--- Frank Arnold <fm.arnold(a)inn-salzach.de> wrote: Presuming you _have_ a spare serial port... (read on) Is there? I don't recall ever seeing one. Yep. Both great alternatives. I have several real TU58s (embedded in each 11/750, and one removed running). I use the ex-11/725 drive with DOS software to backup my cartons and cartons of carts (with about an 80% success rate, owing to the age of the tapes). As for using them with a PDP-8, there are several issues that come to mind... Will (and I) want to hang a "disk" off of a negibus PDP-8/i (I wouldn't mind hanging one off of a posibus PDP-8/L, but that's a similar problem to solve). First, there are no spare serial ports on hardware that old - you get a console TTY port (implemented in a couple of dual-height cards - M706/M707, that plug into pre-wired sections of the backplane) and that's it. For external devices, there is a place to take the I/O bus off to a different cabinet over a wad of cable the diameter of your lower arm - the posi/negi-bus. Second, a "disk" type device the first PIO disk that came out for the PDP-8 was the RX01. The throughput of a serial-port-attached device would be awful, even eliminating the seek time of a real TU58 tape. So... for an OMNIBUS or later machine (DECmate, SBC6120...), it might be a feasible option, once you have a spare serial port (for example, on my PDP-8/a, I have the console port from the DKC8AA and a KL8JA (4 port) that I've never used, but it should be possible, if there's a driver). As to Will's original question, I myself have wondered what it would take to design/build a compatible device. I would think that for maximum compatibility, it would have to resemble something like an RK8, RF08 or DF32. The IOTs and behavior are well known, and AFAIK, the engineering drawings are available from the usual places. One thing that has been slowing me down is deciding how to attach a modern device to an -8/L or -8/i - one way is to use a blank backplane and do it the traditional way, with the multitude of DEC cables. Another way would be to manufacture modern cables with DEC paddle cards on one end, and modern connectors on the other end and use a modern enclosure and connector arrangement to get to the signals. Still another would be to wire-wrap (or use individual connector pins) to tap the backside of the backplane, and route that to a modern box. The third option is most likely to be the least expensive, but a hassle to install/de-install. At a few $$$ per paddle card, the second option is only slightly more expensive (probably less than $100 for the project extra). Thoughts? Suggestions? Has anyone else been kicking this around for years? -ethan P.S. - One of my many long-term projects has been to find a way to attach / replicate an RX8E for use with an -8/i or -8/L. Perhaps that might be a good first step. After all, many of us with the CPUs probably already have the drives and diskettes. P.P.S. - However the attachment is made, whatever the IOTs, I would think that it might be a nice design goal to make the media compatible with that from an SBC6120 - several of us have been using IDE adapter frames with great success. I have an 8MB CF card with three OS/8 partitions on it (2MB each). I was contemplating going with a 20MB card and 6 partitions next. They are, I believe, easy enough to load from a modern PC (but I did mine through the SBC6120 monitor).