UWIN is a computer software package created by David Korn which allows programs written for the operating system Unix to be built and run on Microsoft Windows with few, if any, changes. Some of the software development was subcontracted to Wipro, India. References, correct or not, to the software as U/Win and AT&T Unix for Windows can be found in some cases, especially from the early days of its existence.
UWIN source and binaries are available under the Open Source Eclipse Public License 1.0 at AT&T AST/UWIN open source downloads.
Technically, it is an X/Open library for the Windows 32-bit application programming interface (API), called Win32. UWIN contains:
Most of the Unix API is implemented by the POSIX.DLL dynamically loaded (shared) library. Programs linked with POSIX.DLL run under the Win32 subsystem instead of the POSIX subsystem, so programs can freely intermix Unix and Win32 library calls. A cc(1) command is provided to compile and link programs for UWIN on Windows using traditional Unix build tools such as make(1). The cc(1) command is a front end to the underlying compiler that performs the actual compilation and linking. It can be used with the Microsoft Visual C/C++ 5.X compiler, the Visual C/C++ 6.X compiler, the Visual C/C++ 7.X compiler, the Digital Mars C/C++ compiler, the Borland C/C++ compiler, and the MinGW compiler. The GNU compiler and development tools are also available for download to UWIN.