PDP 11/23 advice

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: