DESQview
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DESQview (DV) is a
text mode Text mode is a computer display mode in which content is internally represented on a computer screen in terms of characters rather than individual pixels. Typically, the screen consists of a uniform rectangular grid of ''character cells'', ea ...
multitasking operating environment developed by Quarterdeck Office Systems which enjoyed modest popularity in the late 1980s and early 1990s. Running on top of DOS, it allows users to run multiple programs concurrently in multiple
windows Windows is a Product lining, product line of Proprietary software, proprietary graphical user interface, graphical operating systems developed and marketed by Microsoft. It is grouped into families and subfamilies that cater to particular sec ...
.


Desq

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. Quarterdeck revamped its package, bringing multitasking in, and adding TopView compatibility. DESQview was released in July 1985, four months before
Microsoft Microsoft Corporation is an American multinational corporation and technology company, technology conglomerate headquartered in Redmond, Washington. Founded in 1975, the company became influential in the History of personal computers#The ear ...
released the first version of
Windows Windows is a Product lining, product line of Proprietary software, proprietary graphical user interface, graphical operating systems developed and marketed by Microsoft. It is grouped into families and subfamilies that cater to particular sec ...
. 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. Under DESQview, well-behaved DOS programs can be run concurrently in resizable, overlapping windows (something the first version of Windows cannot do). A simple hideable menu allows cutting and pasting between programs. DESQview provides support for simple editable macros as well. Quarterdeck also developed a set of optional utilities for DESQview, including a notepad and dialer. Later versions allow graphics mode programs to be loaded as well, but only run in full screen mode. DESQview is not a GUI (graphical user interface)
operating system An operating system (OS) is system software that manages computer hardware and software resources, and provides common daemon (computing), services for computer programs. Time-sharing operating systems scheduler (computing), schedule tasks for ...
. Rather, it is a non-graphical, windowed shell that runs in
real mode Real mode, also called real address mode, is an operating mode of all x86-compatible CPUs. The mode gets its name from the fact that addresses in real mode always correspond to real locations in memory. Real mode is characterized by a 20- bit s ...
on top of DOS, although it can run on any
Intel 8086 The 8086 (also called iAPX 86) is a 16-bit computing, 16-bit microprocessor chip designed by Intel between early 1976 and June 8, 1978, when it was released. The Intel 8088, released July 1, 1979, is a slightly modified chip with an external 8-b ...
- or
Intel 80286 The Intel 80286 (also marketed as the iAPX 286 and often called Intel 286) is a 16-bit microprocessor that was introduced on February 1, 1982. It was the first 8086-based CPU with separate, non- multiplexed address and data buses and also the f ...
-based PC. It can also use
expanded memory In DOS memory management, expanded memory is a system of bank switching that provided additional memory to DOS programs beyond the limit of conventional memory (640 KiB). ''Expanded memory'' is an umbrella term for several incompatible tech ...
add-ons to work around the 640 KB RAM limit of conventional memory on early PCs. DESQview really came into its own on
Intel 80386 The Intel 386, originally released as the 80386 and later renamed i386, is the third-generation x86 architecture microprocessor from Intel. It was the first 32-bit computing, 32-bit processor in the line, making it a significant evolution in ...
machines, which are better at utilizing memory above DOS's limit. However, in either case, it runs in real mode rather than
protected mode In computing, protected mode, also called protected virtual address mode, is an operational mode of x86-compatible central processing units (CPUs). It allows system software to use features such as Memory_segmentation, segmentation, virtual mem ...
, meaning that a misbehaving program can still crash the system.


DESQview and QEMM

To make maximum use of extended memory on
Intel 80386 The Intel 386, originally released as the 80386 and later renamed i386, is the third-generation x86 architecture microprocessor from Intel. It was the first 32-bit computing, 32-bit processor in the line, making it a significant evolution in ...
processors, by transforming it into
expanded memory In DOS memory management, expanded memory is a system of bank switching that provided additional memory to DOS programs beyond the limit of conventional memory (640 KiB). ''Expanded memory'' is an umbrella term for several incompatible tech ...
and upper memory blocks ( UMBs) accessible to DESQview and other real-mode programs, Quarterdeck developed a sophisticated memory manager. Owing to the foresight of its marketing manager, Quarterdeck marketed it as a separate product, QEMM-386 (Quarterdeck Expanded Memory Manager 386). It became more popular than DESQview itself, and sold steadily for many years, generating over US$150 million in sales from 1987 through 1994. After the release of the Intel Pentium processor, the ''386'' in QEMM was dropped. The combination package of DESQview and QEMM-386 was called DESQview 386 (DV386). 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 In the 80386 microprocessor and later, virtual 8086 mode (also called virtual real mode, V86-mode, or VM86) allows the execution of real mode applications that are incapable of running directly in protected mode while the processor is running ...
so that the extended memory can be mapped into addressing frames and accessible to real-mode programs such as DOS. This allows a 386 to implement the LIM ( Lotus,
Intel Intel Corporation is an American multinational corporation and technology company headquartered in Santa Clara, California, and Delaware General Corporation Law, incorporated in Delaware. Intel designs, manufactures, and sells computer compo ...
,
Microsoft Microsoft Corporation is an American multinational corporation and technology company, technology conglomerate headquartered in Redmond, Washington. Founded in 1975, the company became influential in the History of personal computers#The ear ...
) EMS (expanded memory specification). The memory manager is easily controlled by the user with DOS program QEMM.COM. 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. The main copy of DOS and any device and networking drivers have to be loaded before DESQview. The resulting space is the largest single program that can run, but DESQview under QEMM can run as many instances of those programs as the EMS allows. So an 8 MB system can generally have a dozen full-sized DOS programs running concurrently; a 16 MB system can run over twenty, and so on.


DESQview usage

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. It also has a clever interface that is generally unobtrusive while being quickly available and very easy to learn. All normal PCs include a keyboard with three "shift" or "modifier" keys: Control, Alt, and the normal Shift keys. These keys are normally held down in combination with other keys. DESQview, by default, monitors the Alt key for isolated presses (not in combination). Pressing the Alt key by itself brings up the DESQview menu allowing access to the program's features: start new tasks, switch among them, mark text on the screen, paste text as input into the current task, resize or move the text windows, configure new menu items, etc. In addition a Shift+Alt combination causes DESQview to learn a set of keys as a macro. This allows DESQview to run other programs without interfering with any of the "keybindings" they might be using. 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 system A bulletin board system (BBS), also called a computer bulletin board service (CBBS), is a computer server running list of BBS software, software that allows users to connect to the system using a terminal program. Once logged in, the user perfor ...
s were based on it, thanks to its modest hardware requirements, robust multitasking, and superlative handling of multiple communication ports. Most free or inexpensive BBS software of the time ran as a single-
node In general, a node is a localized swelling (a "knot") or a point of intersection (a vertex). Node may refer to: In mathematics * Vertex (graph theory), a vertex in a mathematical graph *Vertex (geometry), a point where two or more curves, lines ...
, single-tasking DOS program. Normally, only one copy of the BBS software could run at once, limiting the host PC to running one node. DESQview, often aided by the installation of 16550 UART chips that buffer, allows multiple copies of the same single-tasking BBS software to run simultaneously on a single computer, resulting in a
multi-user Multi-user software is computer software that allows access by multiple users of a computer. Time-sharing systems are multi-user systems. Most batch processing systems for mainframe computers may also be considered "multi-user", to avoid leavi ...
BBS.


Decline of DESQview

DESQview does not provide a graphical user interface ( GUI). 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. DESQview's ability to run most software with no modification and the cost of "run-time" licenses, combined with the costs of the development suites themselves made this an unreasonable combination for commercial shrink-wrapped software publishers and vendors. Microsoft released Windows 3.0 with its own memory management and multitasking features. 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 Digital Research, Inc. (DR or DRI) was a privately held American software company created by Gary Kildall to market and develop his CP/M operating system and related 8-bit, 16-bit and 32-bit systems like MP/M, Concurrent DOS, FlexOS, Multiuser ...
's DR DOS 5.0, released in 1990. To catch on, Microsoft included its own EMM386 in MS-DOS 5.0, while previously the memory management functionality was only available with Windows. QEMM could still be used instead, notably with Windows 3.1x, but only for incremental benefit. Sales of QEMM declined. 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. As users moved from DESQview to other platforms, notably Windows 3.x and OS/2, third party utility authors wrote utility programs that emulated some DESQview API functions to allow suitably equipped DOS programs to co-operate with these OS. The most notable are TAME (for Windows) and OS/2SPEED (for OS/2).


DESQview/X

Quarterdeck eventually also released a product named DESQview/X (DVX), which is an
X Window System The X Window System (X11, or simply X) is a windowing system for bitmap displays, common on Unix-like operating systems. X originated as part of Project Athena at Massachusetts Institute of Technology (MIT) in 1984. The X protocol has been at ...
server running under DOS and DESQview and thus provides a GUI to which X software (mostly
Unix Unix (, ; trademarked as UNIX) is a family of multitasking, multi-user computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, a ...
) could be ported. DESQview/X had three window managers that it launched with, X/Motif, OPEN LOOK, and twm. The default package contained only ''twm'', the others were costly optional extras, as was the ability to interact on
TCP/IP The Internet protocol suite, commonly known as TCP/IP, is a framework for organizing the communication protocols used in the Internet and similar computer networks according to functional criteria. The foundational protocols in the suite are ...
networks.
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was ported to DVX. DVX itself can serve DOS programs and the 16-bit Windows environment across the network as X programs, which made it useful for those who wished to run DOS and Windows programs from their Unix workstations. The same functionality is available with some versions of NCD Wincenter.


NetWare Access Server

Internetworking company
Novell Novell, Inc. () was an American software and services company headquartered in Provo, Utah, that existed from 1980 until 2014. Its most significant product was the multi-platform network operating system known as NetWare. Novell technolog ...
developed a product called NetWare Access Server (NAS) incorporating features of DESQview 386 and
pcAnywhere pcAnywhere is a discontinued suite of computer programs by NortonLifeLock, Symantec which allowed a user of the pcAnywhere remote program on a computer to connect to a personal computer running the pcAnywhere host if both are connected to interc ...
. 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.


DESQview after X

DESQview development continued in parallel with DESQview/X. After ceasing development on DESQview/X, another version of DESQview was released. QEMM was still developed after the discontinuation of DESQview, and a version compatible with
Windows 98 Windows 98 is a consumer-oriented operating system developed by Microsoft as part of its Windows 9x family of Microsoft Windows operating systems. It was the second operating system in the 9x line, as the successor to Windows 95. It was Software ...
was released. In the mid-1990s, Quarterdeck tried to recast itself as an
Internet The Internet (or internet) is the Global network, global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a internetworking, network of networks ...
company, releasing a version of the Mosaic web browser. Eventually, the company was acquired by Symantec.


Reception

''
BYTE The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable un ...
'' in 1984 stated that DesQ's application compatibility was the highest of the five window managers tested. The magazine's
Jerry Pournelle Jerry Eugene Pournelle (; August 7, 1933 – September 8, 2017) was an American scientist in the area of operations research and ergonomics, human factors research, a science fiction writer, essayist, journalist, and one of the first bloggers. ...
in 1989 noted that "while MultiFinder doesn't work very well yet, DESQView on a big 80386 machine certainly does", and preferable to OS/2 on 286. 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 ... Many users will find that DESQview is all they need".


See also

* GNU Screen * IBM TopView * MultiFinder * tmux * Terminal multiplexer * Twin (windowing system)


References


Further reading

*


External links


Screenshots of DESQview/X
* ({{cite web , url=http://sourceforge.net/projects/opendvx/ , title=Project: OpenDV/X: Summary , access-date=2016-06-25 , url-status=dead , archive-url=https://web.archive.org/web/20050518155818/http://sourceforge.net/projects/opendvx/ , archive-date=2005-05-18) DOS software Operating system APIs Process (computing)