Method and apparatus for testing edge connector inputs and outputs for circuit boards employing boundary scan

A method for testing a plurality of input/output connections of a circuit board, together with at least one device on the board which contains a plurality of first boundary scan registers, comprising the steps of:

• coupling each input/output connection of the circuit board to a separate one of a plurality of second boundary scan registers so that each second boundary scan register is responsive to a signal present at a separate corresponding input/output connection;
• serially coupling the second boundary scan registers with the first boundary scan registers to form a single, common daisy chain;
• entering a known bit stream into the chain of first and second boundary scan registers to that a separate bit in the stream is latched into a separate one of the registers in the chain;
• shifting out the bits latched into the chain of first and second boundary scan registers;
• and
• comparing the bits shifted out of the chain of first and second boundary scan registers to a reference bit stream corresponding to the bits shifted out of the chain of first and second boundary scan registers under defect-free conditions.