Hi all -- Thought I'd share this fix with you all just in case someone in the future might make use of it. Long story short: Got myself a CMD 710/M UNIBUS SCSI controller with the intent to use it in my VAX-11/750, running 4.3BSD-Quasijarus. Unfortunately it won't boot (it hangs shortly after "loading boot" is printed to the console). VMS boots, NetBSD > 1.6 or so boots, Ultrix boots, but no luck with 4.3BSD. I spent some time adding some debug spew to the bootstrap (on SIMH) and testing (on the 750), and the hang is inside udcmd() in sys/vaxstand/uda.c. I then stumbled on this usenet post: https://groups.google.com/forum/#!msg/alt.sys.pdp11/61LZNTo9Dgg/Q6dI9om_LIEJ Which indicates a similar problem with a Viking controller on a different 4.3BSD variant. The code in Quasijarus is a bit different, but the cause is the same. The fix is: Change line 155 of sys/vaxstand/uda.c from: if(u->uda_ca.ca_rspint ==0) to: if(u->uda_ca.ca_rspdc & MSCP_OWN) Rebuild, and re-run disklabel to replace the bootstrap. Hope that helps someone else someday... - Josh