I think he's misremembering about the format part because the UI does have some arbitrary cluster sizes for NTFS: https://github.com/lianthony/NT4.0/blob/b4a8d3

I think he's misremembering about the format part because the UI does have some arbitrary cluster sizes for NTFS: https://github.com/lianthony/NT4.0/blob/b4a8d373d8a082db67583b0db94b617d5378e788/private/windows/shell/shelldll/unicode/format.c#L473 https://github.com/lianthony/NT4.0/blob/b4a8d373d8a082db6758... That code still seemed to be around in (some versions of) XP: https://github.com/tongzx/nt5src/blob/daad8a087a4e75422ec96b7911f1df4669989611/Source/XPSP1/NT/shell/shell32/format.cpp#L462 https://github.com/tongzx/nt5src/blob/daad8a087a4e75422ec96b... As for the ZIP support, I can't find the source code for ZIP folders specifically. There's this excerpt from another company (Schlumberger Technology Corp.): https://github.com/tongzx/nt5src/blob/daad8a087a4e75422ec96b7911f1df4669989611/Source/XPSP1/NT/ds/security/csps/cryptoflex/slbzip/zip.cpp#L7 https://github.com/tongzx/nt5src/blob/daad8a087a4e75422ec96b... which was added in 1996 if the comments are to be believed.