Right, but the problem is that I had dumps which were what the PDP-11 CPU saw, but due to hardware oddities on the M9301 board, the _ROM contents_ were diferent: bits 1-8 (_not_ 0-7, which would have been simpler :-) have to be inverted. I'm not sure any existing tool could manage that! Speaking of hardware oddities in the M9301, it seems the Tech Manual (EK-M9301-TM-001) has an error: it seems to indicate that the first (low) words in the PROM should contain the first words at 173000 ("address locations 773000 .. are located in the lower 256 words of the PROM", pg. 2-7). However, looking at the prints, the signal "765XXX L" is fed into the high address bit of the PROMs, and looking at how it is generated (Fig. 2-8, pg. 2-8) it should be low when the low addresses (765xxx) are being read, so the low addresses in the PROM should correspond to 765xxx? Also, looking at Mattis' read-out of the actual PROMs, they have the code that's at 773000 at 0x100 in the PROM. So it does seem as if the PROMs aren't organized the way the Tech Manual claims... Noel