Porting UNIX to Windows NT

The Software Engineering Research department at Murray Hill writes and distributes several widely used development tools and reusable libraries that are portable across virtually all UNIX platforms. To enhance reuse of these tools and libraries, we want to make them available on systems running Windows NT and/or Windows 95. We did not want to support multiple versions of these libraries, and we wanted to minimize the amount of conditionally compiled code.

This paper describes an effort of trying to build a UNIX interface layer on top of the Windows NT and Windows 95 operating system. The goal was to build an open environment rich enough to be both a good development environment and a suitable execution environment. This meant that the overhead needed to be small enough so that there was no incentive to program to the native operating system directly. The openness meant that the complete facilities of the native operating system were accessible through this environment.

The result of this effort is a set of libraries, headers, and utilities that we collectively refer to as UWIN. UWIN contains nearly all the X/Open Release 4 headers, interfaces and commands. We discuss alternative porting strategies, commercial products, design goals, problems that had to be overcome, and the current status. Some performance measurements of the current system are presented here.