![]() ![]() This allows a 386 to implement the LIM ( Lotus, Intel, Microsoft) EMS (expanded memory specification). With the introduction of the 80386, the memory management features were enhanced to allow the system to shift into protected mode but also allow the addresses to be configured in a virtual 8086 mode so that the extended memory can be mapped into addressing frames and accessible to real-mode programs such as DOS. The combination package of DESQview and QEMM-386 was called DESQview 386 (DV386). After the release of the Intel Pentium processor, the 386 in QEMM was dropped. It became more popular than DESQview itself, and sold steadily for many years, generating over US$150 million in sales from 1987 through 1994. Owing to the foresight of its marketing manager, Quarterdeck marketed it as a separate product, QEMM-386 (Quarterdeck Expanded Memory Manager 386). To make maximum use of extended memory on Intel 80386 processors, by transforming it into expanded memory and upper memory blocks ( UMBs) accessible to DESQview and other real-mode programs, Quarterdeck developed a sophisticated memory manager. However, in either case, it runs in real mode rather than protected mode, meaning that a misbehaving program can still crash the system. DESQview really came into its own on Intel 80386 machines, which are better at utilizing memory above DOS's limit. It can also use expanded memory add-ons to work around the 640 KB RAM limit of conventional memory on early PCs. Rather, it is a non-graphical, windowed shell that runs in real mode on top of DOS, although it can run on any Intel 8086- or Intel 80286-based PC. ĭESQview is not a GUI (Graphical User Interface) operating system. ![]() Later versions allow graphics mode programs to be loaded as well, but only run in full screen mode. Quarterdeck also developed a set of optional utilities for DESQview, including a notepad and dialer. DESQview provides support for simple editable macros as well. ![]() A simple hideable menu allows cutting and pasting between programs. Under DESQview, well-behaved DOS programs can be run concurrently in resizable, overlapping windows (something the first version of MS Windows cannot do). 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, from which DESQview inherited the pop-up menu. Quarterdeck revamped its package, bringing multitasking in, and adding TopView compatibility.ĭESQview was released in July 1985, four months before Microsoft released the first version of Windows. Quarterdeck's predecessor to DESQview was a task switching product called Desq (shipped late April or May 1984 ), which allows users to switch between running programs. Running on top of DOS, it allows users to run multiple programs concurrently in multiple windows. 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. ![]()
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