mmap (Memory Map) and 407 executables - Do they work together?

[Christian S. Collberg]

I am trying to do memory mapped IO in a 407 executable (the old executable
format) and am getting strange results, namely the address returned by the
mmap function being invalid. When I run the same program as a 413
executable everything works fine. 

I use the options PROT_WRITE, PROT_READ, and MAP_SHARED. I am running
Sun's OS 4.0.3c on a SUN 3/80.

Am I missing something obvious or am I just doing something very wrong?

Thanks,
Chris Collberg
collberg at dna.lth.se