This has been a fun thing to go through, but at one point it was a popular trend to convert big expensive 386 computers from the late 1980’s into multi-user, multi-tasking beasts much like a mainframe. But instead of CICS, and PROFS people ran Dbase III, WordPerfect, and all kinds of email solutions from ccmail, to MS mail, and even some dbase programs, compiled by clipper into being email clients.

In a way things were more ‘simple’ back then, and the 80386 CPU had a card up it’s sleeve v86 mode. v86 mode provides hardware emulation of a 8086, allowing the base OS to spawn dozens of these virtual machines. All that was up to the ‘supervisor’ was to create virtual peripherals, much like how Windows/386 of the day ran multiple MS-DOS VM’s on a single machine that you could see at once, these solutions provide the output to multiple terminals.

While Windows/386 sat on top of MS-DOS, these multitasking DOS’s had the v86 mode multitasking as part of it’s core, and some of the later ones were themselves protected mode operating systems.

But juggling multiple MS-DOS applications at one could be quite a challenge. And of course there was the whole dos extender thing, leading up to VCPI, and DPMI.

While MP/M-86 is a grand daddy to a bunch of Digital Research derived OS’s, it’s not 386 specific so I’m going to omit it for now. I’m sure it’ll be worth doing it’s own write up.

I’m sure I’m going to miss a bunch of these, but let’s have a quick rundown.

• Concurrent DOS/386
• DR-Multiuser-DOS 5.0
• Real/32
• TSX-32
• PC-MOS/386
• VM/386
• VMOS/3

If anyone knows of any others feel free to give me a shout. It does seem that multiuser DOS was a good market at one point.