some hours ago I wrote: It *was* my fault! So far, I have only found one bug in V6: The size of swapmap and coremap are configured too small, so they might overflow. The sizes don't take account of shared text segments, that produce extra chunks of free memory. In V6 there are 19 pure executables, so their minimal size should be (NPROC+19)*2, or better yet (NPROC+NTEXT)*2, where NTEXT should be set to 20 instead of 40 as distributed in param.h . I don't think this bug ever showed up. It is very unlikely. In V7 these sizes are choosen to be even smaller than NPROC and even with its many pure executables, I don't think V7 ever crashed because of this bug. So, with the only exception reported by Brian S. Walden, there seem to be no bugs in V6 that crash systems. Greetings Wolfgang