On Sun, Mar 10, 2013 at 11:32:03AM -0700, Ian Finder wrote: Not literally impossible but quite a project since no one (that I know of) still makes connectors that are an exact fit. EDAC makes shallower ones with the correct finger spacing though, so you could use those as long as you add guides/shims etc. to ensure alignment (or just require that the boards be plugged in very carefully). John Wilson D Bit

Hello Ian, In terms of the 11/23 any of the BA11-N chassis work, so to do BA23 boxes,if you are careful with your board layout, and if you have the KDF11-A version of the 11/23 even the BA11-V box will work. Important also is you specific backplane, the later revision KDF11-A can use a 22-bit backplane for 4MB of RAM while the early KDF11-A can only do 18-bit. The KDF11-B (11/23+) is always 22-bit. In any case a 22-bit processor will be happy in an 18-bit backplane. Though, do note that the 11/23+ won't play nice with the Q/CD backolanes, if I remember correctly. In terms of getting a chassis, the BA11-N box looks the best in my opinion, but do note the backplanes for different BA11-N boxes are different. The three that I know of are the H9273 Q18/CD, the H9275 Q22 serpentine and H9276 Q22/CD. A BA11-N with H9275 is one of the best combinations possible. Second best chassis is probably the BA23, which has two rows of Q22/CD and the rest are all Q22 serpentine. In terms of I/O, all you really need to get started is two serial ports, one for console terminal and one for a virtual TU58 DECtape II. In terms of disk, your easiest to find option is probably an RQDX* of some version, though they want ST-506 interface hard disks and Shugart interface floppies. The solution to which you'll find easier to find drices (or equivalents) is a SCSI controller, but those tend to cost a pretty penny. (Though if you can find one a CMD CQD-220A/TM (note its A/TM not A/M/T) gives you a lovely SCSI hard disk and tape controller in one. The A/M/T is either tape or hard disk, not both.) If you want to roll your own, try and find a chassisless H9275 backplane, and bodge together a PSU and a controller board. Otherwise, well to put it lightly "DEC connectors" are expensive, and making a backplane is not an easy task. Cheers, Christian On Sunday, 10 March 2013, Ian Finder <ian.finder at gmail.com> wrote:

On Mar 10, 2013, at 2:32 PM, Ian Finder wrote: What are we calling a "complete boardset"? At minimum, an 11/23 could just be the CPU (and, ideally, some RAM), though if you have the KDF11-A, you'd also probably want a bootstrap ROM board. That's what I've done. It's not hard! I would like to have a chassis at some point, but mine is happy enough as a bare backplane (with an appropriate fan blowing through it, of course). I got mine piecewise. I managed to land an H9270 relatively cheaply on eBay; that's the 4x4 serpentine QBUS backplane that originally came in the BA11-M box (if anyone happens to have the chassis and power supply to sell, I'd be much obliged). I attached a PC power supply that I hacked up to the screw terminals; make sure it's beefy enough, and that you're running enough wires to each terminal, because I have gotten the PC supply wires hot enough to melt the insulation. And of course, MAKE SURE you have decent ventilation running through it; most QBUS boards burned at least a few watts each, so there's some serious heat building up there if you don't have a fan running. Set the boards vertically if you can as well, so you can take some advantage of natural convection. The auxiliary things that the power supply/front panel provide had to be put together myself; the reset and halt switches (and power-on-reset) I bodged up with some TTL gates and transistors, while I've made a sorta-working line clock with a 555 (it's not very accurate, but most operating systems don't work at all without it, so better than nothing; I'd gladly make a line clock like what's in the power supply, but since at the moment I don't have much to build enclosures I'd rather not have bare mains-level wires sitting atop my workbench). For disks, keep an eye out for SCSI cards. I got a nice CMD CQD-220 off eBay a while back (from a list member, but I wasn't on the list at the time) which has done the trick very well. Zip disks make nice 100 MB drives, even if they're not exactly vintage; they also have the advantage that you can blast a disk image from SIMH straight onto them, so you don't have to acquire tape drives or the like to get your OS installed (though more's the fun if you can). Anything that has QBUS will take the 11/23. If you have the KDF11-B board (the quad width one with ROMs and console line units), there's a jumper pair for grant continuity if you're installing it into a serpentine backplane (like the H9270) which can be removed if it's going into a straight-through backplane. The H9270 is 18-bit addressed, but they were nice enough to run wire-wrap stakes all the way through to the back, which makes it very easy to modify (non-permanently, even) to 22-bit. I did so in an evening, and it's worked quite well. Well, you *can*. I wouldn't recommend it. Lots of signals, probably lots of layers, mechanical stability issues, etc. Also, as John Wilson mentioned, it's hard to find proper sockets. I know Douglas claims to sell DEC sockets that they use on their extender boards, but I have no idea how compatible they are: http://www.douglas.com/hardware/pcbs/breadboards/accessories.html And obviously, putting more than a few of those sockets on a backplane (the 4x4 H9270 is a small backplane) might cost you more than finding one on eBay would. For example, you can get an H9273 (4x9, straight through) for $105 on eBay right now (http://r.ebay.com/FnKkpB). Best of luck! - Dave