By default, if your disk is larger than 65535 blocks, the physical unit numbers for the DU device map to partition zero (0-65534) of the selected physical unit. If you want to map another unit of the DU handler to another partition, you issue the command: SET DUn UNIT=m part=p where 'n' is the RT-11 unit number, 'm' is the physical unit number in your MSCP configuration, and 'p' is the partition number (starting at zero). For example, say I have an RQDX3 with an RD54 (169mb) and an RX50 (dual drive): DU0 = Partition zero (0-65534) on phys unit 0 (rd54) DU1 = First of the RX50 drives DU2 = Second of the RX50 drives If I want address more of the RD54, I can do the following: DU0 = Partition zero (0-65534) on phys unit 0 (rd54) DU1 = First of the RX50 drives DU2 = Second of the RX50 drives DU3 = unassigned DU4 = Partition one on phys unit 0 (set du4 unit=0 part=1) DU5 = Partition two on phys unit 0 (set du5 unit=0 part=2) DU6 = Partition three on phys unit 0 (set du6 unit=0 part=3) DU7 = Partition four on phys unit 0 (set du7 unit=0 part=4) This is, in fact, how many partitions you would get on an RD54. All of the partitions except the last one will be full 65535 block units. The last one is about 7k blocks. Megan Gentry Former RT-11 Developer p.s. I forgot... after doing all these SET commands, you'll have to reboot for them to take affect. +--------------------------------+-------------------------------------+ | Megan Gentry, EMT/B, PP-ASEL | Internet (work): gentry!zk3.dec.com | | Unix Support Engineering Group | (home): mbg!world.std.com | | Compaq Computer Corporation | addresses need '@' in place of '!' | | 110 Spitbrook Rd. ZK03-2/T43 | URL: http://world.std.com/~mbg/ | | Nashua, NH 03062 | "pdp-11 programmer - some assembler | | (603) 884 1055 | required." - mbg | +--------------------------------+-------------------------------------+