try loadfix
try booting real dos

Limits on mapping of handles with INT 67/50, maybe? What have you tried changing in the DOSBox source?

Perhaps JEMM (or something like it that also works in DOSBox) will have more flexibility than the internal EMS driver. Just in case it isn't obvious, you need to disable DOSBox's internal memory management when using such a driver.

Loadfix didn't help, the app works fine if I boot an image with dos; but would like to see it working in dosbox without having to create virtual disk images.

Since .74 was released, I looked at the source code again. I've gotten around the application complaining about requiring the B=1000 switch by setting the page frame address in ems.cpp to 0x1000. But the application now complains about:

1EMS is not a full LIM 4.0 implementation, cannot run!

in ems.cpp there is also a

1#define EMM_PAGEFRAME4K ((EMM_PAGEFRAME*16)/4096)

Is EMM_PAGEFRAME4k still valid when the pageframe is set to 0x1000 (original was 0xE000) or does it need tweaking?

Anyother ideas of things to try?

It doesn't need tweaking, it's just a shortcut. The pageframe should not be relevant here,
they're trying to map low memory pages instead of ems pages so check the functions
ripsaw mentioned for limitations to special segments.

Changing some segment limits and providing a full map array is sufficient to get the app running; but I didn't test in depth, so you should make sure that TBBS is working 100% before putting any faith in these experimental changes.

Wow, thank you very much ripsaw. It's working and seems to be working well so far. 😀

After looking at it some more, I think the tphysPage calc should be left alone, otherwise page frame mapping will be broken.

Thanks again.