Editing IBM TopView (section)

== Decline and discontinuation ==
TopView sold below expectations from the start, with many potential users already satisfied with cheaper, less memory-intensive [[terminate-and-stay-resident]] task switchers like Ready, Spotlight, and [[Borland Sidekick]] which didn't need a multitasking environment.<ref>{{citation |title=Speculation About Topview Persists |author-first=Steven |author-last=Burke |work=[[InfoWorld]] |date=1985-10-07 |pages=34–35 |url=https://books.google.com/books?id=jC8EAAAAMBAJ&pg=PA34}}</ref> TopView ran in graphics mode (TOPVIEW /G); however, this was rarely used. By mid-1987, IBM began to shift focus away from TopView and was promoting the use of [[OS/2]] to developers and end users alike. OS/2 1.0 was a pre-emptive multitasking, multithreading OS that allowed one real mode and multiple 16-bit protected mode sessions to run at the same time on the PC/AT based 80286 and provided as a DOS alternative announced in April 1987 and made available later that December. A graphical user interface ([[Presentation Manager]]) was added with OS/2 1.1 in October 1988. 1.1 could run with or without Presentation Manager as well as an [[embedded system]] with no screen, keyboard or mouse interface required. IBM officially stopped marketing the final release of TopView, version 1.12, on 3 July 1990.<ref name="dvorak"/> TopView's concept was carried forward by other DOS multitaskers, most notably Quarterdeck's [[DESQview]], which retained TopView's user interface and many features, plus added more features such as support for the special features of the 80286, 80386 and compatible processors, and, with DESQview/X (released in June 1992), a true GUI interface running on DOS. A variety of similar programs to TopView were also available, including one from [[Nathan Myhrvold#Early career|Dynamical Systems called Mondrian]], which Microsoft bought in 1986 with the stated intention of implementing TopView API compatibility into Windows which never happened.<ref>{{citation |work=[[InfoWorld]] |date=1986-06-30 |title=Software Makers Lean To Microsoft's Windows |author-first=Tom |author-last=Moran |page=5 |url=https://books.google.com/books?id=Wi8EAAAAMBAJ&pg=RA1-PA5}}</ref> Later in April 1992, IBM introduced OS/2 2.0 which included [[virtual 8086 mode]] and full 32-bit support of the Intel 80386 superseding even DESQview and other similar environments. OS/2 2.0 was a priority based preemptive multitasking multithreading OS including 32 levels of priority (from time critical to idle time) for the 386.

TopView requires IBM PC DOS versions 2.0 to 5.0 or MS-DOS 2.0 to 6.0, and will not run with later releases.

Key contributors to TopView included David Morrill (the "father of TopView" code-named "Orion" once the GLASS project was moved to Boca Raton), Dennis McKinley (tasking), Ross Cook (memory management), Bob Hobbs (TopView Toolkit) and Neal Whitten (product manager). [[Bill Gates]], [[Steve Ballmer]], [[Gordon Letwin]] and other key Microsoft executives accepted an invitation from IBM executive [[Don Estridge]] to IBM Boca Raton to see a special demonstration of TopView. Gates was disturbed that Windows did not have the [[Computer multitasking|multitasking]] (Windows used a [[Cooperative multitasking|cooperative]] method to share the CPU) and windowing capabilities (i.e. overlapping windows, etc.) that TopView had.  Gates witnessed TopView running multiple copies of the Microsoft BASIC interpreter running in windows (overlapping and side-by-side) in a [[Computer multitasking|multitasking]] fashion. Microsoft later released a multitasking version of [[MS-DOS 4.0 (multitasking)]] from what it learned from the meeting. Even though there was no joint development agreement with Microsoft for the development of TopView, Estridge asked and later told Whitten (against Whitten's and the TopView team's wishes) to turn over all source code and documentation of TopView to Microsoft. Within a short time after the meeting, Estridge's request was granted. Gates gave the code and documentation to a group headed by [[Nathan Myhrvold]]. Once the code had been modified according to Gates' specifications, he purchased the company. The product itself, Mondrian, was never released.  Gates, however, gave members of the team key positions at Microsoft. This led to a Joint Development Agreement with Microsoft (an agreement that previously only included [[DOS]]) to co-develop [[OS/2]] (an agreement that lasted until 1990). This was all done in order to satisfy the USA vs. IBM anti-trust court case that was filed in 1969. Even though it was dismissed in 1982, IBM was mired in antitrust troubles for more than a decade after the dismissal and did not recover from the legal morass until the early to mid-90s. In June 1990 an FTC probe was launched into possible collusion between Microsoft and IBM in the PC software market.