This is from memory, so apply the proverbial grain, but ISTR that the original concept for the Multics shell was just like that for Unix - i.e. each command would be a separte child process. This was given up when Multics processes turned out to be so computationally expensive, and they went to commands being subroutines that were dynamically linked in (very easy with Multics, where dynamic linking was a fundamental system capability) and called from the shell. Noel