The only problem with that plan is that with a CPU card (say, a KDJ11-A), memory and serial lines courtesy of an MXV11-B, and some sort of disk controller like an RQDX3 and the power draw crowbars the power supply. At least it has done so on every BA11-VA that I've tried... The only configuration I was able to get to work was two BA11-VAs, with the Qbus jumper, CPU and MXV11-B in the first box and the RQDX3 and DELQA in the second box... And that didn't reliably power-up Well, they certainly aren't *typical* pdp-11s with a boot console that can be programmed like any other, or interrupts which work like other ones, and the console takes lots of code to emulate a VT100, that's for sure... they also have a *64*Hz clock... In RT-11, the clock interrupt service drops one clock tick out of every 16 -- so it only processes 60 clock ticks a second... :-) 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 | +--------------------------------+-------------------------------------+