Ok, I looked around for the instructions on how to assemble the Unix v1 kernel and couldn't find anything so I tried: as u0.s u1.s u2.s u3.s u4.s u5.s u6.s u7.s u8.s u9.s ux.s and that made a.out and I stripped it and it looked like it was around the same size as /etc/core (it was 16400 bytes rather than 16448 for some reason). I'm not sure where Unix v1 is loading the kernel from. I'm guessing it's /etc/core and if that's the case then I must have been successful building the kernel. In all the other versions of Unix there was always a file like 'unix' in the root directory but I guess Unix v1 was different? Mark