All, I'm trying to build a split I/D kernel for V7M. I've installed the system following my notes at http://www.tuhs.org/Archive/Distributions/DEC/Jean_Huens_v7m/simh_notes.txt Reading the setup.txt document in the same place, I should be able to do: cd /sys/conf make all44 (build the kern & dev components split I/D) mkconf < hptmconf (set up for hp and tm devices) make unix44 (link the kernel) cp unix_id /nunix (copy it to the root) However, when I try to boot the kernel: PDP-11 simulator V4.0-0 Beta git commit id: 24f1c06d #nunix Trap stack push abort, PC: 071752 (BIS #1,(R3)) Thanks in advance for any help. Warren