Fact-checked by Grok 2 weeks ago

Windows on Windows

Windows on Windows () is a compatibility subsystem in 32-bit versions of the operating system that enables 16-bit Windows applications, originally designed for Windows 3.x, to run seamlessly on 32-bit platforms by translating 16-bit calls into equivalent 32-bit calls. Introduced with in 1993, WOW operates within a (NTVDM) to provide a protected for legacy 16-bit code, ensuring without requiring users to maintain separate 16-bit systems. The subsystem functions through a process known as thunking, where dedicated dynamic-link libraries (DLLs), such as those in the ODBC framework (e.g., Odbc16gt.dll and Odbc32gt.dll), intercept and convert 16-bit function calls to 32-bit equivalents, allowing applications to interact with modern hardware and drivers. This mechanism was essential during the transition from 16-bit to , supporting a vast of legacy software in enterprise and professional environments where was deployed. WOW layered atop the NTVDM, which emulated the environment necessary for running both DOS and early Windows programs, and it remained a core feature in 32-bit Windows editions through Windows 10. Over time, as hardware and software evolved toward 64-bit architectures, the need for WOW diminished; 64-bit Windows versions never included native support for 16-bit applications, relying instead on the separate subsystem for 32-bit compatibility. With the shift to exclusively 64-bit in 2021 and the end of support for 32-bit on October 14, 2025, WOW support has ended. This evolution reflects Microsoft's ongoing emphasis on modern architectures while preserving compatibility layers like to bridge older 32-bit applications into contemporary systems.

Introduction

Overview

Windows on Windows (WoW) is a proprietary compatibility subsystem developed by to enable the execution of 16-bit Windows 3.x applications on 32-bit Windows NT-based operating systems. Introduced on July 27, 1993, with the release of , WoW served as a critical bridge for legacy software during the transition from 16-bit to 32-bit architectures in enterprise environments. WoW extends the NT Virtual DOS Machine (NTVDM), a foundational component for emulating environments, to provide support for 16-bit Windows APIs and graphical user interfaces. It operates via the WOWEXEC.EXE process, a 32-bit user-mode executable that hosts these applications in a virtualized 16-bit environment, ensuring compatibility without native 16-bit support in the underlying kernel. This setup allows multiple 16-bit Windows programs to share a single instance, optimizing resource use on 32-bit systems. Distinct from NTVDM's focus on console-based DOS programs, WoW specifically targets the event-driven, windowed applications of Windows 3.x, employing thunking mechanisms to translate API calls and shimming for behavioral adjustments (as explored in technical sections).

Purpose and Scope

Windows on Windows (WoW) was developed primarily to enable the execution of 16-bit Windows applications on the 32-bit Windows NT platform, facilitating a smooth migration for users from earlier 16-bit environments like Windows 3.1 without necessitating immediate rewrites of legacy software. This compatibility layer addressed the fundamental architectural shift in Windows NT, where the kernel operates exclusively in 32-bit protected mode to enhance portability across processors (such as Intel 486 and MIPS R4000), performance, and system robustness by isolating legacy code in user-mode subsystems rather than integrating it natively into the kernel. The motivation stemmed from the enormous installed base of personal computers—tens of millions by the early 1990s—running 16-bit applications, ensuring that Windows NT could preserve users' investments in existing software while promoting adoption in enterprise settings where abrupt transitions could disrupt operations. The scope of is centered on supporting Windows 3.x applications, particularly Win16 (GUI) programs, by providing a virtualized environment that emulates the 16-bit through translation to Win32 calls. By default, WoW confines multiple 16-bit applications to a single multithreaded (VDM) to mimic the shared address space of Windows 3.x, though it permits separate VDMs for isolated execution to mitigate conflicts. WoW builds upon the NTVDM subsystem as its foundational layer for emulating the necessary 16-bit runtime, but it does not extend direct support to real-mode applications or programs, which rely on distinct subsystems. WoW targeted enterprise and professional users in the 1990s who were transitioning to , particularly those dependent on legacy such as early versions of (e.g., Office 4.3) or custom Win16 applications integral to corporate workflows. This focus allowed organizations to leverage Windows NT's advanced security and stability features—unavailable in 16-bit systems—while gradually modernizing their application portfolios.

History

Origins and Development

Windows on Windows (WoW) originated from the core design principles of , which aimed to create a secure, portable 32-bit operating system fundamentally incompatible with the 16-bit applications prevalent in earlier Windows versions. This incompatibility arose from NT's use of a paged model and preemptive multitasking, which could not directly support legacy 16-bit code without risking system stability. The conceptual foundation drew from the parallel development of Chicago's hybrid 16/32-bit architecture, intended for consumer markets, underscoring the trade-offs between and a clean 32-bit foundation; NT prioritized the latter to enable cross-platform portability while addressing compatibility through layered subsystems. WoW was developed by in the early 1990s as an integral component of the project, under the leadership of David N. Cutler and a team that included approximately 40-50 engineers, many recruited from . The subsystem built upon the existing NTVDM for compatibility, extending it to handle 16-bit Windows environments. This work was influenced by Microsoft's prior efforts in OS/2's Presentation Manager, where compatibility layers had been explored to run Windows applications alongside OS/2's native APIs, providing valuable insights into multi-API subsystem integration. The development timeline synchronized with the evolution of , incorporating adapted code from that platform to ensure robust support for legacy applications. A pivotal decision was to implement via rather than native 16-bit support, preserving 's hardware portability and security model by isolating legacy code in user-mode virtual machines. This approach translated 16-bit calls to Win32 equivalents, allowing multiple 16-bit applications to run in a shared while maintaining performance comparable to native 16-bit Windows systems. Initial prototypes of the and subsystems, including early implementations, underwent testing in 1992 to validate the layer's efficacy before full integration.

Release and Adoption

Windows on Windows (WoW) was bundled with the initial release of on July 27, 1993, providing compatibility for 16-bit Windows applications on the new 32-bit operating system. Subsequent Windows versions continued to offer full WoW support, including (released September 21, 1994), NT 4.0 (released August 24, 1996), (released February 17, 2000), (released October 25, 2001), (released January 30, 2007), (released October 22, 2009), (released October 26, 2012), and the 32-bit edition of (released July 29, 2015). In enterprise environments, played a key role in legacy software persistence, allowing organizations to run existing 16-bit Windows 3.x applications alongside modern 32-bit software without disruption. This facilitated smooth transitions for businesses during the shift to 32-bit systems in the 1990s, avoiding the need for costly rewrites of legacy applications and enabling continued productivity with established software investments.

Deprecation and End of Support

In (2012), disabled the 16-bit subsystem by default in 32-bit editions, requiring manual enabling for affected applications and underscoring the transition away from such support. was fully deprecated with the release of in 2021, an exclusively 64-bit operating system that omits all 16-bit support across editions. Support for concluded alongside the end-of-life for on October 14, 2025, after which no security updates or official compatibility features are provided for 16-bit applications on any active Windows versions. As of November 2025, users must rely on unsupported workarounds to execute such software. The cessation affects a limited but notable subset of legacy dependent on 16-bit components for functionality. advises —via tools like to host 32-bit Windows environments—or third-party emulators as primary mitigation strategies. No revival of is planned, reflecting its diminished relevance amid the predominance of 64-bit architectures.

Technical Implementation

Core Architecture

Windows on Windows (WoW) functions as a protected subsystem that serves as an emulation layer for 16-bit Windows applications, operating in user mode atop the 32-bit Windows NT kernel to provide binary compatibility without requiring source code modifications. It builds upon the NT Virtual DOS Machine (NTVDM), which emulates an MS-DOS 5.0 environment, to host both MS-DOS and 16-bit Windows applications within isolated virtual environments. This design allows WoW to coexist seamlessly with other subsystems such as Win32, POSIX, and OS/2, leveraging the NT executive services for process creation and resource management while presenting a modified view of the system to legacy applications. The core components of include WOWEXEC.EXE, a key that acts as the host responsible for loading and managing 16-bit Windows executables within the VDM . WOWEXEC integrates with the Win32 subsystem to handle (GUI) rendering, input/output operations, and , translating 16-bit calls into Win32 invocations via client-side DLLs and local procedure calls (LPC). By default, employs a shared VDM on a session-wide basis to run multiple 16-bit applications efficiently within a single instance, though separate VDMs can be created for if specified via flags like CREATE_SEPARATE_WOW_VDM or for differing security contexts. This shared model optimizes resource usage while maintaining the illusion of a native 16-bit environment. In terms of memory and process model, 16-bit applications under execute within an emulated 16 MB linear , constrained to mimic the limitations of Windows 3.x while operating in the 32-bit of the kernel's 4 GB (with 2 GB allocated to user mode). This emulation reserves at least 620 KB below the 16 MB boundary for 16-bit code and data, with shared 32-bit code and drivers positioned above it to support extended functionality. Processes in are managed as threads within the VDM host, enabling multiple applications to run concurrently; is emulated by scheduling these threads nonpreemptively within the VDM, aligning with the original 16-bit Windows behavior, while the underlying kernel provides preemptive scheduling at the process level.

Thunking Mechanism

The thunking mechanism in Windows on Windows () serves as the primary method for achieving API-level compatibility by intercepting 16-bit calls from legacy applications and translating them into equivalent 32-bit Win32 invocations. This process relies on functions embedded within modified 16-bit system modules, such as USER.EXE and GDI.EXE, which redirect calls across the 16/32-bit boundary. These stubs invoke entry points in WOW32.DLL, a user-mode that orchestrates the translation, ensuring that 16-bit applications can execute without modification on 32-bit Windows platforms like and later versions.) Implementation of thunking centers on WOW32.DLL's role in bridging the architectural differences between 16-bit segmented memory and the 32-bit flat address space. When a 16-bit application issues an API call, the stub intercepts it and passes control to WOW32.DLL, which maps 16-bit segment:offset addresses to 32-bit linear addresses using functions like WOWGetVDMPointerFix. This mapping prevents invalid memory access by resolving far pointers—prevalent in 16-bit code, where a pointer combines a 16-bit segment and offset—into unified 32-bit pointers through segment arithmetic and linear conversion. Parameter passing is similarly adapted; for instance, near pointers (valid only within the current segment) are expanded or relocated as needed to match Win32 expectations, while handles are converted bidirectionally using APIs such as WOWHandle32 to maintain consistency between 16-bit and 32-bit object references. The thunking process is integrated with the WoW executive via WOWEXEC, which establishes the virtual DOS machine environment for running the 16-bit code.))) A representative example of thunking involves graphics operations from the Windows 3.x GDI subsystem. A 16-bit call to LineTo in GDI.EXE, which draws a line between two points using far pointer coordinates, is intercepted by the and routed to WOW32.DLL. The DLL adjusts the far pointers to 32-bit flat equivalents, maps any device context handles, and forwards the call to the Win32 LineTo function in GDI32.DLL, preserving the original behavior while leveraging 32-bit performance and stability. This translation ensures visual output remains identical without requiring application recompilation.) Thunking also addresses interactive elements like callback functions and message loops essential for event-driven 16-bit applications. When a 32-bit invoked via thunking requires a callback to 16-bit code—such as a window procedure—WOW32.DLL employs WOWCallback16Ex to marshal parameters, convert addresses, and execute the 16-bit routine safely within the context. Message loops are managed similarly; calls to GetMessage or DispatchMessage in the 16-bit subsystem are thunked to their USER32.DLL counterparts, with WOW32.DLL synchronizing the shared across the boundary to handle events like mouse clicks or keyboard input without disrupting the application's flow. This bidirectional handling prevents deadlocks and ensures responsive user interfaces.)

Shimming Techniques

Shimming techniques in Windows on Windows refer to the dynamic insertion of small patches, or shims, into the execution of 16-bit applications to resolve targeted compatibility gaps that extend beyond fundamental translation. These shims consist of lightweight libraries that intercept specific calls at runtime, modifying parameters, redirecting operations, or substituting behaviors to emulate conditions on 32-bit Windows platforms. Stored as database entries in the Application Compatibility Database (AppCompat), shims are selected and applied based on application signatures detected during launch, enabling non-invasive fixes without recompiling or altering the original software. A primary shimming involves and registry redirection, which addresses discrepancies between legacy expectations and modern structures. For example, 16-bit applications often rely on short 8.3 filenames (e.g., "PROGRA~1" for "Program Files"), which Windows automatically generates for but may fail in scenarios requiring precise path mapping. The CorrectFilePaths shim intercepts I/O , such as CreateFile or RegOpenKey, to redirect paths from restricted or outdated locations (e.g., root directories) to user-permissible areas like virtualized folders, preventing access denied errors and ensuring data persistence across sessions. This is particularly vital for applications assuming flat directory hierarchies from Windows 3.x eras. Security descriptor adjustments form another core shimming method, tailored to 16-bit applications designed for environments lacking lists (ACLs), such as those in or early Windows versions. These apps frequently assume unrestricted file and registry access, leading to failures on NT-based systems with mandatory security enforcement. Shims like ForceAdminAccess intercept privilege-checking (e.g., IsUserAnAdmin) and return affirmative responses, effectively simulating elevated permissions without granting actual administrative rights, thus mitigating crashes from unauthorized access attempts. Additional shims, such as those in the WrpMitigation family, handle protected system areas by creating temporary files or virtualizing writes to avoid ACL-related denials. Practical examples of shimming include fixes for 16-bit installer issues, where setup programs fail due to API mismatches or errors; dedicated shims in the NTVDM subsystem emulate compatible behaviors to allow completion. Similarly, mismatches are resolved by shims that map obsolete 16-bit print APIs to 32-bit equivalents, ensuring spooler operations succeed without hardware-specific reconfiguration. These interventions are orchestrated via SHIMENG.DLL, the core Shim Engine library loaded during process initialization, which consults the AppCompat database to hook the application's import address table (IAT) and apply relevant fixes transparently. Shimming complements thunking by targeting niche incompatibilities, providing layered support for robust 16-bit execution.

Legacy and Impact

Limitations and Performance Issues

Windows on Windows (WoW) imposes several key limitations on the execution of 16-bit Windows applications within the 32-bit environment. Primarily, WoW does not support 16-bit drivers or real-mode code, as it operates exclusively in and relies on 32-bit drivers for interaction. This restriction means that applications requiring 16-bit device drivers, such as certain or communication tools, cannot function without 32-bit equivalents. Additionally, WoW is confined to user-mode applications running under the WOWEXEC.EXE , preventing any kernel-mode operations or direct access typical of older 16-bit systems. A significant operational constraint arises from the shared Virtual DOS Machine (VDM) architecture, where all 16-bit Windows applications execute within a single VDM by default. This design leads to potential system-wide instability, as a crash or fault in one 16-bit application can terminate the entire VDM, affecting all co-running 16-bit apps and requiring user intervention to restart them. To mitigate this, separate VDMs can be configured via registry settings, but this increases resource consumption without fully eliminating the risk. Shimming techniques offer partial mitigation for some compatibility issues, though they do not address core architectural flaws. Performance issues in stem largely from the thunking mechanism, which translates 16-bit calls to 32-bit equivalents, introducing overhead that slows execution compared to native 16-bit Windows environments. This thunking process is particularly burdensome for graphics-intensive applications, where frequent interactions amplify the delay. Furthermore, the emulated 16-bit suffers from memory fragmentation due to the shared global heap model inherited from Windows 3.x, limiting efficient allocation for memory-hungry tasks and potentially causing out-of-memory errors even on systems with ample . WoW's single-threaded servicing of 16-bit s imposes limits, especially on multi-processor systems, as only one Win16 thread can execute at a time within the VDM, preventing true parallelism and reducing efficiency on multi-core . Long-running 16-bit tasks exacerbate this by blocking other applications in the shared VDM, leading to unresponsive behavior until completion. In later Windows versions incorporating , incompatibilities emerge with modern features like Data Execution Prevention (DEP), which can trigger access violations in the emulated environment unless explicitly disabled for the VDM process, compromising system security.

Successors and Alternatives

Following the of the original (WoW) subsystem, which provided compatibility for 16-bit applications on 32-bit Windows NT-based systems, Microsoft introduced as its primary successor for maintaining in 64-bit s. , short for Windows 32-bit on Windows 64-bit, enables seamless execution of 32-bit x86 applications on 64-bit x86 and x64 processors by emulating a 32-bit through redirection, registry , and thunking mechanisms. Introduced with in April 2005, has been included in all subsequent 64-bit Windows releases, including and 11, to support the vast ecosystem of 32-bit software without requiring full recompilation to 64-bit. However, unlike the original , explicitly does not support 16-bit applications, processes, or components, as 64-bit Windows architectures lack the necessary segmentation and real-mode capabilities for 16-bit code execution. For legacy 16-bit Windows applications, which ceased native support after the end of the last 32-bit Windows version, , on October 14, 2025, recommends as the official alternative. Using , the built-in hypervisor in and 11 Pro/Enterprise editions, users can deploy virtual machines running 32-bit guest operating systems such as or , where the original WoW subsystem remains functional for 16-bit apps. This approach isolates legacy software in a controlled , mitigating risks associated with unpatched 16-bit code, though it introduces overhead in resource usage and setup complexity. has historically provided tools like Windows XP Mode in (via ) to simplify this process, and similar VM-based solutions continue to be endorsed for enterprise scenarios. Third-party emulators offer non-virtualized alternatives for running 16-bit Windows applications directly on 64-bit hosts. OTVDM (Open-source Task Virtual DOS Machine), an open-source reimplementation of the NTVDM subsystem, translates 16-bit calls to 32-bit equivalents, enabling execution of many Win16 applications on and 11 without a full VM. Similarly, DOSBox-X, an enhanced of the emulator, supports emulating environments for 16-bit apps, particularly useful for games and utilities with dependencies. These tools, while effective for non-protected-mode applications, may encounter limitations with complex 16-bit protected-mode software and are not officially supported by . In modern contexts as of November 2025, following the end of Windows 10 support on October 14, 2025, Microsoft emphasizes migrating to native 64-bit applications to avoid compatibility layers altogether, leveraging the Application Compatibility Toolkit (ACT) for diagnosing and applying shims to resolve issues in 32-bit legacy software during transitions. ACT, a free toolkit available for Windows 10 and 11, inventories applications, tests compatibility, and deploys fixes via the Compatibility Database, but it does not extend to 16-bit emulation, reinforcing virtualization or third-party solutions for those cases. For enterprise users dealing with irreplaceable 16-bit workloads, containerization via Azure or cloud-based legacy support services provides scalable alternatives, though no official 16-bit emulation has been reintroduced in Windows 11 or its updates.

References

  1. [1]
    Using 16-Bit Applications with 32-Bit Drivers - Microsoft Learn
    Jun 25, 2024 · The Windows on Windows (WOW) subsystem runs the applications in 16-bit mode and resolves 16-bit calls to the operating system. ... bit ...
  2. [2]
    2024 year-end link clearance - The Old New Thing
    Windows On ...
  3. [3]
    Microsoft devises new way of making you feel old: Windows NT is 25
    Jul 30, 2018 · While initially not as wildly successful as its Windows/MS-DOS stablemate, Windows NT 3.1 ... The NTVDM (also known as Windows on Windows ...<|control11|><|separator|>
  4. [4]
    [PDF] Deploying Windows 7 - Microsoft Download Center
    The Windows on Windows 32 (WOW32) subsystem allows 16-bit applications to run on the 32-bit Windows platform . The WOW32 subsystem isn't available in ...<|control11|><|separator|>
  5. [5]
    NTVDM and 16-bit app support - Compatibility Cookbook
    Nov 17, 2021 · NTVDM, or the NT Virtual DOS Machine, is a system component introduced in 1993 for all IA-32 editions of the Windows NT family (not included ...
  6. [6]
    Windows 11: Arbitrary Restrictions and Environmental Negligence
    Dec 1, 2024 · Release Date, End of Support Date, Support Duration. Expand table. Windows NT 3.1, July 27, 1993, December 31, 2000, ~7 years, 5 months. Expand ...
  7. [7]
    [PDF] Custer_Inside_Windows_NT_19...
    Figure 5-16 illustrates how MS-DOS and 16-bit Windows fit into Windows NT's system structure. The MS-DOS and the 16-bit Windows subsystems run in user mode in ...<|separator|>
  8. [8]
    Windows NT and VMS: The Rest of the Story - ITPro Today
    Gates decided that compatibility with the 16-bit Windows API and the ability to run Windows 3.x applications unmodified were NT's paramount goals, in addition ...
  9. [9]
    The History of Windows 95 - by Bradford Morgan White
    Aug 27, 2023 · Ultimately, the need for backwards compatibility meant that some 16 bit code remained in Chicago. Without this, the backwards compatibility ...
  10. [10]
    NT and OS/2
    Jul 26, 2010 · At the same time, NT (up to and including Windows 2000) shipped with an OS/2 subsystem which ran character-mode 16-bit OS/2 applications.
  11. [11]
    Windows NT July 1992 Preview - Virtually Fun
    Apr 1, 2011 · In this build 297, and it includes the OS/2 & MS-DOS/WOW subsystems. The POSIX subsystem is absent, further cementing the idea that it was ...Missing: prototypes | Show results with:prototypes
  12. [12]
    Computer industry luminaries salute Dave Cutler's five-decade-long ...
    Apr 15, 2016 · When the PC itself then transitioned to 32 bits from 16, Dave's work on NT was directly responsible for enabling Windows to yet again be the ...Missing: WOW | Show results with:WOW
  13. [13]
    Facts About Microsoft - Stories
    Important Dates ; Aug. 24, 1995, Microsoft launches Windows 95 ; Dec. 7, 1995, Bill Gates outlines Microsoft's commitment to supporting and enhancing the Internet.
  14. [14]
    64-bit versions of Windows don't support 16-bit components, 16-bit ...
    May 29, 2025 · This article discusses the lack of support for 16-bit components, 16-bit processes, or 16-bit applications in x64-based versions Windows.Missing: NT kernel stability
  15. [15]
    Microsoft Renames Windows NT 5.0 Product Line to Windows 2000
    Oct 27, 1998 · The first versions of Windows NT – Windows NT 3.1 and Windows NT Advanced Server 3.1 – were released in July 1993.
  16. [16]
    My 16-bit program has stopped working in Windows 8.1 32-bit
    Nov 12, 2014 · By default, the 16 bit subsystem in 32 bit versions of Windows 8/8.1 is disabled. Make sure it is enabled first attempting to install any such application.Missing: deprecation | Show results with:deprecation
  17. [17]
    Does Windows 8 Support 16-bit Programs? - Super User
    Oct 20, 2012 · While 64-bit copies of Windows 8 do not support 16-bit applications, they are still supported on 32-bit copies.Missing: deprecation | Show results with:deprecation
  18. [18]
    Windows 10 support has ended on October 14, 2025
    Windows 10 support ends on October 14, 2025. Upgrade to Windows 11 now to ensure continued security and feature updates. Learn more about the transition.Missing: WOW | Show results with:WOW
  19. [19]
    Running 16-bit applications on Windows 10 64-bit
    Sep 15, 2020 · I wrote this post as a proof of concept and as a best effort to make a 16-bit application run on Windows 10 64-bit. It will be demonstrated.
  20. [20]
    PRB: Types of Thunking Available in Win32 Platforms (125710)
    The generic thunk is implemented by using a set of API functions that are exported by the WOWKERNEL and Wow32.dll. In Windows NT, 16-bit Windows-based ...
  21. [21]
    Application Compatibility Database - Win32 apps - Microsoft Learn
    Jan 6, 2021 · These hooks point to stub functions that can be called instead of the system functions (also known as shimming). The stub functions perform ...
  22. [22]
    Demystifying Shims - or - Using the App Compat Toolkit to make ...
    A shim is a small library which transparently intercepts an API, changes the parameters passed, handles the operation itself, or redirects the operation ...
  23. [23]
    8.3 Filename - MS-FSCC - Microsoft Learn
    Apr 7, 2025 · The general form of a valid 8.3 filename is a base filename, optionally followed by the "." period character and a filename extension. The base ...
  24. [24]
    ApphelpCheckShellObject function (appcompatapi.h) - Win32 apps
    If the database indicates that a shim should be used to fix the extension and bShimIfNecessary is TRUE, this function loads Shimeng.dll and applies the fix.
  25. [25]
    NTVDM - BetaWiki
    May 11, 2025 · NTVDM is not supported on any 64-bit versions of Windows, but Microsoft ... Windows on WindowsEdit. To provide compatibility with 16-bit ...
  26. [26]
    Secrets of the Application Compatilibity Database (SDB) – Part 1
    May 20, 2007 · The Shim Engine, which is how I'll call it (and is one of the official names), is a technology implemented in various DLLs (mostly shimeng.dll ...
  27. [27]
    Optimizing NT's WOW Subsystem - ITPro Today
    Whether you use 16-bit applications occasionallyor daily, you can optimize NT's Win 16 on Win32 subsystems to get the most from your legacy software.
  28. [28]
    WOW64 Implementation Details - Win32 apps | Microsoft Learn
    Aug 19, 2020 · Explore Windows architecture - Training. This module provides information about the operating system's architecture and supported devices. It ...
  29. [29]
    Overview of the compatibility considerations for 32-bit programs on ...
    Jan 15, 2025 · The x64-based versions of Windows doesn't support 16-bit programs or 16-bit program components. The software emulation that is required to run ...
  30. [30]
    Application Compatibility Toolkit (ACT) - Win32 apps - Microsoft Learn
    Jan 7, 2021 · The Microsoft Application Compatibility Toolkit (ACT) is a lifecycle management tool that assists in identifying and managing your overall application ...