Found a X-DOS 5.2 kernel here https://archive.org/download/ipadDOS not sure it's the latest...

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X-DOS 5.2 from HBS isn't included:
-It didn't support multiconfig commands
-The boot managers I test didn't work (BOOT, MCONFIG, MULTICNF)
-It didn't support the Candyman Multi Bootsector loader.
-The RAMDISKes I use didn't work (XSMDSK, RDISK)

ZDOS 1.68 y ZEBOR Technology isn't included:
-It didn't support multiconfig commands
-The boot managers I test didn't work (BOOT, MCONFIG, MULTICNF)
-The RAMDISKes I use didn't work (XSMDSK, RDISK)