Just a note of thanks for help and encouragement. I finally got my AIM back running again with the help of a local who had some test equipment. First, before getting the help I found several stuck address lines and cleared them by blowing an brushing and vacuuming. We then found that 5 out of 8 2114 RAMs were bad, and the CPU just didn't have enough oomph. After cleaning the board and replacing parts, it works like a charm. Seems weird that the CPU and RAM went bad just sitting, and the board got something stuck in the address lines just sitting in the box for 20 years, It was the original shipping box for the AIM, but I guess more crud got in the box than I realized. Lessons learned anyway. Now the first thing I need to do is to get the 20 mil current loop to RS-252 working so I can use my Mac as a terminal and program development and storage. AndyD