MULTOS/8 progress, and a question...

Hi all -- Having overcome my earlier issues with SIMH, I now have MULTOS/8 happily running on the real hardware, with two terminals. (Yay!). I'd like to get the system up to four terminals and here's where I'm running into trouble. I've modified PARAM.PG appropriately (set JOBS to 4, TERMS to 4, and filled in the device codes for the extra terminals). I've rebuilt JOBS.BN and MULTOS, ran BUILD and inserted J1 through J4 and everything runs and the system comes up with 4 terminals (yay!). What isn't working properly are the job devices J1 through J4 -- each of these provides each terminal/user his/her own "virtual" drive on the system's RK05 pack -- effectively it partitions the RK05 into four smaller drives, J1: through J4:. With the two user setup, J1: and J2: are approximately 3000 blocks in size (so each basically gets one side of the RK05 pack). With the four-user setup, I'd expect J1:, J2:, J3: and J4: to each be about 1500 blocks, but they're still reporting as 3000 blocks each. What's more, the actual starting offsets of J1: through J4: appear to be what I'd expect (that is, J1 starts at 0, J2 starts at ~1500, J3 starts at ~3000, etc.). So if I start filling these drives, eventually they clobber each other. The only manual I've found (http://www.pdp8.net/os/multos8/) suggests that these should be appropriately sized (see section 2.1.1) automagically, but this does not seem to be the case; doing a ZERO on them creates a filesystem 3000 blocks in length. I'm digging through the source code to look for clues, but I haven't found anything yet. Anyone fooled with this before? Thanks, Josh