Windows uses the GEMMIS API to take over memory management from EMM386.EXE.
Global EMM Import Specification (GEMMIS) is supported via a document available to a select number of memory-manager vendors ("Windows/386 Paging Import Specification").
[3][4][5][6] Only a few memory managers implemented the GEMMIS API, some of the ones that include it are: EMM386.EXE, Quarterdeck QEMM, Qualitas 386MAX, Helix Netroom[3] and DOSBox builtin DOS.
None of the FreeDOS memory managers (HIMEMX.EXE, JEMM386.EXE, JEMMEX.EXE) implement the GEMMIS API and Windows fails to start when running in conjunction with JEMMxxx since Windows fails to take over the memory management role.
Three conditions are required: Note that Windows in standard mode is limited in functionality, it lacks virtual memory, it skips the [386Enh] section in SYSTEM.INI and any device drivers in [386Enh] are not loaded.