Win32s is a

32-bit In computer architecture, 32-bit computing refers to computer systems with a processor, memory, and other major system components that operate on data in a maximum of 32- bit units. Compared to smaller bit widths, 32-bit computers can perform la ...

application runtime environment for the

Microsoft 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 ...

3.1 and 3.11

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 ...

s. It allowed some 32-bit applications to run on the

16-bit 16-bit microcomputers are microcomputers that use 16-bit microprocessors. A 16-bit register can store 216 different values. The range of integer values that can be stored in 16 bits depends on the integer representation used. With the two ...

operating system using call thunks. A beta version of Win32s was available in October 1992. Version 1.10 was released in July 1993 simultaneously with Windows NT 3.1.

Concept and characteristics

Win32s was intended as a partial implementation of the Win32 Windows API as it existed in early versions of

Windows NT Windows NT is a Proprietary software, proprietary Graphical user interface, graphical operating system produced by Microsoft as part of its Windows product line, the first version of which, Windows NT 3.1, was released on July 27, 1993. Original ...

. The "s" in Win32s signifies ''subset'', as Win32s lacked a number of Windows NT functions, including multi-threading, asynchronous I/O, newer

serial port A serial port is a serial communication Interface (computing), interface through which information transfers in or out sequentially one bit at a time. This is in contrast to a parallel port, which communicates multiple bits simultaneously in Pa ...

functions and many GDI extensions. This generally limited it to "Win32s applications" which were specifically designed for the Win32s platform, although some standard Win32 programs would work correctly, including Microsoft's '' 3D Pinball Space Cadet'' and some of Windows 95's included applets. Early versions of Internet Explorer (up to Version 5) were also Win32s compatible, although these also existed in 16-bit format. Generally, for a 32-bit application to be compatible with Win32s, it had to not use more than 16MB of memory or any extended features such as

DirectX Microsoft DirectX is a collection of application programming interfaces (APIs) for handling tasks related to multimedia, especially game programming and video, on Microsoft platforms. Originally, the names of these APIs all began with "Direct" ...

. Win32s inherits many of the limitations of the Win16 environment. True Win32 applications execute within a private virtual address space, whereas Windows 3.x used an address space shared among all running applications. An application running on Win32s has the shared address space and cooperative multitasking characteristics of Windows 3.1. Consequently, for a Win32 application to run on Win32s, it must contain relocation information. A technique named thunking is fundamental to the implementation of Win32s as well as Chicago-kernel operating systems, which are

Windows 95 Windows 95 is a consumer-oriented operating system developed by Microsoft and the first of its Windows 9x family of operating systems, released to manufacturing on July 14, 1995, and generally to retail on August 24, 1995. Windows 95 merged ...

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 ...

, and

Windows Me Windows Me (Millennium Edition) is an operating system developed by Microsoft as part of its Windows 9x family of Microsoft Windows operating systems. It was the successor to Windows 98, and was released to manufacturing on June 19, 2000, and t ...

. However, allowing user-level thunking greatly complicates attempts to provide stable memory management or memory protection on a system-wide basis, as well as core or kernel security—this allows poorly written applications to undermine system stability on Win32s, as well as the Chicago-kernel systems. 32-bit versions of

transparently provide a virtual machine for running Win16 applications, although this feature was removed from 64-bit versions of Windows.

Compatibility

Win32s-compatible applications could be built using Microsoft's development tools, as well as at least Borland C++ 4.x and Symantec C++ (now Digital Mars C++). However, several program compilation options (such as EXE relocation information) and DLLs which were implicit in Windows NT 3.1 have to be included with the application in Win32s. Microsoft ceased support for Win32s in Visual C++ version 4.2 released in late 1996. Win32s included an implementation of the card game FreeCell as an example application, a couple of years before the game became famous with its inclusion in

. '' Warcraft II: Tides of Darkness'', a DOS game, included a level editor that required Win32s to run. The editor used a Windows GUI for displaying the large maps because high-resolution graphic modes were already handled by Windows. The NCSA

Mosaic A mosaic () is a pattern or image made of small regular or irregular pieces of colored stone, glass or ceramic, held in place by plaster/Mortar (masonry), mortar, and covering a surface. Mosaics are often used as floor and wall decoration, and ...

web browser A web browser, often shortened to browser, is an application for accessing websites. When a user requests a web page from a particular website, the browser retrieves its files from a web server and then displays the page on the user's scr ...

version 2 also required Win32s. C# applications can be compiled by the CoreRT compiler into Win32 code that is accepted by the 1994 Visual C++ linker. This combination produces Win32 executables that can run on Windows 3.1 with Win32s.Hacker News

Sources and installation

Win32s can still be found using web search engines; PW1118.EXE is generally the installation file used. $ sha512sum pw1118.exe 31b532f324a1eebd1073e043e0c81cb131ad40681b1a7e5e73f881369eafa38ba9d91a541d99fd8b96e937f0e93bfd17cf9c26cc77daf8c77d7c9df803b3aef9 Developers should ensure they are installing OLE if they require consistent clipboard handling. Many applications which need to be made OLE aware (i.e. setting up their OLE server) must be reinstalled. Win32s was also included with some early Win32 programs.

References

External links

Win32 Tutorial by Graeme Chandler
* tp://ftp.microsoft.com/softlib/MSLFILES/PW1118.EXE Download Win32s from Microsoft{cbignore, bot=medic
Download Win32s from mirror
*Andreas C. Hofmann
Win32 subset / Win32s (1993 to 1995)
in: Computing History Dictionary (german) ��11.10.2021 Microsoft application programming interfaces Compatibility layers de:Windows Application Programming Interface#Win32s