I found a couple of pages in the printset which show the board order for some standard configurations (11/04, 11/34 and 11/34a), and one of the pages clearly shows that slot 2 is a MUD slot. It just so happens that the second board of the CPU goes in it. I guess the printset could be wrong... but I'd like to believe I can trust it. Megan Gentry Former RT-11 Developer +--------------------------------+-------------------------------------+ | 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 | +--------------------------------+-------------------------------------+