I'm pretty reluctant to post this, since I'm pretty sure I'm just missing something entirely blatant here.
I've just gotten back into the CoCo end of things after having been out since probably 1994. I managed to get (after some serious struggle; documentation I did find was pretty sketchy) OS-9 Level 2 to work with a VHD, but then decided it was time to try moving up to a 6309 with NitrOS-9.
Now, from what I recall, RS-DOS doesn't exactly support 40 or 80 tracks by default. Back in the day, I used ADOS3 to read the disks, but that hasn't worked here. Trying to boot the NOS-9 disks just brings me back to OK immmediately. Next step was to try replacing my disk rom with the emulator revision of RGBDOS.
That didn't go entirely well until I caught wind of the fact I needed to cut two bytes off the top of the new disk11.rom to use it. RGBDOS is seeing the hard disk just fine, and I've even formatted it. Now I get to the problem point-- I use driveoff to go back to the floppy and type DOS to boot... absolutely nothing. I'm immediately back to an OK prompt.
I've tried to boot 40 and 80 track NOS-9 disk images for both 6809 and 6309 on their respective machine types on MESS with the same results for each.
I'm pretty sure I'm just missing something very simple and embarassing, but I can't figure out what. Anyone have any hints or suggestions?