The DR-DOS/OpenDOS Enhancement Project

Well, I presumed that somebody who would be interested in compiling
the source code would also be capable of finding out how to use the
patch tool. But the point you make here is noted - it seems like a
growing number of non-developers is also interested in compiling the
source code, so perhaps some more detailed instructions are in order.

BTW, using PATCH -? or PATCH /? or something like that results in a
rather infomative message that points the user to the PATCH --help
command which in turn displays a complete list of options.

Regarding RASM, I don't know about any incompatibilities with other
DOSes, but then I have never run it in anything but DR-DOS. Perhaps
it conflicts with the emulated DOS in DOSBox in some way. Try
installing DR-DOS in DOSBox to see if it helps. If it doesn't, it is
probably a problem with the virtual hardware.

I know other applications that run in true DOS but hang or crash in
DOSBox, so that would be my first guess.