On Fri, Jul 15, 2011 at 1:13 PM, John Wilson <wilson at dbit.com> wrote: From: "Steve Davidson" <jeep at scshome.net> This is simple. If the backplane has 2 slots per row then it is a QBUS (/2 variant). If it has 4 slots per row then it is also QBUS but could be either 18-bit or 22-bit - the part number on the side of the backplane will tell you for sure. If the backplane has 6 slots per row then it is UNIBUS. In the wild this seems to be true, but the DDV11B (a hex-high Q-bus backplane) existed at least in the minds of the handbook authors (see p. 159 of Microcomputer Interfaces Handbook 1980). John Wilson D Bit Hello! John W, do you recall what sort of wire wrapping board you sent me? I keep thinking its a typical Q Bus one, but is it? ----- Gregg C Levine gregg.drwho8 at gmail.com "This signature fought the Time Wars, time and again."