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Comment by tombert | Hacker News Reader

I've been on a bit of a rabbit hole with Digital Research in the last few days, specifically because I am utterly fascinated with Concurrent DOS.

I played with Concurrent DOS (and later MultiUser DOS) in PCem and I was utterly amazed. I hadn't realized that there was a preemptive multitasking operating system available to consumers as early as the mid 80's outside of AmigaOS.

I read the Wikipedia and I kind of understand why it didn't catch on, but man I kind of wish DRI (and Gary Kildall) was still around. I suspect if they were, they would have continued to make stuff that was at least interesting.

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A lot of folks never used it, but MS DOS 5.0 came with DOSSHELL which actually had support for task switching - not quite concurrency, but it worked on a 286.

From what I've learned since, when you switched away from a program using Ctrl + Esc, DOSSHELL suspended it and dumped its conventional memory to a swap file on disk.

Used this to great effect so I could swap back and forth between QBASIC and other utilities.

https://en.wikipedia.org/wiki/DOS_Shell

Yeah I saw that when going down my rabbit hole. Definitely a cool and useful thing for what it is.

I just think that Concurrent DOS is cool because it is proper multitasking; proper time slicing and everything! And you could have multiple users logging into the same computer with terminals, à la Unix, all in the mid 80s!

I have been trying to track down whoever the hell owns the license to Concurrent/Multiuser DOS to try and make a case for them to release the source code, but I have had a heck of a time getting ahold of anyone that might be able to point me in the right direction. I suspect the rights for it now reside with OpenText or something and they don’t even realize it.

> I have been trying to track down whoever the hell owns the license to Concurrent/Multiuser DOS to try and make a case for them to release the source code

Yeah, me too.

You can read a little of the results of my digging here:

https://www.theregister.com/2022/08/04/the_many_derivatives_...

Happy to compare notes -- my email is in my profile, or I'm easily Googled.

Well, these days, Google will tell you I'm an aardvark or some other bot slop, but you can find me. I always use this screen name everywhere.

I sent you an email to the address in your profile. Would love to compare notes on this stuff.

I think the main problem was that systems to take advantage of it tended to be either fully bespoke or were produced in runs of dozens or hundreds at most. Customisation and installation (including wiring the terminals, in the days before networking was common) were protracted processes as well.

As a result, they were priced against the low-end of mid-range systems - so rather more than you might expect from looking at the raw bill of materials.

Their niche was rapidly eroded by simply running multiple single user PCs at the low end, and networked small Unix systems at the high end - both of which benefitted from higher economies of scale and needed less systems integration work.

Definitely interesting in a "what might have been?" way, though. I suspect that if DR had done a deal with IBM, then we might have ended up going down that sort of path for most of the 80s.

I wasn't around in the 80's, since I hadn't even been conceived yet, so it's hard for me to really know what the landscape was like then.

Just reading about all the cool stuff that was available in the 80's, a part of me is kind of baffled that Microsoft was the one that ended up winning. DR-DOS and Concurrent DOS seem, at least in a lot of ways, objectively better than MS-DOS. I'm kind of surprised that Microsoft didn't just rip them off, honestly.

I suspect it was largely IBM that was winning, for most of the 80s at least. MS was seen as being very much the junior partner.

Things started to wobble badly around 1988, with the release of the bug-ridden PC/MS DOS 4.x and the travails of OS/2 1.x. Most people doggedly stuck to DOS 3.3 despite its limitations (particularly the max HD size of 32 MB, at a time when 40 MB disks had become commonplace).

The IBM/MS wobble couldn't have come at a worse time for DR, though. Multiuser DOS was being discontinued, and DR-DOS wasn't mature enough until version 5 (the first to include ViewMAX) - by which time Windows 3.0 had already been released.

Honestly, Microsoft were very very lucky to end up in the position they found themselves in in the early 90s. The success of Win 3 was a shock even to them, and it utterly transformed the OS market.

Yeah, I guess I just like envisioning a universe where Gary Kildall was able to keep innovating and making cool stuff, instead of the tragic and depressing way that it actually ended.

I played with DR-DOS and OpenDOS in an emulator as well, and they both seem pretty cool, though bought of them were admittedly the later versions, and as I have stated a bunch of times, I really feel like Concurrent DOS and Multiuser DOS were way ahead of their time. Instead, the winner ended up being the objectively worse versions of things.

What was buggy about DOS 4? I ran it for years until I switched to DR DOS 5.

There were two entirely separate DOS 4s

The multi-tasking DOS 4 that had its next release be branded as OS/2

and the other one, a conventional DOS stopgap product

I used that DOSSHELL method for a while until I got Quarterdeck Desqview set up - and from that point on, to me DOS was nothing more than a terminal interface to my pizzabox.

Sure would've been nice if the Desqview engineers and the GEM guys could've merged their efforts...

> Sure would've been nice if the Desqview engineers and the GEM guys could've merged their efforts...

OMG yes. I thought this myself at the time.

The thing is that they were rivals.

QEMM386 bolted protect-mode memory-management on top of DOS. DESQview bolted multitasking on top of QEMM. DESQview/X bolted a Unix-like GUI on top of that.

DR just sold multitasking OSes for the PC: Multiuser DOS for use with terminals, FlexOS with X/GEM for realtime stuff.

Symantec bought Quarterdeck. Perhaps Novell should have bought it first.

I used dosshell on IBM PC DOS 4.0. I don't remember that feature. Was it added in 5?

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