I fired up an Altair and found it didn't behave as it should (tested with MITs and Polymorphic CPU cards.) Doing an "Examine" does not load the switch settings into the program counter. Doing an "Examine Next" seems to increment the program counter by 3. The preceeding was done with and without a memory card. I tried the "Deposit" but had no way to see what I was doing since the switch settings apparently weren't being loaded. Finally, the "Deposit Next" increments the LEDs. One other strangeness, when I connect the Data Display cable to the MITS card, the "Stop" switch ceases to function although the "Start" seems to work fine. I do have the schematics and will start to dig into it later this morning. BUT, I was hoping to short circuit some of the troubleshooting time if someone on the list has experienced something like this :). Thanks!