RC25 (was Re: Modifying microcode)

I too have heard that RC25s and PDP-11s were used in nuclear subs for some kind of sonar thingie. I've no idea how that worked, except that maybe DEC gave all the good drives to the Navy and the rest of us got the crappy ones. They worked as long as you didn't spin them down or try to change the removable pack. The removable part would crash at the drop of a hat and, of course given the clever shared spindle design, if the removable part wouldn't spin up then neither would the fixed part. I have (I think) three drives, or maybe just two. Two are internal drives for the 725 and one is in the table top enclosure. None work. If anybody has any tips for fixing them, or even just a kludge to spin up the Winchester part without needing the removable part to work too, I'm all ears. AFAIK the LESI ("Low End Storage Interconnect") protocol is not documented anywhere, unlike SDI or MASSBUS which are. If it is, I've never found it. I have several UNIBUS KLESI boards and I've often thought the same thing, but I'm not really interested in trying to reverse engineer the protocol w/o documentation. Bob