I finally finished dumping disk images of the floppies that came with the HM system. This was a slow process but well worth it, as the images reveal a treasure trove of information. Most disks contain a copy of SDOS, but disks HM19, HM20, HM21 and HM22 contain EXOS, presumable an internal experimental OS created at Philips NatLab, related to TOS. Also interesting is disk HM17: while most floppy diskettes are black, this one is white.
I was amazed to discover that this particular TWIN system had been used to develop software for the P1 computer. Disks HM23 and HM24 contain sources for Popmon and other software for the P1.
The set of 25 disk images can be found together with other disk images that I have collected so far.