DESQview (DV) is a text mode multitasking operating environment developed by Quarterdeck Office Systems which enjoyed modest popularity in the late 1980s and early 1990s.

It was widely thought to be the first program to bring multitasking and windowing capabilities to DOS; in fact, there was a predecessor, IBM TopView, which shipped March 1985.

DESQview is able to use QEMM's features far beyond just the LIM EMS API, mapping most of the "conventional" address space (below 640 KB) into multiple extended memory blocks such that each can execute transparently during its context.

DESQview was noteworthy in that it supported all common DOS-compatible programs and achieved a degree of performance and stability that was remarkable, given the constraints of its host operating system.

[4] DESQview was critically acclaimed and won many fans, but it never met with mass appeal, despite Quarterdeck's sustained efforts to win people over.

In one area, however, DESQview was a lasting success: many multiuser bulletin board systems were based on it, thanks to its modest hardware requirements, robust multitasking, and superlative handling of multiple communication ports.

While Quarterdeck did provide suites of programming libraries and utilities to support the development of software to use its features these never became widely popular.

While DESQview was far faster, smaller, and more stable, it was more expensive and didn't include support for the graphical features of MS Windows.

The decline of QEMM started with the bundling of a memory manager in Digital Research's DR DOS 5.0, released in 1990.

In August 1994, after three quarters of losses, the company laid off 25% of their employees and the CEO, president, and founder Terry Myers resigned.

Quarterdeck eventually also released a product named DESQview/X (DVX), which is an X Window System server running under DOS and DESQview and thus provides a GUI to which X software (mostly Unix) could be ported.

Internetworking company Novell developed a product called NetWare Access Server (NAS) incorporating features of DESQview 386 and pcAnywhere.

[6] The DESQview multitasking support was used to create an environment into which up to 16 PC and Macintosh clients can login remotely to access NetWare services and run DOS applications.

[9] The magazine that year listed version 3.0 as among the "Distinction" winners of the BYTE Awards, stating that "unlike OS/2, DESQview lets you run the programs you've already paid for ...