Yes, it too won't work with Q22 memory (tried it, no go - ODT won't even start). I tried some changes in the simulator set-up, to see if that would fix my issue; no luck. It's quite problematic: if I boot Mini-Unix on a clean copy of the RK pack, cd to /usr/sys/dev, cp kl.c to nkl.c, and 'cc -c nlk.c', Mini-Unix reliably restarts (trashing the disk in the process). (If I omit the 'cp', I can 'cc -c kl.c' 3 times, and Mini-Unix restarts on the third.) Something's seriously wrong. I think before I try debugging it directly, I'll try one of the other Mini-Unix repositories; the one I've been using (from Bob Eager's site) may have some bit-rot. Dave Bridgham and I discussed whether the QSIC would work with an -11/03, and that analysis should apply equally to the RLV12. Our conclusion was that it should; here's our reasoning: The device registers on the board should work fine on either Q18 or Q22. That's because when going to the I/O page, the CPU asserts a special bus line, BBS7 (that says 'this cycle is to the I/O page'). The device doesn't look at the higher address lines when that's on, just BDAL00-12; so if the LSI-11 is messing with some of BDAL181-21, it shouldn't matter. For DMA cycles from the device to memory, since the CPU requires Q18 memory to work, the device too should be able to read/write to Q18 memory. At least, that's our theory. I guess all this PDP-11 hardware detail isn't really on-topic for this list; I should move it to Classic Computers, or something. Sorry all; it's intermingled with early Unix stuff, and it was easier to keep it all in one place. Noel