Sorry I didn't follow up yet - my $work load is now back to normal and I'm back to spending my spare time on forums and hobby projects but didn't get around to go back to the thread.
(First, I made an error in an earlier posting.. I mentioned format 15b and 17b for PC floppies, I believe, but that should of course be 15b and 34b (for PC DD or PC HD formats). Can't edit the original posting, unfortunately.)
"Step 1: which Sintran command(s) would I use to get a image copy of a floppy? The same as in step 4?"
It's a little bit tricky to create file images of volumes (device images) using standard Sintran commands. The backup-system command has a device-copy subcommand which is normally great for copying device volumes (making image copies), unfortunately it's geared towards making copies from one device to another. So, making a disk image on a tape is easy.. and the other way around. It's even possible to make a disk image to a bunch of floppies, by treating the floppies as a tape volume (it'll prompt for new floppies). I think you asked about something like that earlier, but your system disk would need an awful lot of 8" floppies.. probably.
The simplest method is probably to just write a program to do it. It can easily be written in Fortran, shouldn't be particularly long, it's just open floppy device, open file, read/write loop, close, close. Maybe a couple of mon144 (aka DeviceFunction aka MAGTP) calls. I could probably write a working program with my emulator setup even.
The Sintran command 'device-function' can also do this though. But you would have to be a bit careful. First, use 'device-function read-format' to check the format of the floppy. Should be 0 or 17b. I don't think you have to use device-function set-floppy-format when reading a floppy, it handles it automatically if it's one of those two formats. But it doesn't hurt, of course. Then you would have to read a number of sectors, as much as you can fit, into memory. Use 'device-copy read-record <address> <number of words>' for this. Then dump the memory to file. You could use the Sintran command 'wfile' to do this. Use 'open' first, to open a file and create a connection number for 'wfile'. Then use device-copy read-record again, it'll remember where you left off. Now it's simpler if you 'wfile' that chunk of memory to _another_ file, instead of trying to append to the first one. So close the first one, open a new one, then write. You can always piece together the parts after you copy the files to a PC if you want an image on the PC, if you want to write a new floppy the pieces come in handy as is (see next step below).
You can fit up to 64 kwords into memory at the time - possibly 128kwords (256KB) if you have 2-bank background segment enabled.
So, if you're careful and do the steps correctly you can copy with only Sintran commands.. but it's slightly tricky.. that's why I always used to make my own programs for such things, back when I worked with ND computers. Do you have the Sintran Commands manual, or the Sintran Reference manual? It would help with the parameters for those Sintran commands I mentioned.
"Step 5: How? (Then copy the file back to a floppy in ND format." The reverse of the above.. with Sintran you would first prepare a floppy with device-function set-floppy-format, device-function format-floppy, then use Sintran commands 'open' and 'rfile' on each file, with 'device-copy write-record'. Then next file.
Or, again, with a program to do it for you. Those Sintran commands could be turned into a script-command to do it all as well, with the help of 'mode' and 'jec' (job execution control), but (particularly with 'jec') it's been so long since I was in front of an ND computer that I don't dare try to produce a working script without anything to test it out on. Anyway, as I said above I almost always turned around and wrote my own program to do file system interactions that took more than one or two Sintran commands to do.. for a programmer type like me it was always the more satisfying option. So I didn't use 'jec' very much ('jec' could extend 'mode' (script) files to use variables, and check for exit codes and the like).
-Tor