Close Combat
Popular game purchased from Atomic Games.
Flight Simulator
Purchased from the Bruce Artwick Organization.
FrontPage
Microsoft's HTML editor was purchased from Vermeer Technologies in 1996.
FoxPro
This database application came along with Microsoft's purchase of Fox Software in 1986.
Internet Explorer
Desperate to play catch-up in the fast-moving Internet world, Microsoft licensed code from Spyglass, Inc. (one of the two licensees of the original Mosaic code base) in 1995, and called it MSIE. Microsoft then proceeded to distribute MSIE for free, denying Spyglass substantial royalties for their key contribution to the product.
MS-DOS
The original Microsoft cash cow, this CP/M clone (then called Q-DOS) was purchased from the Seattle Computer Company in 1981. Microsoft then proceeded to thwart Seattle Computer's license rights to the product. The tiny company sued Microsoft and prevailed in court.
Object Linking Environment (OLE)
Microsoft settled a suit with Wang Labs over patent infringement code portions of OLE, which is also the heart of Microsoft's ActiveX.
PowerPoint
This presentation software package was renamed and rebranded after Microsoft's purchase of Forethought, Inc., in 1987.
SQL Server 6.0
This important database product is based on code purchased from Sybase in 1988.
Visual Basic
Ruby, the foundation for Microsoft's highly important Visual Basic product, was purchased from Cooper Software in 1991.
Visual C++
Microsoft purchased the Lattice C code compiler, which became Visual C++, Microsoft's software development environment.
Visual SourceSafe
Purchased from OneTree Software. Shortly after OneTree's SourceSafe was released, Microsoft preannounced a similar application called Microsoft Delta, which failed to sell. Microsoft then purchased OneTree and renamed SourceSafe as Microsoft Visual SourceSafe.
Windows
Technologies used in Windows multitasking came to Microsoft with their purchase of Dynamical Systems in 1986. Portions of the interface were licensed from Apple Computer, also in 1986.
Xenix
Microsoft's version of Unix was actually written under contract by the Santa Cruz Operation (SCO).