Jerome Fine replies: For novice PDP-11 folk, this part is incorrect, as Allison surely knows, but probably just answered too quickly. Technically, I suppose Allison is correct, but I have never heard of anyone writing their own version of ZRQC?? As Tim said earlier, the utility that is used is ZRQC?? Just a note of clarification (again, Allison this is not a flame that you used LD, but just correcting your "spelling" - anyone who knows realizes and anyone who doesn't understand - it doesn't matter). Allison was referring to the SET DUn: UNIT=u, PART=p commands which are done right within the DU (MSCP) device driver. Remember that if DU is the resident device driver, the SET commands don't take effect until after a boot. Plus, if you do a: "SHOW DEV:DU" command, the old values will be shown if the DU is LOADed or is the resident device driver (permanently LOADed). In V5.3 of RT-11 up to V5.7 of RT-11, for a partition to be hardware bootable, the "n" and "u" have to be the same and the "p" has to be zero. Exceptions are allowed, but are complicated to explain. Also, DEC distributed MSCP device drivers did not allow a software boot of a partition when "p" was non-zero (changed in V5.6 of RT-11). Other restrictions also apply to DEC distributed MSCP device drivers (patches are available to remove most restrictions). Anyone who is really interested, please ask for additional directions. Sincerely yours, Jerome Fine