On Fri, 16 May 2014, Paul_Koning at Dell.com wrote: RSTS accepts a disk with mismatched container size so long as the disk clustersize is unchanged and the SATT.SYS file is the correct length. Actually, the latter condition is sufficient (it implies the first). SATT.SYS size is container size divided by pack cluster size (a parameter set when the pack was initialized), rounded up to an integer. It tells me the clustersize is not (some multiple of 2) I thought RSTS would accept a disk so long as the DCS is right but with wrong SATT if mounted read-only. That turns out to be incorrect, it insists on a good SATT even if it has no need for one (as in the read-only case). I suspect that s a leftover from the days before read-only mode was introduced. If you want to manipulate, or check, RSTS disk images, a useful utility is rstsflx which you can find at svn://akdesign.dyndns.org/flx/trunk I'm limited by the disk space on the RT-11 disk and what I can transfer quickly with kermit (unles someone has a DECnet stack) paul -- Cory Smelosky http://gewt.net Personal stuff http://gimme-sympathy.org Projects