Is that the only issue? If so, that should be 'not too hard' to track down. It's possible that they didn't bother wiring NPG to that slot, but sent it directly to the NPG pin on the 'UNIBUS out' connector; when the -11/40 was done, there were no single-board DMA devices. BTDT! :-) Ah, you're good then - Unix V6 will run fine with a single RK. (Ah, memories: my first experience as a sys-admin was on an 11/40 with a single RK...) The standard V6 distro include systems that will run on an RK. (The V7 distro does not, but it's possible to build RK-based systems. You'd need to bring it up on an emulator to do so.) Well, you can't put all the source and documentation online with a single RK (or even two), but that shouldn't be an issue. If you were actually trying to do _real work_ on the system, a single RK might be something of a PITA. Put that online, and you'll have plenty of room. Also, with two controllers, you'll get higher performance (not that you care :-); you could put e.g. swapping on the RK, and most files on the RL. OK, I'll probably get back to work on it 'soon'. They're available on my "Bringing up V6 Unix on the Ersatz-11 PDP-11 Emulator" page, here: http://mercury.lcs.mit.edu/~jnc/tech/V6Unix.html#RL That page (and it's partner, "Improving V6 Unix") probably contains some other useful stuff, if you're serious about running V6. One off the top of my head: the C on the 'vanilla' V6 distro is fairly primitive. There are no longs or unsigneds, casts don't work, etc, etc. There is a later version (which I think might be the so-called 'phototypsetter C'), available from the 'Shoppa disks', you might want to get that. Noel