Hi Joe The 7109 was made by many manufactures and is a common A/D. It is a dual slope type. Quite accurate when comparing to a reference. It has one funny feature that isn't usually mentioned in the data sheets. If you get an over range, it will transfer some additional energy to the Auto-Zero capacitor. This can take many convertion cycles to recover from. When used with an input mux, make sure that you either have a wait after overrange or some way to clamp it below full scale. Even a single lsb of overscale has significant effect because of the amplification used to do the auto-zero. A single lsb of overscale can be over 100 lsb's on the next read, depending on the A-Z capacitor size. Not good when you are looking to get the most out of the 12 bits. As for the board, maybe just some tracing out will determine the addressing so that you can play with it. I have a 80C188 processor board for the STD with a Forth in Flash on it. I find Forth to be real handy for poking ( and peeking ) at unknown boards such as these. Dwight