest free version. The OSS licence only covered the kernel and some core files. To build the FOSS version, you need the rest of Novell OpenDOS 7.

A heroic programmer called Udo Kuhnt picked up development of the FOSS DR-DOS 7.01 as the DR-DOS Enhancement Project. Its site is long gone now, although there are plenty of mentions of it. He released versions through to 7.01-08. Unfortunately, that is an incomplete work-in-progress version. But both it and the previous releases, which can be found for download in various places, don't work.

So I fixed it!

I started with the floppy disk image from ArchiveOS.org. First, it's the wrong size. VirtualBox can't mount it. VMware can.

I truncated it to exactly 2880 sectors using the advice from ``jleg094'' here. VBox mounts that. But it won't boot, nor in VMware -- it just displays 2 dots and freezes. Embarrassingly late in the troubleshooting process, I found why.

Foolishly, I didn't think to check what was on the image. I tried mounting it on a pre-booted VM and looked, and it's totally blank. There's nothing in the image at all.

So, I mounted the empty image file as a loop device under Linux, copied the boot files in there, followed by the rest of the files in the distro archive. Lo, it worked! It booted my VM just fine, and I had a DR DOS VM running 7.01-08. However, the older DR-DOS SYS command couldn't make a bootable hard disk from this. After further fiddling, I found how to fix that, too.

But I've decided for now to focus on the actual complete version 7.01-07.

I took the downloads for Enhanced DR-DOS 7.01-6 and 7.01-7, trimmed the boot disk image to work with Virtualbox, added the actual files to make the boot images bootable, and also added in the other updated commands -- SYS.COM, XCOPY, TASKMGR, SHARE, and their README files etc.

I have re-zipped them and put them on Dropbox.

Here are the links:

• 7.01-6.


• 7.01-7.


• And the WIP 7.01-8.

Please mirror these elsewhere.

To use them, the easiest way is to get a copy of DR-DOS 7.01, e.g. from BTTR Software or WinWorldPC. Install it in a VM. Reboot and check it all works.

Then, boot from one of my boot floppy images, SYS the hard disk, and copy the other files into C:\DOS or whatever you called the DOS directory.

Reboot and you should be in business.

To forestall some FAQs... A few people have asked me why I am bothering, since FreeDOS is out there and works fine. (I have contributed a few fixes to FreeDOS and my name was in the credits of at least one version that I have seen, which came as a surprise.) That's true and I do not mean to decry or lessen the work of the FreeDOS Project. However, for me, it's just a bit too different from old-style MS- or DR-DOS. Commands don't do what I expect, or the output is weirdly different. Config files are not named as they usually are. I'm told it's pretty compatible, all the same.

I just happen to prefer DR-DOS. Caldera is dead, Lineo is dead, and oddly, I now work for Novell. DeviceLogics owns the later versions of DR-DOS but it is no longer trading and as far as I know the project is no longer available for purchase -- although the rights to the entire line were up for sale.

Thus I am very much hoping not to be prosecuted for this. I have not added anything to the code, merely made the existing code usable.

My future plans include directly-downloadable VM and USB images. I have 7.01-07 working, complete with ViewMax 2, TaskManager multitasking in both text and GUI modes, mouse support, FAT32 and LBA support. I am hoping to add NTFS and USB support as well, if there seems to be any interest.

The reason I got interested in this was trying to get actual IBM PC DOS 7.1 working on my Thinkpad. This is not the same thing as the widely-available PC-DOS 7.01! IBM continued development of DOS after Microsoft lost interest. PC-DOS 7.01 included Y2K fixes. PC-DOS 7.1 also includes FAT32 and LBA support, many long-standing bugs in MS-DOS were fixed, and IBM offers it for free download as part of the Server Guide Scripting Toolkit. However, IBM does not permit re-distribution, and therefore I can't share the complete, fully-working version that I have built for my own use.

I was just prodded by someone when suggesting that some friends try Linux. I forgot to mention that you can try it without risking your existing PC setup. It prompted me to write this...

I forget that non-techies don't _know_ stuff like that.

Download a program called VirtualBox. It's free and it lets you run a whole other operating system - e.g. Linux - under Windows as a program. So you can try it out without affecting your real computer.

https://www.virtualbox.org/

If all you know is Windows, I'd suggest Linux Mint: http://www.linuxmint.com/

It has a desktop that looks and works similarly to Windows' classic pre-Win8 look & feel.

Google for the steps but here's the basic instructions:

[1] Download and install VirtualBox

[2] Then download the Virtualbox Extensions from the same site. Double-click the extensions file to install it into Vbox. (They have to do it this way for copyright reasons.)

[3] Download Mint. It comes as an ISO file, an image of a DVD.

[4] Make a new VM in VBox. Give it 2-3 gig of RAM. Enable display 3D acceleration in the settings. (Remember, anything you don't know how to do, Google it.) Leave all the other settings as they are.

[5] Start your new VM. It will ask for an ISO file. Point it at the ISO file of Mint you downloaded.

[6] It will boot and run. Install it onto the virtual hard disk inside Vbox. Just accept all the defaults.

[7] Reboot your new Mint VM.

[8] Install the Vbox Guess Additions. On the VBox Device menu, choose “Insert Guest Additions ISO”. Google for instruction on how to install them.

[9] When it’s finished, reboot the VM.

[10] Update your new copy of Linux Mint. (Remember, Google for instructions.)

That’s it. Play with it. See if you can do the stuff you normally do on Windows all right. If you can’t, Google for what program to use and how to install it. It’s not as quick as a real PC but it works.

Don’t assume that because you know how to do something on Windows, it works that way on Linux. E.g. you never should download programs from a website and install them into Linux — it has a better way. Be prepared to learn some stuff.

If you can work it, then you can install it on your PC alongside Windows. This is called Dual Booting. It’s quite easy really and then you choose whether you want Windows or Linux when you turn it on.

All my PCs do it, but I use Windows about once or twice a year, when I absolutely need it. Which is almost never. I only use Windows if someone is paying me too — it is a massive pain to maintain and keep running properly compared to more grown-up equivalents. (Linux and Mac OS X are based on a late-1960s project; they are very mature and polished. The first version of the current Windows family is from 1993. It’s still got a lot of growing up to do — it’s only half the age.)

It’s genuinely better. No, you don’t get all the Windows programs. There aren’t many games for it, for instance. But it can do anything Windows can do, it’s faster, it’s immune to all the Windows viruses and nasties so you don’t need antivirus or a firewall or anything. That means it’s faster, too — antivirus slows computers down, but you need it on Windows.

All the apps are free. All the updates are free, forever. There are thousands of people on web fora who will help you if you have problems, you just have to ask. It’s educational — you will learn more about computers from learning a different way to use them, but that means you won’t be so helpless. You don’t need to be a white-coated genius scientist, but what it means is you take control back from some faceless corporation. Remember, the world’s richest man got that way by selling people stuff they could have had for free if they just knew how.