I'm trying to read the flash ROM using a SOIC8 clip, on board. I am horrible at surface mount soldering. Is there a way to use the clip on the board, without removing the chip, and not have the SOIC8 & reader (e.g. Bus Pirate) backfeed power into the board / processor? I've read about people shorting the processor's clock, or adding a capacitor, so that even though the the board is getting power from my Bus Pirate, the processor won't try to run instructions. What's the best way?
If you want to avoid strange problems from the microcontroller, hold its RESET pin on (usually low) and it should halt it from doing anything. For AVRs (Arduino's usual microcontroller) it resets internal registers to defaults, which means that everything is an input.
Other microcontrollers or components may do strange things, however. Without looking at a circuit diagram there's not much telling.