> From: Chris Zach > the DD11-B is a MUD backplane
No, it's SPC; other sources, e.g. http://www.chdickman.com/pdp11/Notes/DD11.shtml agree. So if you have a DD11-B, you must have a BA11-D, with the 9-pin power plugs. The best thing to do is get a DD11-C or -D, and build an adapter cable to go from a 9-pin male (shell; female pins) to a 15-pin female (shell; male pins), so you don't have to mess with the harness. Part numbers here: https://gunkies.org/wiki/DEC_power_distribution_connectors Then you can plug in any memory you've got the right voltages for; the MS11-E takes + and -15V (in addition to +5V, of course). Noel