On 2013-03-11 21:37, Bob Armstrong wrote: I'm trying to SYSGEN an 11M 4.1 system from the distribution on RL01s using a dual RL PDP-11/23+ (which is simh in this case, so I know the hardware works). I'm letting it autoconfigure and I'm taking pretty much the default answer for everything. The build seems to go without error and yet the resulting system crashes as soon as it boots. I give up - what am I doing wrong? Somebody give me a clue, please! The simh log is attached. When RSX is building the system, it at one point creates the new system image to run, called [1,54]RSX11M.SYS. The relevant line is Now, your machine only have 128kW. That is 256 kByte. Of this, 8 kByte goes away because of the I/O page. Leaving 248 kByte. This is 496 disk blocks. It *might* be that your disk file is too big, making the system assume that it can place stuff in memory that don't exist. RSX11M.SYS is pretty close to just a memory dump. Try creating a new RSX11M.SYS, which is a bit smaller, and then rerun the VMR command, and try booting that file instead and see if that helps? Johnny