Jerome Fine replies: There is one gotcha that should be considered - while there are arrangements to run V5.03 and prior under the SIMH emulator for hobby users (I presume that using a real DEC PDP-11/20 is ONLY for hobby use), that is still not legal without a very expensive license for a Unibus product - I think that the PDP-11/20 is a Unibus. As for actually being able to run, if you can get a copy on a bootable RX01 floppy, RT-11 should actually run - very slowly. An EAE is not required. BUT, I have never had the opportunity to try is myself, so I am not actually positive it can be done. Also, it might not be possible to run V5.06 in which there is no longer an RT11SJ flavour. But up to V5.05 should probably be OK as long as V4.00 will still work. I might have an image of a DOS/BATCH RK05 media, but it might be hiding????????????????????????????? Sincerely yours, Jerome Fine -- If you attempted to send a reply and the original e-mail address has been discontinued due a high volume of junk e-mail, then the semi-permanent e-mail address can be obtained by replacing the four characters preceding the 'at' with the four digits of the current year.