WSL9x is a project by Hailey Somerville that enables running Windows 9x inside Linux by heavily patching a Linux kernel (based on user-mode Linux) to call Windows 9x kernel APIs instead of POSIX ones. Users must build the modified kernel (currently version 6.19) and prepare a Windows 9x disk image, after which both kernels run cooperatively side-by-side. The approach is conceptually similar to Cooperative Linux (coLinux), which previously ran Windows NT and Linux kernels together.
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