On Mar 15 2005, 13:31, David Betz wrote: A SCSI controller might be better, insofar as SCSI drives are easier to find. Unfortunately they tend to be expensive, and you need to be aware that some only support tapes, not disks. An RQDX3 should be fine if you can find a suitable drive. It needn't be a genuine DEC drive, as the formatter for the RQDX3 can be told what the drive parameters are. They're a pain to work out from scratch (I've done it) but the formatter contains tables for several standard drives, including one or two standard Seagate drives, and if you don't mind using less than 100% of the theoretical capacity, there's usually at least one table entry that will do. Avoid RQDX1 and RQDX2 boards, unless they're free, as they have a number of limitations. For example, RQDX1 doesn't pass grant signals, so it has to be the last device on the bus. RQDX1/2 are fussy about the drives; they have internal tables of drive parameters and play tricks to see what's connected. They're slower, too. You want to make sure you get the latest (or next-to-latest) RQDX3 firmware ROMs (not hard, and most have them anyway) and you'll need a bootable copy of XXDP and the formatter program (ZRQCxx). You also need either a signal distribution board, which splits out the signals connectors, and has provision for the front-panel buttons (which control online/offline and write-protect). I made my own (two versions), or you could just make up a fancy cable. You want the button panel, or a homemade substitute (you can get away with some jumpers and a pullup resistor or two, if necessary). Once formatted, for which you need XXDP and ZRQCxx, or a MicroVAX with its diagnostics, RT-11 V.5.x will recognise an RQDX controller and drive, but it needs to be V.5.03 or higher for an RQDX3 (earlier version of V5 have a bug that causes it to fail to initialise RQDX3 controllers properly -- though I wrote a patch if you need it). If you get an RQDX3, it can also control one or two RX33 floppies, which are rebadged TEAC FD-55-GFR 5.25" floppy drives. Layouts for my signal distribution board are on my website, along with a document listing the RQDX3 pinouts, and a bunch of ROM images: http://www.dunnington.u-net.com/public/RQDX/ http://www.dunnington.u-net.com/public/PDP-11/XXDP.pdf http://www.dunnington.u-net.com/public/DECROMs/ROMlist http://www.dunnington.u-net.com/public/DECROMs/ -- Pete Peter Turnbull Network Manager University of York