I'm still working on the last1120 C compiler, so I've added the original code to svn. Right now, the compiler executes fine under Apout (enough to recompile itself), but not on V1 with the 0407 patch. I can compile simple C programs, and execute the resulting 0407 binary on V1. I'm running this program to get a memory dump of the process while it is running: main() { char c[]; int i; printf("Hello world\n"); c= main; while (c != 0) { i= *c & 0277; printf("%o %o\n", c, i); c++; } } so I can compare the Apout memory environment with the V1 memory environment. But it's very sloooow. I wonder why; V7 on simh is much faster than V1. Cheers, Warren P.S The C compiler doesn't have for loops :-)