Today I tried to put an EMS card into my Philips NMS9100

it complains that it doesn't find 64k of contiguous free address space to map the EMS window into

this is probably because the computer has 128k of memory up there

and also a HDD card with an option ROM

so I'll have to go and check how to fix this

128k RAM is likely D000-EFFF. Some part of the F segment (or the complete one) is for the BIOS, so no dice putting the frame up there. If you have any BIOS extension, like your HDD ROM, it has to go into the C area, so also no way to put EMS into the C segment. Disable some of the high RAM or give up.

Unfortunately it seems like the high RAM cannot be disabled

maybe I overlooked something