Ok, this is a long shot. Background: DSSI disk controller (KFQSA), two DSSI disks (RF71's), BA213 Chassis, with a three disk active control panel on the front. The control panel has three "unit number" plug in keys. One labeled "0", one labeled "1", and one blank. One RF71 is plugged into the top connector and one is plugged into the middle connector. In this configuration the "ready" lights under the UNIT1 and UNIT0 plugs light up on power up. Symptom: The controller only sees one of the two drives. The drive it sees is the one connected to the control port with plug id '0' in it. If I swap the ID plugs, the drive that gets talked to also swaps. Other Data: In the PARAMS program on these disks (or perhaps in the controller I don't know which) there are several "MSCP" variables associated with the drive. One of them is "UNITNUM" which defaults to 0. Both disks initially had unit numbers in this field of 0. I set one of them to have a UNITNUM of 1, wrote it with the WRITE command and power cycled. Rerunning PARAMS shows it now thinks it is unit 1, but it doesn't respond if it is connected to the control panel with the unit 1 plug in it. There are a few other parameters that I can set one is called "FORCEUNI" which defaults to 'true'. I've tried turning it off on one of the disks (where I set the unitnum to 1, but to no avail). Triva Challenge: One of my thoughts was that perhaps the ID plug was incorrectly "customized". The "0" plug has one center plug on top and one center plug on bottom. The "1" plug has the center and right leg in, and the center leg on the bottom. I'm wondering if it is actually another unit number. Misc Note: With the #3 and #4 switches "on" on the KFQSA, the board shows up both in the Qbus scan and in the SHOW DEV scan as disk controller 0. Any help appreciated... --Chuck