Now that I have a working 11/40 I can start messing with disks.
The first disk I booted was RT-11 v 5.3. It will boot with 16K, but you can't do much with it. I put in the MOS RAM card with 64K so I could attempt newer OS's, maybe even UNIX.
Next I booted XXDP+, which loaded and ran diagnostics. Then I found a 2nd copy on another RL02 disk.
I attempted other RL02 disks on hand, but they were mostly data disks for a 11/44 or VMS.
One disk was labled RSX-11M, it crashed. (or disk bad)
Good. Now I have some scratch disks to use to build alternative operating systems. I have collected a few RL02 disk images.
There's a UNIX 7 on RL02 but I think one needs at least 192K to run it. I will start with a small RT-11 5.0 disk, see how long it takes. I got a copy of UNIX 6 in RL02 format to try after that.
It took about an hour or a little more to build an RT-11 5 distribution disk using PDPGUI and a serial cable. Tested, boots!
Next, UNIX 6.