DesqView was a program made by Quarterdeck (of QEMM fame) in the early 90s. Just before Windows began to dominate the PC world, DesqView allowed people with 386 processors and higher to multitask under DOS. Each "task" could be set up to load its own set of config files, drivers, and make the most efficient use of your whopping 2-8 megs of RAM.
I am unsure what, if any, practical use was ever made of DesqView; as far as I can tell it was primarily used by BBS SysOps who wished to run multi-node systems on one machine. This required getting creative with IRQ settings and COM ports to accommodate all the modems, but one could typically run about three nodes of, say, a Renegade-style BBS on a decent 386.
DesqView had its own unique problems and idiosyncrasies; I vaguely remember being terrorized by "exception 13" errors (or was it exception 6?) that required frequent full reboots. And, dammit, even the allegedly multi-player version of TradeWars 2002 never seemed to work right.
As Windows continued to be very unfriendly to DOS-based BBS software, OS/2 began to replace DesqView for many SysOps, and then the ascent of the Internet's popularity among PC users started wiping out the appeal of the Bulletin Board System altogether. But as late as 1998, we were still using DesqView to run an antiquated BBS and using a packet driver multiplexer to allow telnet access. Sick, sick, sick.
DesqView was made during the heyday of InterCapping.