According to the Vaxstation II/GPX hardware manual, the correct sequence of boards is: 1) CPU 2) Memory 3) Ethernet interface 4) VCB02 base 5) VCB02 memory 6) VCB02 memory 7) Async comm (DZQ) 8) Asyn multiplexor (DHV) 9) Sync Comm (DMV) 10) Disk controller (RQDX3) 11) Tape controller (TQK50) But I have always placed the disk controller after the ethernet interface and before the VCB02... it puts the controller electrically closer to the CPU, which should make disk I/O a little faster (I know, almost infinitesimal, but the delay has got to be measurable, and adds up over time). 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 | +--------------------------------+-------------------------------------+