First, Thanks for all the helpful suggestions! I plan to swap the RAM around this weekend, and do as Tony suggested, which is to use my VOM just to see if the clocks and/or address data lines are stuck high or low. I also have the assembler and basic ROMs installed (they were both options when my AIM was new) and I guess maybe it might be a good idea to remove them as well, just to have only the absolute minimum on the board. Also, I have been corresponding with another person off-list, so maybe I can get this thing repaired after-all!! :) Couple of things about general AIM-lore: Most AIM 65's were sold as boards, the case came later, but I never got around to getting one. The original AIM 65 (not the AIM 65/40) had a 20 char alpha LED display. The Aim 65/40 had a 40 character vacuum fluorescent display and 40 character printer, much more friendly for development than the 20 char display and printer. The stock AIM 65 did not come with the Assembler or Basic (those were options) Later Rockwell also offered a set of FORTH ROMs ( I have them, never did program much FORTH though) The stock AIM 65 was offered with either 1K or 4K RAM, I bought a 1K and a guy I knew at Rockwell gave me the other 3K. Way back then, I used to be a consultant, did most of my work with Rockwell PPS 4 and PPS 8 and 6502 I even used to teach seminars for Rockwell to their customers on PPS 4 and 8 (mostly PPS 4). The AIM 65 was a fair development platform, we used to use a Rockwell System 65 for much of our code development and test, but we also used the AIM 65 for development and test, and I could also my AIM 65 at home when I didn't go to the office. Way more than anyone wanted to hear, I hope it is not too long a message. Later, AndyD