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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mikestorrent 6 hours ago | parent [-]

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

	▲	tombert 5 hours ago \| parent [-]
		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.