Microsoft's newest operating system still contains remnants of code written for Windows 95, according to a report by PCGH. The leftover sits in the memory management layer of Windows 11, including version 26H2, and exists to keep very old software running. PCGH traces the origin of the code to a bug in the original SimCity.
The component is a compatibility feature called EmulateHeap. According to PCGH, Microsoft developer Raymond Chen has said the feature is built on freshly compiled source code from the Windows 95-era memory manager. PCGH stresses that this is neither a security hole nor evidence that Windows 11's own memory handling rests on outdated engineering. It is a targeted aid for legacy programs.
Why it matters
Backward compatibility is one of the quiet promises that keeps Windows usable for businesses and hobbyists alike. A program written decades ago can still launch on a current machine because Microsoft carries small, purpose-built shims for software that would otherwise break. EmulateHeap is one of those shims, and its survival into Windows 11 shows how far back that commitment reaches.
The story also illustrates how a single defect in a popular game can shape the design of an operating system for decades. What began as a workaround for one title became a general compatibility mechanism that Microsoft still ships today.
A game that touched memory it had already released
PCGH reports that the first SimCity release for Windows suffered from a programming error: the game read from memory regions it had already handed back to the system. Under Windows 3.x this caused no visible trouble, because the data stayed where it was in memory. In the beta versions of Windows 95, however, the game stopped working.
Microsoft's response, as PCGH describes it, was to add a check. When the system recognized the game, it switched the memory manager into a special mode that did not immediately reuse freed memory. PCGH credits former Microsoft engineer Joel Spolsky with recounting this episode in 2000, and notes that the story resurfaces from time to time.
SimCity was not alone. PCGH reports that other applications also depended on the Windows 95 memory manager to run correctly in later releases. Microsoft therefore folded the recompiled heap manager into all subsequent Windows versions as a compatibility correction. EmulateHeap still redirects an application's memory calls to substitute routines that imitate Windows 95 behavior, so the program can run. According to PCGH, the old code is loaded only when the correction is active for a specific program.
When the fix itself causes trouble
Keeping the code around does not guarantee smooth results. PCGH reports that users have logged problems after Windows updates while the correction was active, including missing audio in GTA Vice City and crashes in Need for Speed: Most Wanted.
For readers who want to see the feature for themselves, PCGH points to guidance from Windows Latest. The free Application Compatibility Tools, installed through the Windows ADK, include a Compatibility Administrator. Opening the 32-bit version and creating a new database under custom databases, PCGH says, brings up EmulateHeap in the list of available compatibility corrections.
PCGH frames the whole arrangement as a deliberate trade-off: Microsoft keeps old software alive under Windows 11, at the cost of carrying code whose roots predate the current OS by three decades. The publication also invites readers to share their views in its comments section.
What to watch is whether Microsoft continues to maintain these per-program shims as Windows evolves, or whether the EmulateHeap path is eventually retired as the software it serves fades from use.
