It looks like the documentation on the NCR89C100 chip (aka esp) is wrong or incomplete. Actually nothing new. Earlier I found that timer is definitely described wrong. But at least timer is described correctly in the Sun4m architecture manual, and for the scsi part the only source is the NCR document.
The subunits of the real machine are much more integrated than described. DVMA works differently compared to qemu, the expected interrupts are not triggered, and "Select with(out) attention" commands work differently too. At least in the mode NetBSD uses.
Starting to wonder why qemu is capable to boot anything at all. Looking at all this errors makes me feel like getting lost 100 meters away from the home. Or even in my own basement. Have to experiment further.